— C —

 

cabinet, moist — 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 about 73 °F (23 °C) temperature and at least 95% relative humidity.  (See also moist room.)

 

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.                     

 

caisson pile — see pile, caisson.

 

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 — a mineral having the composition calcium carbonate (CaCO₃) and a specific crystal structure; the principal constituent of limestone, chalk, and marble; 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-aluminate cement — see cement, calcium-aluminate.

 

calcium chloride — a crystalline solid, CaCl₂; in various technical grades, used as a drying agent, as an accelerator of concrete, as a deicing chemical, and for other purposes.   (See also admixture, accelerating.)

 

calcium chloride, anhydrous (CaCl₂) — a solid, usually 94% calcium chloride, typically in pellet form.

 

calcium chloride, hydrous (CaCl₂·2H₂O) — a solid, usually 77% calcium chloride, in flake form.

 

calcium chloride solution — an aqueous solution of calcium chloride (usually at a specified concentration so that a given amount can be gauged to provide a specific concentration) usually expressed as a percent calcium chloride by mass of portland cement.

 

calcium hydroxide — see lime, hydrated.

 

calcium stearate — Ca(C₁₈H₃₅O₂)₂, commonly marketed in powder form, insoluble in water, used as a  water repellent admixture in concrete.

 

calcium-silicate brick — see brick, calcium-silicate.

 

calcium-silicate hydrate — see hydrate, calcium-silicate.

 

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

 

California bearing ratio (CBR) — the ratio of the force per unit area required to penetrate a soil mass with a 3 in.² (1940 mm²) circular piston at the rate of 0.05 in. (1.3 mm) per min to the force required for corresponding penetration of a standard material; the ratio is usually determined at 0.1 in. (2.5 mm) penetration.

 

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 nullify the deflection of the element under the effects of loads, shrinkage, and creep. History

 

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. History

 

cant strip — see strip, chamfer (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 cables — short cables (tendons) introduced to prestress the zone of negative moment only.

 

capacity — 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; also the output of concrete, aggregate, or other product per unit of time (as plant capacity or screen capacity); also load-carrying limit of a structure.

 

capacity-reduction factor — see 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.  (See also flow, capillary.)

 

capillary flow — see flow, capillary.

 

capillary space — see space, capillary.

 

cap, pile — a concrete element that transfers load from a column or pedestal to the top of one or more supporting piles. History

 

cap, rider — see cap, pile (preferred term).

 

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

 

carbonation shrinkage — see shrinkage, carbonation.

 

cast-in-place — referring to a cementitious mixture that is deposited in the place where it is required to harden as part of the structure, as opposed to precast concrete.

 

cast-in-place concrete — see concrete, cast-in-place.

 

cast-in-place pile — see pile, cast-in-place.

 

cast-in-situ — see cast-in-place (preferred term).

 

cast stone — see stone, cast.

 

castable refractory — see refractory, castable.

 

catalyst, negative — a substance that slows a chemical reaction and which, itself, does not enter into the reaction; inhibitor.

 

catface — blemish or rough depression in the finish plaster coat caused by variations in the base coat thickness.

 

cathead — a notched wedge placed between two formwork members meeting at an oblique angle; a spindle on a hoist; 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 filler, joint or sealant, joint.)

 

cavitation damage — see damage, cavitation.

 

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

 

cellular concrete — see concrete, cellular.

 

cellular construction — see construction, cellular.

 

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

 

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

 

cement, aluminous — see cement, calcium-aluminate (preferred term).

 

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

 

cement, bituminous — 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.

 

cement, blended — a hydraulic cement essentially consisting of portland cement, slag cement, or both, uniformly mixed with each other or a pozzolan through intergrinding or blending. History

 

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

 

cement, calcium-aluminate — 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.

 

cement, chemically prestressing — 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.  (See also cement, expansive.)

 

cement, expanding — see cement, expansive (preferred term).

 

cement, expansive — a cement that, when mixed with water, produces a paste that, after setting, increases in volume to a significantly greater degree than does portland-cement paste; used to compensate for volume decrease due to shrinkage or to induce tensile stress in reinforcement (post-tensioning).

