Table of Contents

A

B

C

D

E

F

G

H

I

J

K

L

M

N

O

P

Q

R

S

T

U

V

W

X

Y

Z

Publication Information

ACI Membership Benefits

The American Concrete Institute

A

A/F ratio

the molar or mass ratio of aluminum oxide (Al_2O_3) to iron oxide (Fe_2O_3), as in portland cement.

Abrams’ law

a rule stating that, with given concrete materials and conditions of test, the ratio of the amount of water to the amount of the cement in the mixture determines the strength of the concrete, provided the mixture is of a workable consistency. (See also water-cement ratio.)

abrasion damage

wearing away of a surface by rubbing and friction. (See also cavitation damage and erosion.)

abrasion resistance

ability of a surface to resist being worn away by rubbing and friction.

absolute volume

(1) in the case of solids, the displacement volume of particles themselves, including their permeable and impermeable voids, but excluding space between particles; (2) in the case of fluids, their volume.

absorbed moisture

moisture that has entered the permeable pores of a solid and has physical properties not substantially different from ordinary water at the same temperature and pressure. (See also absorption.)

absorbed water

see absorbed moisture

absorption

(1) the process by which a liquid is drawn into and tends to fill permeable voids in a porous solid body; (2) the increase in mass of a porous solid body resulting from the penetration of a liquid into its permeable voids.

abutment

(1) in bridges, the end foundation that is typically constructed with concrete that supports the superstructure of the bridge; (2) in dams, the side of the gorge or bank of the stream against which a dam abuts.

accelerating admixture

an admixture that causes an increase in the rate of hydration of the hydraulic cement and thus shortens the time of setting, increases the rate of strength development, or both.

acceleration

increase in rate of natural progress of setting or hardening of concrete. (See also accelerating admixture.)

accelerator

see accelerating admixture

accidental air

see entrapped air (preferred term)

acid etching

the removal of a cementitious surface through controlled dissolution to expose sand or aggregates, roughen a smooth cementitious surface in preparation for cementitious coating material application, or create art, create design, or create an architectural finish.

acrylic resin

one of a group of thermoplastic resins formed by polymerizing the esters or amides of acrylic acid used to make polymer-modified concrete and polymer concretes.

active crack

a crack whose width changes with time.

addition

a material that is interground or blended in limited amounts into a hydraulic cement during manufacture either as a processing addition to aid in manufacturing and handling the cement or as a functional addition to modify the use properties of the finished product.

additive

a substance added to another in relatively small amounts to impart or improve desirable properties or suppress undesirable properties.

adhesion

the state in which two surfaces are held together by interfacial effects that may consist of molecular forces, interlocking action, or both.

adhesives

the group of materials used to join or bond similar or dissimilar materials, for example, in concrete work, the epoxy resins.

adiabatic

a condition in which heat neither enters or leaves a system.

admixture

a material other than water, aggregates, cementitious materials, and fiber reinforcement, used as an ingredient of a cementitious mixture to modify its freshly mixed, setting, or hardened properties and that is added to the batch before or during its mixing.

adsorbed water

water held on surfaces of a material by electrochemical forces and having physical properties substantially different from those of absorbed water or chemically combined water at the same temperature and pressure. (See also adsorption.)

adsorption

(1) development of a higher concentration of a substance at the surface of either a liquid or solid, such as cement, cement paste, or aggregates, than exists in the bulk of the medium; (2) the process by which a substance is adsorbed. (See also adsorbed water.)

advancing-slope grouting

a method of grouting by which the front of a mass of grout is caused to move horizontally through preplaced aggregate by use of a suitable grout injection sequence.

advancing-slope method

a method of placing concrete, as in tunnel linings, in which the face of the fresh concrete is not vertical and moves forward as concrete is placed.

aerated concrete

see cellular concrete and foamed concrete

afwillite

a mineral with composition 3CaO·2SiO_2·3H_2O occurring naturally in South Africa, Northern Ireland, and California, and artificially in some hydrated portland cement mixtures.

agent

a general term for a material that may be used either as an addition to cement or an admixture in concrete, for example, an air-entraining agent.

agglomeration

a gathering into a ball or mass.

aggregate

granular material, such as sand, gravel, crushed stone, crushed hydraulic-cement concrete, or iron blast-furnace slag, used with a cementing medium to produce either concrete or mortar. (See also heavyweight aggregate and lightweight aggregate.)

aggregate blending

the process of intermixing two or more aggregates to produce a combination with improved grading or other properties

aggregate gradation

see grading (preferred term).

aggregate interlock

the effect of portions of aggregate particles from one side of a joint or crack in concrete protruding into recesses in the other side of the joint or crack so as to transfer load in shear and maintain alignment.

aggregate transparency

discoloration of a concrete surface consisting of darkened areas over coarse aggregate particles immediately below the concrete surface.

aggregate-cement ratio

the ratio of total aggregate to cement, either by mass or volume.

agitating speed

the rate of rotation of the drum of a truck mixer or agitator when used for agitating mixed concrete.

agitating truck

a vehicle in which freshly mixed concrete can be conveyed from the site of mixing to the site of placement; while being agitated, the truck body can either be stationary and contain an agitator or it can be a drum rotated continuously so as to agitate the contents (also called agitating lorry in the United Kingdom).

agitation

(1) the process of providing motion in mixed concrete just sufficient to prevent segregation or loss of workability; (2) the mixing and homogenization of slurries or finely ground powders by either mechanical means or injection of air. (See also agitator.)

agitator

a device for maintaining workability and preventing segregation of mixed concrete by agitation. (See also agitation.)

air content

the volume of air voids in cement paste, mortar, or concrete, exclusive of pore space in aggregate particles, usually expressed as a percentage of total volume of the paste, mortar, or concrete.

air entraining

the capability of a material or process to develop a system of microscopic bubbles of air in cement paste, mortar, or concrete during mixing. (See also air entrainment.)

air entrainment

the incorporation of air in the form of microscopic bubbles (typically smaller than 1 mm [0.04 in.]) during the mixing of either concrete or mortar. (See also air entraining and entrained air.)

air lift

equipment whereby slurry or dry powder is lifted through pipes by means of compressed air.

air meter

a device for measuring the air content of concrete and mortar.

air ring

perforated manifold in nozzle of wet-mix shotcrete equipment through which high-pressure air is introduced into the material flow.

air separator

an apparatus that separates various size fractions of ground materials pneumatically; fine particles are discharged as product, oversized particles are returned to the mill as tailing.

air void

a space in cement paste, mortar, or concrete filled with air. (See also entrained air and entrapped air.)

air-blown mortar

see shotcrete (preferred term).

air-cooled blast-furnace slag

see blast-furnace slag.

air-entraining admixture

an admixture that causes the development of a system of microscopic air bubbles in concrete, mortar, or cement paste during mixing, usually to increase its workability and resistance to freezing and thawing. (See also entrained air.)

air-entraining agent

see air-entraining admixture

air-entraining hydraulic cement

hydraulic cement containing sufficient amounts of air-entraining agent to produce a cementitious mixture containing entrained air within specified limits.

air-permeability test

a procedure for measuring the fineness of powdered materials such as portland cement. (See also Blaine test.)

air-water jet

a high-velocity jet of air and water mixed at the nozzle, used in clean-up of surfaces of rock or concrete, such as horizontal construction joints.

alignment wire

see ground wire (preferred term)

alite

a form of tricalcium silicate that is the principal phase in portland-cement clinker. (See also belite and celite.)

alkali

salts of alkali metals, principally sodium and potassium; specifically sodium and potassium occurring in constituents of concrete and mortar, usually expressed in chemical analyses as the oxides Na_2O and K_2O. (See also low-alkali cement.)

alkali reactivity (of aggregate)

susceptibility of aggregate to alkali-aggregate reaction.

alkali-aggregate reaction

chemical reaction in either mortar or concrete between alkalies (sodium and potassium) from portland cement or other sources and certain constituents of some aggregates.

alkali-carbonate rock reaction

the reaction between the alkalies (sodium and potassium) in portland cement and certain carbonate rocks, particularly calcitic dolomite and dolomitic limestones, present in some aggregates.

alkali-silica reaction

the reaction between the alkalies (sodium and potassium) in portland cement and certain siliceous rocks or minerals, such as opaline chert, strained quartz, and acidic volcanic glass, present in some aggregates.

alkyl aryl sulfonate

synthetic detergent used to entrain air in hydraulic-cement mixtures.

allowable bearing capacity

the maximum pressure to which a soil or other material should be subjected to guard against shear failure or excessive settlement.

allowable load

see service dead load and service live load.

allowable stress

maximum permissible stress used in design of members of a structure and based on a factor of safety against rupture or yielding of any type.

alumina

aluminum oxide (Al_2O_3).

aluminate cement

see calcium-aluminate cement

aluminate concrete

concrete made with calcium-aluminate cement.

aluminous cement

see calcium-aluminate cement (preferred term)

amount of mixing

the extent of mixer action employed in combining the ingredients for either concrete or mortar; in the case of stationary mixers, the mixing time; in the case of truck mixers, the number of revolutions of the drum at mixing speed after the intermingling of the cementitious materials with water and aggregates. (See also mixing time.)

amplitude

the maximum displacement from the mean position in connection with vibration.

anchor

(1) in prestressed concrete, to lock the stressed tendon in position so that it will retain its stressed condition; (2) in precast-concrete construction, to attach the precast units to the building frame; (3) in slabs-on-grade or walls, to fasten to rock or adjacent structures to prevent movement of the slab or wall with respect to the foundation, adjacent structure, or rock.

anchor bolt

a metal bolt or stud, headed or threaded, cast in place, grouted in place, or drilled and fastened into existing concrete either by expansion or by chemical adhesives.

anchorage

(1) in post-tensioning, a device used to anchor the tendon to the concrete member; (2) in pretensioning, a device used to maintain the elongation of a tendon during the time interval between stressing and release; (3) in precast-concrete construction, the devices for attaching precast units to the building frame; (4) in slab or wall construction, the device used to anchor the slab or wall to the foundation, rock, or adjacent structure.

anchorage bond stress

the bar forces divided by the product of the bar perimeter or perimeters and the embedment length.

anchorage deformation

the loss of elongation or stress in the tendons of prestressed concrete due to the deformation or seating of the anchorage when the prestressing force is transferred from the jack to the anchorage (also called anchorage loss). (See also slip.)

anchorage device

see anchorage (preferred term)

anchorage loss

see anchorage deformation

anchorage slip

see anchorage deformation or slip.

anchorage zone

(1) in post-tensioning, the region adjacent to the anchorage subjected to secondary stresses resulting from the distribution of the prestressing force; (2) in pretensioning, the region in which the transfer bond stresses are developed.

angle of repose

the angle between the horizontal and the natural slope of loose material below which the material will not slide.

angular aggregate

aggregate particles that possess well-defined edges formed at the intersection of roughly planar faces.

anhydrite

(1) a mineral, anhydrous calcium sulfate (CaSO_4); (2) gypsum from which the water of crystallization has been removed, usually by heating above 325°F (160°C).

anhydrous calcium chloride (CaCl_2)

a solid, usually 94 percent calcium chloride, typically in pellet form.

anti-washout admixture

a concrete admixture that reduces the loss of fine material from concrete when placed in water.

apparent specific gravity

the ratio of the mass of a volume of the impermeable portion of a material at a stated temperature to the mass of an equal volume of distilled water at a stated temperature.

arc spectrography

spectrographic identification of elements in a sample of material heated to volatilization in an electric arc or spark.

architect-engineer

architect, engineer, architectural firm, engineering firm, or architectural and engineering firm issuing contract documents, administering the work under contract documents, or both (also called engineer-architect).

architectural concrete

concrete that will be permanently exposed to view and therefore requires special care in selection of the concrete materials, forming, placing, and finishing to obtain the desired architectural appearance.

area of steel

the cross-sectional area of the steel reinforcement.

arenaceous

composed primarily of sand; sandy.

argillaceous

composed primarily of clay or shale; clayey.

arris

the sharp external corner edge that is formed at the junction of two planes or surfaces.

arrissing tool

a tool similar to a float, but having a form suitable for rounding an edge of freshly placed concrete.

artificial pozzolan

materials such as fly ash and silica fume. (See also fly ash and silica fume).

asbestos-cement products

products manufactured from rigid material composed essentially of asbestos fiber and portland cement.

ashlar masonry

masonry composed of bonded blocks of concrete, either rectangular or square, always of two or more sizes.

asphalt

a dark brown to black cementitious material in which the predominating constituents are bitumens that occur in nature or are obtained in petroleum processing.

asphalt cement

asphalt that is refined to meet specifications for use in the manufacture of bituminous pavements.

asphaltic concrete

a mixture of asphalt cement and aggregate.

atmospheric-pressure steam curing

steam curing of concrete products or cement at atmospheric pressure, usually at maximum ambient temperature between 100 to 200°F (40 to 95°C).

autoclave

a high-pressure steam vessel.

autoclave curing

curing of concrete products in an autoclave at maximum ambient temperature generally between 340 and 420°F (170 and 215°C).

autoclave cycle

(1) the time interval between the start of the temperature-rise period and the end of the blowdown period; (2) a schedule of the time and temperature-pressure conditions of periods that make up the cycle.

autoclaved

see autoclave curing.

autoclaving

see autoclave curing.

autogenous healing

a natural process of filling and sealing dormant cracks in concrete or in mortar when kept damp.

autogenous length change

length change caused by autogenous volume change. (See also autogenous volume change.)

autogenous shrinkage

see autogenous volume change.

autogenous volume change

change in volume due to the chemical process of hydration of cement, exclusive of effects of applied load and change in either thermal condition or moisture content.

automatic batcher

see batcher.

auxiliary reinforcement

reinforcement in addition to that required by analysis for strength.

average bond stress

the force in a bar divided by the product of the perimeter and the development length of the bar.

axle load

the portion of the gross weight of a vehicle transmitted to a structure or a roadway through wheels supporting a given axle.

axle steel

steel from carbon-steel axles for railroad cars.

axle-steel reinforcement

either plain or deformed reinforcing bars rolled from axle steel.

B

b/bo

see coarse-aggregate factor (preferred term).

back form

see top form (preferred term).

back plastering

plaster applied to one face of a lath system following application and subsequent hardening of plaster applied to the opposite face. (See also parge.)

back stay

see brace (preferred term).

backfill concrete

nonstructural concrete used to over-fill excavated pockets in rock or prepare a surface to receive structural concrete. (See also controlled low-strength material  [preferred term].)

backshores

shores placed snugly under a concrete slab or structural member after the original formwork and shores have been removed from a small area without allowing the entire slab or member to deflect or support its own mass or existing construction loads.

bacterial corrosion

destruction of a material by bacterial processes brought about by the activity of certain bacteria that consume the material and produce substances, such as hydrogen sulfide, ammonia, and sulfuric acid.

bag of cement

a quantity of portland cement: 94 lb (43 kg) in the United States; for other kinds of cement, a quantity indicated on the bag. (Also called sack of cement.)

balanced load

load capacity at simultaneous crushing of concrete and yielding of tension steel. (See also load balancing.)

balanced moment

moment capacity at simultaneous crushing of concrete and yielding of tension steel.

balanced reinforcement

(1) an amount and distribution of reinforcement in a flexural member such that in working-stress design, the allowable tensile stress in the steel and the allowable compressive stress in the concrete are attained simultaneously; (2) an amount and distribution of reinforcement in a flexural member such that in strength design, the tensile reinforcement reaches its specified yield strength simultaneously with the concrete in compression reaching its assumed ultimate strain of 0.003.

ball mill

horizontal, cylindrical, rotating mill charged with large grinding media.

ball test

a test to determine the consistency of freshly mixed concrete by measuring the depth of penetration of a cylindrical metal weight with a hemispherical bottom. (See also Kelly ball.)

bar

a long, slender structural element, normally composed of steel, used to reinforce concrete.

bar bender

(1) a tradesman who cuts and bends steel reinforcement; (2) a machine for bending steel reinforcement.

bar mat

see mat (1).

bar schedule

a list of the reinforcement showing the shape, number, size, and dimensions of every different element required for a structure or a portion of a structure.

bar spacing

the distance between parallel reinforcing bars, measured center to center of the bars perpendicular to their longitudinal axes.

bar support

hardware used to support or hold reinforcing bars in proper position to prevent displacement before and during concrete placement. (See also slab bolster.)

bar-end check

a check of the ends of reinforcing bars to determine whether they fit the devices intended for connecting the bars. (See also mechanical connection.)

barite

a mineral, barium sulfate (BaSO_4), used in either pure or impure form as concrete aggregate primarily for the construction of high-density radiation shielding concrete (also called barytes in the United Kingdom).

barrel (of cement)

(obsolete) a quantity of portland cement: four bags or 376 lb in the United States.

base

(1) a subfloor slab or working mat, either previously placed and hardened or freshly placed, on which floor topping is placed in a later operation; (2) the underlying stratum on which a concrete slab, such as a pavement, is placed. (See also mud mat and subbase.)

base bead

see base screed (preferred term).

base coat

any plaster coat or coats applied before application of the finish coat.

base course

(1) a layer of specified select material of planned thickness constructed on the subgrade or subbase of a pavement to serve one or more functions, such as distributing loads, providing drainage, or minimizing frost action; (2) the lowest course of masonry in a wall or pier.

base plate

a metallic plate, typically steel, used to distribute forces and moments.

base screed

a preformed metal screed with perforated or expanded flanges to provide a guide for thickness and planeness of plaster and to provide a separation between plaster and other materials.

basic creep

creep that occurs without migration of moisture to or from the concrete. (See also creep and drying creep.)

bassanite

calcium sulfate hemihydrate, 2CaSO_4·H_2O. (See also hemihydrate and plaster of paris.)

batch

(1) quantity of material mixed at one time or in one continuous process; (2) to weigh or volumetrically measure and introduce into the mixer the ingredients for a quantity of material.

batch mixer

a machine that mixes batches of either concrete or mortar.

batch plant

an installation for batching or for batching and mixing concrete materials.

batch weights

the quantities of the various ingredients (cement, water, the several sizes of aggregate, and admixtures, if used) that compose a batch of concrete.

batched water

see mixing water.

batcher

a device for measuring ingredients for a batch of concrete.
(1) manual batcher — a batcher equipped with gates or valves that are operated manually, with or without supplementary power (pneumatic, hydraulic, or electrical), the accuracy of the weighing operation being dependent on the operator’s observation of the scale.
(2) semiautomatic batcher — a batcher equipped with gates or valves that are separately opened manually to allow the material to be weighed but that are closed automatically when the designated quantity of each material has been reached.
(3) automatic batcher — a batcher equipped with gates or valves that, when actuated by a single starter switch, will open automatically at the start of the weighing operation of each material and close automatically when the designated quantity of each material has been reached, interlocked in such a manner that: (a) the charging mechanism cannot be opened until the scale has returned to zero; (b) the charging mechanism cannot be opened if the discharge mechanism is open; (c) the discharge mechanism cannot be opened if the charging mechanism is open; (d) the discharge mechanism cannot be opened until the designated quantity has been reached within the allowable tolerance; and (e) if different kinds of aggregates or different kinds of cements are measured cumulatively in a single batcher, interlocked sequential controls are provided.

batten

a narrow strip of wood placed over the vertical joint of sheathing or paneling; also used to hold several boards together (also called batten strip). (See also cleat.)

batter pile

a pile installed at an angle to the vertical.

bauxite

a rock composed principally of hydrous aluminum oxides that is the principal ore of aluminum and a raw material for manufacture of calcium-aluminate cement.

bay

(1) the space, in plan, between the centerlines of adjacent piers, mullions, or columns; (2) a small, well-defined area of concrete placed at one time in the course of placing large areas, such as floors, pavements, or runways.

beam

a structural member subjected primarily to flexure but may also be subjected to axial load. (See also spandrel beam, girder, joist, ledger, and stringer.)

beam bottom

soffit or bottom form for a beam.

beam pocket

(1) opening left in a vertical member in which a beam is to rest; (2) an opening in the column or girder form where forms for an intersecting beam will be framed.

beam test

a method of measuring the flexural strength (modulus of rupture) of concrete by testing a standard unreinforced beam.

beam-column

a structural member subjected to axial load and bending moment.

bearing capacity

see allowable bearing capacity.

bearing stratum

the soil or rock stratum on which a concrete footing or mat bears or that carries the load transferred to it by a concrete pile, caisson, or similar deep foundation unit.

belite

a form of dicalcium silicate that occurs as a phase in portland-cement clinker. (See also alite and celite.)

belled pier

a drilled pier shaft with an enlarged base.

bending moment

the bending effect at any section of a structural element equal to the algebraic sum of the moments of the vertical and horizontal forces, with respect to the centroidal axis of a member, acting on a freebody of the member.

bending-moment diagram

a graphical representation of the variation of bending moment along the length of the member for a given stationary system of loads.

beneficiation

improvement of the chemical or physical properties of a raw material or intermediate product by the removal or modification of undesirable components or impurities.

bent bar

a reinforcing bar bent to a prescribed shape. (See also hook, hooked bar, stirrup, and tie.)

bentonite

a clay composed principally of minerals of the montmorillonoid group, characterized by high adsorption and large volume change with wetting or drying.

billet steel

steel, either produced directly from ingots or continuously cast, made from properly identified heats of open-hearth, basic oxygen, or electric-furnace steel, or lots of acid Bessemer steel and conforming to specified limits on chemical composition.

binary mixture

concrete containing two cementitious materials.

binder

(1) material forming the matrix of concretes, mortars, and sanded grouts; (2) chemical treatment applied to fibers to give integrity to mats, roving, and reinforcement.

biological shielding

shielding provided to attenuate or absorb nuclear radiation, such as neutron, proton, alpha, and beta particles, and gamma radiation; the shielding is provided mainly by the density of the concrete, except that in the case of neutrons, the attenuation is achieved by compounds of some of the lighter elements (for example, hydrogen and boron). (See also shielding concrete.)

bituminous cement

a black solid, semisolid, or liquid substance at natural air temperatures and appreciably soluble only in carbon disulfide or some volatile liquid hydrocarbon, being composed of mixed indeterminate hydrocarbons mined from natural deposits, produced as a residue in the distillation of petroleum, or obtained by the destructive distillation of coal or wood.

Blaine apparatus

air-permeability apparatus for measuring the surface area of a finely ground cement, raw material, or other product. See ASTM C204.

Blaine fineness

the fineness of powdered materials such as cement and pozzolans, expressed as surface area per unit mass usually in square meters per kilogram, determined by the Blaine apparatus. (See also specific surface.)

Blaine test

a method for determining the fineness of cement or other fine material on the basis of the permeability to air of a sample prepared under specified conditions.

blast-furnace slag

the nonmetallic product consisting essentially of silicates and aluminosilicates of calcium and other bases that develops in a molten condition simultaneously with iron in a blast furnace.
(1) air-cooled blast-furnace slag — the material resulting from solidification of molten blast-furnace slag under atmospheric conditions; subsequent cooling may be accelerated by application of water to the solidified surface.
(2) expanded blast-furnace slag — the low density cellular material obtained by controlled processing of molten blast-furnace slag with water, or water and other agents, such as steam, compressed air, or both.
(3) granulated blast-furnace slag — the glassy, granular material formed when molten blast-furnace slag is rapidly chilled, as by immersion in water.
(4) ground-granulated blast-furnace slag — (obsolete) see slag cement (preferred term).

bleed

to undergo bleeding. (See also bleeding.)

bleeding

the autogenous flow of mixing water within, or its emergence from, a newly placed cementitious mixture caused by the settlement of solid materials within the mass.

bleeding capacity

the ratio of volume of water released by bleeding to the volume of paste or mortar.

bleeding rate

the rate at which water is released from a paste or mortar by bleeding.

blemish

any superficial defect that causes visible variation from a consistently smooth and uniformly colored surface of hardened concrete. (See also bug holes, efflorescence, honeycomb, lift joint, laitance, popout, rock pocket, and sand streak.)

blended cement

a hydraulic cement consisting of portland cement uniformly mixed with slag cement or pozzolan, or both.

blinding

the filling or plugging of the openings in a screen or sieve by the material being separated.

blistering

(1) the irregular raising of a thin layer at the surface of a placed cementitious mixture during or soon after completion of the finishing operation, or, in the case of pipe, after spinning; (2) bulging of a finish coat as it separates and draws away from a base coat.

block beam

a flexural member composed of individual blocks that are joined together by prestressing.

blockout

a space within a concrete structure under construction in which fresh concrete is not to be placed, called core in United Kingdom.

blowholes

see surface air voids (preferred term).

blowpipe

air jet used in shotcrete gunning to remove rebound or other loose material from the work area.

blowup

the raising of two concrete slabs off the subgrade where they meet as a result of greater expansion than the joint between them will accommodate; typically occurs only in unusually hot weather where joints have become filled with incompressible material; often results in cracks on both sides of the joint and parallel to it.

board butt joint

construction joint in shotcrete formed by sloping the sprayed surface to a 1 in. (25 mm) board laid flat.

bolt sleeve

a tube surrounding a bolt in a concrete wall to prevent concrete from adhering to the bolt and acting as a spreader for the formwork.

bond

(1) adhesion of concrete or mortar to reinforcement or other surfaces against which it is placed, including friction and mechanical interlock; (2) adhesion of cement paste to aggregate; (3) adhesion, cohesion, or both between materials; (4) patterns formed by the exposed faces of masonry units, for example, running bond or Flemish bond.

bond area

the nominal area of interface between two elements across which adhesion, cohesion, or both, develop(s) or may develop, as between cement paste and aggregate.

bond breaker

a material used to prevent adhesion of newly placed concrete to the substrate. (See also form oil and release agent.)

bond length

see development length (preferred term).

bond plaster

a specially formulated gypsum plaster designed as first-coat application over monolithic concrete.

bond prevention

measures taken to prevent adhesion of concrete or mortar to surfaces against which it is placed.

bond strength

(1) resistance to separation of mortar and concrete from reinforcing and other materials with which it is in contact; (2) a collective expression for forces such as adhesion, friction due to shrinkage, and longitudinal shear in the concrete engaged by the bar deformations that resist separation.

bond stress

(1) the force of adhesion per unit area of contact between two bonded surfaces, such as concrete and reinforcing steel, or any other material, such as foundation rock; (2) shear stress at the surface of a reinforcing bar, preventing relative movement between the bar and the surrounding concrete when the bar carries tensile force.

bonded hollow-wall masonry

a cavity wall, built of masonry units, in which the inner and outer walls are tied together by bonders.

bonded member

a prestressed concrete member in which the tendons are bonded to the concrete either directly or through grouting.

bonded post-tensioning

post-tensioned construction in which the annular spaces around the tendons are grouted after stressing, thereby bonding the tendon to the concrete section.

bonded tendon

a prestressing tendon that is bonded to the concrete either directly or through grouting.

bonder

a masonry unit that ties two or more wythes (leaves) of a wall together by overlapping. (See also header and wythe [leaf].)

bonding agent

a substance applied to a suitable substrate to create a bond between it and a succeeding layer.

bonding layer

a layer of mortar, usually 1/8 to 1/2 in. (3 to 13 mm) thick, which is spread on a moist and prepared hardened concrete surface before placing fresh concrete.

bored pile

see drilled pier.

boring

(1) the removal of a sample by drilling of rock; (2) a generic name for cylindrical sample of soil or rock.

boron frits

clear, colorless, synthetic glass produced by fusion and quenching, containing boron. (See also boron-loaded concrete.)

boron-loaded concrete

high density concrete including a boron-containing admixture or aggregate, such as the mineral colemanite, boron frits, or boron metal alloys, to act as a neutron attenuator. (See also biological shielding and shielding concrete.)

box out

a formed opening in concrete (also called a boxout).

brace

a structural member used to provide lateral support for another member, generally for the purpose of ensuring stability or resisting lateral loads.

bracing

see brace (preferred term).

bracket

(1) an overhanging member projecting from a wall or other body to support weight acting outside the wall; (2) formed shapes of channel or pencil rod used as structural reinforcement in erecting furred assemblies. (See also corbel.)

bredigite

a mineral, alpha prime dicalcium silicate (2CaO·SiO_2), occurring in slags and portland cement.

breeze

(1) usually clinker; (2) fine divided material from coke production.

brick seat

ledge on wall or footing to support a course of masonry.

bridge deck

the structural concrete slab or other structure that is supported on the bridge superstructure and serves as the roadway or other traveled surface.

briquette

a molded specimen of mortar with enlarged extremities and reduced center having a cross section of definite area, used for measurement of tensile strength (also called a briquet).

broadcast

to toss granular material, such as sand, over a horizontal surface so that a thin, uniform layer is obtained.

broom finish

the surface texture obtained by stroking a broom over freshly placed concrete.

brown coat

the leveling coat of plaster, either the second coat of plaster in a three-coat application or the entire base coat of plaster in a two-coat application.

brown out

to complete application of base coat plaster.

brownmillerite

a ternary compound originally regarded as 4CaO·Al_2O·Fe_2O_3 (C_4AF) occurring in portland and calcium-aluminate cement, now used to refer to a series of solid solutions between 2CaO·Fe_2O_3 (C_2F) and 2CaO·Al_2O_3 (C_2A).

brucite

a mineral having the composition magnesium hydroxide, Mg(OH)2, and a specific crystal structure.

buckling

lateral or torsional instability of a structural member.

bug holes

see surface air voids (preferred term).

buggy

a two-wheeled hand- or motor-driven cart (usually rubber-tired) for transporting small quantities of concrete from hoppers or mixers to forms (also called a concrete cart).

building official

(1) the official charged with administration and enforcement of the applicable building code; (2) the duly authorized representative of the official.

build-up

(1) spraying of shotcrete in successive layers to form a thicker mass; (2) the accumulation of residual hardened concrete in a mixer.

bulk cement

cement that is transported and delivered in bulk (usually in specially constructed vehicles) instead of in bags.

bulk density

the mass of a material per unit volume including voids between particles.

bulk specific gravity

(obsolete) see oven-dry specific gravity (preferred term).

bulkhead

(1) a partition in formwork blocking fresh concrete from a section of the form, or a partition closing a section of the form, such as at a construction joint; (2) a partition in a storage tank or bin, as for cement or aggregate.

bulking

increase in the volume occupied by a quantity of sand in a moist condition over the volume of the same quantity dry or completely inundated.

bulking factor

ratio of the volume of moist sand to the volume of the sand when dry.

bull float

a tool comprising a large, flat, rectangular piece of wood, aluminum, or magnesium usually 8 in. (200 mm) wide and 42 to 60 in. (1 to 1.50 m) long, and a handle 4 to 16 ft (1 to 5 m) in length used to smooth unformed surfaces of freshly placed concrete.

bundled bars

a group of not more than four parallel reinforcing bars in contact with each other, usually tied together.

burlap

a coarse fabric of jute, hemp, or less commonly flax for use as a water-retaining covering in curing concrete surfaces (also called Hessian).

burnishing

(1) to hard trowel the surface of concrete or plaster up to time of final setting; (2) to otherwise produce a smooth surface.

bush hammer

(1) a hammer having a serrated face, as rows of pyramidal points used to roughen or dress a surface; (2) to finish a concrete surface by application of a bush hammer.

butt joint

a plain square joint between two members.

butter

(1) to spread mortar on a masonry unit with a trowel; (2) the process by which the interior of a concrete mixer, transportation unit, or other item coming in contact with fresh concrete is provided with a mortar coating so that fresh concrete coming in contact with it will not be depleted of mortar.

buttress

a projecting structure to support either a wall or a building.

butyl stearate

a colorless, oily, and practically odorless material (C_17H_35COOC_4H_9) used as an admixture for concrete to provide dampproofing.

