absolute specific gravity — see specific gravity, absolute.
absolute volume — see volume, absolute.
absorbed moisture — see moisture, absorbed.
absorbed water — see moisture, absorbed.
absorption — the process by which a liquid is drawn into and tends to fill permeable voids in a porous solid body; also, the increase in mass of a porous solid body resulting from the penetration of a liquid into its permeable voids.
abutment — in bridges, the end structure (usually of concrete) that supports the beams, girders, and deck of the bridge, or combinations thereof, and sometimes retains the earthen bank or supports the end of the approach pavement slab; in prestressing, the structure against which the tendons are stressed in producing pretensioned precast members or post-tensioned pavement; in dams, the side of the gorge or bank of the stream against which a dam abuts.
accelerating admixture — see admixture, accelerating.
acceleration — increase in velocity or in rate of change, especially the quickening of the natural progress of a process such as setting or strength development (hardening) of concrete. (See also admixture, accelerating.)
accelerator — see admixture, accelerating.
accidental air — see air, entrapped.
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, design, or an architectural finish. History
acrylic resin — see resin, acrylic.
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. History
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 nor leaves a system.
adiabatic curing — see curing, adiabatic.
adjustment screw — see screw, adjustment.
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. History
admixture, accelerating — 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.
admixture, air-entraining — 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 air, entrained.)
admixture, anti-washout — a concrete admixture that reduces the loss of fine material from concrete when placed in water. History
admixture, retarding — an admixture that causes a decrease in the rate of hydration of the hydraulic cement and lengthens the time of setting.
admixture, water-reducing — 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.
admixture, water-reducing (high-range) — 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.
adsorbed water — see water, adsorbed.
adsorption — development (at the surface of either a liquid or solid) of a higher concentration of a substance than exists in the bulk of the medium; especially formation of one or more layers of molecules of gases, of dissolved substances, or of liquids at the surface of a solid (such as cement, cement paste, or aggregates), or of air-entraining agents at the air-water interfaces; also the process by which a substance is adsorbed. (See also water, adsorbed.) History
advancing-slope grouting — see grouting, advancing-slope.
advancing-slope method — see method, advancing-slope.
aerated concrete — see concrete, cellular and concrete, foamed.
A/F ratio — see ratio, A/F.
afwillite — a mineral with composition 3CaO·2SiO2·3H2O 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.
agent, air-entraining — see admixture, air-entraining.
agent, bonding — a substance applied to a suitable substrate to create a bond between it and a succeeding layer.
agent, curing — a catalytic or reactive agent that induces cross-linking in a thermosetting resin (also hardener or initiator.) History
agent, parting — see agent, release (preferred term).
agent, release — material used to prevent bonding of concrete to a surface. (See also bond breaker and oil, form.)
agent, surface-active — a substance that affects markedly the interfacial or surface tension of solutions when present even in low concentrations.
agent, wetting — 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.
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 hydraulic cementing medium to produce either concrete or mortar. (See also aggregate, heavyweight and aggregate, lightweight.)
aggregate, angular — aggregate particles that possess well-defined edges formed at the intersection of roughly planar faces.
aggregate, coarse — aggregate predominantly retained on the 4.75 mm (No. 4) sieve or that portion retained on the 4.75 mm (No. 4) sieve. (See also aggregate.)
aggregate, crusher-run — aggregate that has been mechanically broken and has not been subjected to subsequent screening.
aggregate, dense-graded — aggregates graded to produce low void content and maximum density when compacted. (See also aggregate, well-graded.)
aggregate, fine — 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; or that portion passing the 4.75 mm (No. 4) sieve and predominantly retained on the 75 mm (No. 200) sieve. (See also aggregate and sand.)
aggregate, gap-graded — aggregate graded so that certain intermediate sizes are substantially absent.
aggregate, heavyweight — aggregate of high density, such as barite, magnetite, hematite, limonite, ilmenite, iron, or steel, used in heavyweight concrete.
aggregate, lightweight — aggregate of low density, such as: (a) expanded or sintered clay, shale, slate, diatomaceous shale, perlite, vermiculite, or slag; (b) natural pumice, scoria, volcanic cinders, tuff, and diatomite; or (c) sintered fly ash or industrial cinders used in lightweight concrete.