 

1. cement, expansive, Type K — a mixture of portland cement, anhydrous tetracalcium trialuminate sulfate (C₄A₃S), calcium sulfate (CaSO₄), and lime (CaO); the C₄A₃S is a constituent of a separately burned clinker that is interground with portland cement or alternately, it may be formed simultaneously with the portland-cement clinker compounds during the burning process;

 

2. cement, expansive, Type M — interground or blended mixtures of portland cement, calcium-aluminate cement, and calcium sulfate suitably proportioned; and

 

3. cement, expansive, Type S — a portland cement containing a high computed tricalcium aluminate (C₃A) content and an amount of calcium sulfate above the usual amount found in portland cement

 

cement, high-alumina — see cement, calcium-aluminate (preferred term).

 

cement, high-early-strength — portland cement characterized by attaining a given level of strength in mortar or concrete earlier than does normal portland cement; referred to in the United States as Type III.

 

cement, high-fineness — 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.

 

cement, hot — newly manufactured cement that has not had an opportunity to cool after burning and grinding of the component materials.

 

cement, hydraulic — 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. History

 

cement, hydrophobic — unhydrated cement treated so as to have reduced tendency to take up moisture.

 

cement, Keene’s — a cement composed of finely ground, anhydrous, calcined gypsum, the set of which is accelerated by the addition of other materials.

 

cement, low-alkali — a portland cement that contains a relatively small amount of sodium or potassium or both; in the United States a portland cement containing not more than 0.60% Na₂O equivalent, that is, percent Na₂O + 0.658 x percent K₂O.

 

cement, low-heat — a portland cement for use when a low heat of hydration is desired, referred to in United States as Type IV.

 

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

 

cement, moderate sulfate-resisting — a portland cement for use when either moderate sulfate resistance or moderate heat of hydration or both is desired, now referred to as Type II.

 

cement, modified — a portland cement for use when either moderate heat of hydration, moderate sulfate resistance, or both, is desired, now referred to as Type II (an obsolete term).

 

cement, natural — a hydraulic cement produced by calcining an argillaceous limestone at a temperature below the sintering point and then grinding to a fine powder.

 

cement, nonstaining — a masonry cement that contains not more than a stipulated amount of water-soluble alkali as measured by a stipulated test method.

 

cement, normal — general purpose portland cement, referred to in the United States as Type I.

 

cement, oil-well — 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; often contains retarders to meet the requirements of use.

 

cement, ordinary portland — the term used in the United Kingdom and elsewhere to designate the equivalent of American normal portland cement or Type I cement; commonly abbreviated OPC.

 

cement, plastic — 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. History

 

cement, portland — a hydraulic cement produced by pulverizing clinker formed by heating a mixture, usually of limestone and clay, to 1400 to 1600 °C (2550 to 2900 °F). Calcium sulfate is usually ground with the clinker to control set. History

 

cement, portland blast-furnace slag — 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.

 

cement, portland-pozzolan — 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.

 

cement, regulated-set — a hydraulic cement containing fluorine-substituted calcium aluminate, capable of very rapid setting.

 

cement, Roman — a misnomer for a hydraulic cement made by calcining a natural mixture of calcium carbonate and clay, such as argillaceous limestone, to a temperature below that required to sinter the material but high enough to decompose the calcium carbonate, followed by grinding; so named because its brownish color resembles ancient Roman cements produced by use of lime-pozzolan mixtures.

 

cement, self-stressing — see cement, expansive.

 

cement, shrinkage-compensating — see cement, expansive.

 

cement, slag — granulated blast-furnace slag that has been finely ground and that is hydraulic cement. History

 

cement, sticky — finished cement that develops low or zero flowability during or after storage in silos, or after transportation in bulk containers, hopper-bottom cars, etc.; may be caused by: (a) interlocking of particles; (b) mechanical compaction; (c) electrostatic attraction between particles.  (See also set, warehouse.)

 

cement, sulfate-resistant — portland cement, low in tricalcium aluminate, to reduce susceptibility of concrete to attack by dissolved sulfates in water or soils, designated Type V in the United States.

 

cement, sulfoaluminate — see cement, expansive, Type K.

 

cement, supersulfated — 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.

 

cement, white — 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.