C

cable

see tendon (preferred term).

cage

a rigid assembly of reinforcement ready for placing in position.

caisson

part of a foundation, a watertight chamber used in construction underwater, or a hollow floating box used as a floodgate for a dock or basin.

calcareous

containing calcium carbonate or, less generally, containing the element calcium.

calcine

to alter composition or physical state by heating below the temperature of fusion.

calcite

(1) a mineral having the composition calcium carbonate (CaCO_3) and a specific crystal structure; (2) the principal constituent of limestone, chalk, and marble; (3) a major constituent in the manufacture of portland cement.

calcium

a silver-white metallic element of the alkaline-earth group occurring naturally only in combination with other elements.

calcium chloride

CaCl_2, a crystalline solid, is primarily used in concrete as an accelerating admixture. (See also accelerating admixture.)

calcium chloride solution

an aqueous solution of calcium.

calcium hydroxide

see hydrated lime.

calcium stearate

Ca(C_18H_35O_2)2, commonly marketed in powder form, insoluble in water, used as a water repellent admixture in concrete.

calcium-aluminate cement

the product obtained by pulverizing clinker consisting essentially of hydraulic calcium aluminates resulting from fusing or sintering a suitably proportioned mixture of aluminous and calcareous materials (called high-alumina cement in the United Kingdom).

calcium-silicate brick

a concrete product made principally from sand and lime that is hardened by autoclave curing.

calcium-silicate hydrate

the primary product of silicate reactions that contribute to concrete strength and density. (See also dicalcium silicate and tricalcium silicate.)

caliche

gravel, sand, and desert debris cemented by calcium carbonate or other salts.

California bearing ratio (CBR)

a method to determine the load-bearing capacity of soil.

calorimeter

an instrument for measuring heat exchange during a chemical reaction, such as the quantity of heat liberated by the combustion of a fuel or hydration of a cement.

camber

a deflection that is intentionally built into a structural element or form to improve appearance or to compensate for the deflection of the element under the effects of loads, shrinkage, and creep.

canister-type anchor bolt

anchorage assembly that includes a sleeve, a threaded rod, and means of removing the rod and adjusting rod location, projection, and tension.

cant strip

see chamfer strip (preferred term).

cap

a smooth, plane surface of suitable material bonded to the bearing surfaces of test specimens to distribute the load during strength testing.

cap pile

a concrete element that transfers load from a column or pedestal to the top of one or more supporting piles.

capacity

(1) a measure of the rated volume of a particular concrete mixer or agitator, usually limited by specifications to a maximum percentage of total gross volume; (2) the output of concrete, aggregate, or other product per unit of time (as plant capacity or screen capacity); (3) load-carrying limit of a structure.

capacity-reduction factor

see nominal strength reduction factor (preferred term).

capillarity

the movement of a liquid in the interstices of concrete, soil, or other finely porous material due to surface tension (also called capillary rise, capillary action, or capillary suction).

capillary action

see capillarity.

capillary pores

microscopic channels within hydrated paste that will draw liquid water due to surface tension.

capillary rise

see capillarity.

capillary suction

see capillarity.

carbon black

a finely divided form of carbon produced by the combustion or partial decomposition of hydrocarbon, used as an admixture to color concrete.

carbonation

(1) reaction between carbon dioxide and a hydroxide or oxide to form a carbonate, especially in cement paste, mortar, or concrete; (2) the reaction with calcium compounds to produce calcium carbonate.

carbonation shrinkage

shrinkage resulting from carbonation.

cast stone

concrete or mortar cast into blocks or small slabs in special molds so as to resemble natural building stone.

castable refractory

a packaged dry mixture of hydraulic cement, generally calcium-aluminate cement, and specially selected and proportioned refractory aggregates that, when mixed with water, will produce refractory concrete or mortar.

cast-in-place concrete

concrete that is deposited and allowed to harden in the place where it is required to be in the completed structure, as opposed to precast concrete.

cast-in-place pile

a concrete pile that is cast with or without a casing in its permanent location, as distinguished from a precast pile. (See also drilled pier and precast pile.)

cast-in-situ

see cast-in-place concrete (preferred term).

cathead

(1) a notched wedge placed between two formwork members meeting at an oblique angle; (2) a spindle on a hoist; (3) the large, round retention nut used on she bolts.

cathodic protection

the form of corrosion protection wherein one metal is caused to corrode in preference to another, thereby protecting the latter from corrosion.

caulk

to place a material in a crack or joint with the intent of retarding entry of dirt or water. (See also joint filler or joint sealant.)

cavitation damage

pitting of concrete caused by implosion, that is, the collapse of vapor bubbles in flowing water that form in areas of low pressure and collapse as they enter areas of higher pressure. (See also abrasion damage and erosion.)

celite

a name used to identify the calcium aluminoferrite constituent of portland cement. (See also alite and belite.)

cellular concrete

a low-density product consisting of portland cement, cement-silica, cement-pozzolan, lime-pozzolan, or lime-silica pastes, or pastes containing blends of these ingredients and having a homogeneous void or cell structure, attained with gas-forming chemicals or foaming agents.

cellular construction

a method of cast-in-place concrete construction where a large ratio of hollow cores is produced in a flat slab.

cement

any of a number of materials that are capable of binding aggregate particles together. (See also hydraulic cement.)

cement bacillus

see ettringite (preferred term).

cement content

quantity of cement contained in a concrete, mortar, or grout preferably expressed as mass per unit volume of concrete, mortar, or grout.

cement factor

see cement content (preferred term).

cement gel

the colloidal material that makes up the major portion of the porous mass of which mature hydrated cement paste is composed.

cement gun

a machine for pneumatic placement of mortar or small aggregate concrete. (See also shotcrete.)

cement paint

a paint consisting generally of white portland cement and water, pigments, hydrated lime, water repellents, or hygroscopic salts.

cement paste

binder of concrete and mortar consisting essentially of cement, water, hydration products, and any admixtures together with very finely divided materials included in the aggregates. (See also neat cement paste.)

cement plaster

see plaster and stucco.

cement rock

natural impure limestone that contains the ingredients for production of portland cement in approximately the required proportions.

cementation process

the process of injecting cement grout under pressure into certain types of ground (for example, gravel, fractured rock) to solidify it.

cement-bound macadam

a road consisting of crushed stone, crushed slag, or gravel and either a grout or mortar filler.

cementitious

having cementing properties.

cementitious materials

pozzolans and hydraulic cements. (See also fly ash, silica fume, and slag cement.)

cementitious mixture

a mixture (mortar, concrete, or grout) containing hydraulic cement.

centering

falsework used in the construction of arches, shells, space structures, or any continuous structure where the entire falsework is lowered (struck or decentered) as a unit. (See also falsework and formwork.)

central mixer

a stationary concrete mixer from which the freshly mixed concrete is transported to the work.

central-mixed concrete

concrete that is completely mixed in a stationary mixer from which it is transported to the delivery point.

centrifugal process

a process for producing concrete products, such as pipe, that uses an outer form that is rotated about a horizontal axis and into which concrete is fed by a conveyor, also called spinning process. (See also centrifugally cast concrete, dry-cast process, packerhead process, tamp process, and wet-cast process.)

centrifugally cast concrete

concrete compacted by centrifugal action, for example, in the manufacture of pipe and poles. (See also centrifugal process.)

ceramic bond

bond that is the result of thermo-chemical reactions between materials exposed to temperatures approaching the fusion point of the mixture.

chair

see bar support (preferred term).

chalk

a soft limestone composed primarily of the calcareous remains of marine organisms.

chalking

formation of a loose powder resulting from the disintegration of the surface of concrete or of applied coating, such as cement paint.

chamfer

either a beveled edge or corner formed in concrete work by means of a chamfer strip.

chamfer strip

either a triangular or curved insert placed in an inside form corner to produce either a rounded or flat chamfer or to form a rustication (also called a cant strip, fillet, dummy joint, and skew back).

charge

to introduce, feed, or load materials into a concrete or mortar mixer, furnace, or other container or receptacle where they will be further treated or processed.

checking

development of shallow cracks at closely spaced but irregular intervals on the surface of plaster, cement paste, mortar, or concrete. (See also crack and crazing.)

chemical attack of concrete

the alteration or deterioration of concrete through chemical reaction or just presence of chemicals with either the cement paste, coarse aggregate, or embedded steel reinforcement.

chemical bond

bond between materials that is the result of cohesion and adhesion developed by chemical reaction.

chemically prestressing cement

a type of expansive cement containing a higher percentage of expansive component than a shrinkage-compensating cement, when used in concretes with adequate internal or external restraint, that will expand sufficiently due to chemical reactions within the matrix to develop the stresses necessary for prestressing the concrete.

chert

a very fine-grained siliceous rock characterized by hardness and conchoidal fracture in dense varieties, the fracture becoming splintery and the hardness decreasing in porous varieties and in a variety of colors; composed of silica in the form of chalcedony, cryptocrystalline or microcrystalline quartz, opal, or a combination of any of these minerals.

chipping

treatment of a hardened concrete surface by chiseling.

chips

broken fragments of marble or other mineral aggregate screened to specified sizes.

chute

a sloping trough or tube for conducting concrete, cement, aggregate, or other free-flowing materials from a higher to a lower point.

clamp

see coupler (preferred term).

class (of concrete)

an arbitrary characterization of concrete of various qualities or usages, usually by compressive strength.

classifier

machine for separating coarse and fine particles of granular material.

clay

natural mineral material having plastic properties and composed of very fine particles; the clay mineral fraction of a soil is usually considered to be the portion consisting of particles finer than 2 µm; clay minerals are essentially hydrous aluminum silicates or occasionally hydrous magnesium silicates.

clay content

mass fraction of clay of a heterogeneous material such as a soil or a natural concrete aggregate or crushed stone.

cleanout

(1) an opening in the forms for removal of refuse to be closed before the concrete is placed; (2) a port in tanks, bins, or other receptacles for inspection and cleaning.

cleanup

treatment of horizontal construction joints to remove surface material and contamination down to a condition of soundness corresponding to that of a freshly broken surface of hardened concrete.

cleat

small board used to connect formwork members or used as a brace. (See also batten.)

climbing form

a form that is raised vertically for succeeding lifts of concrete in a given structure.

clinker

(1) a partially fused product of a kiln that is ground to make cement; (2) other vitrified or burnt material. (See also portland-cement clinker.)

clip

wire or sheet-metal device used to attach various types of lath to supports or to secure adjacent lath sheets.

coarse aggregate

aggregate predominantly retained on the 4.75 mm (No. 4) sieve or that portion retained on the 4.75 mm (No. 4) sieve.

coarse-aggregate factor

the ratio, expressed as a decimal, of the amount (mass or solid volume) of coarse aggregate in a unit volume of well-proportioned concrete to the amount of dry-rodded coarse aggregate compacted into the same volume (b/bo).

coarse-grained soil

soil in which the larger grain sizes, such as sand and gravel, predominate.

coat

a film or layer as of paint or plaster applied in a single operation.

coated bar

a bar on which a coating has been applied, usually to increase resistance to corrosion.

coating

(1) (on concrete) — material applied to a surface by brushing, dipping, mopping, spraying, troweling, etc., to preserve, protect, decorate, seal, or smooth the substrate.
(2) (on aggregate particles) — foreign or deleterious substances found adhering to the aggregate particles.
(3) (on architectural concrete) — material used to protect a concrete surface from atmospheric contaminants and those that penetrate slightly and leave a visible clear or pigmented film on the surface. (See also sealer.)

cobble

in geology, a rock fragment between 2-1/2 and 10 in. (64 and 256 mm) in diameter; as applied to coarse aggregate for concrete, the material in the nominal size range 3 to 6 in. (75 to 150 mm).

cobblestone

a rock fragment, usually rounded or semirounded, with an average dimension between 3 and 12 in. (75 and 300 mm).

coefficient of permeability to water

the rate of discharge of water under laminar flow conditions through a unit cross-sectional area of a porous medium under a unit hydraulic gradient and standard temperature conditions, usually 20°C (68°F).

coefficient of subgrade friction

the coefficient of friction between a slab and its subgrade, commonly used in design of slabs-on-grade to estimate the force induced in the slab due to volume changes and elastic shortening if prestressed.

coefficient of subgrade reaction

ratio of the load per unit area of soil to the corresponding settlement of the soil, typically evaluated in place per ASTM D1196 (also called modulus of subgrade reaction).

coefficient of thermal expansion

change in linear dimension per unit length per degree of temperature change.

coefficient of variation

the standard deviation divided by the mean value of a variable.

cold joint

a joint or discontinuity resulting from a delay in placement of sufficient duration to preclude intermingling and bonding of the material, or where mortar or plaster rejoin or meet.

cold strength

the compressive or flexural strength of refractory concrete determined before drying or firing.

cold weather

a period when the average daily ambient temperature is below 40°F (5°C) for more than 3 successive days.
Note: The average daily temperature is the average of the highest and lowest temperature during the period from midnight to midnight. When temperatures above 50°F (10°C) occur during more than half of any 24-hour duration, the period shall no longer be regarded as cold weather.

cold-drawn wire

wire made from rods that are hot-rolled from billets and then cold-drawn through dies. (See also cold-drawn wire reinforcement.)

cold-drawn wire reinforcement

steel wire made from rods that have been hot rolled from billets and cold-drawn through a die.

cold-joint lines

visible lines on the surfaces of formed concrete indicating the presence of discontinuities where one layer of concrete had reached final set before subsequent concrete was placed. (See also cold joint.)

cold-worked steel reinforcement

steel bars or wires that have been rolled, twisted, or drawn at normal ambient temperatures.

colemanite

a mineral, hydrated calcium borate (Ca_2B_6O_11·5H_2O). (See also boron-loaded concrete.)

colloidal grout

grout in which a substantial proportion of the solid particles have the size range of a colloid.

colloidal mixer

a mixer designed to produce colloidal grout.

colorimetric value

an indication of the amount of organic impurities present in fine aggregate.

column

member with a ratio of height-to-least-lateral-dimension exceeding 3 used primarily to support axial compressive load.

column capital

an enlargement of a column below a slab intended to increase the shearing resistance.

column clamp

any of various types of tying or fastening units to hold column form sides together.

column side

one of the vertical panel components of a column form.

column strip

the portion of a flat slab over the columns and consisting of the two adjacent quarter panels on each side of the column center line.

combined footing

a structural unit or assembly of units supporting more than one column.

combined-aggregate grading

particle-size distribution of a mixture of fine and coarse aggregate.

come-along

(1) a hoe-like tool with a blade approximately 4 in. (100 mm) high and 20 in. (500 mm) wide and curved from top to bottom, used for spreading concrete; (2) a colloquial name for a device (load binder) used to tighten chains holding loads in place on a truck bed.

compacted strand

prestressing strand that is drawn through a circular die to deform the wires and produce a strand with a smaller circular shape.

compacting factor

the ratio obtained by dividing the observed mass of concrete that fills a container of standard size and shape when allowed to fall into it under standard conditions of test by the mass of fully compacted concrete that fills the same container.

compaction

the process of reducing the volume of voids in a material such as soil by input of mechanical energy. (See also consolidation.)

composite

engineering materials made from two or more constituent materials that remain distinct but combine to form materials with properties not possessed by any of the constituent materials individually.

composite column

a concrete compression member reinforced longitudinally with structural steel shapes, pipe, or tubing with or without longitudinal reinforcing bars.

composite concrete flexural members

concrete flexural members consisting of concrete elements constructed in separate placements but so interconnected that the elements respond to loads as a unit.

composite construction

a type of construction using members produced by combining different materials (for example, concrete and structural steel), members produced by combining cast-in-place and precast concrete, or cast-in-place concrete elements constructed in separate placements but so interconnected that the combined components act together as a single member and respond to loads as a unit.

composite pile

a pile made up of different materials, usually concrete and wood, or steel fastened together end to end, to form a single pile.

composite sample

sample obtained by blending two or more individual samples of a material.

compression flange

the widened portion of an I, T, or similar cross-sectional beam that is compressed by bending under normal loads.

compression member

any member in which the primary stress is longitudinal compression.

compression reinforcement

reinforcement designed to carry compressive stresses. (See also stress.)

compression test

test made on a test specimen of mortar or concrete to determine the compressive strength.

concentric tendons

tendons following a line coincident with the gravity axis of the prestressed concrete member.

concordant tendon

a tendon with a profile that does not produce secondary moments and support reactions due to the prestressing force.

concrete

mixture of hydraulic cement, aggregates, and water, with or without admixtures, fibers, or other cementitious materials.

concrete block

a concrete masonry unit, usually containing hollow cores.

concrete breakout failure

a concrete failure mode that develops a cone or edge failure of the test member due to setting of the anchor or to applied loads.

concrete brick

solid concrete masonry units of relatively small prescribed dimensions.

concrete cart

see buggy.

concrete compressive strength

the measured maximum resistance of a concrete specimen to axial compressive loading and expressed as force per unit cross sectional area.

concrete containment structure

a composite concrete and steel assembly that is designed as an integral part of a pressure retaining barrier that, in an emergency, prevents the release of radioactive or hazardous effluents from nuclear power plant equipment enclosed therein.

concrete finishing machine

(1) a machine mounted on flanged wheels that ride on forms or on specially set tracks, used to finish surfaces such as those of pavements; (2) a portable power-driven machine for floating and finishing of floors and other slabs.

concrete flatwork

a general term applicable to concrete floors and slabs that require finishing operations.

concrete masonry unit

either a hollow or solid unit (block) composed of portland-cement concrete.

concrete paver

(1) a slipforming machine that places concrete pavement on the subgrade; (2) precast-concrete paving brick.

concrete pile

see cast-in-place pile and precast pile.

concrete pryout strength

the strength corresponding to formation of concrete spall behind short, stiff anchors displaced in the direction opposite to the applied shear force.

concrete pump

an apparatus that forces concrete to the placing position through a pipeline or hose.

concrete reactor vessel

a composite concrete and steel assembly that functions as a component of the principal pressure-containing barrier for the nuclear fuel’s primary heat extraction fluid (primary coolant).

concrete spreader

a machine, usually carried on side forms or on rails parallel thereto, designed to spread concrete from heaps already dumped in front of it, or to receive and spread concrete in a uniform layer.

concrete strength

see concrete compressive strength, fatigue strength, flexural strength, shear strength, splitting tensile strength, tensile strength, and ultimate strength

concrete vibrating machine

a machine that consolidates a layer of freshly mixed concrete by vibration.

condensed silica fume

see silica fume (preferred term).

cone bolt

a type of tie rod for wall forms with cones at each end inside the forms so that a bolt can act as a spreader as well as a tie.

confined concrete

concrete within the reinforcement cage.

confined region

region with transverse reinforcement within beam-column joints.

consistency

the degree to which a freshly mixed concrete, mortar, grout, or cement paste resists deformation. (See also normal consistency, plastic consistency, and wettest stable consistency.)

consistency factor

a measure of grout fluidity, roughly analogous to viscosity, which describes the ease with which grout may be pumped into voids or fissures; usually a laboratory measurement in which consistency is reported in degrees of rotation of a torque viscosimeter in a specimen of grout.

consistometer

an apparatus for measuring the consistency of cement pastes, mortars, grouts, or concretes.

consolidation

the process of reducing the volume of voids, air pockets, and entrapped air in a fresh cementitious mixture, usually accomplished by inputting mechanical energy. (See also compaction, vibration, rodding, and tamping.)

construction joint

interface between concrete placements intentionally created to facilitate construction.

construction loads

the loads to which a permanent or temporary structure is subjected during construction.

contact ceiling

a ceiling that is secured in direct contact with the construction above without use of furring.

contact pressure

pressure acting at and perpendicular to the contact area between soil and a concrete element.

contact splice

a means of connecting reinforcing bars in which the bars are lapped and in direct contact. (See also lap splice.)

continuous beam

see continuous slab or beam.

continuous grading

a particle size distribution in which intermediate size fractions are present, as opposed to gap-grading. (See also gap-graded aggregate.)

continuous mixer

a mixer into which the ingredients of the mixture are fed without stopping, and from which the mixed product is discharged in a continuous stream.

continuous mixing

producing concrete by continuously blending ingredients in fixed proportions. The discharge of the concrete mixture may be started or stopped as required.

continuous sampling

sampling without interruptions throughout an operation or for a predetermined time.

continuous slab or beam

a slab or beam that extends as a unit over three or more supports in a given direction.

continuously reinforced pavement

a pavement with uninterrupted longitudinal steel reinforcement and no intermediate transverse expansion or contraction joints.

contract documents

a set of documents supplied by the owner to the contractor as the basis for construction. These documents contain contract forms, contract conditions, specifications, drawings, addenda, and contract changes.

contraction joint

formed, sawed, or tooled groove in a concrete structure to create a weakened plane to regulate the location of cracking resulting from the dimensional change of different parts of the structure. (See also isolation joint, expansion joint, and construction joint.)

contraction-joint grouting

injection of grout into contraction joints.

contractor

the person, firm, or corporation with whom the owner enters into an agreement for construction of the work.

control joint

formed, sawed, or tooled groove in a concrete structure to create a weakened plane to regulate the location of cracking resulting from the dimensional reduction of adjacent sections of the structure.

controlled low-strength material (CLSM)

self-consolidating cementitious mixture that is intended to result in a compressive strength of 1200 psi (8.3 MPa) or less.

conveying hose

see delivery hose (preferred term).

conveyor

a device for moving materials, usually a continuous belt, an articulated system of buckets, a confined screw, or a pipe through which material is moved by air or water.

coping

the material or units used to form a cap or finish on top of a wall, pier, pilaster, or chimney.

corbel

a projection from the face of a beam, girder, column, or wall used as a beam seat or a decoration.

core (n.)