aggregate, mineral — aggregate consisting essentially of inorganic nonmetallic rock materials, either natural or crushed and graded.
aggregate, normalweight — aggregate that is neither heavyweight nor lightweight.
aggregate, open-graded — aggregate in which the voids are relatively large when the aggregate is compacted.
aggregate, reactive — 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.
aggregate, refractory — aggregate having refractory properties that, when bound together into a conglomerate mass by a matrix, forms a refractory body.
aggregate, single-sized — aggregate in which a major portion of the particles is in a narrow size range.
aggregate, well-graded — aggregate having a particle-size distribution that produces maximum density, that is, minimum void space.
aggregate blending — the process of intermixing two or more aggregates to produce a different set of properties; generally, but not exclusively, to improve grading.
aggregate-cement ratio — see ratio, aggregate-cement.
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.
agitating speed — see speed, agitating.
agitating truck — see truck, agitating.
(1) the process of providing motion in mixed concrete just sufficient to prevent segregation or loss of plasticity; and
(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 plasticity and preventing segregation of mixed concrete by agitation. (See also agitation.)
aids, grinding — materials used to expedite the process of grinding by eliminating ball coating, dispersing the finely ground product, or both.
air, accidental — see air, entrapped (preferred term).
air, entrained — microscopic air bubbles intentionally incorporated in mortar or concrete during mixing, usually by use of a surface-active agent; typically between 10 and 1000 μm (1 mm) in diameter and spherical or nearly so. (See also air entrainment.)
air, entrapped — air voids in concrete that are not purposely entrained and that are larger, mainly irregular in shape, and less useful than those of entrained air; and 1 mm or larger in size.
air blow pipe — air jet used in shotcrete gunning to remove rebound or other loose material from the work area.
air-blown mortar — see shotcrete (preferred term).
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-cooled blast-furnace slag — see blast-furnace slag.
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-entraining agent — see admixture, air-entraining.
air-entraining hydraulic cement — see cement, air-entraining hydraulic.
air entrainment — the incorporation of air in the form of microscopic bubbles (typically smaller than 1 mm) during the mixing of either concrete or mortar. (See also air entraining and air, entrained.)
air lift — equipment whereby slurry or dry powder is lifted through pipes by means of compressed air.
air meter — see meter, air.
air-permeability test — see test, air-permeability and test, Blaine.
air ring — see ring, air.
air separator — see separator, air.
air void — see void, air.
air-water jet — see jet, air-water.
akermanite — a mineral of the melilite group, Ca2MgSi2O7 . (See also gehlenite, melilite, and merwinite.)
alabaster — a compact crystalline, weakly textured form of practically pure gypsum.
alignment wire — see wire, ground (preferred term).
alite — a name used to identify tricalcium silicate, including small amounts of MgO, Al2O3, Fe2O3, and other oxides; a principal constituent of portland-cement clinker. (See also belite, celite, and felite.)
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 Na2O and K2O. (See also cement, low-alkali.)
alkali-aggregate reaction — see reaction, alkali-aggregate.
alkali-carbonate rock reaction — see reaction, alkali-carbonate rock.
alkali reactivity (of aggregate) — see reactivity (of aggregate), alkali.
alkali-silica reaction — see reaction, alkali-silica.
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 load, service dead and load, service live.
allowable stress — see stress, allowable.
alternate-lane construction — see construction, alternate-lane.
alumina — aluminum oxide (Al2O3).
aluminate cement — see cement, calcium-aluminate.
aluminate concrete — see concrete, aluminate.
aluminous cement — see cement, calcium-aluminate.