 

cement-aggregate ratio — see ratio, aggregate-cement.

 

cement bacillus — see ettringite (preferred term).

 

cement-bound macadam — see macadam, cement-bound.

 

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 — see gel, cement.

 

cement gun — see gun, cement.

 

cement kiln — see kiln, cement.

 

cement paint — see paint, cement.

 

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 cement paste, neat).

 

cement paste, neat — a plastic mixture of hydraulic cement and water both before and after setting and hardening.

 

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.

 

cementitious — having cementing properties.

 

cementitious material — see material, cementitious.

 

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-mixed concrete — see concrete, central-mixed.

 

central mixer — see mixer, central.

 

centrifugally cast concrete — see concrete, centrifugally cast.

 

centrifugal process — see process, centrifugal.

 

ceramic bond — see bond, ceramic.

 

chair — see bar support (preferred term), bat.

 

chalk — a soft limestone composed chiefly 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 — see strip, chamfer.

 

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 cracks and crazing.)

 

chemical bond — see bond, chemical.

 

chemically prestressing cement — see cement, chemically prestressing.

 

chemically prestressing concrete — see concrete, chemically prestressing.

 

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; it is composed of silica in the form of chalcedony, cryptocrystalline or microcrystalline quartz, or opal, or combinations 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.

 

chord modulus — see modulus of elasticity.

 

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.

 

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

 

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

 

cleanout — an opening in the forms for removal of refuse, to be closed before the concrete is placed; 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 — see form, climbing.

 

clinker — a partially fused product of a kiln, which is ground to make cement; also other vitrified or burnt material.  (See also clinker, portand-cement.)

 

clinker, portland-cement — a partially fused ceramic material consisting primarily of hydraulic calcium silicates and calcium aluminates.  (See also clinker.)

 

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

 

closed-circuit grouting — see grouting, closed-circuit.

 

coarse aggregate — see aggregate, coarse.

 

coarse-aggregate factor — see factor, coarse-aggregate.

 

coarse-grained soil — see soil, coarse-grained.

 

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

 

coat, brown — 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. History

 

coat, dash-bond — 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.

 

coat, finish —

1) final thin coat of shotcrete in preparation for hand finishing; and

 

2) final exposed coat of plaster or stucco. History

 

coat, flash — a light coat of shotcrete used to cover minor blemishes on a concrete surface.

 

coat, scratch — 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.

 

coated bar — see bar, coated.

 

coating —

 

(a) (on concrete) — material applied to a surface by brushing, dipping, mopping, spraying, troweling, etc., to preserve, protect, decorate, seal, or smooth the substrate;

 

(b) (on aggregate particles) — foreign or deleterious substances found adhering to the aggregate particles; or

 

(c) (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.)

 

coating, polysulfide — a protective-coating system prepared by polymerizing a chlorinated alkyl polyether with an inorganic polysulfide.

 

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

 

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 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: (1) load per unit area of horizontal surface of a mass of soil, to (2) corresponding settlement of the surface; determined as the slope of the secant, drawn between the point corresponding to zero settlement and the point of 0.05 in. (1.3 mm) settlement, of a load-settlement curve obtained from a plate load test on a soil using a 30 in. (762 mm) or greater diameter loading plate; used in the design of concrete pavements by the Westergaard method; also called subgrade modulus.  (See also modulus of subgrade reaction.)

 

coefficient of thermal expansion — change in linear dimension per unit length or change in volume per unit volume per degree of temperature change.

 

coefficient of variation — the standard deviation divided by the mean value of a variable.  (See also standard deviation.) History

 

cold-drawn wire reinforcement — see reinforcement, cold-drawn wire.

 

cold face — the surface of a refractory section not exposed to the source of heat; surface of concrete or masonry exposed to low ambient temperatures.

 

cold joint — see joint, cold.

 

cold-joint lines — visible lines on the surfaces of formed concrete indicating the presence of discontinuities where one layer of concrete had hardened before subsequent concrete was placed.  (See also joint, cold.)

 

cold strength — see strength, cold.

 

cold-water paint — see paint, cold-water.

 

cold weather — a period when the average daily ambient temperature is below 40 °F (5 °C) for more than three 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. History

 

cold-worked steel reinforcement — see reinforcement, cold-worked steel.