(1) the soil material enclosed within a tubular pile after driving (it may be replaced with concrete); (2) the mandrel used for driving casings for cast-in-place piles; (3) a structural shape used to internally reinforce a drilled-in-caisson; (4) a cylindrical sample of hardened concrete or rock obtained by means of a core drill; (5) the molded open space in a concrete masonry unit or precast concrete unit (see also blockout); (6) the area enclosed by ties or spiral reinforcement in a concrete column.

core (v.)

the act of obtaining cores from concrete structures, rock foundations, or soils.

core test

compression test on a concrete specimen cut from hardened concrete by means of a core drill.

cored beam

a beam whose cross section is partially hollow or a beam from which cored samples of concrete have been taken.

coring

the act of obtaining cores from hardened concrete or masonry structures, rock, or soil.

corner reinforcement

(1) concrete reinforcement used at wall intersections or near corners of square or rectangular openings in walls, slabs, or beams; (2) metal reinforcement for plaster at reentrant corners to provide continuity between two intersecting planes.

corrosion

deterioration of a material, usually a metal, that results from a chemical reaction with its environment.

corrosion inhibitor

a chemical compound that effectively decreases corrosion rate of steel reinforcement without reducing the concentration of the corrosive agent at the bar level.

cotton mats

cotton-filled quilts fabricated for use as a water-retaining covering in curing concrete surfaces.

coupler

(1) a device for connecting reinforcing bars or prestressing tendons end to end; (2) a device for locking together the component parts of a tubular metal scaffold (also known as a clamp); (3) internal threaded device for joining reinforcing bars with matching threaded ends for the purpose of providing transfer of either axial compression, axial tension, or both from one bar to the other. (See also coupling sleeve, end-bearing sleeve, and mechanical connection.)

coupling agent

a substance used between the transducer and test surface to permit or improve transmission of ultrasonic energy.

coupling sleeve

device fitting over the ends of two reinforcing bars for the eventual purpose of providing transfer of either axial compression or axial tension or both from one bar to the other. (See also coupler, end-bearing sleeve, and mechanical connection.)

course

in concrete construction, a horizontal layer of concrete, usually one of several making up a lift; in masonry construction, a horizontal layer of block or brick. (See also lift.)

cover

the least distance between the surface of embedded reinforcement and the surface of the concrete.

crack

a complete or incomplete separation of either concrete or masonry into two or more parts produced by breaking or fracturing. (See also fracture.)

crack-control reinforcement

reinforcement in concrete construction designed to minimize opening of cracks, often effective in limiting them to uniformly distributed small cracks. (See also shrinkage reinforcement and temperature reinforcement.)

cracked section

a section designed or analyzed on the assumption that concrete has no resistance to tensile stress.

cracking load

the load that causes tensile stress in a member to exceed the tensile strength of the concrete.

craze cracks

fine random cracks or fissures in a surface of plaster, cement paste, mortar, or concrete.

crazing

the development of craze cracks; the pattern of craze cracks existing in a surface. (See also checking and crack.)

creep

time-dependent deformation due to sustained load.

critical saturation

a condition describing the degree of filling by freezable water of a pore space in cement paste or aggregate that affects the response of the material to freezing; usually taken to be 91.7 percent because of the 9 percent increase in volume of water undergoing the change of state to ice.

cross bracing

crossing members usually designed to act only in tension, often used in scaffolding systems. (See also sway brace and X-brace.)

cross section

(1) a plane through a body perpendicular to a given axis of the body; (2) a drawing showing such a plane.

crush plate

an expendable strip of wood attached to the edge of a form or intersection of fitted forms to protect the form from damage during prying, pulling, or other stripping operations.

crushed gravel

the product resulting from the artificial crushing of gravel with a specified minimum percentage of fragments having one or more faces resulting from fracture. (See also coarse aggregate.)

crushed stone

the product resulting from the artificial crushing of rocks, boulders, or large cobblestones, substantially all faces of that possess well-defined edges resulting from the crushing operation. (See also coarse aggregate.)

crusher-run aggregate

aggregate that has been mechanically broken and has not been subjected to subsequent screening.

cube strength

concrete compressive strength determined using a standard cube test specimen. (See also concrete compressive strength.)

cumulative batching

measuring more than one ingredient of a batch in the same container by bringing the batcher scale into balance at successive total weights as each ingredient is accumulated in the container.

curing

action taken to maintain moisture and temperature conditions in a freshly placed cementitious mixture to allow hydraulic cement hydration and (if applicable) pozzolanic reactions to occur so that the potential properties of the mixture may develop.

curing agent

a catalytic or reactive agent that induces cross-linking in a thermosetting resin. (See also hardener.)

curing blanket

a covering of sacks, matting, burlap, straw, waterproof paper, or other suitable material placed over freshly finished concrete. (See also burlap.)

curing compound

a liquid applied to the surface of newly placed concrete that retards the loss of water and, if pigmented, reflects sunlight. (See also curing and membrane curing.)

curing cycle

see autoclave.

curing delay

see presteaming period (preferred term).

curing kiln

see autoclave curing.

curing membrane

see membrane curing and curing compound.

curling

out-of-plane deformation of the corners, edges, and surface of a pavement, slab, or wall panel from its original shape. (See also warping.)

curtain grouting

injection of grout into a subsurface formation in such a way as to create a zone of grouted material transverse to the direction of anticipated water flow.

curvature friction

friction resulting from bends or curves in the specified prestressing cable profile.

cutting screed

sharp-edged tool used to trim shotcrete to the finished outline. (See also rod.)

cylinder strength

see concrete compressive strength and splitting tensile strength.

D

dampproofing

treatment of concrete or mortar to retard the passage or absorption of water or water vapor either by application of a suitable coating to exposed surfaces, or by use of a suitable admixture or treated cement, or by use of a preformed film such as polyethylene sheets placed on ground before placing a slab. (See also vapor retarder.)

darby

a hand-manipulated straightedge, usually 3 to 8 ft (1 to 2.5 m) long, used in the early stage leveling operations of concrete or plaster, preceding supplemental floating and finishing.

dash-bond coat

a thick slurry of portland cement, sand, and water flicked on surfaces with a paddle or brush to provide a base for subsequent portland cement plaster coats, sometimes used as a final finish on plaster.

davit

a device used to support and swing the access covers away from openings of vessels and tanks.

D-cracking

a series of cracks in concrete near and roughly parallel to joints and edges resulting from use of coarse aggregate that is susceptible to damage during cycles of freezing and thawing.

dead end

in the stressing of a tendon from one end only, the end opposite that to which the load is applied.

dead load

(1) the weights of the structural members, supported structure, and permanent attachments or accessories that are likely to be present on a structure in service; (2) loads meeting specific criteria found in the governing building code (without load factors).

dead-end anchorage

the anchorage at that end of a tendon that is opposite the jacking end.

deadman

an anchor for a guy line, usually a beam, block, or other heavy item buried in the ground, to which a line is attached.

debonding

(1) preventing bond of prestressing tendons to surrounding concrete; (2) bond failure at the interface between a substrate and a strengthening or repair system.

decentering

lowering or removing centering or shoring.

deck

the form on which concrete for a slab is placed, also the floor or roof slab itself. (See also bridge deck.)

decking

sheathing material for a deck or slab form.

decorative concrete

concrete that has received treatments to create aesthetic effects. These treatments may include coloring, polishing, texturing, embossing, molding, etching, applying cementitious toppings, embedding items, or a combination of these.

deflected tendons

see draped tendons (preferred term).

deflection

movement of a point on a structure or structural element, usually measured as a linear displacement or as succession displacements transverse to a reference line or axis.

deformation

a change in dimension or shape. (See also expansion, creep, length change, volume change, shrinkage, and time-dependent deformation.)

deformed bar

a reinforcing bar with a manufactured pattern of surface ridges intended to reduce slip and increase pullout resistance of bars embedded in concrete.

deformed reinforcement

metal bars, wire, or reinforcement with a manufactured pattern of surface ridges that provide a locking anchorage with surrounding concrete.

deformed tie bar

see tie bar.

dehydration

removal of chemically bound, adsorbed, or absorbed water from a material.

deicer

a chemical, such as sodium or calcium chloride, used to melt ice or snow on slabs and pavements; such melting being due to depression of the freezing point.

delamination

a planar separation in a material that is roughly parallel to the surface of the material.

delay

see presteaming period.

delayed ettringite formation

a form of sulfate attack by which mature hardened concrete is damaged by internal expansion during exposure to cyclic wetting and drying in service and caused by the late formation of ettringite, not because of excessive sulfate; not likely to occur unless the concrete has been exposed to temperatures during curing of 158ºF (70ºC) or greater and less likely to occur in concrete made with pozzolan or slag cement. (See also ettringite.)

delivery hose

hose through which shotcrete, grout, or pumped concrete or mortar passes (also called conveying hose or material hose).

demold

to remove molds from concrete test specimens or precast products. (See also strip.)

dense-graded aggregate

aggregates graded to produce low void content and maximum density when compacted. (See also well-graded aggregate.)

density

mass per unit volume.

density (dry)

the mass per unit volume of a dry substance at a stated temperature.

density control

control of density of concrete in field construction to ensure that specified values as determined by standard tests are obtained.

design load

applicable loads and forces or their related internal moments and forces used to proportion members.

design strength

nominal strength multiplied by a strength reduction factor Φ. (See also nominal strength and phi factor).

deterioration

(1) physical manifestation of failure of a material (for example, cracking, delamination, flaking, pitting, scaling, spalling, and staining) caused by environmental or internal autogenous influences on rock and hardened concrete as well as other materials; (2) decomposition of material during either testing or exposure to service. (See also disintegration and weathering.)

development bond stress

see anchorage bond stress (preferred term).

development length

the bonded length required to achieve the design strength of a reinforcement at a critical section.

devils float

a wooden float with two nails protruding from the toe used to roughen the surface of a brown plaster coat. (See also texturing.)

diagonal crack

(1) in a flexural member, an inclined crack caused by shear stress, usually at approximately 45 degrees to the axis; (2) a crack in a slab, not parallel to either the lateral or longitudinal directions.

diagonal cracking

development of diagonal cracks. (See also diagonal tension.)

diagonal tension

the principal tensile stress resulting from the combination of normal and shear stresses acting upon a structural element.

diametral compression test

see splitting tensile test.

diamond mesh

a metallic fabric having rhomboidal openings in a geometric pattern. (See also expanded-metal lath.)

diatomaceous earth

a friable earthy material composed primarily of nearly pure hydrous amorphous silica (opal) in the form of frustules of the microscopic plants called diatoms.

dicalcium silicate

a compound having the composition 2CaO·SiO_2, abbreviated C_2S, an impure form of which occurs in portland-cement clinker (belite). (See also belite.)

differential thermal analysis (DTA)

indication of thermal reaction by differential thermocouple recording of temperature changes in a sample under investigation compared with those of a thermally passive control sample, both of which are subjected simultaneously to the same heating condition.

dilation

an expansion of concrete during cooling or freezing generally calculated as the maximum deviation from the normal thermal contraction predicted from the length change/temperature curve or length change/time curve established at temperatures before initial freezing.

direct dumping

discharge of concrete directly into place from crane bucket or mixer.

discoloration

departure of color from that which is normal or desired.

disintegration

reduction into small fragments and subsequently into particles. (See also deterioration and weathering.)

dispersing agent

a material capable of increasing the fluidity of pastes, mortars, or concretes by reduction of inter-particle attraction.

distortion

see deformation

distress

physical manifestation of cracking and distortion in a concrete structure as the result of stress, chemical action, or both.

distribution-bar reinforcement

small diameter bars, usually at right angles to the main reinforcement, intended to spread a concentrated load on a slab and to prevent cracking.

D-line cracks

see D-cracking (preferred term).

dome

square prefabricated pan form used in two-way (waffle) concrete joist floor construction.

dormant crack

a crack whose width does not change with time.

double-tee beam

a precast-concrete member composed of two stems and a combined top flange, commonly used as a beam but also used vertically in exterior walls.

double-up

a method of plastering characterized by application in successive operations with no setting or drying time between coats.

dowel

(1) a steel pin, commonly a plain or coated round steel bar that extends into adjoining portions of a concrete construction, as at an expansion or contraction joint in a pavement slab, so as to transfer shear loads; (2) a deformed reinforcing bar intended to transmit tension, compression, or shear through a construction joint.

dowel rod

see dowel (preferred term).

dowel-bar reinforcement

see dowel.

drainage fill

(1) base course of granular material placed between floor slab and subgrade to impede capillary rise of moisture; (2) lightweight concrete placed on floors or roofs to promote drainage.

draped tendons

tendons that have a trajectory that is curved or bent with respect to the gravity axis of the concrete member.

drier

chemical that promotes oxidation or drying of a paint or adhesive.

drilled pier

a concrete pier with or without a casing, cast in place in a hole previously bored in soil or rock. (See also cast-in-place pile.)

drilled pile

see drilled pier.

drilled-in caisson

cast-in-place pile formed by driving an open-ended steel pipe into bedrock or other bearing layer, cleaning out the pipe, drilling a socket into the bedrock or other bearing layer, and placing the steel reinforcement and concrete (also called caisson foundation or caisson).

drip

a transverse groove in the underside of a projecting piece of wood, stone, or concrete to prevent water from flowing back to a wall.

drop panel

the thickened structural portion of a flat slab in the area surrounding column, column capital, or bracket to reduce the intensity of stresses.

dropchute

a device used to confine or to direct the flow of a falling stream of fresh concrete.
(1) articulated dropchute — a device consisting of a succession of tapered metal cylinders so designed that the lower end of each cylinder fits into the upper end of the one below
(2) flexible dropchute — a device consisting of a heavy rubberized canvas or plastic collapsible tube.

dry mix

(1) a concrete, mortar, or plaster mixture, commonly sold in bags, containing all components except water; (2) a concrete of near-zero slump.

dry mixing

blending of the solid materials for mortar or concrete before adding the mixing water.

dry pack

concrete or mortar mixtures deposited and consolidated by dry packing.

dry packing

placing of zero-slump, or near zero-slump, concrete, mortar, or grout by ramming into a confined space.

dry process

in the manufacture of cement, the process in which the raw materials are ground, conveyed, blended, and stored in a dry condition. (See also wet process.)

dry rodding

in measurement of the mass per unit volume of coarse aggregates, the process of consolidating dry material in a calibrated container by rodding under standardized conditions.

dry topping

see dry-shake (preferred term)

dry-batch weight

the mass of the materials, excluding water, used to make a batch of concrete.

dry-cast process

a process for producing concrete products, such as pipe, using low-frequency high-amplitude vibration to consolidate dry-mix concrete in the form. (See also centrifugal process, packerhead process, tamp process, and wet-cast process.)

dry-mix shotcrete

shotcrete in which most of the mixing water is added at the nozzle (also called dry-process shotcrete).

dry-packed concrete

concrete placed by dry packing.

dry-rodded density

mass per unit volume of dry aggregate, which includes the volume of the particles and the voids between particles, compacted by rodding under standardized conditions.

dry-rodded volume

the bulk volume occupied by a dry aggregate compacted by rodding under standardized conditions; used in measuring density of aggregate.

dry-rodded weight

(deprecated term) see dry-rodded density.

dry-shake

a dry mixture of hydraulic cement and fine aggregate (either mineral or metallic) that is distributed evenly over the surface of concrete flatwork and worked into the surface before time of final setting and then floated and troweled to desired finish.

dry-tamp process

see dry packing (preferred term).

drying creep

creep caused by drying. (See also creep and basic creep.)

drying shrinkage

shrinkage resulting from loss of moisture.

duct

the material creating a conduit in a concrete member to accommodate the prestressing steel of a post-tensioning tendon.

ductility

the ability of a material to undergo large permanent deformation without rupture.

Dunagan analysis

(obsolete) a method of separating the ingredients of freshly mixed concrete or mortar to determine the proportions of the mixture.

durability

the ability of a material to resist weathering action, chemical attack, abrasion, and other conditions of service.

durability factor

(1) a measure of the change in a material property over a period of time as a response to exposure to a treatment that can cause deterioration, usually expressed as percentage of the value of the property before exposure; (2) in ASTM C666/C666M, a measure of the effects of freezing and thawing action on concrete specimens.

dust of fracture (in aggregate)

rock dust created during production, processing, or handling.

dusting

the development of a powdered material at the surface of hardened concrete.

dynamic analysis

analysis of stresses in framing as functions of displacement under transient loading.

dynamic load

an imposed load that is in motion and may vary with time in magnitude or direction.

dynamic loading

loading from units (particularly machinery) that, by virtue of their movement or vibration, impose stresses in excess of those imposed by their dead load.

dynamic modulus of elasticity

the modulus of elasticity computed from the size, mass, shape, and fundamental frequency of vibration of a concrete test specimen, or from pulse velocity. (See also pulse velocity.)

E

early age (of concrete)

the period after final setting during which properties are changing rapidly.

early stiffening

the early development of an abnormal reduction in the working characteristics of a hydraulic-cement paste, mortar, or concrete, which may be further described as false setting, quick setting, or flash setting.

early strength

strength of concrete or mortar usually as developed at various times during the first 72 hours after placement.

early-entry dry cut saw

a tool designed to cut joints in concrete commencing 1 to 4 hours after finishing and without raveling the cut edges.

eccentric tendon

a prestressing tendon that follows a trajectory not coincident with the gravity axis of the concrete member.

edge beam

a stiffening beam at the edge of a slab.

edge form

formwork used to limit the horizontal spread of fresh concrete on flat surfaces such as pavements or floors.

edge reinforcement

tensile reinforcement sometimes used to strengthen otherwise inadequate edges in a slab without resorting to edge thickening.

edger

a finishing tool used on the edges of fresh concrete to provide a rounded edge.

edging

the operation of tooling the edges of a fresh concrete slab to provide a rounded corner.

effective area of concrete

area of a concrete section assumed to resist shear or flexural stresses.

effective depth

depth of a beam or slab section measured from the compression face to the centroid of the tensile reinforcement.

effective flange width

width of slab adjoining a beam stem where the slab is assumed to function as the flange element of a T-beam section.

effective prestress

stress remaining in prestressing steel after all losses have occurred (also called final prestress or final stress).

effective span

the lesser of the two following distances: (a) the distance between supports; (b) the clear distance between supports plus the effective depth of the beam or slab.

effective stress

see effective prestress

effective width of slab

that part of the width of a slab taken into account when designing T- or L-beams.

efflorescence

a generally white deposit formed when water-soluble compounds emerge in solution from concrete, masonry, or plaster substrates and precipitate by reaction such as carbonation or crystallize by evaporation.

elastic design

design based on a linear distribution of flexural stresses and strains and corresponding limiting elastic properties of the material.

elastic limit

the limit of stress beyond which the strain is not wholly recoverable.

elastic loss

in prestressed concrete, the reduction in prestressing load resulting from the elastic shortening of the member.

elastic shortening

in prestressed concrete, the shortening of a member that occurs immediately on the application of forces induced by prestressing.

elasticity

that property of a material by virtue of which it tends to recover its original size and shape after deformation.

electrical curing

a system in which a favorable temperature is maintained in freshly placed concrete by supplying heat generated by electrical resistance.

electrolysis

production of chemical changes by the passage of current through an electrolyte.

electrolyte

a conducting medium in which the flow of current is accompanied by movement of matter; usually an aqueous solution.

elephant trunk

an articulated tube or chute used in concrete placement. (See also dropchute and tremie.)

elongated piece (of aggregate)

particle of aggregate for which the ratio of the length to the width of its circumscribing rectangular prism is greater than a specified value. (See also flat piece [of aggregate].)

elongation

increase in length. (See also expansion, elastic shortening, and swelling.)

embedment length

the length of embedded reinforcement provided beyond a critical section.

emery

a rock consisting essentially of an intercrystalline mixture of corundum and either magnetite or hematite. (See also dry-shake.)

emulation

designing precast elements and their structural connections to perform as if the structure was a conventional cast-in-place concrete structure.

emulative detail

a connection in which the structural performance is equivalent to that of a continuous member or a monolithic connection.

emulsion

a two-phase liquid system in which small droplets of one liquid (the internal phase) are immiscible in, and dispersed uniformly throughout, a second continuous liquid phase (the external phase).

enclosure wall

a nonload-bearing wall intended only to enclose space.

encrustation

see incrustation (preferred term).

end anchorage

(1) length of reinforcement, mechanical anchor, hook, or combination thereof, beyond the point of nominal zero stress in the reinforcement of cast-in-place concrete; (2) mechanical device to transmit prestressing force to the concrete in a post-tensioned member. (See also anchorage.)

end block

an enlarged end section of a member intended to reduce anchorage stresses to allowable values and provide space needed for post-tensioning anchorages.

end-bearing sleeve

device fitting over the abutting ends of two reinforcing bars for the purpose of assuring transfer of only axial compression from one bar to the other. (See also coupler, coupling sleeve, and mechanical connection.)

endothermic reaction

a chemical reaction that occurs with the absorption of heat.

engineer-architect

see architect-engineer.

entrained air

microscopic air bubbles intentionally incorporated in mortar or concrete during mixing, usually by use of a surface-active agent; typically between 10 µm (0.004 in.) and 1 mm (0.04 in.) in diameter and spherical or nearly so. (See also air entrainment.)

entrapped air

air voids incorporated into concrete during mixing that are mainly irregular in shape and usually 1 mm (0.04 in.) or larger in size.

epoxy

a thermosetting polymer that is the reaction product of epoxy resin and an amino hardener. (See also epoxy resin.)

epoxy concrete

a mixture of epoxy resin and hardener, fine aggregate, and coarse aggregate. (See also polymer concrete, mortar, epoxy, and epoxy resin.)

epoxy grout

a grout consisting of an epoxy bonding system, aggregate or fillers, and possibly other materials.

epoxy mortar

a mixture of epoxy resin, hardener, and fine aggregate. (See also epoxy resin.)

epoxy resin

a class of organic chemical bonding systems used in the preparation of special coatings or adhesives for concrete or as binders in epoxy-resin mortars, concretes, and fiber reinforced polymer composites.

epoxy-coated bar

a reinforcing bar coated with an epoxy resin.

equilibrium density

the density reached by structural lightweight concrete after exposure to relative humidity of 50 ± 5 percent and a temperature of 73.5 ± 3.5°F (23 ± 2°C) for a period of time sufficient to reach a density that changes less than 0.5 percent in a period of 28 days.

equivalent embedment length

the length of embedded reinforcement that can develop the same stress as that which can be developed by a hook or mechanical anchorage.

equivalent fiber diameter

diameter of a circle having an area equal to the average cross-sectional area of a fiber.

equivalent rectangular stress distribution

an assumption of uniform stress on the compression side of the neutral axis in the strength design method to determine flexural capacity.

erosion

progressive loss of material from a solid surface due to a mechanical interaction between that surface and a fluid, a multi-component fluid, or solid particles carried with the fluid. (See also abrasion damage and cavitation damage.)

ettringite

(1) a mineral, high-sulfate calcium sulfoaluminate (3CaO·Al_2O_3·3CaSO_4·30-32H_2O), occurring in nature or formed by sulfate attack on mortar and concrete; (2) the product of the principal expansion-producing reaction in expansive cements.

evaporable water

water in set cement paste present in capillaries or held by surface forces; measured as that removable by drying under specified conditions. (See also nonevaporable water.)

evaporation reducer

see evaporation retardant.

evaporation retardant

a material applied to the surface of concrete before initial setting to reduce the evaporation rate of water without interfering with finishing operations (also called evaporation reducer). (See also monomolecular.)

exfoliation

disintegration occurring by peeling off in successive layers, swelling up and opening into leaves or plates like a partly opened book.

exothermic reaction

a chemical reaction that occurs with the evolution of heat.

expanded blast-furnace slag

see blast-furnace slag.

expanded shale (clay or slate)

lightweight vesicular aggregate obtained by firing suitable raw materials in a rotary kiln or on a sintering grate under controlled conditions.

expanded-metal fabric reinforcement

see expanded-metal lath.

expanded-metal lath

a metal network, often used as reinforcement in construction, formed by suitably stamping or cutting sheet metal and stretching it to form open meshes, either of diamond-shaped or rhomboidal-shaped openings. (See also diamond mesh.)

expansion

increase in either length or volume. (See also shrinkage, volume change, and autogenous volume change.)

expansion joint

(1) a separation provided between adjacent sections of a concrete structure to allow movement due to dimensional increases and reductions of the adjacent sections and through which some or all of the bonded reinforcement is interrupted; (2) a separation between pavement slabs on ground, filled with a compressible filler material.

expansion sleeve

a tubular metal covering for a dowel bar to allow its free longitudinal movement at a joint.

expansive cement

a cement that when mixed with water produces a paste that after setting increases in volume to a greater degree than does portland-cement paste.
(1) Type K expansive cement — a mixture of portland cement, anhydrous tetracalcium trialuminate sulfate (C_4A_3S), calcium sulfate (CaSO_4), and lime (CaO).
(2) Type M expansive cement — interground or blended mixtures of portland cement and calcium sulfate suitably proportioned.
(3) Type S expansive cement — a portland cement containing a high computed tricalcium aluminate (C_3A) content and an amount of calcium sulfate above the usual amount found in portland cement.

expansive component

the portion of an expansive cement that is responsible for the expansion, generally one of several anhydrous calcium aluminate or sulfoaluminate compounds and a source of sulfate, with or without free lime (CaO).

exposed-aggregate finish

a decorative finish for concrete work achieved by removing, generally before the concrete has hardened, the outer skin of mortar and exposing the coarse aggregate.

exposure class

designation used to describe environmental conditions to which concrete will be exposed.

extender

a finely divided inert mineral added to provide economical bulk in paints, synthetic resins and adhesives, or other products.

extensibility

that property by virtue of which a material can undergo extension or elongation following the application of force.

exterior panel

in a flat slab, a panel having at least one edge that is not in common with another panel.

external vibrator

see vibrator.

extreme compression fiber

farthest fiber from the neutral axis on the compression side of a member subjected to bending.

extreme tension fiber

farthest fiber from the neutral axis on the tension side of a member subjected to bending.

exudation

a liquid or viscous gel-like material discharged through a pore, crack, or opening in the surface of concrete.

