— B —

 

b/bo — see factor, coarse-aggregate (preferred term).

 

bacillus, cement — see ettringite (preferred term).

 

backfill concrete — see concrete, backfill.

 

back form — see form, top (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).

 

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. History

 

bacterial corrosion — see corrosion, bacterial.

 

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

 

balanced load — see load, balanced.

 

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

 

balanced reinforcement — 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; or 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 — see mill, ball.

 

ball test — see test, ball.

 

band iron — thin metal strap used as form tie, hanger, etc.

 

bar — an element, normally composed of steel, with a nominally uniform cross-sectional area used to reinforce concrete.

 

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

 

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

 

bar, epoxy-coated — a reinforcing bar coated by an epoxy-resin system, usually to increase resistance to corrosion.

 

bar, high-bond — see bar, deformed (preferred term).

 

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

 

bar, standard hooked — a reinforcing bar with the end bent into a hook to provide anchorage.

 

bar, plain — a reinforcing bar without surface deformations, or one having deformations that do not conform to the applicable requirements.

 

bar, tie — bar at right angles to and tied to reinforcement to keep it in place.

 

bar bender — a tradesman who cuts and bends steel reinforcement; or a machine for bending steel reinforcement.

 

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.)

 

bar mat — see mat (1). History

 

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 concreting.  (See also bat; bolster, slab.)

 

barite — a mineral, barium sulfate (BaSO₄), used in either pure or impure form as concrete aggregate primarily for the construction of high-density radiation shielding concrete; designated “barytes” in United Kingdom.

 

barrel (of cement) — a quantity of portland cement: 376 lb (4 bags) in the United States (obsolete); also wood or metal container formerly used for shipping cement.

 

barrel-vault roof — see roof, barrel-vault.

 

barrier, moisture — a vapor barrier.

 

barrier, vapor — membranes located under concrete floor slabs that are placed on grade to retard transmission of water vapor from the subgrade.

 

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

 

bars, stem — bars used in the wall section of a cantilevered retaining wall or in the webs of a box; when a cantilevered retaining wall and its footing are considered as an integral unit, the wall is often referred to as the stem of the unit.

 

base — a subfloor slab or “working mat,” either previously placed and hardened or freshly placed, on which floor topping is placed in a later operation; also the underlying stratum on which a concrete slab, such as a pavement, is placed.  (See also mud slab 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 — 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; also the lowest course of masonry in a wall or pier.

 

base plate — a plate of metal or other material formerly placed under pavement joints and the adjacent slab ends to prevent the infiltration of soil and moisture from the sides or bottom of the joint opening; also a steel plate used to distribute vertical loads, as for bridge beams, building columns, or machinery.

 

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 — see creep, basic.

 

basket — see load-transfer assembly (preferred term).

 

bassanite — calcium sulfate hemihydrate, 2CaSO₄·H₂O.  (See also hemihydrate and plaster of paris.)

 

bat — a broken brick sometimes used to support reinforcement.  (See also bar support.)

 

batch —

(1) quantity of material mixed at one time or in one continuous process; or

 

(2) to weigh or volumetrically measure and introduce into the mixer the ingredients for a quantity of material. History

 

batch, trial — a batch of concrete prepared to establish or check proportions of the constituents.

 

batch box — container of known volume used for measuring constituents of a batch of either concrete or mortar in proper proportions.

 

batch mixer — see mixer, batch.

 

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 — the mixing water added by a batcher to a cementitious mixture either before or during the initial stages of mixing (also called batch 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.

 

batching, cumulative — 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.

 

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

 

batter boards — pairs of horizontal boards nailed to wooden stakes adjoining an excavation; used as a guide to elevations and to outline the building.

 

batter pile — see pile, batter.

 

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

 

bay — the space, in plan, between the centerlines of adjacent piers, mullions, or columns; 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 to axial load and flexure but primarily to flexure; also the graduated horizontal bar of a weighing scale on which the balancing poises ride.  (See also beam, spandrel; girder; girt; joist; ledger; purlin; and stringer.) History

 

beam, double-tee — 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.

 

beam, drop-in — a precast element simply supported on adjacent cantilevered elements.

 

beam, edge — a stiffening beam at the edge of a slab.

 

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

 

beam, simple — a beam without rotational restraint or continuity at its supports; also known as a simply supported beam.