 

colemanite — a mineral, hydrated calcium borate (Ca₂B₆O₁₁·5H₂O).  (See also concrete, boron-loaded.)

 

colloid — a substance that is in a state of division preventing passage through a semipermeable membrane, consisting of particles ranging from 0.1 to 0.001 μm in diameter.

 

colloidal concrete — see concrete, colloidal.  

 

colloidal mixer — see mixer, colloidal.

 

colloidal grout — see grout, colloidal.

 

colloidal particle — see particle, colloidal.

 

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. History

 

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

 

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

 

column, pipe — column made of steel pipe; often filled with concrete.

 

column, short — a column whose load capacity is limited by strength rather than buckling; a column that is customarily so stocky and sufficiently restrained that at least 95% of the cross-sectional strength can be developed.

 

column, slender — a column whose load capacity is reduced by the increased eccentricity caused by secondary deflection moments.

 

column, spirally reinforced — a column in which the vertical bars are enveloped by spiral reinforcement, that is, closely spaced continuous hooping.

 

column, tied — a column laterally reinforced with ties.

 

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

 

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. History

 

combined-aggregate grading — see grading, combined-aggregate.

 

combined footing — see footing, combined.

 

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; or

 

(2) a colloquial name for a device (load binder) used to tighten chains holding loads in place on a truck bed.

 

compacted strand — see strand, compacted.

 

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 which fills the same container.

 

compaction— the process of reducing the volume or voids in a material such as soil by input of mechanical energy (see also consolidation). History

 

component, expansive — 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); the expansive component may be produced separately and later ground or blended with a normal portland-cement clinker, in other instances, produced by firing in a kiln with the constituents of portland cement.

 

composite — engineering materials—for example, concrete or fiber reinforced polymer—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; the constituent materials are generally characterized as matrix and reinforcement or matrix and aggregate. History

 

composite column — see column, composite.

 

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 — see construction, composite.

 

composite pile — see pile, composite.

 

composite sample — see sample, composite.

 

compound, curing — a liquid that can be applied as a coating to the surface of newly placed concrete to retard the loss of water and, in the case of pigmented compounds, to reflect heat so as to provide an opportunity for the concrete to develop its properties in a favorable temperature and moisture environment.  (See also curing and curing, membrane.) History

 

compound, joint-sealing — an impervious material used to fill joints in pavements or structures.

 

compound, sealing — see sealer.

 

compound, waterproofing — material used to impart water repellency to a structure or a constructional unit.

 

compression flange — see flange, compression.

 

compression member — see member, compression.

 

compression reinforcement — see reinforcement, compression.

 

compression test — see test, compression.

 

compressive strength — see strength, concrete compressive.

 

compressive strength, average — the average compressive strength of a given class or strength level of concrete; in ACI 214, defined as average compressive strength required to statistically meet a designated specific strength.

 

compressive stress — see stress.

 

concentric tendons — see tendons, concentric.

 

concordant tendon — see tendon, concordant.

 

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

 

concrete, aerated — see concrete, foamed and concrete, cellular.

 

concrete, aluminate — concrete made with calcium-aluminate cement; used primarily where high-early-strength and refractory or acid-resistant concrete is required.

 

concrete, architectural — 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.

 

concrete, asphaltic — a mixture of asphalt cement and aggregate.

 

concrete, backfill — nonstructural concrete used to correct over-excavation, fill excavated pockets in rock, or prepare a surface to receive structural concrete.

 

concrete, boron-loaded — 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 concrete, shielding.)

 

concrete, cast-in-place — 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.

 

concrete, cellular — 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 (for cellular concretes containing binder ingredients other than, or in addition to, portland cement, autoclave curing is usually employed).

 

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

 

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

 

concrete, chemically prestressing — concrete made with expansive cement and reinforcement under conditions such that the expansion of the cement induces tensile stress in the reinforcement so as to produce prestressed concrete.

 

concrete, colloidal — concrete in which the aggregate is bound by colloidal grout.

 

concrete, confined — concrete containing closely spaced special transverse reinforcement that is provided to restrain the concrete in directions perpendicular to the applied stress.