F

factor of safety

the ratio of the ultimate capacity to the magnitude of the demand at the service level.

factored load

load, multiplied by appropriate load factors, used to proportion members by the strength-design method.

false header

see header.

false setting

the rapid development of rigidity in a freshly mixed portland cement paste, mortar, or concrete without the evolution of much heat, which rigidity can be dispelled and plasticity regained by further mixing without addition of water. (See also flash setting.)

falsework

the temporary structure erected to support work in the process of construction. (See also formwork.)

fascia

a flat member or band at the surface of a building or the edge beam of a bridge; also exposed eave of a building.

fastener

a device designed to attach, join, or hold two or more objects one to another.

fatigue

the weakening of a material by repeated loads.

fatigue failure

rupture of a material, when subjected to repeated loadings, at a stress substantially less than the static strength.

fatigue strength

the greatest stress that can be sustained for a given number of stress cycles without failure.

faulting

differential displacement of a slab or wall along a joint or crack.

feather edge

the edge of a concrete or mortar patch or topping that is beveled at an acute angle.

feed wheel

material distributor or regulator in certain types of shotcrete equipment.

ferrocement

a composite structural material comprising thin sections consisting of cement mortar reinforced by a number of closely spaced layers of steel wire mesh.

fiber

a slender and elongated solid material, generally with a length at least 100 times its diameter.

fiber aspect ratio

the ratio of length to diameter of a fiber in which the diameter may be an equivalent diameter. (See also equivalent fiber diameter.)

fiber count

the number of fibers in a unit volume of fiber-reinforced concrete.

fiber-reinforced concrete

concrete containing dispersed, randomly oriented fibers.

fiber-reinforced polymer (FRP)

a general term for a composite material comprising a polymer matrix reinforced with fibers in the form of fabric, mat, strands, or any other fiber form. (See composite.)

field bending

bending of reinforcing bars at the job site rather than in a fabricating shop.

field concrete

concrete delivered to or mixed, placed, and cured on the job site.

field-cured cylinders

test cylinders that are left at the job site for curing as nearly as practicable in the same manner as the concrete in the structure to indicate when supporting forms may be removed, additional construction loads may be imposed, or the structure may be placed in service.

field-proportioned grout

a hydraulic-cement grout batched at the job site using water and predetermined portions of hydraulic cement, aggregate, and other ingredients.

filler

(1) a finely divided, relatively inert material (such as pulverized limestone, silica, or colloidal substances) added to portland cement, paint, resin, or other materials to reduce shrinkage, improve workability, reduce cost, or reduce density; (2) material used to fill an opening in a form.

fillet

see chamfer strip.

fin

(1) a narrow linear projection on a formed concrete surface, resulting from mortar flowing into spaces in the formwork; (2) a type of blade in a concrete mixer drum.

final curing

deliberate action taken between the final finishing and termination of curing to reduce the loss of water from the surface of the concrete and control the temperature of the concrete.

final prestress

see effective prestress.

final setting

a degree of stiffening of a cementitious mixture greater than initial setting, generally stated as an empirical value indicating the time required for the cementitious mixture to stiffen sufficiently to resist, to an established degree, the penetration of a weighted test device. (See also initial setting.)

final setting time

the time required for a freshly mixed cement paste, mortar, or concrete to achieve final set. (See also initial setting time.)

final stress

see effective prestress (preferred term).

fine aggregate

(1) aggregate passing the 9.5 mm (3/8 in.) sieve, almost entirely passing the 4.75 mm (No. 4) sieve, and predominantly retained on the 75 mm (No. 200) sieve; (2) that portion of aggregate passing the 4.75 mm (No. 4) sieve and predominantly retained on the 75 mm (No. 200) sieve. (See also aggregate and sand.)

fine-grained soil

soil in which the smaller grain sizes predominate, such as fine sand, silt, and clay.

fineness

a measure of particle size.

fineness modulus

a factor obtained by adding the total percentages of material in the sample that are coarser than each of the following sieves (cumulative percentages retained), and dividing the sum by 100: 150 µm (No. 100), 300 µm (No. 50), 600 µm (No. 30), 1.18 mm (No. 16), 2.36 mm (No. 8), 4.75 mm (No. 4), 9.5 mm (3/8 in.), 19.0 mm (3/4 in.), 37.5 mm (1-1/2 in.), 75 mm (3 in.), and 150 mm (6 in.)

finish

the texture of a concrete surface after consolidating and finishing operations have been performed.

finish coat

(1) final thin coat of shotcrete in preparation for hand finishing; (2) final exposed coat of plaster or stucco.

finish grinding

(1) the final grinding of clinker into cement, with calcium sulfate in the form of gypsum or anhydrite generally being added; (2) the final grinding operation required for a finished concrete surface, for example, bump cutting of pavement, fin removal from structural concrete, and terrazzo floor grinding.

finish screens

vibrating horizontal screens operated at a batching plant so that an excessive amount of significant undersize material is removed.

finishing

leveling, smoothing, consolidating, and otherwise treating surfaces of fresh or recently placed concrete or mortar to produce desired appearance and service. (See also float and trowel.)

finishing machine

a power-operated machine used to produce the desired surface texture on a concrete slab.

fire clay

an earthy or stony mineral aggregate that has as the essential constituent hydrous silicates of aluminum with or without free silica and that is plastic when sufficiently pulverized and wetted, rigid when subsequently dried, and of suitable refractoriness for use in commercial refractory products.

fire resistance

(1) the property of a material or assembly to withstand fire or give protection from it; (2) the ability of building elements to confine a fire or, when exposed to fire, to continue to perform a given structural function, or both.

fired strength

the compressive or flexural strength of refractory concrete determined upon cooling after first firing to a specified temperature for a specified time.

flash coat

a thin coat of shotcrete used to cover minor blemishes on a concrete surface.

flash setting

the rapid development of rigidity in a freshly mixed portland cement paste, mortar, or concrete, characteristically with the evolution of considerable heat, which rigidity cannot be dispelled nor can the plasticity be regained by further mixing without addition of water (also called quick setting). (See also false setting.)

flashing

a thin impermeable sheet (narrow in comparison with its length) installed as a cover to exclude water from exposed joints and at roof valleys, hips, parapets, or intersections of roof and chimney.

flat jack

a hydraulic jack consisting of light gauge metal that is folded and welded to a flat shape that expands under internal pressure.

flat piece (of aggregate)

one in which the ratio of the width to thickness of its circumscribing rectangular prism is greater than a specified value. (See also elongated piece [of aggregate].)

flat plate

a flat slab without column capitals or drop panels. (See also flat slab.)

flat slab

a concrete slab reinforced in two or more directions and having drop panels, column capitals, or both. (See also flat plate.)

flexible pavement

a pavement structure that maintains intimate contact with and distributes loads to the subgrade and depends on aggregate interlock, particle friction, and cohesion for stability.

flexural bond stress

in structural-concrete members, the stress between the concrete and the reinforcing element that results from the application of external load.

flexural rigidity

a measure of stiffness of a member, indicated by the product of modulus of elasticity and moment of inertia divided by the length of the member.

flexural strength

the measured maximum resistance of a concrete specimen to flexural loading and reported as modulus of rupture. (See also modulus of rupture.)

flint

a variety of chert. (See also chert.)

float

a tool (not a darby), usually of wood, aluminum, or magnesium used in finishing operations to impart a relatively even but still open texture to an unformed fresh concrete surface. (See also darby.)

float finish

a rough, granular concrete surface texture obtained by finishing with a float.

floating

smoothing and subsequent compaction and consolidation of the unformed concrete surface.

flow

(1) time-dependent irrecoverable deformation (see also creep); (2) a measure of the consistency of freshly mixed concrete, mortar, or cement paste expressed in terms of the increase in diameter of a molded truncated cone specimen after jigging a specified number of times; (3) movement of uncured resin under gravity loads or differential pressure.

flow cone

(1) a device for measurement of grout consistency in which a predetermined volume of grout is permitted to escape through a precisely sized orifice, the time of efflux being used as the indication of consistency; (2) the mold used to prepare a specimen for the flow test.

flow line

detectable line on a concrete wall or column usually departing somewhat from horizontal, that shows where the concrete in one placement has flowed horizontally before succeeding placement has been made.

flow table

a flat, circular jigging device used in making flow tests for consistency of cement paste, mortar, or concrete. (See also flow [2].)

flow trough

a sloping trough used to convey concrete by gravity flow from either a truck mixer or a receiving hopper to the point of placement. (See also chute.)

flowable consistency

the consistency at which a grout will form a nearly level surface when lightly rodded; the consistency of a grout with at least 125 percent at five drops on the ASTM C230/C230M flow table and an efflux time through the ASTM C939 flow cone of more than 30 seconds.

flowing concrete

a cohesive concrete mixture with a slump greater than 7-1/2 in. (190 mm).

fluid consistency

(1) the consistency at which a grout will form a nearly level surface without vibration or rodding; (2) the consistency of a grout that has an efflux time of less than 30 seconds through an ASTM C939 flow cone.

fluidifier

an admixture employed in grout to increase fluidity without changing water content. (See also water-reducing admixture.)

fly ash

the finely divided residue that results from the combustion of ground or powdered coal and that is transported by flue gases from the combustion zone to the particle removal system.

flying forms

large prefabricated units of formwork incorporating support and designed to be moved from place to place.

foamed concrete

low-density concrete made by the addition of a prepared foam or by generation of gas within the fresh mixture.

fog curing

(1) storage of concrete in a moist room in which the desired high humidity is achieved by the atomization of water (see also moist room); (2) application of atomized water to concrete, stucco, mortar, or plaster.

fog room

see moist room (preferred term).

folded plate

(1) a framing assembly composed of sloping slabs in a hipped or gabled arrangement; (2) prismatic shell with open polygonal section.

footing

a structural element of a foundation that transmits loads directly to the soil.

form

a temporary structure or mold for the support of concrete while it is setting and gaining sufficient strength to be self-supporting. (See also formwork.)

form anchor

device used to secure formwork to previously placed concrete of adequate strength, normally embedded in the concrete during placement.

form coating

a liquid applied to formwork surfaces to promote easy release from the concrete, preserve the form material, or retard setting of the near-surface matrix for preparation of exposed-aggregate finishes.

form hanger

device used to support formwork from a structural framework (the dead load of forms, mass of concrete, and construction and impact loads must be supported).

form insulation

insulating material applied to the outside of forms between studs and over the top in sufficient thickness and air tightness to conserve heat of hydration to maintain concrete at required temperatures in cold weather.

form lining

materials used to line the concreting face of formwork either to impart a smooth or patterned finish to the concrete surface, to absorb moisture from the concrete, or to apply a set-retarding chemical to the formed surface. (See also sheathing.)

form oil

oil applied to the interior surfaces of forms to promote easy release from the concrete when the forms are removed. (See also release agent and bond breaker.)

form pressure

lateral pressure acting on vertical or inclined formed surfaces, resulting from the fluid-like behavior of the fresh concrete confined by the forms.

form release agent

see release agent.

form spacer

see spacer and spreader.

form spreader

see spreader.

form tie

a mechanical connection in tension used to prevent concrete forms from spreading due to the fluid pressure of fresh concrete.

formwork

total system of support for freshly placed concrete including the mold or sheathing that contacts the concrete as well as supporting members, hardware, and necessary bracing (also called shuttering in the United Kingdom). (See also falsework and centering.)

formwork tiers

the number of frames of scaffolding erected one above the other.

foundation

a system of structural elements that transmits loads from the structure above to the earth.

foundation bolt

see anchor bolt (preferred term).

fracture

(1) a crack or break in concrete or masonry; (2) the configuration of a broken surface; (3) the action of cracking or breaking. (See also crack.)

free fall

(1) descent of freshly mixed concrete into forms without dropchutes or other means of confinement; (2) the distance through which such descent occurs; (3) uncontrolled fall of aggregate.

free lime

calcium oxide (CaO) (as in clinker and cement) that has not combined with SiO_2, Al_2O_3, or Fe_2O_3 during the burning process, usually because of underburning, insufficient grinding of the raw mixture, or the presence of traces of inhibitors.

free moisture

(1) moisture having essentially the properties of pure water in bulk; (2) moisture not absorbed by aggregate. (See also surface moisture.)

free water

see free moisture and surface moisture.

fresh concrete

concrete that possesses enough of its original workability that it can be placed and consolidated by the intended methods.

fresno trowel

a thin steel trowel that is rectangular (with or without rounded corners), usually 4 to 10 in. (100 to 250 mm) wide and 20 to 36 in. (420 to 900 mm) long, with a 4 to 16 ft (1 to 5 m) long handle, and used to smooth surfaces of nonbleeding concrete and shotcrete.

friction loss

the stress loss in a prestressing tendon resulting from friction between the tendon and duct or other device during stressing.

friction pile

a load-bearing pile that receives its principal vertical support from skin friction between the surface of the buried pile and the surrounding soil.

frog

a depression in the bed surface of a masonry unit (also called a panel).

Fuller’s curve

an empirical curve for gradation of aggregates. (See also grading curve.)

Fuller-Thompson ideal grading curve

see Fuller’s curve (preferred term).

furring

strips of wood or metal fastened to a wall or other surface to even it, to form an air space, to give appearance of greater thickness, or for the application of an interior finish such as plaster.

G

ganged forms

prefabricated panels joined to make a much larger unit (up to 30 by 50 ft) (9 by 15 m) for convenience in erecting, stripping, and reusing; usually braced with wales, strongbacks, or special lifting hardware.

gap-graded aggregate

aggregate graded so that portions of aggregate retained on specified intermediate sieves is substantially absent.

gehlenite

a mineral of the melilite group, Ca_2Al(AlSi)O_7. (See also melilite and merwinite.)

Gillmore needle

a device used in determining time of setting of hydraulic cement.

girder

a large beam, usually horizontal, that serves as a main structural member.

glass-transition temperature

the midpoint of the temperature range over which an amorphous material (such as glass or a high polymer) changes from (or to) a brittle, vitreous state to (or from) a plastic state.

go-devil

(1) a ball of rolled-up burlap or paper or a specially fabricated device put into the pump end of a pipeline and forced through the pipe by water pressure to clean the pipeline; (2) a device used with tremie concrete operations.

grab setting

see flash setting (preferred term).

gradation

see grading (preferred term).

grade

(1) the prepared surface on which a concrete slab is cast; (2) the process of preparing a plane surface of granular material or soil on which to cast a concrete slab.

grade beam

a reinforced-concrete beam, usually at ground level, that strengthens or stiffens the foundation or supports overlying construction.

grade strip

usually a thin strip of wood tacked to the inside surface of forms at the elevation to which the top of the concrete lift is to rise, either at a construction joint or the top of the structure.

graded standard sand

see standard sand.

gradient

rate of change in a variable over a distance.

grading

the distribution of particles of granular material among various sizes.

grading curve

a graphical representation of the proportions of different particle sizes in a granular material, obtained by plotting the cumulative or individual percentages of the material passing through sieves in which the aperture sizes form a given series.

granolithic concrete

concrete suitable for use as a wearing surface finish to floors, made with specially selected aggregate of suitable hardness, surface texture, and particle shape.

granolithic finish

a surface layer of granolithic concrete that may be laid on a base of either fresh or hardened concrete.

granulated blast-furnace slag

see blast-furnace slag.

gravel

aggregate retained on the 4.75 mm (No. 4) sieve and resulting either from natural disintegration and abrasion of rock or processing of weakly bound conglomerate. (See also coarse aggregate.)

green concrete

concrete that has undergone final setting but not hardened appreciably.

grid foundation

a combined footing formed by intersecting continuous footings, loaded at the intersection points, and covering much of the total area within the outer limits of the assembly.

grinding aids

materials used to expedite the process of grinding by eliminating ball coating, dispersing the finely ground product, or both.

grinding medium

a hard, free-moving charge in a ball or tube mill to reduce the particle size of introduced materials by attrition or impact.

grizzly

a simple, stationary screen or series of equally spaced parallel bars set at an angle to remove oversized particles in processing aggregate or other material.

grog

burned refractory material, usually calcined clay or crushed brick bats.

groove joint

see control joint (preferred term).

groover

a tool used to form grooves or weakened-plane joints in a concrete slab before final setting to control crack location or provide pattern.

ground wire

small-gauge high-strength steel wire used to establish line and grade as in shotcrete work (also called alignment wire and screed wire).

ground-granulated blast-furnace slag

(obsolete) see slag cement (preferred term).

grout

mixture of cementitious materials and water, or other binding medium, with fine aggregate. (See also neat cement grout and sanded grout.)

grout slope

the natural slope of fluid grout injected into preplaced-aggregate concrete.

grouted masonry

unit masonry composed of either hollow units wherein the cells are filled with grout or multiple wythes where spaces between the wythes are filled with grout.

grouted-aggregate concrete

see preplaced-aggregate concrete.

grouting

the process of filling with grout. (See also grout.)

gun

(1) shotcrete material delivery equipment; (2) pressure cylinder used to propel freshly mixed concrete pneumatically.

gun finish

undisturbed final layer of shotcrete as applied from nozzle without hand finishing.

Gunite

a proprietary term for shotcrete.

gunman

workman on shotcreting crew who operates delivery equipment.

gunning

the act of applying dry-mix shotcrete.

gypsum

a mineral having the composition calcium sulfate dihydrate (CaSO_4·2H_2O).

gypsum plaster

plaster made with plaster of paris. (See plaster and plaster of paris.)

H

hairline crack

a concrete surface crack with a width so small as to be barely perceptible.

hairpin

(1) the wedge used to tighten some types of form ties; (2) a hairpin-shaped anchor set in place before concrete reaches initial setting; (3) a light hairpin-shaped reinforcing bar used for shear reinforcement in beams, tie reinforcement in columns, or prefabricated column shear heads.

Hamm tip

(1) flared shotcrete nozzle having a larger diameter at midpoint than at either inlet or outlet; (2) designated premixing tip.

hanger

a device used to suspend one object from another object. (See also form hanger.)

hard-burned lime

the product of heating limestone to temperatures sufficient to change the calcium carbonate to calcium oxide, which can undergo expansion when it slowly reacts with water.

hardened concrete

concrete that has developed sufficient strength to serve a defined purpose or resist stipulated loading without failure.

hardener

(1) a chemical (including certain fluosilicates or sodium silicate) applied to concrete floors to reduce wear and dusting; (2) in a two-component adhesive or coating, the chemical component that causes the resin component to cure.

hardening

gain of strength and other properties of a cementitious mixture as a result of hydration after final setting.

Hardy Cross method

see moment distribution.

harped tendons

see draped tendons (preferred term).

harsh mixture

a concrete mixture that lacks desired workability due to a deficiency of mortar or aggregate fines.

haunch

a deepened portion of a beam in the vicinity of a support.

hawk

a tool used by plasterers to hold and carry plaster mortar; generally a flat piece of wood or metal approximately 10 to 12 in. (0.25 to 0.3 m) square with a wooden handle centered and fixed to the underside. (See also hod and mortar board.)

head

a separate piece of steel of any shape firmly attached to the end of a bar or a protuberance of the bar itself at the end, used to anchor a steel reinforcing bar in concrete.

head anchorage capacity

the maximum force that can be transmitted from the head of the bar to the surrounding concrete.

head bearing area

area of the head projected onto a plane orthogonal to the longitudinal axis of the bar minus the bar cross sectional area, representing the contact surface between head and concrete where the bar tensile force is transferred through compression stress.

headed bar

a steel reinforcing bar that has steel head(s) on one or both ends with the purpose of anchoring the bar in concrete.

header

a masonry unit laid flat with its greatest dimension at a right angle to the face of the wall (when the unit is only the depth of the face wythe, it is known as a false header). (See also bonder and wythe [leaf].)

heat of hydration

(1) heat evolved by chemical reactions with water; (2) the difference between the heat of solution of dry cement and that of partially hydrated cement. (See also heat of solution.)

heat of solution

heat evolved or absorbed when a substance is dissolved in a solvent.

heat-deflection temperature

the temperature at which a plastic material has an arbitrary deflection when subjected to an arbitrary load and test condition; this is an indication of the glass-transition temperature.

heating rate

the rate expressed in degrees per hour at which the temperature is raised to the desired maximum temperature.

heavy concrete

see high-density concrete (preferred term).

heavy-media separation

a method in which a liquid or suspension of given specific gravity is used to separate particles into a portion lighter than (those that float) and a portion heavier than (those that sink) the medium.

heavyweight aggregate

aggregate of high density, such as barite, magnetite, hematite, limonite, ilmenite, iron, or steel, used in heavyweight concrete.

heavyweight concrete

see high-density concrete.

helical reinforcement

see spiral reinforcement (preferred term).

hematite

a mineral, iron oxide (Fe_2O_3), used as aggregate in high-density concrete and in finely divided form as a red pigment in colored concrete.

hemihydrate

(1) a hydrate containing one-half molecule of water to one molecule of compound; (2) partially dehydrated gypsum (also known as plaster of paris), CaSO_4·1/2H_2O. (See also bassanite and plaster of paris.)

hesitation setting

see false setting (preferred term).

Hessian

see burlap (preferred term).

high-alumina cement

see calcium-aluminate cement (preferred term).

high-density concrete

concrete of substantially higher density than that made using normal-density aggregates, usually obtained by use of high-density aggregates and used especially for radiation shielding.

high-discharge mixer

see inclined-axis mixer (preferred term).

high-early-strength cement

portland cement characterized by attaining a given level of strength in mortar or concrete earlier than does normal portland cement (referred to as ASTM C150 Type III).

high-early-strength concrete

concrete that, through the use of additional cement, high-early-strength cement, or admixtures, has accelerated early-age strength development.

high-fineness cement

a hydraulic cement of substantially higher specific surface and substantially smaller mean particle diameter than typical for products of similar composition produced by additional grinding or by separation by particle size.

high-lift grouting

a technique in masonry wall construction in which the grouting operation is delayed until the wall has been laid up to a full story height. (See also low-lift grouting.)

high-performance concrete

concrete meeting special combinations of performance and uniformity requirements that cannot always be achieved routinely using conventional constituents and normal mixing, placing, and curing practices.

high-pressure steam curing

see autoclave curing (preferred term).

high-range water-reducing admixture

a water-reducing admixture capable of producing large water reduction or great flowability without causing undue set retardation or entrainment of air in mortar or concrete.

high-strength concrete

concrete that has a specified compressive strength for design of 8000 psi (55 MPa) or greater.

high-strength reinforcement

see high-strength steel.

high-strength steel

steel with a high yield point (in the case of reinforcing bars 60,000 psi [414 MPa] and greater). (See also prestressing steel.)

high-temperature steam curing

see atmospheric-pressure steam curing and autoclave curing

hod

a V-shaped trough or a tray, supported by a pole handle that is borne on the carrier’s shoulder, for carrying small quantities of brick, tile, mortar, or similar load. (See also hawk and mortar board.)

hold-down bolt

anchor bolt provided near the ends of shear walls for transferring boundary-member loads from the shear wall to the foundation. (See also anchor bolt.)

hollow-unit masonry

masonry consisting either entirely or partially of hollow masonry units laid in mortar.

honeycomb

voids left in concrete between coarse aggregates due to inadequate consolidation.

hook

a bend in the end of a reinforcing bar.

Hooke’s law

the law, for strains within the elastic limit, that the strain is proportional to the stress producing it. (See also elastic limit and proportional.)

hooked bar

a reinforcing bar with the end bent into a hook to provide anchorage.

hoop reinforcement

a closed or continuously wound tie, each having hooks meeting seismic detailing requirements.

horizontal shoring

metal or wood load-carrying strut, beam, or trussed section used to carry a shoring load from one bearing point, column, frame, post, or wall to another (may be adjustable).

horizontal-shaft mixer

a mixer having a stationary cylindrical mixing compartment, with the axis of the cylinder horizontal and one or more rotating horizontal shafts to which mixing blades or paddle are attached (also called a pugmill).

hot cement

newly manufactured cement that has not had an opportunity to cool after grinding of the clinker.

hot face

the surface of a refractory section exposed to the source of heat.

hot-load test

a test for determining the resistance to deformation or shear of a refractory material when subjected to a specified compressive load at a specified temperature for a specified time.

Hoyer effect

radial expansion of the prestress material due to its Poisson coefficient caused by the release of pretension.

hydrate

a chemical combination of water with another compound or an element.

hydrated lime

calcium hydroxide, a dry powder obtained by treating quicklime with water.

hydration

the chemical reaction between hydraulic cement and water.

hydraulic cement

a binding material that sets and hardens by chemical reaction with water and is capable of doing so underwater. For example, portland cement and slag cement are hydraulic cements.

hydraulic hydrated lime

the hydrated dry cementitious product obtained by calcining a limestone containing silica and alumina to a temperature short of incipient fusion so as to form sufficient free calcium oxide to permit hydration and at the same time leaving unhydrated sufficient calcium silicates to give the dry powder its hydraulic properties.

hydraulic-cement grout

a grout that is a mixture of hydraulic cement, aggregate, water, and possibly admixtures.

hydromix nozzle

a shotcrete hose and nozzle configuration used in place of a predampening system to introduce pressurized water into the material stream via a water ring.

hydrous calcium chloride (CaCl_2·2H_2O)

a solid, usually 77 percent calcium chloride, in flake form.

I

ignition loss

see loss on ignition (preferred term).

ilmenite

a mineral, iron titanate (FeTiO_3), that, in pure or impure form, is commonly used as aggregate in high-density concrete.

impact hammer

see rebound hammer (preferred term).

impending slough

consistency of a shotcrete mixture containing the maximum amount of water such that the product will not flow or sag after placement.

inclined-axis mixer

a truck with a revolving drum that rotates about an axis inclined to the bed of the truck chassis.

incrustation

a crust or coating, generally hard, formed on the surface of concrete or masonry construction or on aggregate particles.

indented wire

wire having machine-made surface indentations intended to improve bond; depending on type of wire, used for either concrete reinforcement or pretensioning tendons.

initial curing

deliberate action taken between placement and final finishing of concrete to reduce the loss of water from the surface of the concrete.

initial prestress

the prestressing stress (or force) applied to the concrete at the time of stressing.

initial setting

a degree of stiffening of a cementitious mixture less than final set, generally stated as an empirical value indicating the time required for the cementitious mixture to stiffen sufficiently to resist, to an established degree, the penetration of a weighted test device. (See also final setting.)

initial setting time

the time required for a freshly mixed cement paste, mortar, or concrete to achieve initial setting. (See also final setting time.)

initial stresses

the stresses occurring in prestressed-concrete members before any losses occur.

insert

anything other than reinforcing steel that is rigidly positioned within a concrete form for permanent embedment in the hardened concrete.

in-situ concrete

see cast-in-place concrete (preferred term).

insoluble residue

the portion of a cement or aggregate that is not soluble in dilute hydrochloric acid of stated concentration.

insulating concrete

concrete having low thermal conductivity. (See also lightweight concrete and low-density concrete.)

internal curing

process by which the hydration of cement continues because of the availability of internal water that is not part of the mixing water.

internal vibration

see vibration.

inverted L-beam

a beam having a cross section in the shape of an inverted L. (See also L-beam.)

inverted T-beam

a beam having a cross section in the shape of an inverted T. (See also T-beam.)

I-section

beam cross section consisting of top and bottom flanges connected by a vertical web.

isolation joint

a separation between adjacent sections of a concrete structure to allow relative movement in three directions and through which all of the bonded reinforcement is interrupted.

J

jacking device

(1) the device used to stress the tendons for prestressed concrete; (2) the device for raising a vertical slipform.

jacking force

in prestressed concrete, the temporary force exerted by the device that introduces tension into the tendons.

jacking stress

the maximum stress occurring in a prestressed tendon during stressing.

jaw crusher

a machine having two inclined jaws, one or both being actuated by a reciprocating motion so that the charge is repeatedly nipped between the jaws.

jitterbug

a grate tamper for pushing coarse aggregate slightly below the surface of a slab to facilitate finishing. (See also tamper.)

joint

(1) a physical separation in a concrete system, whether precast or cast-in-place, including cracks if intentionally made to occur at specified locations; (2) the region where structural members intersect.

joint filler

compressible material used to fill a joint to prevent the infiltration of debris and provide support for sealants applied to the joint.

joint sealant

compressible material used to exclude water and solid foreign materials from joints.

joint spall

a spall adjacent to a joint.

jointed detail

a connection where the bending stiffness differs from that of the members and requires special design to collect, transfer, and redistribute forces from one member to another through the connection.

jointer (concrete)

a metal tool used to cut a joint in fresh concrete.

jointing

the process of producing joints in a concrete slab.

joint-sealing compound

an impervious material used to fill joints in pavements or structures.

joist

a comparatively narrow beam used in closely spaced arrangements to support floor or roof slabs.

K

kaolinite

a common clay mineral having the general formula Al_2(Si_2O_5)(OH_4) and the primary constituent of kaolin.

Kelly ball

(1) an apparatus used for indicating the consistency of fresh concrete in accordance with ASTM C360 (withdrawn); (2) an apparatus used for determining suitability for load application in controlled low strength material (CLSM) in accordance with ASTM D6024. (See also ball test.)

kern area

the area within a geometric shape in which a compressive force may be applied without tensile stresses resulting in any of the extreme fibers of the section.

key

see keyway.

keyway

a recess or groove in one lift or placement of concrete that is filled with concrete of the next lift, giving shear strength to the joint. (See also tongue and groove.)

kick strip

see kicker.

kicker

a wood block or board attached to a formwork member in a building frame or formwork to make the structure more stable.)

kiln

a furnace or oven for drying, charring, hardening, baking, calcining, sintering, or burning various materials.

L

lacing

horizontal bracing between shoring members.

lagging

heavy sheathing used in underground work to withstand earth pressure. (See also sheathing.)

laitance

a layer of weak material derived from cementitious material and aggregate fines either: (1) carried by bleeding to the surface or to internal cavities of freshly placed mixture; (2) separated from the mixture and deposited on the surface or internal cavities during placement of the mixture.

lap

the length by which one bar or sheet of reinforcement overlaps another.

lap splice

a connection of reinforcing steel made by lapping the ends of bars.

lapping (reinforcing steel)

the overlapping of reinforcing steel bars, welded-wire reinforcement, or expanded metal so that there may be continuity of stress in the reinforcing when the concrete member is subjected to loading.

lateral reinforcement

transverse reinforcement usually applied to ties, hoops, and spirals used to enclose reinforcement in columns or column-like members.

latex

a dispersion of organic polymer particles in water.

layer

see course and lift.