 

beam, slender — a beam that, if loaded to failure without lateral bracing of the compression flange, would fail by buckling rather than in flexure.

 

beam, spandrel — a beam in the perimeter of a building, spanning between columns and usually supporting a floor or roof.

 

beam-and-slab floor (roof) — a reinforced-concrete system in which a slab is supported by and is often monolithic with reinforced-concrete beams.

 

beam bottom — soffit or bottom form for a beam.

 

beam-column — a structural member subjected to axial load and flexure forces but primarily axial load.

 

beam form — a retainer or mold so erected as to give the necessary shape, support, and finish to a concrete beam.

 

beam form-clamp — any of various types of tying or fastening units used to hold the sides of beam forms.

 

beam hanger — a wire, strap, or other hardware device that supports formwork from structural members.

 

beam pocket — opening left in a vertical member in which a beam is to rest; also an opening in the column or girder form where forms for an intersecting beam will be framed.

 

beam saddle — see beam hanger (preferred term).

 

beam side — vertical or sloping side of a beam.

 

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

 

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 name used to identify one form of the constituent of portland-cement clinker now known when pure as dicalcium silicate (2CaO·SiO₂).  (See also alite; celite; and felite.)

 

belled pier — see pier belled.

 

bench — see pretensioning bed.

 

bending moment — see moment, bending.

 

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, pile — two or more piles driven in a row transverse to the long dimension of the structure and fastened together by capping and (sometimes) bracing.

 

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

 

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

 

Berliner — a type of terrazzo topping using small and large pieces of marble paving, usually with a standard terrazzo matrix between pieces, also called Palladiana.

 

billet steel — see steel, billet.

 

binder —

(1) material forming the matrix of concretes, mortars, and sanded grouts; or

 

(2) chemical treatment applied to fibers to give integrity to mats, roving, and fabric. History

 

binary mixture — see mixture, binary.

 

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 concrete, shielding.)

 

bituminous cement — see cement, bituminous.

 

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 surface, specific.)

 

Blaine test — see test, Blaine.

 

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

 

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) blast-furnace slag, air-cooled — 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) blast-furnace slag, expanded — 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) blast-furnace slag, granulated — the glassy, granular material formed when molten blast-furnace slag is rapidly chilled, as by immersion in water; and

 

(4) blast-furnace slag, ground-granulated — obsolete term; see cement, slag.

 

bleed — to undergo bleeding.  (See 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. History

 

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; joint, lift; laitance; popout; rock pocket; sand streak.)

 

blended cement — see cement, blended.

 

blinding — the application of a layer of lean concrete or other suitable material to reduce surface voids or to provide a clean, dry working surface; also the filling or plugging of the openings in a screen or sieve by the material being separated.  (See concrete, lean.)

 

blistering — 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; also bulging of a finish coat as it separates and draws away from a base coat. History

 

bloated — swollen, as in certain lightweight aggregates as a result of processing.

 

block —

 

block, concrete — a concrete masonry unit, usually containing hollow cores.

 

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

 

block, wood — a solid piece of wood used in concrete formwork to fill space or prevent movement of the formwork.

 

block beam — a flexural member composed of individual blocks that are joined together by prestressing.  (See also member, segmental.)

 

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 — a long pipe used to direct a compressed air stream that cleans a rock face or removes possible entrapped shotcrete rebound while placing shotcrete. History

 

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.

 

bolster, slab — continuous wire bar support used to support bars in the bottom of slabs; top wire is corrugated at 1 in. centers to hold bars in position.  (See also bar support.)

 

bolt —

 

bolt, anchor — a metal bolt or stud, headed or threaded, either cast in place, grouted in place, or drilled into finished concrete, used to hold various structural members or embedments in the concrete, and to resist shear, tension, and vibration loadings from various sources, such as wind and machine vibration; known also as a hold-down bolt or a foundation bolt.

 

bolt, foundation — see bolt, anchor.

 

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

 

bolt, she — a type of form tie and spreader bolt in which the end fastenings are threaded into the end of the bolt, thus eliminating cones and reducing the size of holes left in the concrete surface.

 

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 due to shrinkage and longitudinal shear in the concrete engaged by the bar deformations;

 

(2) adhesion of cement paste to aggregate;

 

(3) adhesion or cohesion between plaster coats or between plaster and a substrate produced by adhesive or cohesive properties of plaster or supplemental materials;

 

(4) patterns formed by the exposed faces of masonry units, for example, running bond or flemish bond.