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 cement with water and aggregates. (See also mixing time.)
amplitude — the maximum displacement from the mean position in connection with vibration.
analysis, dynamic — analysis of stresses in framing as functions of displacement under transient loading.
analysis, mechanical — the process of determining particle-size distribution of an aggregate. (See also analysis, sieve.)
analysis, sieve — particle-size distribution; usually expressed as the mass percentage retained upon each of a series of standard sieves of decreasing size and the percentage passed by the sieve of finest size. (See also grading.)
anchor — in prestressed concrete, to lock the stressed tendon in position so that it will retain its stressed condition; in precast-concrete construction, to attach the precast units to the building frame; 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. (See also anchor, form.)
anchor, form — device used to secure formwork to previously placed concrete of adequate strength; the device is normally embedded in the concrete during placement.
anchor bolt — see bolt, anchor.
anchorage — in post-tensioning, a device used to anchor the tendon to the concrete member; in pretensioning, a device used to maintain the elongation of a tendon during the time interval between stressing and release; in precast-concrete construction, the devices for attaching precast units to the building frame; in slab or wall construction, the device used to anchor the slab or wall to the foundation, rock, or adjacent structure.
anchorage, dead-end — the anchorage at that end of a tendon that is opposite the jacking end.
(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; and
(2) mechanical device to transmit prestressing force to the concrete in a post-tensioned member. (See also anchorage.)
anchorage, mechanical — any mechanical device capable of developing the strength of the reinforcement without damage to the concrete.
anchorage, threaded — an anchorage device that is provided with threads to facilitate attaching the jacking device and to effect the anchorage.
anchorage, wedge — a device for anchoring a tendon by wedging.
anchorage bond stress — see stress, anchorage bond.
anchorage deformation — see deformation, anchorage or slip.
anchorage device — see anchorage (preferred term).
anchorage loss — see deformation, anchorage.
anchorage slip — see deformation, anchorage or slip.
anchorage zone — see zone, anchorage.
angle float — see float, angle.
angle of repose — the angle between the horizontal and the natural slope of loose material below which the material will not slide.
angular aggregate — see aggregate, angular.
anhydrite — a mineral, anhydrous calcium sulfate (CaSO4); gypsum from which the water of crystallization has been removed, usually by heating above 325 °F (160 °C); natural anhydrite is less reactive than that obtained by calcination of gypsum.
anhydrous calcium chloride — see calcium chloride, anhydrous.
anti-washout admixture — see admixture, anti-washout.
apparent specific gravity — see specific gravity, absolute.
architect-engineer or engineer-architect — the architect, engineer, architectural firm, engineering firm, or architectural and engineering firm issuing project drawings and specifications, administering the work under contract specifications and drawings, or both. History
architectural concrete — see concrete, architectural.
arc spectrography — spectrographic identification of elements in a sample of material heated to volatilization in an electric arc or spark.
area of steel — the cross-sectional area of the steel reinforcement. (See also effective area of 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. History
arrissing tool — see tool, arrissing.
artificial pozzolan — see pozzolan, artificial.
asbestos-cement products — products manufactured from rigid material composed essentially of asbestos fiber and portland cement.
ashlar — see masonry, ashlar.
ashlar, patterned — see masonry, ashlar.
ashlar masonry — see masonry, ashlar.
ashlar, random — see masonry, ashlar.
aspect ratio, fiber — the ratio of length to diameter of a fiber in which the diameter may be an equivalent diameter. (See also fiber,equivalent diameter.)
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 — see cement, asphalt.
asphaltic concrete — see concrete, asphaltic.
atmospheric-pressure steam curing — see curing, atmospheric-pressure steam.
autoclave — a pressure vessel in which an environment of steam at high pressure may be produced; used in the curing of concrete products and in the testing of hydraulic cement.
autoclave curing — see curing, autoclave.
autoclave cycle — see cycle, autoclave.
autoclaved — see curing, autoclave.
autoclaving — see curing, autoclave.
autogenous healing — see healing, autogenous.
autogenous length change — see length change, autogenous.
autogenous shrinkage — see volume change, autogenous.
autogenous volume change — see volume change, autogenous.
automatic batcher — see batcher.
auxiliary reinforcement — see reinforcement, auxiliary.
average bond stress — see bond stress, average.
average compressive strength — see compressive strength, average.
axis, neutral — a line in the plane of a structural member subject to bending where the longitudinal stress is zero.
axle load — see load, axle.
axle steel — see steel, axle.
axle-steel reinforcement — see reinforcement, axle-steel.
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