L-beam

(1) a beam having a cross section in the shape of an L; (2) a beam having a ledge on one side only.

leaf

see wythe (leaf).

lean concrete

concrete of low cementitious material content.

lean mixture

see lean concrete.

ledger

any member with a protrusion or protrusions that support other structural members. (See also L-beam and inverted T-beam.)

length change

increase or decrease in length. (See also volume change and deformation.)

lever arm

(1) in a structural member, the distance from the center of the tensile reinforcement to the center of action of the compression zone; (2) the perpendicular distance of a transverse force from a point about which moment is taken.

licensed design professional

(1) an engineer or architect who is licensed to practice structural design as defined by the statutory requirements of the professional licensing laws of a state or jurisdiction; (2) the architect or engineer, licensed as described, who is responsible for the structural design of a particular project (also historically engineer of record).

lift

the concrete placed between two consecutive horizontal construction joints, usually consisting of several layers or courses.

lift joint

surface at which two successive lifts meet.

lift slab

(1) a method of concrete construction in which floor and roof slabs are cast on or at ground level and hoisted into position by jacking; (2) a slab that is a component of such construction.

lightweight aggregate

aggregate of low density such as (1) expanded or sintered clay, shale, slate, diatomaceous shale, perlite, vermiculite, or slag; (2) natural pumice, scoria, volcanic cinders, tuff, and diatomite; (3) sintered fly ash or industrial cinders.

lightweight concrete

concrete of substantially lower density than that made using aggregates of normal density; consists entirely of lightweight aggregate or a combination of lightweight aggregate and normal-density aggregate; its equilibrium densities are generally between 70 and 120 lb/ft^3 (1120 and 1920 kg/m^3). (See also insulating concrete and low-density concrete.)

lime

specifically, calcium oxide (CaO), loosely, a general term for the various chemical and physical forms of quicklime, hydrated lime, and hydraulic hydrated lime. (See also hydrated lime, hydraulic hydrated lime, and quicklime.)

limestone

a sedimentary rock consisting primarily of calcium carbonate.

limit design

a method of proportioning reinforced-concrete members based on calculation of their strength. (See also strength-design method.)

limonite

an iron ore composed of a mixture of hydrated ferric oxides occasionally used in heavyweight concrete because of its high density and combined-water content, which contribute to its effectiveness in radiation shielding; a mineral occurring commonly as a constituent of particles of natural aggregate.

linear transformation

the method of altering the path of the prestressing tendon in any statically indeterminate prestressed structure by changing the location of the tendon at one or more interior supports without altering its position at the end supports and without changing the basic shape of the path between any supports (does not change the location of the path of the pressure line).

linear-traverse method

determination of the volumetric composition of a solid by integrating the distance traversed across areas of each component along a line or along regularly spaced lines in one or more planes intersecting a sample of the solid; frequently employed to determine characteristics of the air-void system in hardened concrete by microscopical examination along a series of traverse lines on finely ground sections of the concrete (also called the Rosiwal method). (See also point count method and point count method [modified].)

lining

any sheet, plate, or layer of material attached directly to the inside face of formwork to improve or alter the surface texture and quality of the finished concrete. (See also form lining, tunnel lining, and sheathing.)

lintel

a horizontal supporting member above an opening, such as a window or a door.

live load

(1) load that is not permanently applied to a structure but is likely to occur during the service life of the structure (excluding environmental loads); (2) loads meeting specific criteria found in the governing building code (without load factors).

load balancing

a technique used in the design of prestressed-concrete members in which the amount and path of the prestressing is selected so that the forces imposed upon the member or structure by the prestressing counteract or balance a portion of the dead and live loads for which the member or structure must be designed.

load factor

a factor by which a service load is multiplied to determine a factored load used in the strength-design method.

load-bearing wall

a wall designed and built to carry superimposed vertical loads, in-plane and shear loads, or both. (See also nonbearing wall.)

long column

a column whose load capacity is limited by buckling rather than strength. (See also slender column.)

longitudinal bar

see longitudinal reinforcement (preferred term).

longitudinal crack

a crack that develops parallel to the length of a member.

longitudinal joint

a joint parallel to the length of a structure or pavement.

longitudinal reinforcement

reinforcement parallel to the length of a concrete member or pavement.

Los Angeles abrasion test

test for abrasion resistance of concrete aggregates.

loss of prestress

(1) the reduction in the prestressing force that results from the combined effects of slip at anchorage; (2) relaxation of steel stress; (3) frictional loss due to curvature in the tendons; (4) the effects of elastic shortening, creep, and shrinkage of the concrete.

loss on ignition

the percentage loss in mass of a sample ignited to constant mass at a specified temperature, usually 1650 to 1830°F (900 to 1000°C).

low-alkali cement

(1) a portland cement that contains a relatively small amount of sodium, potassium, or both; (2) in ASTM C150, a portland cement containing not more than 0.60 percent Na_2O equivalent, that is, percent Na_2O + 0.658   percent K_2O.

low-density concrete

concrete having an oven-dry density of less than 50 lb/ft^3 (800 kg/m^3). (See also insulating concrete and lightweight concrete.)

low-heat cement

a portland cement for use when a low heat of hydration is desired, referred to as ASTM C150 Type IV cement.

low-lift grouting

a technique of masonry wall construction in which the wall sections are built to a height of not more than 5 ft (1.7 m) before the cells of the masonry units are filled with grout. (See also high-lift grouting.)

low-pressure steam curing

see atmospheric-pressure steam curing (preferred term).

low-strength materials

see controlled low-strength material (preferred term).

M

machine-base grout

a grout that is used in the space between plates or machinery and the underlying foundation and that is expected to maintain complete contact with the base and to maintain uniform support.

macrofiber

a fiber with an equivalent diameter greater than or equal to 0.012 in. (0.3 mm) for use in concrete.

macroscopic

visible to the naked eye.

magnetite

a mineral, ferrous ferric oxide (FeO·Fe_2O_3), the principal constituent of magnetic black iron ore with a density of approximately 5.2 g/cc (325 lb/ft^3)and Mohs hardness of approximately 6 that is used as an aggregate in high-density concrete.

manual batcher

see batcher (1).

manufactured sand

see sand.

map cracking

intersecting cracks that extend below the surface of hardened concrete that vary in width from fine and barely visible to open and well-defined (also called pattern cracking). (See also checking and crazing.)

marble

a metamorphic rock composed essentially of recrystallized calcite, dolomite, or both.

mason

an artisan who builds with concrete masonry units, bricks, stone, and tile; name sometimes given to a concrete finisher.

masonry

construction composed of shaped or molded units, usually small enough to be handled by one person and composed of stone, ceramic brick or tile, concrete, glass, adobe, or the like.

masonry cement

a hydraulic cement used for masonry and plastering construction, containing one or more of the following materials: portland cement, portland-pozzolan cement, natural cement, slag cement, or hydraulic hydrated lime, and, in addition, usually contains one or more materials such as hydrated lime, limestone, chalk, calcareous shell, talc, slag, or clay as prepared for this purpose.

masonry grout

a mixture of hydraulic cement, aggregate, water, and possibly other materials (ASTM C476) used for filling designated spaces in masonry construction.

masonry lift

the height to which masonry is laid between periods of grouting.

mass

(1) the physical property of matter that causes it to have weight in a gravitational field; (2) the quantity of matter in a body.

mass concrete

any volume of concrete in which a combination of dimensions of the member being cast, the boundary conditions can lead to undesirable thermal stresses, cracking, deleterious chemical reactions, or reduction in the long-term strength as a result of elevated concrete temperature due to heat from hydration.

mass density

see density.

mat

(1) an assembly of steel reinforcement composed of two or more layers of bars placed at angles to each other and secured together either by welding or tying; (2) a thin layer of randomly oriented chopped filaments, short fibers (with or without a carrier fabric), or long random filaments loosely held together with a binder and used as reinforcing for a fiber-reinforced polymer composite material.

mat foundation

a foundation consisting of a continuous concrete slab extending in both directions that is usually reinforced and supports an array of columns, walls, or both.

material hose

see delivery hose.

matrix

(1) the cement paste in which the fine aggregate particles in mortar are embedded; (2) the mortar in which the coarse aggregate particles in concrete are embedded; (3) the resin or binders that hold the fibers in fiber-reinforced polymer together, transfer load to the fibers, and protect them against environmental attack and damage due to handling.

maturity factor

a factor that is a function of the age of the concrete (hours or days) multiplied by the difference between the mean temperature of the concrete (degrees) during curing and a datum temperature below which hydration stops. (See also temperature-time factor.)

maximum size (of aggregate)

in specifications for and in description of aggregate, the smallest sieve opening through which the entire amount of aggregate is required to pass. (See also nominal maximum size [of aggregate].)

mean stress

the average of the maximum and minimum stress in one cycle of fluctuating loading.

mechanical anchorage

any mechanical device capable of developing the specified yield strength of the reinforcement without damage to the concrete.

mechanical bond

interlock created when a fresh cementitious mixture is placed and hardens to conform to the surface texture of the existing solid material.

mechanical connection

the complete assembly of an end-bearing sleeve, a coupler, or a coupling sleeve, and possibly additional intervening material or other components to effect connection of reinforcing bars. (See also bar-end check, coupler, coupling sleeve, and end-bearing sleeve.)

mechanical lap splice

complete assembly of a coupling sleeve device and any additional components configured to accomplish positive splicing of overlapping reinforcing bars.

megascopic

see macroscopic (preferred term).

melilite

a group of minerals ranging from the calcium magnesium silicate (akermanite) to the calcium aluminate silicate (gehlenite) that occur as crystals in blast-furnace slag. (See also gehlenite and merwinite.)

melt

the molten portion of the raw material mass during the burning of cement clinker, firing of lightweight aggregates, or expanding of blast-furnace slags.

membrane curing

a process that involves the application of a liquid membrane-forming compound or covering with a protective sheet material, both of which function as a barrier to restrict evaporation of mixing water from concrete surfaces.

membrane theory

a theory of design for thin shells, based on the premise that a shell cannot resist bending because it deflects; the only stresses that exist, therefore, in any section are shear stress and direct compression or tension.

merwinite

one of the principal crystalline phases found in blast-furnace slags. (See also gehlenite and melilite.)

mesh reinforcement

see welded-wire reinforcement and woven-wire reinforcement.

mesh roller

a finishing tool consisting of a rolling drum attached to a handle of which the surface of the drum is made of mesh, sometimes used for rolling over the surface of fresh concrete to embed coarse aggregate.

Mesnager hinge

a permanent semiarticulation or flexible joint in a reinforced-concrete arch wherein the angles of rotation at the hinge are very small; by crossing steel reinforcing bars within the opening between the concrete structural segments, the resultant articulation presents very small resistance to rotation, resists either axial thrust or shearing forces, and is permanently flexible; the center of rotation occurs at the intersection of the reinforcing bars.

metakaolin

a natural pozzolan produced by heating kaolin-containing clays.

microconcrete

a mixture of portland cement, water, and suitably graded sand for simulating concrete in small-scale structural models.

microcracks

small, numerous cracks that develop in hardened concrete.

microfiber

a fiber with an equivalent diameter less than 0.012 in. (0.3 mm) for use in concrete.

microscopic

discernible only with the aid of a microscope.

microsilica

see silica fume (preferred term).

middle strip

in flat-slab framing, the slab portion that occupies the middle half of the span between columns. (See also column strip.)

mill scale

the partially adherent layers of oxidation products (heavy oxides) developed on metallic surfaces during either hot fabrication or heat treatment of metals, as on hot-rolled steel reinforcing bars.

mineral aggregate

aggregate consisting essentially of inorganic nonmetallic rock materials, either natural or crushed and graded.

mineral filler

a finely divided mineral product at least 65 percent of which passes the 75 µm (No. 200) sieve. (See also silt.)

minimum film-forming temperature

the minimum temperature at which a synthetic latex or emulsion will coalesce when laid on a substrate as a thin film.

mix (n.)

see mixture.

mix design

see mixture proportion (preferred term).

mixer

a machine used for blending the constituents of concrete, grout, mortar, cement paste, or other mixture.

mixer efficiency

the adequacy of a mixer in rendering a homogeneous product within a stated period.

mixing cycle

the time taken for a complete cycle in a batch mixer, that is, the time elapsing between successive repetitions of the same operation (for example, successive discharges of the mixer).

mixing plant

see batch plant (preferred term).

mixing speed

rotation rate of a mixer drum or of the paddles in an open-top, pan, or trough mixer when mixing a batch, expressed in revolutions per minute (rpm) or in peripheral feet per minute (meters per minute) of a point on the circumference at maximum diameter.

mixing time

the period during which the constituents of a batch of concrete are mixed by a mixer; for a stationary mixer, time is given in minutes from the completion of mixer charging until the beginning of discharge; for a truck mixer, time is given in total minutes at a specified mixing speed or expressed in terms of total revolutions at a specified mixing speed. (See also amount of mixing.)

mixing water

the water in freshly-mixed cementitious mixtures, exclusive of any previously absorbed by the aggregate (also called batch water or batched water.) (See also water-cement ratio and surface moisture.)

mixture

(1) the assembled, blended, commingled ingredients of mortar, concrete, or the like; (2) the proportions for their assembly.

mixture proportion

the proportions of ingredients that make the most economical use of available materials to produce mortar or concrete of the required properties. (See also proportion.)

mobile placer

a small belt conveyor mounted on wheels or a truck that can be readily moved to the job site for conveying concrete from the concrete truck to the forms or slab.

mobility

the ability of fresh concrete or mortar to flow.

moderate exposure condition

an environment, normally in temperate climate regions, in which concrete will only occasionally be exposed to moisture and will not be saturated before freezing and where no deicing agents or other aggressive chemicals are used.

moderate sulfate-resisting cement

a portland cement for use when either moderate sulfate resistance, moderate heat of hydration, or both is desired, now referred to as ASTM C150 Type II cement.

modified cement

(obsolete) a portland cement for use when either moderate heat of hydration, moderate sulfate resistance, or both, is desired, now referred to as ASTM C150 Type II cement.

modified cube

a portion of a rectangular beam of hardened concrete previously broken in flexure, used in determining the compressive strength of the concrete.

modified portland cement

(obsolete) a portland cement having moderate heat of hydration; this term was replaced by ASTM C150 Type II cement beginning in 1960. (See also modified cement.)

modular ratio

the ratio of modulus of elasticity of steel Es to that of concrete Ec usually denoted by the symbol n.

modulus of resilience

see resilience.

modulus of rupture

the calculated apparent tensile stress in the extreme tension fiber of a plain concrete beam test specimen under flexure at the load that produces rupture. (See also flexural strength.)

modulus of subgrade reaction

ratio of the load per unit area of soil to the corresponding settlement of the soil, typically evaluated in place per ASTM D1196 (also called coefficient of subgrade reaction).

Mohs scale

relative scale of the hardness of minerals ranging from 1 through 10.

moist cabinet

an upright and compartmented case having doors and shelves of moderate dimensions for storing and curing small test specimens of cement paste, mortar, and concrete in an atmosphere of approximately 73°F (23°C) and at least 95 percent relative humidity. (See also moist room.)

moist room

a room with controlled temperature and relative humidity for the purpose of curing and storing cementitious test specimens (also called a fog room).

moisture barrier

see vapor barrier.

moisture content of aggregate

the ratio expressed as a percentage of the mass of water in a given quantity of aggregate to the dry mass of that quantity of aggregate.

moisture-free

the condition of a material that has been dried in air until there is no further significant change in its mass. (See also mass.)

mold

(1) a device containing a cavity into which neat cement, mortar, or concrete test specimens are cast; (2) a form used in the fabrication of precast mortar or concrete units (for example, masonry units).

moment distribution

a method of structural analysis for continuous beams and rigid frames whereby successive converging corrections are made to an assumed set of moments until the desired precision is obtained (also called the Hardy Cross method).

monolithic concrete

concrete cast with no joints other than construction joints.

monolithic surface treatment

see dry-shake.

monolithic topping

on flatwork, a higher quality, more serviceable topping course placed promptly after the base course has lost all slump and bleed water.

monomolecular

composed of single molecules; specifically, films that are one molecule thick; denotes a thickness equal to one molecule, for example, certain chemical compounds develop a monomolecular film over bleeding water at the surface of freshly placed concrete or mortar as a means of reducing the rate of evaporation. (See also evaporation retardant.)

montmorillonite

a swelling clay mineral of the smectite group; main constituent of bentonite. (See also smectite.)

mortar

a mixture of cement paste and fine aggregate; in fresh concrete, the material occupying the interstices among particles of coarse aggregate; in masonry construction, joint mortar may contain masonry cement, or may contain hydraulic cement with lime (and possibly other admixtures) to afford greater plasticity and workability than are attainable with standard portland cement mortar. (See also hydraulic cement and masonry.)

mortar board

a platform or tray for holding freshly mixed mortar. (See also hawk and hod.)

mortar-flow

see flow (2).

mosaic

inlaid exposed surface designs of aggregates or other material.

mottling

uneven color shading or blotchiness across a surface. (See also discoloration.)

moving forms

large prefabricated units of formwork incorporating supports and designed to be moved horizontally on rollers or similar devices with a minimum amount of dismantling between successive uses.

mud mat

a layer of concrete beneath a structural concrete floor or footing over soft, wet soil.

mud pumping

see pumping (of pavements).

mudjacking

see slab-jacking (preferred term).

multielement prestressing

prestressing accomplished by stressing an assembly of several individual structural elements as a means of producing one integrated structural member.

N

nailer

a strip of wood or other fitting attached to or set in concrete or attached to steel to facilitate making nailed connections.

natural cement

a hydraulic cement produced by calcining an argillaceous limestone at a temperature below the sintering point and then grinding to a fine powder.

natural pigment

the class of pigments that are produced by physical processing of materials mined directly from the earth (also called natural or mineral pigments or colors).

natural pozzolan

a raw or calcined natural material that has pozzolanic properties.

natural sand

sand resulting from natural disintegration and abrasion of rock. (See also sand and fine aggregate.)

neat cement grout

a fluid mixture of hydraulic cement and water with or without other ingredients.

neat cement paste

a mixture of hydraulic cement and water.

neat plaster

plaster without sand.

negative moment

a condition of flexure in which top fibers of a horizontally placed member, or external fibers of a vertically placed exterior member, are subjected to tensile stresses.

negative reinforcement

steel reinforcement for negative moment.

net cross-sectional area (of masonry)

the gross cross-sectional area of a section of masonry minus the area of cavities, cells, or cored spaces.

net mixing water

see mixing water.

neutral axis

a line in the plane of a structural member subject to bending where the longitudinal stress is zero.

neutral refractory

a refractory that is resistant to chemical attack by either acidic or basic substances.

no-fines concrete

a concrete mixture containing little or no fine aggregate. (See pervious concrete.)

nominal flexural strength

the flexural strength of a member or cross section calculated in accordance with provisions and assumptions of the strength-design method before application of any strength-reduction (Φ) factor.

nominal maximum size (of aggregate)

in specifications for and in descriptions of aggregate, the smallest sieve opening through which the entire amount of the aggregate is permitted to pass. (See also maximum size [of aggregate].)

nominal shear strength

the shear strength of a member or cross section calculated in accordance with provisions and assumptions of the strength-design method before application of any strength-reduction (Φ) factor.

nominal size

see nominal maximum size (of aggregate).

nominal strength

strength of a member or cross section calculated in accordance with provisions and assumptions of the strength design method before application of any strength-reduction (Φ) factor.

nominal strength reduction factor

the factor by which the nominal strength is multiplied to obtain the design strength.

nonagitating unit

a truck-mounted container for transporting central-mixed concrete not equipped to provide agitation (slow mixing) during delivery.

non-air-entrained concrete

concrete in which neither an air-entraining admixture nor air-entraining cement has been used.

nonbearing wall

a wall that supports no vertical load other than its own weight and no in-plane shear loads. (See also load-bearing wall.)

noncombustible

any material that neither ignites nor supports combustion in air when exposed to fire.

nonevaporable water

the water that is chemically combined during cement hydration. (See also evaporable water.)

nonferrous

relating to metals other than iron, not containing or including iron.

nonprestressed reinforcement

reinforcing steel not subjected to either pretensioning or post-tensioning.

nonrecoverable creep

the residual or nonreversible deformation remaining in hardened concrete after removal of sustained load.

nontilting mixer

a horizontal rotating drum mixer that charges, mixes, and discharges without tilting.

nonvolatile content

the portion of a material that remains after volatile matter has been evaporated under specified ambient or accelerated conditions.

normal cement

general purpose portland cement, referred to as ASTM C150 Type I cement.

normal consistency

the consistency of cement paste satisfying appropriate limits defined in a standard test method, for example, ASTM C187.

normal portland cement

see normal cement.

normal stress

the stress component that is perpendicular to the plane on which the force is applied, designated tensile if the force is directed away from the plane and compressive if the force is directed toward the plane. (See also stress.)

normalweight aggregate

aggregate that is neither heavyweight nor lightweight.

normalweight concrete

concrete having a density of approximately 150 lb/ft^3 (2400 kg/m^3) made with normal-density aggregates.

no-slump concrete

freshly mixed concrete exhibiting a slump of less than 1/4 in. (6 mm). (See also zero-slump concrete.)

nozzle

a metal or rubber tip attached to the discharge end of a heavy thick-walled rubber hose from which a continuous stream of shotcrete is ejected at high velocity.

nozzle liner

a replaceable rubber lining fitted into the nozzle tip to prevent abrasion of the interior surface of the nozzle.

nozzle operator

the technician who manipulates the nozzle of a placing machine and controls placement of the shotcrete.

nozzle velocity

the rate at which shotcrete is ejected from the nozzle.

O

obsidian

a natural volcanic glass of relatively low water content, usually of rhyolite composition. (See also perlite.)

offset

(1) an abrupt change in alignment or dimension, either horizontally or vertically; (2) a horizontal ledge occurring along a change in wall thickness of the wall above.

offset bend

(1) an intentional distortion from the normal straightness of a steel reinforcing bar to move the center line of a segment of the bar to a position parallel to the original position of the center line; (2) a mechanical operation commonly applied to vertical bars that reinforce concrete columns.

offset yield strength

the stress at which the strain exceeds, by a specified amount, an extension of the initially proportional part of the stress-strain curve.

oil-well cement

hydraulic cement suitable for use under high pressure and temperature in sealing water and gas pockets and setting casing during the drilling and repair of wells, and often contains retarders to meet the requirements of use.

one-way system

the arrangement of steel reinforcement within a slab that presumably bends in only one direction.

opal

a mineral composed of amorphous hydrous silica (SiO_2·nH_2O).

opaline chert

chert composed entirely or mainly of opal.

open-graded aggregate

aggregate where the voids between the particles are relatively large when compacted.

open-top mixer

a truck-mounted mixer consisting of a trough or a segment of a cylindrical mixing compartment within which paddles or blades rotate about the horizontal axis of the trough. (See also horizontal-shaft mixer.)

ordinary portland cement

the term used in the United Kingdom and elsewhere to designate the equivalent to ASTM C150 Type I cement.

orthotropic

a hypothetical plate consisting of beams and a slab acting together with different flexural rigidities in the longitudinal and transverse directions, as in a composite beam bridge. (This term is a contraction of the terms “orthogonal anisotropic” as in the phrase “orthogonal anisotropic plate.”)

oven-dry

the condition resulting from having been dried to essentially constant mass in an oven at a temperature that has been fixed.

oven-dry specific gravity

the ratio of the mass of a volume of a material (including the permeable and impermeable pores in the material but not including the voids between particles of the material) at a stated temperature to the mass of an equal volume of distilled water at a stated temperature. (Historically called bulk specific gravity.)

overlay

a layer of concrete or mortar placed on a concrete slab to either restore or improve the function of the previous surface.

oversanded

containing more sand than would be necessary to produce adequate workability and a satisfactory condition for finishing.

overvibration

excessive use of vibrators during placement of freshly mixed concrete causing segregation, stratification, and excessive bleeding.

owner

the corporation, association, partnerships, individual, or public body or authority with whom the contractor enters into an agreement and for whom the work is provided.

P

pack setting

see sticky cement and warehouse setting.

packaged concrete, mortar, or grout

mixtures of dry ingredients in packages, requiring only the addition of water to produce concrete, mortar, or grout.

packer

a device inserted into a hole in which grout is to be injected that acts to prevent return of the grout around the injection pipe, usually an expandable device actuated mechanically, hydraulically, or pneumatically.

packerhead process

a process for producing concrete pipe that uses a rotating device that forms the interior surface of the pipe as concrete is fed into the form from above. (See also centrifugal process, dry-cast process, tamp process, and wet-cast process.)

paddle mixer

see open-top mixer (preferred term).

pan

(1) a prefabricated form unit used in concrete joist floor construction; (2) a container that receives particles passing the finest sieve during sieve analysis of granular materials.

pan mixer

see vertical-shaft mixer (preferred term).

panel

(1) a section of form sheathing that can be erected and stripped as a unit; (2) a concrete element that is relatively thin with respect to other dimensions and is bordered by joints or edges; (3) a region of a suspended slab system bounded by column, beam, or wall centerlines.

panel strip

a strip extending across the length or width of a flat slab for structural design and construction or for architectural purposes.

parapet

(1) the part of a wall that extends above the roof level; (2) a low wall along the top of a dam.

parge

to coat with plaster, particularly foundation walls and rough masonry. (See also back plastering.)

partial prestressing

prestressing to a stress level such that, under design loads, tensile stresses exist in the precompressed tensile zone of the prestressed member.

particle shape

the form of a particle. (See also elongated piece [of aggregate], and flat piece [of aggregate].)

particle-size distribution

see grading.

parting agent

see release agent (preferred term).

pass

layer of shotcrete placed in one movement over the area of operation.

paste

see neat cement paste.

paste content

amount of cement paste in concrete, mortar, or the like, expressed as volume percent of the entire mixture. (See also neat cement paste.)

paste volume

see paste content.

pattern cracking

see crack, craze cracks, and map cracking.

pattern cracks

see crack, craze cracks, and map cracking.

patterned ashlar

see ashlar masonry.

pavement (concrete)

a layer of concrete on such areas as roads, sidewalks, canals, playgrounds, and those used for storage or parking. (See also rigid pavement.)

paving train

an assemblage of equipment designed to place and finish a concrete pavement.

pea gravel

screened gravel, most of the particles of which pass a 9.5 mm (3/8 in.) sieve and are retained on a 4.75 mm (No. 4) sieve.

peak load

the highest load sustained by a specimen or structural element during a test.

peak load strength

strength computed using the peak load.

pedestal

compression member with a ratio of height-to-least lateral dimension less than or equal to three.

peeling

a process in which thin flakes of mortar are broken away from a concrete surface, such as by deterioration or by adherence of surface mortar to forms as forms are removed.

pencil rod

plain metal rod of approximately 1/4 in. (6 mm) diameter.

penetration

an opening through which pipe, conduit, or other item passes through a wall or floor.

penetration probe

a device for obtaining an indirect measure of the concrete compressive strength by measuring the resistance of concrete to penetration, customarily determined by the distance that a steel pin is driven into the concrete from a special gun by a precisely measured explosive charge.

penetration resistance

(1) the resistance of fresh mortar or cement paste to penetration by a plunger or needle under standard conditions used to determine time of setting; (2) the resistance of hardened concrete to penetration by a steel rod driven into the surface by a high-powered driver.

percent fines

(1) the amount, expressed as a percentage, of material in aggregate finer than a given sieve, usually the 75 µm (No. 200); (2) the amount of fine aggregate in a concrete mixture expressed as a percent by absolute volume of the total amount of aggregate.

percentage of reinforcement

the ratio of cross-sectional area of reinforcing steel to the effective cross-sectional area of a member, expressed as a percentage.

performance-based specification

a specification in which the requirements are stated in terms of required results with criteria for verifying compliance rather than specific composition, design, or procedure.

periclase

a crystalline mineral, magnesia (MgO), the equivalent of which may be present in portland-cement clinker, portland cement, and other materials such as open-hearth slags and certain basic refractories.

perlite

a volcanic glass having a perlitic structure, usually having a higher water content than obsidian and, when expanded by heating, used as an insulating material and as a lightweight aggregate in concretes, mortars, and plasters.

permanent setting

inelastic elongation or shortening.

permeability

the ability of a given concrete to permit liquids or gases to pass through.

pervious concrete

concrete containing little, if any, fine aggregate that results in sufficient voids to allow air and water to pass easily from the surface to underlying layers.

pervious pavement

a pavement comprising material with sufficient continuous voids to allow water to pass from the surface to the underlying layers.

petrography

(1) the branch of petrology dealing with description and systematic classification of rocks aside from their geologic relations, mainly by laboratory methods, largely chemical and microscopical (also, loosely, petrology or lithology); (2) laboratory study of concrete and mortar samples to determine various characteristics including, but not limited to, w/c, paste-aggregate bond, and air content.

petrology

the science of rocks, treating of their origin, structure, and composition from aspects and in all relations. (See also petrography.)

phenolic resin

a class of synthetic, oil-soluble resins (plastics) produced as condensation products of phenol, substituted phenols and formaldehyde, or some similar aldehyde that may be used in paints for concrete.

phi (Φ) factor

see nominal strength reduction factor (preferred term).