 

bond, ceramic — the development of fired strength as a result of thermo-chemical reactions between materials exposed to temperatures approaching the fusion point of the mixture such as that which may occur, under these conditions, between calcium-aluminate cement and a refractory aggregate.

 

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

 

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

 

bond, mechanical — physical interlock created when a plastic cementitious mixture is placed and hardens to conform with the surface texture of the existing solid material. History

 

bond, transfer — in pretensioning, the bond stress resulting from the transfer of stress from the tendon to the concrete.

 

bond area — the nominal area of interface between two elements across which adhesion develops 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 oil, form and agent, release.)

 

bond length — see length, development (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 — see strength, bond.

 

bond stress — see stress, bond.

 

bond stress, average — the force in a bar divided by the product of the perimeter and the development length of the bar.

 

bond stress, development — see stress, anchorage bond (preferred term).

 

bonded hollow-wall masonry — see masonry, bonded hollow-wall.

 

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

 

bonded post-tensioning — see post-tensioning, bonded.

 

bonded tendon — see tendon, bonded.

 

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 — see agent, bonding.

 

bonding layer — see layer, bonding.

 

bored pile — see pier, drilled.

 

boring — the removal by drilling of rock; a sample of soil or concrete for tests.

 

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

 

boron-loaded concrete — see concrete, boron-loaded.

 

box out — to form an opening in concrete by a box-like form.

 

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 or a similar piece to strengthen an angle; and

 

2) formed shapes of channel or pencil rod used as structural reinforcement in erecting furred assemblies.  (See also corbel.) History

 

bredigite — a mineral, alpha prime dicalcium silicate (2CaO·SiO₂), occurring naturally at Scawt Hill, northern Ireland; and at the Isle of Muck, Scotland; also in slags and portland cement.

 

breeze — usually clinker; also fine divided material from coke production.

 

brick —

 

brick, calcium-silicate — a concrete product made principally from sand and lime that is hardened by autoclave curing.

 

brick, concrete — solid concrete masonry units of relatively small prescribed dimensions.

 

brick, rubbing — a silicon-carbide brick used to smooth and remove irregularities from surfaces of hardened concrete.

 

brick, sand-lime — see brick, calcium-silicate (preferred term).

 

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

 

bridge deck — see deck, bridge.

 

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

 

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

 

broom finish — see finish, broom.

 

brown coat — see coat, brown.

 

brown out — to complete application of base coat plaster.

 

brown oxide — see oxide, brown.

 

brownmillerite — a ternary compound originally regarded as 4CaO·Al₂O·Fe₂O₃ (C₄AF) occurring in portland and calcium-aluminate cement; now used to refer to a series of solid solutions between 2CaO·Fe₂O₃ (C₂F) and 2CaO·Al₂O₃ (C₂A).

 

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

 

brushed surface — see surface, brushed.

 

buck — framing around an opening in a wall; a door buck encloses the opening in which a door is placed.

 

buckling — failure by lateral or torsional instability of a structural member, occurring with stresses below the yield or ultimate values.

 

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; sometimes called a concrete cart.

 

building official — the official charged with administration and enforcement of the applicable building code, the duly authorized representative of the official.

 

build-up — spraying of shotcrete in successive layers to form a thicker mass; also the accumulation of residual hardened concrete in a mixer.

 

bulk cement — see cement, bulk.

 

bulk density — see density, bulk.

 

bulk loading — see loading, bulk.

 

bulk modulus — see modulus, bulk.

 

bulk specific gravity — see specific gravity, absolute and density, bulk.

 

bulk specific gravity (saturated-surface dry) — see specific gravity, absolute.

 

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; or (2) a partition in a storage tank or bin, as for cement or aggregate. History

 

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 curve — graph of change in volume of a quantity of sand due to change in moisture content.

 

bulking factor — see factor, bulking.

 

bull float — see float, bull.

 

bundled bars — see bars, bundled.

 

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 final set; and

 

2) to otherwise produce a very smooth surface. History

 

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

 

bush-hammer finish — see finish, bush-hammer.

 

butt joint — see joint, butt.

 

butter — to spread mortar on a masonry unit with a trowel; also 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 (C₁₇ H₃₅ COOC₄ H₉) used as an admixture for concrete to provide dampproofing.