Philleo factor

a distance, used as an index of the extent to which hardened cement paste is protected from the effects of freezing, so selected that only a small portion of the cement paste (usually 10 percent) lies farther than that distance from the perimeter of the nearest air void. (See also protected paste volume.)

pier

(1) a slender isolated foundation member of either plain or reinforced concrete that is cast on end in the ground; (2) an isolated vertical masonry member whose horizontal dimension measured at right angles to its thickness is not less than three times its thickness nor greater than six times its thickness and whose height is less than five times its length.

pigment

a coloring matter, usually in the form of an insoluble fine powder.

pilaster

column built with a wall, usually projecting beyond the wall.

pile

a slender structural element that is driven, jetted, or otherwise embedded on end in the ground to support a load or compact the soil. (See also composite pile.)

pile bent

two or more piles driven in a row transverse to the long dimension of the structure and fastened together by capping and (sometimes) bracing.

pile cap

a structural member that is placed on top of a group of piles and used to transmit loads from the structure through the pile group into the soil.

pipe column

column made of steel pipe, often filled with concrete.

pipe pile

a steel pipe generally driven with open ends to firm bearing and then excavated and filled with concrete.

pitting

development of relatively small cavities in a surface; in concrete, localized disintegration, such as a popout; in steel, localized corrosion evident as minute cavities on the surface.

placeability

see workability.

placement

(1) the process of placing and consolidating concrete; (2) a quantity of concrete placed and finished during a continuous operation (often inappropriately referred to as pouring).

placing

the deposition, distribution, and consolidation of freshly mixed concrete in the place where it is to harden (often inappropriately referred to as pouring).

plain bar

a reinforcing bar without surface deformations, or one having deformations that do not conform to the applicable requirements.

plain concrete

structural concrete with no reinforcement or with less reinforcement than the minimum amount specified for reinforced concrete in the applicable building code.

plain masonry

(1) masonry without reinforcement; (2) masonry reinforced only for shrinkage or thermal change.

plain pavement

unreinforced concrete pavement.

plane of weakness

the plane along which a body under stress will tend to fracture and which may exist by design, by accident, or because of the nature of the structure and its loading.

plaster

(1) a mixture consisting essentially of a cementitious material or materials, fine aggregate, and water that forms a cohesive and workable mass; (2) the act of placing such material. (See also stucco.)

plaster of paris

gypsum, CaSO_4·1/2H_2O, from which three-quarters of the chemically bound water has been driven off by heating. (See also hemihydrate and bassanite.)

plastic

possessing plasticity adequate plasticity. (See also plasticity.)

plastic cement

a cement manufactured for plaster and stucco applications consisting of a blend of cement and lime that may include pozzolans, fillers, or additives to increase plasticity, workability, and crack resistance of the cement and the plaster.

plastic consistency

the consistency at which a mixture subjected to a constant shearing stress undergoes increasing deformation without rupture.

plastic flow

see creep and stress relaxation.

plastic hinge

region where ultimate moment capacity in a member may be developed and maintained with corresponding significant inelastic rotation as main tensile steel elongates beyond yield strain.

plastic shrinkage

shrinkage that takes place before cement paste, mortar, grout, or concrete sets.

plasticity

the property of freshly mixed cement paste, concrete, or mortar that determines its resistance to deformation or ease of molding.

plasticity index (PI)

the range of water content in which a soil remains plastic, evaluated as the numerical difference between liquid limit and plastic limit, as calculated according to ASTM D4318 (also called plasticity).

plasticizer

(1) a material that increases the plasticity of a fresh cementitious mixture; (2) a substance added to a material to improve the material’s flexibility.

plastic-shrinkage crack

surface crack that occurs in concrete before initial set.

plumb

vertical or to make vertical.

pneumatically applied mortar

see shotcrete.

point count method

method for determination of the volumetric composition of a solid by observation of the frequency with which areas of each component coincide with a regular system of points in one or more planes intersecting a sample of the solid. (See also linear-traverse method.)

point count method (modified)

the point count method supplemented by a determination of the frequency with which areas of each component of a solid are intersected by regularly spaced lines in one or more planes intersecting a sample of the solid.

point load

a load whose area of contact with the resisting body is negligible in comparison with the area of the resisting body.

point of contraflexure

see point of inflection (preferred term).

point of inflection

the point on the length of a structural member subjected to flexure where the bending moment is zero and the curvature changes from concave to convex or convex to concave (also called point of contraflexure).

Poisson’s ratio

the absolute value of the ratio of transverse strain to the corresponding longitudinal strain resulting from uniformly distributed axial stress below the proportional limit of the material.

polarizing microscope

a microscope equipped with elements permitting observations and determinations to be made using polarized light.

polish or final grind

the final operation in which fine abrasives are used to hone a surface to its desired smoothness and appearance.

polyethylene

a thermoplastic high-molecular-weight organic compound used in formulating protective coatings or, in sheet form, as a protective cover for concrete surfaces during the curing period, or to provide a temporary enclosure for construction operations.

polymer

the product of polymerization or, more commonly, a rubber or resin consisting of large molecules formed by polymerization.

polymer concrete

concrete in which an organic polymer serves as the binder.

polymer-cement concrete

a mixture comprising hydraulic cement and aggregate combined at the time of mixing with organic monomers or polymers that are dispersed in water.

polymer-impregnated concrete

a hydrated hydraulic-cement concrete that has been impregnated with a monomer that is subsequently polymerized.

polymerization

the reaction in which two or more molecules of the same substance combine to form a compound containing the same elements and in the same proportions but of higher molecular weight.

polystyrene resin

synthetic resins, varying from colorless to yellow, formed by the polymerization of styrene on heating with or without catalysts, which may be used in paints for concrete, for making sculptured molds, or as insulation.

polyurethane

reaction product of an isocyanate with any of a wide variety of other compounds containing an active hydrogen group, also used to formulate tough, abrasion-resistant coatings.

polyvinyl chloride

a synthetic resin prepared by the polymerization of vinyl chloride, used in the manufacture of nonmetallic waterstops for concrete.

ponding

(1) the creation and maintaining of a shallow pond of water on the surface of a concrete slab to assist curing; (2) accidental or incidental occurrence of a shallow pond or ponds on a nominally flat surface of concrete; (3) a condition in which a horizontal slab deforms downward between supports.

popout

the breaking away of small portions of a concrete, mortar, and plaster surface due to localized internal pressure that leaves a shallow, typically conical, depression.

porosity

the ratio, usually expressed as a percentage of the volume of voids in a material to the total volume of the material including the voids.

portland blast-furnace slag cement

a hydraulic cement consisting of an intimately interground mixture of portland-cement clinker and granulated blast-furnace slag or an intimate and uniform blend of portland cement and fine granulated blast-furnace slag in which the amount of the slag constituent is within specified limits.

portland cement

a hydraulic cement produced by pulverizing portland-cement clinker and usually with addition of calcium sulfate to control setting.

portland-cement clinker

a partially fused product of kiln that is ground to make cement.

portland-cement concrete

see concrete.

portlandite

a crystalline calcium hydroxide (Ca(OH)2).

portland-pozzolan cement

a hydraulic cement consisting of an intimate and uniform blend of portland cement or portland blast-furnace slag cement and fine pozzolan produced by intergrinding portland-cement clinker and pozzolan, by blending portland cement or portland blast-furnace slag cement and finely divided pozzolan, or a combination of intergrinding and blending, in which the pozzolan constituent is within specified limits.

position coupler

threaded device for joining reinforcing bars where bars are not rotated.

positive moment

a condition of flexure in which, for a horizontal simply supported member, the deflected shape is normally considered to be concave downward and the top fibers subjected to compression stresses (for other members and other conditions, consider positive and negative as relative terms). (See also negative moment.)
Note: for structural design and analysis, moments may be designated as positive or negative with satisfactory results as long as the sign convention adopted is used consistently.

positive reinforcement

reinforcement for positive moment.

post

vertical formwork member used as a support (also called shore, prop, and jack).

post shore

individual vertical member used to support loads.
(1) adjustable timber single-post shore — individual timber used with a fabricated clamp to obtain adjustment and not normally manufactured as a complete unit.
(2) fabricated single-post shore — Type I: single all-metal post with a fine-adjustment screw or device in combination with pin-and-hole adjustment or clamp; Type II: single or double wooden post members adjustable by a metal clamp or screw and usually manufactured as a complete unit.
(3) timber single-post shore — timber used as a structural member for shoring support.

post-tensioning

method of prestressing reinforced concrete in which tendons are tensioned after the concrete has attained a specified minimum strength or a specified minimum age.

pot life

time interval after mixing of thermosetting resin and initiators during which the mixture can be applied without degrading the final performance of the resulting polymer beyond specified limits.

pouring (of concrete)

see placement and placing.

power float

see rotary float (preferred term).

Powers’ spacing factor

see spacing factor (preferred term).

pozzolan

a siliceous or silico-aluminous material that will, in finely divided form and in the presence of moisture, chemically react with calcium hydroxide at ordinary temperatures to form compounds having cementitious properties (there are both natural and artificial pozzolans).

pozzolanic

of or pertaining to a pozzolan.

pozzolanic reaction

reaction between calcium hydroxide and the oxides in a pozzolan resulting in reaction products having cementitious properties similar to the products that result from the hydration of portland cement.

pozzolanic-activity index

an index that measures pozzolanic activity based on the strength of cementitious mixtures containing hydraulic cement with and without the pozzolan, or containing the pozzolan with lime.

preblended grout

a hydraulic-cement grout that is a commercially available mixture of hydraulic cement, aggregate, and other ingredients that requires only the addition of water and mixing at the job site (also called premixed grout).

precast concrete

concrete cast elsewhere than its final position.

precast pile

a reinforced pile manufactured in a casting plant or at the site but not in its final position. (See also cast-in-place pile.)

precompressed zone

the area of a flexural member that is compressed by the prestressing tendons.

prefire

to raise the temperature of refractory concrete under controlled conditions before placing it in service.

preformed foam

foam produced in a foam generator before introduction of the foam into a mixer with other ingredients to produce cellular concrete. (See also cellular concrete.)

premature stiffening

see early stiffening (preferred term).

preplaced-aggregate concrete

concrete produced by placing coarse aggregate in a form and later injecting a portland cement-sand grout, usually with admixtures, to fill the voids.

pre-post-tensioning

a method of fabricating prestressed concrete in which some of the tendons are pretensioned and a portion of the tendons are post-tensioned.

preservation

the process of maintaining a structure in its present condition and arresting further deterioration. (See also rehabilitation, repair, and restoration).

preset period

see presteaming period (preferred term).

preshrunk concrete (mortar or grout)

(1) concrete that has been mixed for a short period in a stationary mixer before being transferred to a transit mixer; (2) grout, mortar, or concrete that has been mixed 1 to 3 hours before placing to reduce shrinkage during hardening.

pressed edge

edge of a footing along which the greatest soil pressure occurs under conditions of overturning.

presteaming period

in the manufacture of concrete products, the time between molding of a concrete product and start of the temperature-rise period.

prestress

(1) to place a hardened concrete member or an assembly of units in a state of compression before application of service loads; (2) the stress developed by prestressing, such as by pretensioning or post-tensioning. (See also prestressed concrete, prestressing steel, pretensioning, and post-tensioning.)

prestressed concrete

structural concrete in which internal stresses have been introduced to reduce potential tensile stresses in concrete resulting from loads.

prestressing steel

high-strength steel elements such as wire, bar, or strands used to impart prestress forces to concrete. (See also prestress, prestressed concrete, pretensioning, and post-tensioning.)

pretensioning

method of prestressing in which prestressing steel is tensioned before the concrete is placed.

pretensioning bed (or bench)

the casting bed on which pretensioned members are manufactured and which resists the pretensioning force before release.

primary crusher

a heavy crusher suitable for the first stage in a process of size reduction of rock, slag, or the like.

principal planes

see principal stress.

principal stress

maximum and minimum stresses at any point acting at right angles to the mutually perpendicular planes of zero shearing stress, which are designated as the principal planes.

probabilistic design

design based on principles of statistics (probability) for evaluation of structural safety.

prop

see post and shore.

proportion

to select proportions of ingredients to make the most economical use of available materials to produce mortar or concrete of the required properties. (See also mixture.)

proportional limit

the greatest stress that a material can sustain without any deviation from proportionality of stress to strain. (See also Hooke’s law.)

protected paste volume

the portion of hardened cement paste that is protected from the effects of freezing by proximity to an entrained air void. (See also Philleo factor and spacing factor.)

pugmill

see horizontal-shaft mixer.

pullout failure

a failure mode in which the anchor pulls out of the concrete without development of the full steel or concrete capacity.

pull-through failure

a failure mode in which the anchor body pulls through the expansion mechanism without development of the full steel or concrete capacity.

pulse velocity

the speed at which a pulse of ultrasonic compressional stress waves travel through a material.

pulverized-fuel ash

see fly ash (preferred term).

pumice

a highly porous and vesicular lava usually of relatively high silica content composed largely of glass drawn into approximately parallel or loosely entwined fibers, which themselves contain sealed vesicles.

pumicite

naturally occurring finely divided volcanic ash composed of angular and porous particles of siliceous glass and varying proportions of crystal fragments differing from pumice only in grain size. (See also pumice.)

pumping (of pavements)

the ejection of water or water and solid materials such as clay or silt along transverse or longitudinal joints and cracks and along pavement edges caused by downward slab movement activated by the passage of loads over the pavement after the accumulation of free water on or in the base course, subgrade, or subbase.

punching shear

failure of a base or slab when a concentrated load punches a hole through it or where a heavily loaded suspended slab breaks away at the perimeter of a column.

putty

a plaster composed of quicklime or hydrated lime and water with or without plaster of paris or sand.

pyrite

a mineral, iron disulfide (FeS_2), that, if it occurs in aggregate used in concrete, can cause popouts and dark brown or orange-colored staining.

Q

quality assurance

actions taken by an organization to provide and document assurance that what is being done and what is being provided are in accordance with the contract documents and standards of good practice for the work.

quality control

actions taken by an organization to provide control and documentation over what is being done and what is being provided so that the applicable standard of good practice or the contract documents for the work are followed.

quick setting

see flash setting (preferred term).

quicklime

calcium oxide (CaO).

R

rail-steel reinforcement

reinforcing bars hot-rolled from standard T-section rails.

ramming

a form of heavy tamping of concrete, grout, or the like by means of a blunt tool forcibly applied. (See also dry pack and tamping.)

random ashlar

see ashlar masonry (preferred term).

raveling

the wearing away of the concrete surface caused by the dislodging of aggregates particles.

raw mix

blend of raw materials ground to desired fineness, correctly proportioned, and blended ready for burning, used in the manufacture of cement clinker.

Rayleigh wave

a surface wave in which the particle motion is elliptical and effective penetration is less than one wavelength.

reactive aggregate

aggregate containing substances capable of reacting chemically with the products of solution or hydration of the portland cement in concrete or mortar under ordinary conditions of exposure, resulting in some cases in harmful expansion, cracking, or staining.

reactive silica material

several types of materials that react at high temperatures with portland cement or lime during autoclaving, includes pulverized silica, natural pozzolan, and fly ash.

ready-mixed concrete

concrete manufactured for delivery to a purchaser in a fresh state. (See also central-mixed concrete, shrink-mixed concrete, and transit-mixed concrete.)

rebar

colloquial term for reinforcing bar. (See also reinforcement.)

rebound

shotcrete materials or wet shotcrete that bounces away from the surface against which the shotcrete is being projected.

rebound hammer

an apparatus that provides a relative indication of the strength or hardness of concrete based on the rebound distance of a spring-driven mass after it impacts a rod in contact with the concrete surface.

recycled concrete

hardened concrete that has been processed for reuse, usually as aggregate.

reference standards

standardized mandatory language documents of a technical society, organization, or association, including the building codes of local or state authorities that are referenced in the contract documents or other standardized documents.

refractories

materials, usually nonmetallic, used to withstand high temperatures.

refractoriness

in refractories, the property of being resistant to softening or deformation at high temperatures.

refractory

resistant to high temperatures.

refractory aggregate

aggregate that is resistant to high temperatures and suitable to produce refractory concrete.

refractory concrete

hardened hydraulic-cement concrete that that is suitable for use at temperatures between 600 and 2400°F (315 and 1315°C).

refractory-insulating concrete

refractory concrete having low thermal conductivity.

regulated-set cement

a hydraulic cement containing fluorine-substituted calcium aluminate, capable of very rapid setting.

rehabilitation

the process of repairing or modifying a structure to a desired useful condition. (See also preservation, repair, and restoration.)

reinforced concrete

structural concrete reinforced with no less than the minimum amount of prestressing steel or nonprestressed reinforcement as specified in the applicable building code.

reinforced masonry

unit masonry in which reinforcement is embedded in such a manner that the two materials act together in resisting forces.

reinforcement

bars, wires, strands, fibers, or other slender elements that are embedded in a matrix such that they act together to resist forces.

reinforcement bar

see reinforcement.

reinforcement ratio

ratio of the area of the reinforcement to the area of the concrete at any section of a structural member. (See also percentage of reinforcement.)

reinforcing bar

see bar and deformed reinforcement.

relative humidity

the ratio of the quantity of water vapor actually present to the amount present in a saturated atmosphere at a given temperature expressed as a percentage.

release agent

material used to prevent bonding of concrete to a surface. (See also bond breaker and form oil.)

remoldability

the readiness with which freshly mixed concrete responds to a remolding effort such as jigging or vibration, causing it to reshape its mass around reinforcement and to conform to the shape of the form. (See also remolding test.)

remolding test

a test to measure remoldability. (See remoldability.)

render

to apply a coat of mortar by a trowel or float.

repair

to replace or correct deteriorated, damaged, or faulty materials, components, or elements of a structure. (See also preservation, rehabilitation, and restoration.)

repeatability

variability among replicate test results obtained on the same material within a single laboratory by one operator.

reproducibility

variability among test results obtained on the same material in different laboratories.

required average strength

the average strength of concrete used in mixture proportioning to ensure a high likelihood that the concrete will meet specified strength acceptance criteria

required strength

strength of a member or cross section required to resist factored loads or related internal moments and forces in such combinations as are stipulated in the applicable code or specification.

resetting (of forms)

setting of forms separately for each successive lift of a wall to avoid offsets at construction joints.

reshore

a temporary support placed against the bottom of a slab or other structural member immediately after the forms and original shores have been removed.

residual deformation

see nonrecoverable creep.

residual strength

strength in the post-peak load region of a static load-deflection curve.

resilience

the capability of a strained body to recover its size and shape after deformation.

resin

(1) general term for a class of materials made by polymerization of organic liquid compounds called monomers; (2) a plastic, viscous liquid, or monomer that is capable of hardening when mixed with appropriate catalysts or hardeners.

resin concrete

see polymer concrete (preferred term).

resin mortar

see polymer concrete.

restoration

the process of reestablishing the materials, form, and appearance of a structure to those of a particular era of the structure. (See also preservation, rehabilitation, and repair.)

restraint (of concrete)

restriction of free movement of fresh or hardened concrete following completion of placing in formwork or molds or within an otherwise confined space.

retardation

(1) reduction in the rate of either setting, hardening, or both; (2) an increase in the time required to reach time of initial and final setting or to develop early strength in a cementitious mixture. (See also retarder.)

retarder

an admixture that delays the setting of a cementitious mixture. (See also retarding admixture.)

retarding admixture

an admixture that causes a decrease in the rate of hydration of the hydraulic cement and lengthens the time of setting.

retemper

to add water and remix a cementitious mixture to restore workability to a condition in which the mixture is placeable or usable. (See also temper.)

reveal (n.)

(1) the vertical surface forming the side of an opening in a wall, as for a window or door; (2) depth of exposure of aggregate in an exposed aggregate finish. (See also exposed-aggregate finish.)

revibration

one or more applications of vibration to fresh concrete after completion of placing and initial consolidation but preceding initial setting of the concrete.

revolving-blade (or paddle) mixer

see open-top mixer.

rib

(1) one of a number of parallel structural members backing sheathing; (2) the portion of a T-beam that projects below the slab; (3) in deformed reinforcing bars, the deformations or the longitudinal parting ridge.

ribbed panel

a panel composed of a thin slab reinforced by a system of ribs in one or two directions, usually orthogonal.

ribbed slab

see ribbed panel.

ribbon loading

method of batching concrete in which the solid ingredients, and sometimes also the water, enter the mixer simultaneously (also called ribbon feeding).

rich concrete

concrete of high cement content. (See also lean concrete.)

rich mixture

a concrete mixture containing a high proportion of cement.

rider cap

see pile cap (preferred term).

rigid frame

a frame depending on moment in joints for stability.

rigid pavement

pavement that will provide high bending resistance and distribute loads to the foundation over a comparatively large area.

rock pocket

a porous, mortar-deficient portion of hardened concrete consisting of coarse aggregate and open voids. (See also honeycomb.)

rod

(1) a tool that is used as a straightedge or screed to provide a uniform and even surface across a plaster coat usually by trimming to a ground or dot; (2) a tool used as a guide for a scoring (combed) finish or similar repeating pattern finish; (3) a sharp-edged cutting screed used to trim shotcrete to forms or ground wires. (See also screed.)

rodding

consolidation of concrete by means of a tamping rod. (See also rod and tamping.)

roller compaction

a process for compacting concrete using a roller, often a vibratory roller.

roller-compacted concrete

(1) concrete compacted by roller compaction; (2) concrete that, in its unhardened state, will support a roller while being compacted.

rotary float

a motor-driven revolving disc that smooths, flattens, and compacts the surface of concrete floors and floor toppings (also called a power float).

rotary kiln

a long steel cylinder with a refractory lining supported on rollers so that it can rotate about its own axis, and erected with a slight inclination from the horizontal so that prepared raw materials fed into the higher end move to the lower end where fuel is blown in by air blast.

rout

to deepen and widen a crack to prepare it for patching or sealing.

rubbed finish

a finish obtained by using an abrasive to remove surface irregularities from concrete. (See also sack rub.)

rubber setting

see false setting (preferred term).

rubbing brick

a silicon-carbide brick used to smooth and remove irregularities from surfaces of hardened concrete.

rubble

(1) rough stones of irregular shape and size, broken from larger masses by geological processes or by quarrying; (2) concrete reduced to irregular fragments, as by demolition or natural catastrophe.

rupture modulus

see modulus of rupture.

rupture strength

see modulus of rupture.

rustication

a groove in a concrete surface.

rustication strip

a strip of wood or other material attached to a form surface to produce a groove or rustication in the concrete.

R-value

see thermal resistance.

S

sack

see bag of cement (preferred term).

sack rub

a finish for formed concrete surfaces, designed to produce even texture and fill pits and air holes. (See also surface air voids and rubbed finish.)

sagging

see sloughing (preferred term).

sample

either a group of units or portion of material taken, respectively, from a larger collection of units or a larger quantity of material that serves to provide information that can be used as a basis for action on the larger collection or quantity or on the production process.

sampling plan

(1) a procedure that specifies the number of units of product from a lot that is to be inspected to establish acceptability of the lot; (2) a prearranged program stipulating locations and procedures for securing samples of a material for testing purposes, for example, as concrete in construction or aggregates in a quarry, pit, or stockpile.

sand

(1) granular material passing the 9.5 mm (3/8 in.) sieve and almost entirely passing the 4.75 mm (No. 4) sieve and predominantly retained on the 75 µm (No. 200) sieve, and resulting either from natural disintegration and abrasion of rock or processing of completely friable sandstone; (2) that portion of an aggregate passing the 4.75 mm (No. 4) sieve and predominantly retained on the 75 µm (No. 200) sieve, and resulting either from natural disintegration and abrasion of rock or processing of completely friable sandstone. (See also fine aggregate.)
Note: the definitions are alternatives to be applied under differing circumstances. Definition (1) is applied to an entire aggregate either in a natural condition or after processing. Definition (2) is applied to a portion of an aggregate. Requirements for properties and grading should be stated in the specifications. Fine aggregate produced by crushing rock, gravel, or slag commonly is known as manufactured sand.

sand equivalent

a measure of the relative proportions of detrimental fine dust, clay-like material, or both in soils or fine aggregate.

sand pocket

a zone in concrete or mortar containing fine aggregate with little or no cement.

sand streak

a streak of exposed fine aggregate in the surface of formed concrete caused by bleeding.

sandblast

a system of cutting or abrading a surface such as concrete by a stream of sand ejected from a nozzle at high speed by compressed air, often used for cleanup of horizontal construction joints or for exposure of aggregate in architectural concrete.

sand-coarse aggregate ratio

ratio of fine to coarse aggregate in a batch of concrete, by mass or by volume.

sanded grout

grout in which fine aggregate is incorporated into the mixture.

sand-lightweight concrete

concrete made with a combination of expanded clay, shale, slag, or slate or sintered fly ash and natural sand, with a density generally between 105 and 120 lb/ft^3 (1680 and 1920 kg/m^3).

sand-lime brick

see calcium-silicate brick (preferred term).

sandstone

a cemented or otherwise indurated sedimentary rock composed predominantly of sand grains.

sandwich panel

a prefabricated panel that is a layered composite formed by attaching two thin facings to a thicker core, for example, a precast-concrete panel consisting of two layers of concrete separated by a nonstructural insulating core.

Santorin earth

a volcanic tuff originating on the Greek island of Santorin (also called Santorini, Thira, or Thera) and used as a pozzolan.

saponification

the alkaline hydrolysis of fats forming a soap, more generally the hydrolysis of an ester by an alkali with the formation of an alcohol and a salt of the acid portion.

saturated surface-dry

condition of an aggregate particle or other porous solid when the permeable pores are filled with water and no water is on the exposed surfaces.

saturated surface-dry particle density

the mass of the saturated surface-dry aggregate divided by its displacement volume in water.

saturated surface-dry bulk specific gravity

see saturated surface-dry specific gravity.

saturated surface-dry specific gravity

the ratio of the saturated surface-dry mass of a volume of a material, including the volume of impermeable pores and permeable water-filled pores but not including voids between particles, at a stated temperature to the mass of an equal volume of distilled water at a stated temperature. (See also density.)

saturation

the condition such that no more liquid can be held or placed within aggregate or hardened concrete.

saw cut

a cut in hardened concrete made using abrasive blades or discs.

sawdust concrete

concrete in which the aggregate consists mainly of sawdust from wood.

sawed joint

a joint cut in hardened concrete, generally not to the full depth of the member, by means of special equipment.

scaffolding

a temporary structure for the support of deck forms, cartways, or workers, or a combination of these, such as an elevated platform for supporting workers, tools, and materials; adjustable metal scaffolding is frequently adapted for shoring in concrete work.

scaling

local flaking or peeling away of the near-surface portion of hardened concrete or mortar.

scalping screen

a sieve for removing oversize particles.

scanning electron microscope

an electron microscope in which the image is formed by a beam operating in synchronism with an electron probe scanning the object; the intensity of the image-forming beam is proportional to the scattering or secondary emission of electrons by the specimen where the probe beam strikes it.

scarf connection

a connection made by precasting, beveling, halving, or notching two pieces to fit together; after overlapping, the pieces are secured by bolts or other means.

Schmidt hammer

see rebound hammer.

scoria

vesicular volcanic ejecta of larger size, usually of basic composition and characterized by dark color; the material is relatively heavy and partly glassy, partly crystalline; the vesicles do not generally interconnect. (See also lightweight aggregate.)

scour

(1) erosion of soil around concrete members by water; (2) erosion of a concrete surface, exposing the aggregate.

scratch coat

the first coat of plaster or stucco applied to a surface in three-coat work, usually cross-raked or scratched to form a mechanical key with the brown coat.

screed

(1) to strike off a cementitious mixture lying beyond the desired plane or shape; (2) a tool for striking off the cementitious mixture surface, sometimes referred to as a strikeoff; (3) a ribbon or pad of a cementitious mixture that is preplaced to act as a guide for maintaining the desired level as more material is placed.

screed guide

firmly established grade strips or side forms for unformed concrete that guide the strikeoff in producing the desired plane or shape.

screed rails

see screed guide.

screed wire

see ground wire.

screeding

the operation of forming a surface using a screed. (See also strikeoff.)

screen

production equipment for separating granular material according to size using woven-wire cloth or other similar device with regularly spaced openings of uniform size.

sealant

see joint sealant.

sealer

a liquid that is applied to the surface of hardened concrete, is colorless, is absorbed by the concrete, leaves little or nothing visible on the surface, and either prevents or decreased the penetration of liquid or gaseous media. (See also coating and curing compound.)

sealing compound

see sealer.

seating

see anchorage deformation.

secondary crusher

a crusher used for the second stage in a process of size reduction of aggregate and the like. (See also primary crusher.)

segmental construction

method of construction whereby individual elements are prestressed together by post-tensioning so that the elements act as a monolithic unit in resisting applied loads.

segregation

(1) nonuniform concentration of components in concrete or mortar; (2) nonuniform distribution of size fractions in a mass of aggregate; (3) the gravitational settlement of solids from a liquid (also called separation). (See also bleeding.)

self-consolidating concrete

fresh concrete that can flow around reinforcement and consolidate within formwork under its own weight without vibration.

self-desiccation

the consumption of free water by chemical reaction so as to leave insufficient water to cover the solid surfaces and cause a decrease in the relative humidity of the system.

self-furring

metal lath or welded-wire reinforcement formed in the manufacturing process to include means by which the material is held away from the supporting surface, thus creating a space for keying of the insulating concrete, plaster, or stucco.

self-stressing concrete (mortar or grout)

expansive-cement concrete (mortar or grout) in which expansion, if restrained, induces compressive stresses in the concrete (mortar or grout).

selvage

a finished edge of woven-wire screen cloth produced in the weaving process of the finer meshes.

semiautomatic batcher

see batcher.

sensor

a device designed to respond to a physical stimulus (as temperature, illumination, and motion) and transmit a resulting signal for interpretation, measurement, or for operating a control.

separation

see segregation.

service dead load

unfactored dead loads.

service live load

unfactored live loads.

service load

all loads, static or dynamic, imposed on a structure, or element thereof, during operation of a facility.

set (n.)

see setting.

set-accelerating admixture

see accelerator.

set-retarding admixture

see retarding admixture and retarder.

setting

a chemical process that results in a gradual development of rigidity of a cementitious mixture, adhesive, or resin.

setting time

(1) time to achieve either initial setting or final setting (see also initial setting and final setting); (2) the length of time required to set or harden resin or adhesive under heat or pressure.

settlement

sinking of solid particles in a fresh cementitious mixture after placement and before initial setting. (See also bleeding.)

settling

the lowering in elevation of sections of pavement or structures due to their mass, the loads imposed on them, or shrinkage or displacement of the support.

severe exposure condition

an environment, normally in cold climate regions, in which concrete may be saturated or in almost continuous contact with moisture before freezing, and where deicing agents are used.

shale

a laminated and fissile sedimentary rock, the constituent particles of which are principally in clay and silt sizes (the laminations are bedding planes of the rock).

sharp sand

coarse sand consisting of particles of angular shape.

she bolt

a type of form bolt that has female threads at one end of the bolt, allowing for a threaded insert to be attached.

shear

an internal force tangential to the plane on which it acts.

shear reinforcement

reinforcement designed to resist shear or diagonal tension stresses. (See also dowel.)

shear strength

the maximum shearing stress a flexural member can support at a specific location as controlled by the combined effects of shear forces and bending moment.

shear stress

the stress component acting tangentially to a plane.

shearhead

assembled unit in the top of the columns of flat slab or flat plate construction to transmit loads from slab to column.

shearwall

a wall portion of a structural frame intended to resist lateral forces, such as earthquake, wind, and blast, acting in the plane of the wall.

sheath

an enclosure in which post-tensioning tendons are encased to prevent bonding during concrete placement. (See also duct.)

sheathing

(1) material encasing prestressing steel to prevent bonding of the prestressing steel with the surrounding concrete to provide corrosion protection and to contain the corrosion inhibiting coating (also called a sheath); (2) the material forming the contact face of forms (also called lagging or sheeting).

sheet pile

a pile in the form of a plank driven in close contact or interlocking with others to provide a tight wall to resist the lateral pressure of water, adjacent earth, or other materials.

sheeting

see sheathing (preferred term).

shelf angles

structural angles with holes or slots in one leg for bolting to the structure to support brick work, stone, or terra cotta.

shielding concrete

concrete employed as a biological shield to attenuate or absorb nuclear radiation, usually characterized by high density or high hydrogen (water) or boron content, having specific radiation attenuation effects. (See also biological shielding.)

shim

a strip of metal, wood, or other material employed to set base plates or structural members at the proper level for placement of grout, or to maintain the elongation in some types of post-tensioning anchorages.

shooting

placing of shotcrete. (See also gunning.)

shore

a temporary support for formwork and fresh concrete or for recently built structures that have not developed full design strength (also called prop, tom, post, and strut).

shoring

(1) props or posts of timber or other material in compression used for the temporary support of excavations, formwork, or unsafe structures; (2) the process of erecting shores.

shoring layout

a drawing prepared before erection showing arrangements of equipment for shoring.

short column

(1) a column whose load capacity is limited by strength rather than buckling; (2) a column so stocky and sufficiently restrained that at least 95 percent of the cross-sectional strength can be developed.

shorten

to decrease in length. (See also elongation and shrinkage.)

shotcrete

concrete placed by a high velocity pneumatic projection from a nozzle.

shoulder

an unintentional offset in a formed concrete surface usually caused by bulging or movement of formwork.

shrinkage

decrease in either length or volume of a material resulting from changes in moisture content or chemical changes.

shrinkage crack

crack due to restraint of shrinkage.

shrinkage cracking

cracking of a structure or member due to failure in tension caused by external or internal restraints as moisture content is reduced, carbonation occurs, or both.

shrinkage loss

reduction of stress in prestressing steel resulting from shrinkage of concrete.

shrinkage reinforcement

reinforcement designed to resist shrinkage stresses in concrete.

shrinkage-compensating

a characteristic of grout, mortar, or concrete made using expansive cement in which volume increases after setting and, if properly elastically restrained, induces compressive stresses that are intended to approximately offset the tendency of drying shrinkage to induce tensile stresses.

shrinkage-compensating cement

see expansive cement.

shrinkage-compensating concrete

concrete containing expansive components usually based on formation of calcium sulfoaluminate (ettringite) in a mixture of calcium aluminate and gypsum. (See also expansive cement.)

shrink-mixed concrete

ready-mixed concrete mixed partially in a stationary mixer and then mixed in a truck mixer.

SI (Système International)

the modern metric system (refer to ASTM E380).

side-face blowout failure

concrete spalling on the side face around the embedded head with no major breakout at the top concrete surface.

sieve

a metallic plate or sheet, woven-wire cloth, or other similar device with regularly spaced apertures of uniform size mounted in a suitable frame or holder for use in separating granular material according to size.

sieve analysis

the process of determining particle-size distribution of an aggregate. (See also grading.)

sieve fraction

that portion of a sample that passes through a standard sieve of specified size and is retained by some finer sieve of specified size.

sieve number

a number used to designate the size of a sieve. (See also sieve size [preferred term].)

sieve size

nominal size of openings between cross wires of a testing sieve.

significant

values of a test statistic that lie outside of predetermined limits of test precision and so taken to indicate a difference between populations (also called statistically significant).

silica

silicon dioxide (SiO_2).

silica flour

very finely divided silica, a siliceous binder component that reacts with lime under autoclave curing conditions, prepared by grinding silica, such as quartz, to a fine powder (also called silica powder).

silica fume

very fine noncrystalline silica produced in electric arc furnaces as a byproduct of the production of elemental silicon or alloys containing silicon.

silica powder

see silica flour (preferred term).

silicate

salt of a silicic acid. (See also alite, belite, blast-furnace slag, bredigite, calcium-silicate brick, calcium-silicate hydrate, celite, clay, dicalcium silicate, fire clay, hydraulic hydrated lime, kaolinite, melilite, siliceous-aggregate concrete, smectite, Stratling’s compound, tricalcium silicate, vermiculite, and xonotlite).

siliceous-aggregate concrete

concrete made with normal-density aggregates having constituents composed mainly of silica or silicates.

silicone

a resin characterized by water-repellent properties in which the main polymer chain consists of alternating silicon and oxygen atoms with carbon-containing side groups.

silt

a granular material resulting from the disintegration of rock with grains largely passing a 75 µm (No. 200) sieve; particles in the range from 2 to 50 µm diameter.

simple beam

a beam without rotational restraint or continuity at its supports (also called a simply supported beam).

single-sized aggregate

aggregate in which a major portion of the particles is in a narrow size range.

sinter

(1) a ceramic material or mixture fired to less than complete fusion, resulting in a coherent mass; (2) the process of creating a ceramic material or mixture fired to less than complete fusion, resulting in a coherent mass.

sintering

the formation of a porous mass of material by the agglomeration of fine particles during particle fusion.

skid resistance

a measure of the frictional characteristics of a surface.

slab

a molded layer of plain or reinforced concrete, flat, horizontal (or nearly so), usually of uniform but sometimes of variable thickness, and supported by beams, columns, walls, other framework, or on the ground. (See also flat slab and flat plate.)

slab bolster

continuous wire bar support used to support bars in the bottom of slabs where the top wire is corrugated at 1 in. (25 mm) centers to hold bars in position. (See also bar support.)

slab strip

see middle strip (preferred term).

slab-jacking

the process of either raising concrete pavement slabs or filling voids under them, or both, by injecting a material (cementitious, noncementitious, or asphaltic) under pressure.

slab-on-ground

a slab cast directly on the ground (also called slab-on-grade).

slag

see blast-furnace slag.

slag cement

granulated blast-furnace slag that has been finely ground and that is hydraulic cement.

slag-activity index

the ratio of the compressive strength of a mortar cube made with equal amounts of slag and portland cement to the compressive strength of a mortar cube made with the same portland cement.

slate

a fine-grained metamorphic rock possessing a well-developed fissility (slaty cleavage), usually not parallel to the bedding planes of the rock.

sleeve

(1) a pipe or tube passing through formwork for a wall or slab through which pipe, wires, or conduit can be passed after the forms have been stripped; (2) a device used around an anchor to accommodate adjustment and preloading of the anchor after the concrete has hardened.

slender beam

a beam that, if loaded to failure without lateral bracing of the compression flange, would fail by buckling rather than in flexure.

slender column

a column whose load capacity is reduced by the increased eccentricity caused by secondary deflection moments.

slenderness ratio

the effective unsupported length of a uniform column divided by the least radius of gyration of the cross-sectional area.

slick line

end section of a pipe line used in placing concrete by pump that is immersed in the placed concrete and moved as the work progresses.

sliding form

see slipform (preferred term).

slip

movement occurring between steel reinforcement and concrete in stressed reinforced concrete, indicating anchorage breakdown.

slipform

a form that is pulled or raised as concrete is placed

sloped footing

a footing having sloping top or side faces.

sloughing

subsidence of shotcrete, plaster, or the like, generally due to excessive water in the mixture (also called sagging).

slugging

pulsating and intermittent flow of shotcrete material due to improper use of delivery equipment and materials.

slump

a measure of consistency of freshly mixed concrete, mortar, or stucco equal to the subsidence measured to the nearest 1/4 in. (5 mm) of the molded specimen immediately after removal of the slump cone.

slump cone

a mold in the form of the lateral surface of the frustum of a cone with a base diameter of 8 in. (203 mm), top diameter 4 in. (102 mm), and height 12 in. (305 mm), used to fabricate a specimen of freshly mixed concrete for the slump test.

slump loss

the amount by which the slump of freshly mixed concrete changes during a period of time after an initial slump test was made on a sample or samples thereof.

slurry

a mixture of water and any finely divided insoluble material, such as portland cement, slag, or clay in suspension.

smectite

a group of clay minerals, including montmorillonite, characterized by a sheet-like internal atomic structure, consisting of extremely finely-divided hydrous aluminum or magnesium silicates that swell on wetting, shrink on drying, and are subject to ion exchange.

snap tie

a proprietary concrete wall-form tie, the end of which can be twisted or snapped off after the forms have been removed.

snow load

the force considered in the design of a flat or pitched surface, usually a roof, for the possible amount of snow, ice, or both, lying on it.

soffit

the underside of a part or member of a structure, such as a beam, stairway, or arch.

soil

a generic term for unconsolidated natural surface material above bedrock.

soil cement

a mixture of soil and measured amounts of portland cement and water compacted to a high density.

soil pressure

see contact pressure.

soil stabilization

chemical or mechanical treatment designed to either increase or maintain the stability of a mass of soil or otherwise to improve its engineering properties.

solid masonry unit

a unit whose net cross-sectional area in every plane parallel to the bearing surface is 75 percent or more of its gross cross-sectional area measured in the same plane.

solid masonry wall

a wall built of blocks or solid masonry units, the mortar completely filling the joints between units.

solid panel

a solid slab, usually of constant thickness.

solid volume

see absolute volume.

solid-unit masonry

masonry consisting wholly of solid masonry units laid in mortar.

solubility

the amount of one material that will dissolve in another, generally expressed as mass percent, as volume percent, or parts per 100 parts of solvent by mass or volume at a specified temperature.

solution

a liquid consisting of at least two substances, one of which is a liquid solvent in which the other or others, that may be either solid or liquid, are dissolved.

soundness

the freedom of a solid from cracks, flaws, fissures, or variations from an accepted standard; in the case of a cement, freedom from excessive volume change after setting; in the case of aggregate, the ability to withstand the aggressive action to which concrete containing it might be exposed, particularly that due to weather.

spacer

device that maintains reinforcement in proper position, also a device for keeping wall forms apart at a given distance before and during concreting. (See also spreader.)

spacing factor

an index related to the maximum distance of any point in a cement paste or in the cement paste fraction of mortar or concrete from the periphery of an air void (also called Powers’ spacing factor). (See also Philleo factor.)

spading

consolidation of mortar or concrete by repeated insertion and withdrawal of a flat, spade-like tool.

spall

a fragment, usually in the shape of a flake, detached from a larger mass by a blow, the action of weather, pressure, or expansion within the larger mass.

spalling

the development of spalls.

span

distance between the support reactions of members carrying transverse loads.

span length

see effective span.

span-depth ratio

the numerical ratio of total span to member depth.

spandrel

that part of a wall between the head of a window and the sill of the window above it.

spandrel beam

a beam in the perimeter of a building, spanning between columns and usually supporting a floor or roof.

spatterdash

a rich mixture of portland cement and coarse sand thrown onto a background by a trowel, scoop, or other appliance so as to form a thin, coarse-textured, continuous coating; as a preliminary treatment before rendering, it assists bond of the undercoat to the background, improves resistance to rain penetration, and evens out the suction of variable backgrounds. (See also dash-bond coat and parge.)

specific gravity factor

the ratio of the mass of aggregates (including moisture), as introduced into the mixer, to the effective volume displaced by the aggregates.

specific heat

the amount of heat required per unit mass to cause a unit rise of temperature over a small range of temperature.

specific surface

the surface area of particles or of air voids contained in a unit mass or unit volume of a material.

specification (in ASTM)

an explicit set of requirements to be satisfied by a material, product, system, or service.

specified compressive strength

compressive strength of concrete used in design.

specified concrete compressive strength

the specified resistance of a concrete specimen to axial compressive loading used in design calculations and as the basis for acceptance of concrete used in the work.

specified concrete equivalent strength

in-place concrete compressive strength adjusted by correction factors that can be directly substituted into conventional strength equations with customary strength reduction factors.

specimen

a piece or portion of a sample used to make a test.

spinning

the essential factor of the process of producing spun concrete. (See also spun concrete.)

spiral reinforcement

continuously wound reinforcement in the form of a cylindrical helix.

spirally reinforced column

a column in which the vertical bars are enveloped by spiral reinforcement. (See also spiral reinforcement)

splice

(1) connection of one reinforcing bar to another by lapping, welding, mechanical couplers, or other means; (2) connection of welded-wire reinforcement by lapping; (3) connection of piles by mechanical couplers.

split-face block

a concrete masonry unit with one or more faces purposely fractured to provide architectural effects in masonry wall construction.

splitting tensile strength

tensile strength of concrete determined by a splitting tensile test (also called indirect tension strength).

splitting tensile test

a test for tensile strength in which a cylindrical specimen is loaded to failure in diametral compression applied along the entire length (also called indirect tension test).

spray drying

a method of evaporating the liquid from a solution or dispersion by spraying it into a heated gas.

sprayed concrete

see shotcrete (preferred term).

sprayed mortar

see shotcrete (preferred term).

spread footing

a generally rectangular prism of concrete, larger in lateral dimensions than the column or wall it supports, to distribute the load of a column or wall to the subgrade.

spreader

(1) a piece of lumber approximately 1 by 2 in. (25 by 50 mm) cut to the thickness of a wall or other formed element and inserted in the form to hold it temporarily at the correct dimension against tension of form ties; (2) a device consisting of reciprocating paddles, a revolving screw, or other mechanism for distributing concrete to required uniform thickness in a paving slab.

spud vibrator

a vibrator with a vibrating casing or a vibrating head used to consolidate freshly placed concrete by insertion into the mass.

spun concrete

see centrifugally cast concrete (preferred term).

stacking tube

a slender, free-standing tubular structure used to store granular materials; the material is loaded into the top of the tube and spills out of wall openings to make a conical pile surrounding the tube.

stain

discoloration by foreign matter.

standard curing

exposure of test specimens to specified conditions of moisture and temperature.

standard fire test

the test prescribed by ASTM E119.

standard hook

a hook at the end of a reinforcing bar made in accordance with a standard.

standard hooked bar

a reinforcing bar with the end bent into a hook of prescribed geometry to provide anchorage.

standard sand

silica sand, composed almost entirely of naturally rounded grains of nearly pure quartz, used for preparing mortars in the testing of hydraulic cements.

standard time-temperature curve

the graphic time table for application of temperature to a material or member for the ASTM E119 fire test.

static load

(1) the mass of a single stationary body or the combined masses of stationary bodies in a structure (such as the load of a stationary vehicle on a roadway); (2) during construction, the combined mass of forms, stringers, joists, reinforcing bars, and the actual concrete to be placed. (See also dead load.)

static modulus of elasticity

the value of Young’s modulus of elasticity obtained by arbitrary criteria from measured stress-strain relationships derived from other than dynamic loading.

stationary hopper

a container used to receive and temporarily store freshly mixed concrete.

steam curing

(1) curing of concrete, mortar, grout, or neat-cement paste in water vapor at atmospheric or higher pressures and at temperatures between approximately 100 and 420°F (40 and 215°C). (See also atmospheric-pressure steam curing, and autoclave curing.)

stearic acid

a white crystalline fatty acid, obtained by saponifying tallow or other hard fats containing stearin. (See also butyl stearate).

steel sheet

cold-formed sheet or strip steel shaped as a structural member for the purpose of carrying the live and dead loads in lightweight concrete roof construction.

steel trowel

see trowel.

stepped footing

a step-like support consisting of prisms of concrete of progressively diminishing lateral dimensions superimposed on each other to distribute the load of a column or wall to the subgrade.

sticky cement

finished cement that develops low or zero flowability during or after storage in silos or after transportation in bulk containers or hopper-bottom cars; may be caused by interlocking of particles, mechanical compaction, or electrostatic attraction between particles. (See also warehouse setting.)

stiffback

see strongback (preferred term).

stiffness

resistance to deformation.

stirrup

bar or wire reinforcement oriented normal to or at an acute angle to the longitudinal reinforcement in a flexural member and extending as close as practical to the extreme tension and compression fibers of the cross section. (See also transverse reinforcement and tie.)

stoichiometric

(1) characterized by or being a proportion of substances or energy in a specific chemical reaction in which there is no excess of any reactant or product; (2) proportioning based on atomic or molecular weight.

stone sand

fine aggregate resulting from the mechanical crushing and processing of rock. (See also fine aggregate and sand.)

storage hopper

see stationary hopper.

straightedge

(1) a rigid, straight piece of either wood or metal used to strikeoff or screed a concrete surface to proper grade or to check the planeness of a finished grade (see also rod, screed, and strikeoff); (2) a highway tool for truing surfaces instead of a bull float.

straight-line theory

an assumption in reinforced-concrete analysis according to which the strains in a member under flexure are assumed to vary in linear proportion to the distance from the neutral axis.

strain

the change in length per unit of length, in a linear dimension of a body.

strand

a prestressing tendon composed of a number of wires twisted above the center wire or core.

strand wrapping

application of high tensile strand, wound under tension by machines around circular concrete or shotcrete walls, domes, or other tension-resisting structural components.

stratification

(1) the separation of overwet or overvibrated concrete into horizontal layers with increasingly lighter material toward the top; water, laitance, mortar, and coarse aggregate tend to occupy successively lower positions in that order; (2) a layered structure in concrete resulting from placing of successive batches that differ in appearance; (3) occurrence in aggregate stockpiles of layers of differing grading or composition; (4) a layered structure in a rock foundation.

Stratling’s compound

dicalcium aluminate monosilicate-8-hydrate, a compound that has been found in reacted lime-pozzolan and cement-pozzolan mixtures.

strength

a generic term for the ability of a material to resist strain or rupture induced by external forces. (See also concrete compressive strength, fatigue strength, flexural strength, shear strength, splitting tensile strength, tensile strength, ultimate strength, and yield strength.)

strength-design method

a design method that requires service loads to be multiplied by load factors and computed nominal strengths to be multiplied by strength reduction factors.

stress

force per unit area.

stress corrosion

corrosion of a metal either initiated or accelerated by stress.

stress relaxation

the time-dependent decrease in stress in a material held at constant strain. (See also  creep.)

stressing end

in prestressed concrete, the end of the tendon at which the load is applied when tendons are stressed from one end only.

stress-strain diagram

a diagram in which corresponding values of stress and strain are plotted against each other.

stretcher

a masonry unit laid with its length horizontal and parallel with the face of a wall or other masonry member. (See also header.)

strikeoff

to remove concrete in excess of that which is required to fill the form evenly or bring the surface to grade; performed with a straightedged piece of wood or metal by means of a forward sawing movement or by a power-operated tool appropriate for this purpose (this is also the name applied to the tool). (See also screed and screeding.)

stringer

a secondary flexural member that is parallel to the longitudinal axis of a bridge or other structure. (See also beam.)

strip

(1) to remove formwork or a mold; (2) a long thin piece of wood, metal, or other material. (See also demold and stripping.)

strip foundation

a continuous foundation wherein the length considerably exceeds the breadth.

stripper

a liquid compound formulated to remove coatings by either chemical action, solvent action, or both.

stripping

the removal of formwork or a mold. (See also demold.)

strongback

a frame attached to the back of a form or precast structural member to stiffen or reinforce the form or member during concrete placing operations or handling operations.

structural adhesive

a bonding agent used for transferring required loads between adherents exposed to service environments typical for the structure involved.

structural concrete

plain or reinforced concrete in a member that is part of a structural system required to transfer gravity loads, lateral loads, or both, along a load path to the ground.

structural end-point

the acceptance criterion of ASTM E119, which states that the specimen shall sustain the applied load without collapse.

structural lightweight concrete

structural concrete made with lightweight aggregate and having an air-dry density of not more than 115 lb/ft^3 (1850 kg/m^3).

structural load test

procedure consisting of applying loads to verify the load-carrying capacity of a structure or structural member.

structural repair

a repair that reestablishes or enhances the structural capacity of a member.

structural sandwich construction

a laminar construction comprising a combination of alternating dissimilar simple or composite materials assembled and intimately fixed in relation to each other so as to use the properties of each to attain specific structural and thermal advantages for the whole assembly.

strut

see shore.

stub wall

low wall, usually 4 to 8 in. (100 to 200 mm) high, placed monolithically with a concrete floor or other members to provide for control and attachment of wall forms (also called kicker in the United Kingdom).

stucco

a portland cement-based plaster used for coating exterior walls and other exterior surfaces. (See also plaster.)

stud

(1) member of appropriate size and spacing to support sheathing of concrete forms; (2) a headed steel device used to anchor steel plates or shapes to concrete members.

subaqueous concrete

see underwater concrete.

subbase

the layer in a pavement system between the subgrade and the base course, or between the subgrade and the pavement.

subgrade

the soil prepared and compacted to support a structure or a pavement system.

subgrade modulus

see coefficient of subgrade reaction.

subgrade reaction

see contact pressure and coefficient of subgrade reaction.

substrate

any material on the surface of which another material is applied.

substructure

all of that part of a structure below grade.

sulfate attack

a chemical reaction, physical reaction, or both, between sulfates usually in soil or ground water and concrete or mortar.

sulfate resistance

ability of concrete or mortar to withstand sulfate attack. (See also sulfate attack.)

sulfate-resistant cement

portland cement that is low in tricalcium aluminate, to reduce susceptibility of concrete to attack by dissolved sulfates in water or soils, referred to as ASTM C150 Type V cement.

sulfoaluminate cement

see expansive cement (1).

superimposed load

the load, other than its own weight, that is resisted by a structural member or system.

superplasticizer

see high-range water-reducing admixture (preferred term).

superstructure

all of that part of a structure above grade.

supersulfated cement

a hydraulic cement made by intimately intergrinding a mixture of granulated blast-furnace slag; calcium sulfate; and a small amount of lime, portland cement, or portland cement clinker; so named because the equivalent content of sulfate exceeds that for portland blast-furnace slag cement.

supplementary cementitious material

inorganic material such as fly ash, silica fume, metakaolin, or slag cement that reacts pozzolanically or hydraulically.

surface active

having the ability to modify surface energy and to facilitate wetting, penetrating, emulsifying, dispersing, solubilizing, foaming, frothing, and other substances.

surface air voids

small regular or irregular cavities, usually not exceeding 5/8 in. (15 mm) in diameter, resulting from entrapment of air bubbles in the surface of formed concrete during placement and consolidation. (See also sack rub.)

surface area

see specific surface.

surface bonding (of masonry)

bonding of dry-laid masonry by parging with a thin layer of fiber-reinforced mortar.

surface moisture

free water retained on surfaces of aggregate particles and considered to be part of the mixing water in concrete, as distinguished from absorbed moisture.

surface retarder

a retarder applied to the contact surface of a form or to the surface of newly placed concrete to delay setting of the cement, facilitate construction joint cleanup, or facilitate production of exposed-aggregate finish.

surface tension

an internal molecular force that exists in the surface film of all liquids and affects the wetting characteristics of the liquid.

surface texture

degree of roughness or irregularity of the exterior surfaces of aggregate particles and also of hardened concrete.

surface vibrator

a vibrator used for consolidating concrete by application to the surface of a mass of freshly mixed concrete; four principal types exist: vibrating screeds, pan vibrators, plate or grid vibratory tampers, and vibratory roller screeds.

surface voids

cavities visible on the surface of a solid. (See also surface air voids.)

surface water

see surface moisture (preferred term)

surface-active agent

a substance that affects markedly the interfacial or surface tension of solutions when present, even in low concentrations.

surfactant

a shortened form of the term surface-active agent.

sustained modulus of elasticity

term including elastic and inelastic effects in one expression to aid in visualizing net effects of stress-strain up to any given time, computed by dividing the unit sustained stress by the sum of the elastic and inelastic deformations at that time.

sway brace

a diagonal brace used to resist wind or other lateral forces. (See also bracing, cross bracing, and X-brace.)

swelling

increase in either length or volume. (See also expansion, volume change, and autogenous volume change.)

swirl finish

a nonskid texture imparted to a concrete surface during final troweling by keeping the trowel flat and using a rotary motion.

Swiss hammer

see rebound hammer (preferred term).

syngenite

potassium calcium sulfate hydrate, a compound sometimes produced during hydration of portland cement, found in deteriorating portland-cement concrete and said to form in portland cement during storage by reaction of potassium sulfate and gypsum.

Système International

see SI.

T

talc

a mineral with a greasy or soapy feel, very soft, having the composition Mg_3Si_4O_10(OH)2. (See also masonry cement and Mohs scale).

tamp process

a process for producing concrete products, such as pipe, that uses direct mechanical action to consolidate the concrete by the action of tampers that rise automatically as the form is rotated and filled with concrete from above. (See also centrifugal process, dry-cast process, packerhead process, and wet-cast process.)

tamper

(1) an implement used to consolidate concrete or mortar in molds or forms; (2) a hand-operated device for consolidating floor topping or other unformed concrete by impact from the dropped device in preparation for strikeoff and finishing; contact surface often consists of a screen or a grid of bars to force coarse aggregates below the surface to prevent interference with floating or troweling. (See also jitterbug.)

tamping

the operation of consolidating freshly placed concrete by repeated blows or penetrations with a tamper. (See also consolidation and rodding.)

tamping rod

a straight steel rod of circular cross section and having one or both ends rounded to a hemispherical tip.

T-beam

a beam composed of a stem and a flange in the form of a T.

telltale

any device designed to indicate movement of formwork or of a point on the longitudinal surface of a pile under load.

temper

to add water to a cementitious mixture as necessary to initially bring the mixture to the desired workability. (See also retemper.)

temperature cracking

cracking due to tensile failure caused by temperature drop in members subjected to external restraints or by temperature differential in members subjected to internal restraints (also called thermal cracking).

temperature reinforcement

reinforcement designed to carry stresses resulting from temperature changes; also the minimum reinforcement for areas of members that are not subjected to primary stresses or necessarily to temperature stresses.

temperature rise

the increase of temperature caused by either absorption of heat or internal generation of heat, for example, hydration of cement in concrete.

temperature stress

stress in a restrained structure or a member due to changes or differentials in temperature in the structure or member.

temperature-rise period

the time interval during which the temperature of a concrete product rises at a controlled rate to the desired maximum in autoclave or atmospheric-pressure steam curing.

temperature-time factor

product of temperature multiplied by time for a specific interval. (See also maturity factor.)

template

(1) a thin plate or board frame used as a guide in positioning or spacing form parts, reinforcement, or anchors; (2) a full-size mold, pattern, or frame, shaped to serve as a guide in forming or testing contour or shape.

temporary stress

a stress that may be produced in a precast-concrete member or in a component of a precast-concrete member during fabrication or erection, or in cast-in-place concrete structures due to construction or test loadings.

tendon

an assembly consisting of a tensioned element (such as a wire, bar, rod, strand, or a bundle of these elements) used to impart compressive stress in concrete, along with any associated components used to enclose and anchor the tensioned element.

tendon profile

the path or trajectory of the prestressing tendon.

tensile strain capacity

the maximum tensile strain that hardened cement paste, mortar, or concrete can sustain before cracking occurs.

tensile strength

maximum stress that a material is capable of resisting under axial tensile loading based on the cross-sectional area of the specimen before loading.

tension reinforcement

reinforcement designed to carry tensile stresses such as those in the bottom of a simple beam.

ternary mixture

concrete containing three cementitious materials.

terrazzo concrete

marble-aggregate concrete that is cast-in-place or precast and ground smooth for decorative surfacing purposes on floors and walls.

test

a trial, examination, observation, or evaluation used as a means of measuring either a physical or a chemical characteristic of a material, or a physical characteristic of either a structural element or a structure.

tetracalcium aluminoferrite

a compound in the calcium aluminoferrite series, having the composition 4CaO·Al_2O_3·Fe_2O_3, abbreviated C_4AF, that is usually assumed to be the aluminoferrite present when compound calculations are made from the results of chemical analysis of portland cement. (See also brownmillerite.)

texture

the pattern or configuration apparent in an exposed surface, as in concrete and mortar, including roughness, streaking, striation, or departure from flatness.

texturing

the process of producing a special texture on either unhardened or hardened concrete.

thermal conductance

(of a gas, liquid, or solid) a measure of the rate at which heat passes perpendicularly through a unit area of material of specified thickness for a temperature difference of one degree.

thermal conductivity

the ability of a homogeneous material to conduct heat, measured as the steady state heat flow per unit area through a body of unit thickness with one degree temperature difference between the surfaces.

thermal contraction

contraction caused by decrease in temperature.

thermal diffusivity

(1) thermal conductivity divided by the product of specific heat and density; (2) an index of the ease which a material undergoes temperature change.

thermal expansion

expansion caused by increase in temperature.

thermal movement

change of dimension of concrete or masonry resulting from change of temperatures. (See also thermal contraction and thermal expansion.)

thermal resistance

the reciprocal of thermal conductance expressed by the symbol R.

thermal shock

the subjection of newly hardened concrete to a rapid change in temperature that may cause surface cracking.

thermal stress

see temperature stress.

thermal volume change

the increase or decrease in volume caused by changes in temperature. (See thermal contraction and thermal expansion.)

thermoplastic

capable of being repeatedly softened by heating and hardened by cooling.

thermosetting

becoming rigid by chemical reaction and not remeltable.

thin-shell precast

precast concrete characterized by thin slabs and web sections.

thixotropy

a property of a material to thin upon isothermal agitation and to thicken upon subsequent rest.

threaded anchorage

an anchorage device that is provided with threads to facilitate attaching the jacking device and to affect the anchorage.

tie

(1) loop of reinforcing bars encircling the longitudinal steel in columns; (2) a tensile unit adapted to holding concrete forms secure against the lateral pressure of unhardened concrete; (3) a tension member in a strut-and-tie model.

tie bar

bar at right angles to and tied to reinforcement to keep it in place.

tie rod

see form tie and tieback.

tieback

a rod fastened to a deadman, a rigid foundation, or either a rock or soil anchor to prevent lateral movement of formwork, sheet pile walls, retaining walls, and bulkheads.

tied column

a column laterally reinforced with ties.

tilting mixer

a revolving-drum mixer that discharges by tilting the drum about a fixed or movable horizontal axis at right angles to the drum axis; the drum axis may be horizontal or inclined while charging and mixing.

tilt-up

a construction technique for casting concrete elements in a horizontal position at the job site and then tilting them to their final position in a structure.

time of haul

in production of ready-mixed concrete, the period from first contact between mixing water and cement until completion of discharge of the freshly mixed concrete.

time of setting

(1) the time required for a freshly mixed cement paste, mortar, or concrete to achieve initial setting (see initial setting); (2) the time required for a freshly mixed cement paste, mortar, or concrete to achieve final set. (See also final setting.)

time-dependent deformation

deformation resulting from effects such as autogenous volume change, thermal contraction or expansion, creep, shrinkage, and swelling, each of which is a function of time.

tobermorite gel

the binder of concrete cured moist or in atmospheric-pressure steam, a lime-rich gel-like solid containing 1.5 to 1.0 mols of lime per mol of silica.

tolerance

the permitted deviation from a specified dimension, location, or quantity.

tom

see shore (preferred term)

tongue and groove

a joint in which a protruding rib on the edge of one side fits into a groove in the edge of the other side, abbreviated T & G. (See also keyway.)

tooling

the act of compacting and contouring a material in a joint.

top form

form required on the upper or outer surface of a sloping slab or thin shell.

topping

(1) a layer of concrete or mortar placed to form a floor surface on a concrete base; (2) a structural, cast-in-place surface for precast floor and roof systems; (3) the mixture of marble chips and matrix that, when properly processed, produces a terrazzo surface.

torque viscometer

an apparatus used for measuring the consistency of slurries in which the energy required to rotate a device suspended in a rotating cup is proportional to viscosity.

torsional stress

the shear stress on a transverse cross section resulting from a twisting action.

toughness

(1) the ability of a material to absorb energy without rupturing; (2) the amount of energy per unit volume of material required to rupture the material.

transfer

to shift the tensioning force for a strand or strands from a jack or pretensioning bed to a concrete or masonry member.

transfer bond

in pretensioning, the bond stress resulting from the transfer of stress from the tendon to the concrete.

transfer length

the length from the end of the member where the tendon stress is zero to the point along the tendon where the prestress is fully effective.

transfer strength

the concrete strength required before stress is transferred from the stressing mechanism to the concrete.

transit mixer

see truck mixer.

transit-mixed concrete

concrete that is mixed totally or mostly in a truck mixer.

translucent concrete

a combination of glass and concrete used together in precast and prestressed panels.

transmission length

see transfer length.

transverse crack

a crack that occurs across the longer dimension of the member.

transverse joint

a joint normal to the longitudinal dimension of a structural element, assembly of elements, slab, or structure.

transverse prestress

prestress that is applied at right angles to the longitudinal axis of a member or slab.

transverse reinforcement

reinforcement at right angles to the longitudinal reinforcement.

transverse strength

see flexural strength and modulus of rupture.

traprock

any of various fine-grained, dense, dark-colored igneous rocks, typically basalt or diabase (also called trap).

trass

a natural pozzolan of volcanic origin found in Germany, namely, trachytic tuffs that are intensely altered by geologic processes.

traveler

an inverted-U-shaped structure usually mounted on tracks that permit it to move from one location to another to facilitate the construction of an arch, bridge, or building.

travertine

dense to irregularly porous, commonly stratified or banded calcium carbonate, either aragonite or calcite, formed by deposition from hot spring waters.

tremie

a pipe or tube through which concrete is deposited under water, having at its upper end a hopper for filling and a bail for moving the assemblage.

tremie seal

(1) the depth to which the discharge end of the tremie pipe is kept embedded in the fresh concrete that is being placed; (2) a layer of tremie concrete placed in a cofferdam for the purpose of preventing the intrusion of water when the cofferdam is dewatered.

trench form

the vertical sides and semicircular bottom of a trench excavated through compacted soil to provide the exterior form and base for a cast-in-place concrete pipe.

trial batch

a batch of concrete prepared to establish acceptable proportions of the constituents.

triaxial compression test

a test in which a specimen is subjected to a confining hydrostatic pressure and then loaded axially to failure.

triaxial test

a test in which a specimen is subjected simultaneously to lateral and axial loads.

tricalcium aluminate

a compound having the composition 3CaO·Al_2O_3, abbreviated C_3A.

tricalcium silicate

a compound having the composition 3CaO·SiO_2, abbreviated C_3S, an impure form of which (alite) is a main constituent of portland cement. (See also alite.)

trough mixer

see open-top mixer (preferred term).

trowel

(1) a flat, broad-blade steel hand tool used in the final stages of finishing operations to impart a relatively smooth surface to concrete floors and other unformed concrete surfaces; (2) a flat, triangular-blade tool used for applying mortar; (3) a flat, broad-blade steel hand tool used to place, spread, shape, finish, or otherwise apply materials. (See also fresno trowel.)

trowel finish

the smooth finish of an unformed concrete surface obtained by troweling.

troweling

smoothing and compacting the unformed surface of fresh concrete by strokes of a trowel.

troweling machine

a motor-driven device that operates orbiting steel trowels on radial arms from a vertical shaft.

truck mixer

a concrete mixer suitable for mounting on a truck chassis and capable of mixing concrete in transit. (See also horizontal-shaft mixer, inclined-axis mixer, open-top mixer, and agitator.)

truck-mixed concrete

see transit-mixed concrete.

T-shore

a shore with a T-head.

tub mixer

see open-top mixer (preferred term).

tube-and-coupler shoring

a load-carrying assembly of tubing or pipe that serves as posts, braces, and ties, a base supporting the posts, and special couplers that connect the uprights and join the various members.

tunnel lining

a structural system of concrete, steel, or other materials to provide support for a tunnel for exterior loads, to reduce water seepage, or to increase flow capacity.

turbidimeter

a device for measuring the particle-size distribution of a finely divided material by taking successive measurements of the turbidity of a suspension in a fluid.

turbidimeter fineness

the fineness of a material such as portland cement, usually expressed as total surface area in square centimeters per gram, as determined with a turbidimeter. (See also Wagner fineness.)

turbine mixer

see open-top mixer (preferred term).

twin-twisted bar reinforcement

two bars of the same nominal diameter twisted together.

two-way reinforced footing

a footing having reinforcement in two directions generally perpendicular to each other.

two-way reinforcement

reinforcement arranged in bands of bars at right angles to each other.

two-way system

a system of reinforcement; bars, rods, or wires placed at right angles to each other in a slab and intended to resist stresses due to bending of the slab in two directions.

Type I cement

see normal cement.

Type II cement

see modified cement.

Type III cement

see high-early-strength cement.

Type IV cement

see low-heat cement.

Type V cement

see sulfate-resistant cement.

U

ultimate load

the maximum load that may be placed on a structure or structural element before its failure.

ultimate moment

(obsolete) see nominal flexural strength.

ultimate shear strength

(obsolete) see nominal shear strength.

ultimate shear stress

see shear strength.

ultimate strength

the maximum stress developed in a specimen.

ultimate-strength design

see strength-design method.

ultrasonic

pertaining to mechanical vibrations having a frequency greater than approximately 20,000 Hz.

unbonded member

a prestressed-concrete member post-tensioned with tendons that are not bonded to the concrete between the end anchorages after stressing.

unbonded post-tensioning

post-tensioning in which the tendons are not grouted after stressing.

unbonded tendon

a tendon that is permanently prevented from bonding to the concrete after stressing.

unbraced length of column

distance between lateral supports.

underbed

the base mortar, usually horizontal, into which strips are embedded and on which terrazzo topping is applied.

undersanded

concrete containing an insufficient proportion of fine aggregate to produce optimum properties in the fresh mixture, especially workability and finishing characteristics.

undersize

particles of aggregate passing a designated sieve.

underwater concrete

concrete placed underwater by tremie or other means.

unhardened concrete

see fresh concrete (preferred term).

unit masonry

a construction element consisting of masonry units.

unit water content

the quantity of water per unit volume of freshly mixed concrete excluding water absorbed by the aggregate.

unit weight

(deprecated term) see density.

unreinforced concrete

see plain concrete.

unsound

not firmly made, placed, or fixed; subject to deterioration or disintegration during service exposure.

U-value

overall coefficient of heat transmission; a standard measure of the rate at which heat will flow through a unit area of a material of known thickness.

V

vacuum concrete

concrete from which excess water and entrapped air are extracted by a vacuum process before setting occurs.

vacuum dewatering

see vacuum concrete.

vacuum saturation

a process for increasing the moisture content of lightweight aggregate by subjecting it to a vacuum in a sealed chamber, flooding the chamber with water, and releasing the vacuum.

valve bag

paper bag for cement or other material, either glued or sewn, made of four or five plies of kraft paper and completely closed except for a self-sealing paper valve through which the contents are introduced and released.

vapor barrier

membrane located under a concrete floor slab that is placed on the ground to retard transmission of water vapor.

vapor pressure

the pressure exerted when a vapor is in equilibrium with its liquid or solid form at a given temperature.

vapor retarder

a membrane that impedes the transmission of gas molecules.

vebe apparatus

an apparatus for measuring workability of very low-slump or no-slump concrete, including a vibrating table, a sample container, and other ancillary items, that permits measurement of the time (vebe time) required to be consolidated in a mold.

vehicle

liquid carrier or binder of solids.

veneer

a masonry facing that is attached to the backup, but not so bonded as to act with it under load.

Venetian

a type of terrazzo topping that incorporates large chips of stone.

vermiculite

(1) a micaceous mineral; (2) a group name for certain platy minerals, hydrous silicates of aluminum, magnesium, and iron characterized by marked exfoliation on heating; (3) a constituent of clays.

vertical-shaft mixer

a cylindrical or annular mixing compartment having an essentially level floor and containing one or more vertical rotating shafts to which blades or paddles are attached; the mixing compartment may be stationary or rotate about a vertical axis.

vibrated concrete

concrete consolidated by vibration during and after placing.

vibration

energetic agitation of freshly mixed concrete during placement by mechanical devices, either pneumatic or electric, that create vibratory impulses of moderately high frequency to assist in consolidating the concrete in the form or mold.
(1) external vibration — employs vibrating devices attached at strategic positions on the forms and is particularly applicable to manufacture of precast items and for vibration of tunnel-lining forms; in manufacture of concrete products, external vibration or impact may be applied to a casting table.
(2) internal vibration — employs one or more vibrating elements that can be inserted into the fresh concrete at selected locations, and is more generally applicable to in-place construction.
(3) surface vibration — employs a portable horizontal platform on which a vibrating element is mounted.

vibration limit

the age at which fresh concrete has undergone a sufficient degree of setting and developed adequate strength to resist flow when subjected to vibration.

vibrator

an oscillating machine used to agitate fresh concrete so as to eliminate gross voids, including entrapped air but not entrained air, and to produce intimate contact with form surfaces and embedded materials. (See also vibration.)

Vicat apparatus

a penetration device used in the testing of hydraulic cements and similar materials.

Vicat needle

a weighted needle for determining time of setting of hydraulic cements.

viscometer

instrument for determining viscosity of slurries, mortars, or concretes.

viscosity

a measure of the resistance of a fluid to deform under shear stress.

visual concrete

see architectural concrete.

void-cement ratio

volumetric ratio of air plus net mixing water to cement in a concrete or mortar mixture.

volatile material

material that is subject to release as a gas or vapor; liquid that evaporates readily.

volume batching

combining the constituents of mortar or concrete based on volumetric measurement. (See also volumetric measuring.)

volume change

an increase or decrease in volume due to any cause. (See also deformation and time-dependent deformation.)

volumetric measuring

dispensing an ingredient based on volume, either in discrete quantities or by continuous flow.

volumetric mixer

equipment that uses measurements based on the volumes of the ingredients to feed a container that continually agitates and combines those ingredients for the production of concrete (also called volumetric-measuring and continuous-mixing concrete equipment [VMCM]).

W

w/c

see water-cement ratio.

w/cm

see water-cementitious materials ratio.

waffle

see dome.

Wagner fineness

the fineness of portland cement, expressed as total surface area in square centimeters per gram, determined by the Wagner turbidimeter apparatus and procedure.

wale

a long formwork member (usually double) used to gather loads from several studs (or similar members) to allow wider spacing of the restraining ties; when used with prefabricated panel forms, this member is used to maintain alignment.

wall

a vertical element used primarily to enclose or separate spaces.

wall form

a retainer or mold so erected as to give the necessary shape, support, and finish to a concrete wall.

warehouse pack

see warehouse setting and sticky cement.

warehouse setting

(1) the partial hydration of cement stored for a time and exposed to atmospheric moisture; (2) mechanical compaction occurring during storage. (See also sticky cement.)

warping

out-of-plane deformation of the corners, edges, and surface of a pavement, slab, or wall panel from its original shape. (See also curling.)

warping joint

a joint with the sole function of permitting warping of pavement slabs when moisture and temperature differentials occur between the top and bottom of the slabs, that is, longitudinal or transverse joints with bonded steel or tie bars passing through them.

wash water

water carried on a truck mixer in a special tank for flushing the interior of the mixer after discharge of the concrete.

water blast

a system of cutting or abrading a surface such as concrete by a stream of water ejected from a nozzle at high velocity.

water pocket

see water void.

water ring

a device in the nozzle body of dry-mix shotcrete equipment through which water is added to the materials.

water void

void along the underside of an aggregate particle or reinforcing steel that formed during the bleeding period, initially filled with bleed water.

water-cement ratio

the ratio of the mass of water, exclusive only of that absorbed by the aggregates, to the mass of portland cement in a cementitious mixture, stated as a decimal and abbreviated as w/c. (See also water-cementitious materials ratio.)

water-cementitious materials ratio

the ratio of the mass of water, excluding that absorbed by the aggregate, to the mass of cementitious material in a mixture, stated as a decimal and abbreviated w/cm. (See also water-cement ratio.)

waterproof

an idealized property of a material indicating imperviousness to water in either liquid or vapor state. (See also dampproofing.)
Note: because nothing can be completely impervious to water under infinite pressure over infinite time, this term should not be used.

waterproofed cement

see water-repellent.

waterproofing

see dampproofing (preferred term).

waterproofing compound

material used to impart water repellency to a structure or a constructional unit.

water-reducing admixture

an admixture that either increases slump of freshly mixed mortar or concrete without increasing water content, or maintains slump with a reduced amount of water, the effect being due to factors other than air entrainment.

water-repellent

property of a surface that resists wetting (by matter in either liquid or vapor state) but permits passage of water when hydrostatic pressure occurs. (See also watertight.)

water-resistant

see water-repellent (preferred term).

waterstop

a thin sheet of metal, rubber, plastic, or other material inserted across a joint to obstruct the seepage of water through the joint.

watertight

impermeable to water except when under hydrostatic pressure sufficient to produce structural discontinuity by rupture.

wearing course

a topping or surface treatment to increase the resistance of a concrete pavement or slab to abrasion.

weathering

changes in color, texture, strength, chemical composition or other properties of a natural or artificial material due to the action of the weather.

web bar

see web reinforcement (preferred term).

web reinforcement

reinforcement placed in a concrete member to resist shear and diagonal tension.

wedge

a piece of wood or metal tapering to a thin edge, used to adjust elevation or tighten formwork.

wedge anchorage

a device for anchoring a tendon by wedging.

weigh batching

measuring the constituent materials for mortar or concrete by mass.

welded-butt splice

a reinforcing bar splice made by welding the butted ends.

welded-wire fabric

(obsolete) see welded-wire reinforcement (preferred term).

welded-wire reinforcement

a series of longitudinal and transverse wires arranged approximately at right angles to each other and welded together at all points of intersection.

well-graded aggregate

aggregate having a particle-size distribution that produces high density, that is, low void space.

wet

covered with visible free moisture.

wet process

in the manufacture of cement, the process in which the raw materials are ground, blended, mixed, and pumped while mixed with water. (See also dry process.)

wet screening

screening to remove from fresh concrete aggregate particles larger than a certain size.

wet sieving

use of water to facilitate sieving of a granular material on standard sieves.

wet-cast process

a process for producing concrete items, such as pipe, that uses concrete having a measurable slump, generally placed from above, and consolidated by vibration. (See also centrifugal process, dry-cast process, packerhead process, and tamp process.)

wet-mix shotcrete

shotcrete in which the ingredients, including water, are mixed before introduction into the delivery hose (also called wet-process shotcrete).

wettest stable consistency

the condition of maximum water content at which cement grout and mortar will adhere to a vertical surface without sloughing.

wetting agent

a substance capable of lowering the surface tension of liquids, facilitating the wetting of solid surfaces and permitting the penetration of liquid into the capillaries.

wheel load

the portion of the gross mass of a loaded vehicle transferred to the supporting structure under a given wheel of the vehicle.

white cement

portland cement that hydrates to a white paste; made from raw materials of low iron content, the clinker for which is fired by a reducing flame.

wind load

pressure or suction due to wind on part or all of a surface of a structure.

wing pile

a bearing pile, usually of concrete, widened in the upper portion to form part of a sheet pile wall.

wire mesh

see welded-wire reinforcement.

wire wrapping

application of high tensile wire, wound under tension by machines, around circular concrete or shotcrete walls, domes, or other tension-resisting structural components.

wobble coefficient

a coefficient used in determining the friction loss occurring in post-tensioning, which is assumed to account for the secondary curvature of the tendons.

wobble friction

in prestressed concrete, the friction caused by the unintended deviation of the prestressing sheath or duct from its specified profile.

workability

that property of freshly mixed concrete or mortar that determines the ease with which it can be mixed, placed, consolidated, and finished to a homogenous condition.

working load

forces normally imposed on a member in service.

working stress

maximum permissible design stress using working-stress design methods.

working-stress design

a method of proportioning either structures or members for prescribed service loads and assuming linear stress-strain relationships for the materials. (See also elastic design.)

woven-wire fabric

see woven-wire reinforcement.

woven-wire reinforcement

a prefabricated steel reinforcement composed of cold-drawn steel wires mechanically interlaced to form shape openings.

wrapping

see strand wrapping and wire wrapping.

wythe (leaf)

each continuous vertical section of a wall that is one masonry unit or grouted space in thickness.

X

X-brace

paired set of crossing sway braces. (See also brace, cross bracing, and sway brace.)

xonotlite

calcium silicate monohydrate (Ca_6Si_6O_17(OH)2), a natural mineral that is readily synthesized at 302 to 662°F (150 to 350°C) under saturated steam pressure; a constituent of sand-lime masonry units.

X-ray diffraction

(1) the diffraction of X-rays by substances having a regular arrangement of atoms; (2) a phenomenon used to identify substances having a regular arrangement of atoms.

X-ray emission spectroscopy

see X-ray fluorescence.

X-ray fluorescence

characteristic secondary radiation emitted by an element as a result of excitation by X-rays, used to yield chemical analysis of a sample.

Y

yellowing

development of yellow color or cast in white or clear coatings as a consequence of aging.

yield

(1) the volume of freshly mixed concrete produced from a known quantity of ingredients; (2) the total mass of ingredients divided by the density mass of the freshly mixed concrete; (3) the number of units produced per bag of cement or per batch of concrete.

yield point

the first engineering stress in a test in which stresses and strains are determined for a material that exhibits the phenomenon of discontinuous yielding, of which an increase in strain occurs without an increase in stress.

yield strength

the stress at which a material exhibits a specific limiting deviation from the proportionality of stress to strain.

yoke

(1) a tie or clamping device around column forms or over the top of wall or footing forms to keep them from spreading because of the lateral pressure of fresh concrete; (2) part of a structural assembly for slipforming that keeps the forms from spreading and transfers form loads to the jacks.

Z

zero-slump concrete

concrete of stiff or extremely dry consistency showing no measurable slump after removal of the slump cone. (See also slump and no-slump concrete.)

Publication Information

ACI Concrete Terminology

January 2013

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Fax: 248-848-3701

www.concrete.org