 

concrete, cyclopean — mass concrete in which large stones, each of 100 lb (50 kg) or more, are placed and embedded in the concrete as it is deposited.  (See also concrete, rubble.)

 

concrete, decorative — 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. History

 

concrete, dense — concrete containing a minimum of voids.

 

concrete, dry-packed — concrete placed by dry packing.

 

concrete, epoxy — a mixture of epoxy resin and catalyst (binder), fine aggregate, and coarse aggregate.  (See also concrete, polymer, mortar, epoxy, and resins, epoxy.)

 

concrete (mortar or grout), expansive-cement — a concrete (mortar or grout) made with expansive cement.

 

concrete, exposed — concrete surfaces formed so as to yield an acceptable texture and finish for permanent exposure to view.  (See also concrete, architectural.)

 

concrete, fair-face — a concrete surface that, on completion of the forming process, requires no further (concrete) treatment other than curing.  (See also concrete, architectural.)

 

concrete, fiber-reinforced — concrete containing dispersed, randomly oriented fibers.

 

concrete, fibrous — see concrete, fiber-reinforced.

 

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

 

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

 

concrete, foamed — low-density concrete made by the addition of a prepared foam or by generation of gas within the unhardened mixture.

 

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

 

concrete, gap-graded — concrete containing a gap-graded aggregate.

 

concrete, gas — lightweight concrete produced by developing voids with gas generated within the fresh mixture (usually from the action of cement alkalies on aluminum powder used as an admixture).  (See also concrete, foamed.)

 

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

 

concrete, green — concrete that has set but not hardened appreciably.

 

concrete, grouted-aggregate — see concrete, preplaced-aggregate.

 

concrete, gypsum — concrete in which the cementitious constituent is partially dehydrated calcium sulfate (plaster).

 

concrete, hardened — concrete that has developed sufficient strength to serve some purpose or resist breaking under stipulated loading.

 

concrete, heat-resistant — any concrete that will not disintegrate when exposed to constant or cyclic heating at any temperature below that at which a ceramic bond is formed.

 

concrete, heavy — see concrete, high-density (preferred term).

 

concrete, heavyweight — see concrete, high-density (preferred term).

 

concrete, high-density — 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.

 

concrete, high-early-strength — concrete which, through the use of high-early-strength cement or admixtures, attains a given level of strength earlier than normal concrete does.

 

concrete, high-strength — concrete that has a specified compressive strength for design of 8000 psi (55 MPa) or greater. History

 

concrete, high-performance — 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.

 

concrete, in-situ — see concrete, cast-in-place (preferred term).

 

concrete, insulating — concrete having low thermal conductivity; used as thermal insulation.  (See also concrete, lightweight and concrete, low-density.)

 

concrete, lean — concrete of low cementitious material content.

 

concrete, lightweight — concrete of substantially lower density than that made using aggregates of normal density.  (See also concrete, insulating and concrete, low-density.) History

 

concrete, low-density — concrete having an oven-dry density of less than 50 lb/ft³ (800 kg/m³).  (See also concrete, insulating and concrete, lightweight.)

 

concrete, mass — any volume of concrete with dimensions large enough to require that measures be taken to cope with generation of heat from hydration of the cement and attendant volume change to minimize cracking.

 

concrete, monolithic — concrete cast with no joints other than construction joints.

 

concrete, negative-slump — concrete of a consistency such that it not only has zero slump but still has zero slump after adding additional water.  (See also concrete, zero-slump and concrete, no-slump.)

 

concrete, no-fines — a concrete mixture containing little or no fine aggregate.

 

concrete, nonair-entrained — concrete in which neither an air-entraining admixture nor air-entraining cement has been used.

 

concrete, nonslip —

 

(1) a floor, pavement, or walkway of concrete the surface of which has been roughened, before final set, either by sprinkling fine particles of abrasive material thereon and then troweling or by swirling with either a coarse-bristled brush or a trowel; or

 

(2) after final set, by acid etching, mechanically abrading, or grooving.

 

concrete, normalweight — concrete having a density of approximately 150 lb/ft³ (2400 kg/m³) made with normal-density aggregates. History

 

concrete, normalweight refractory — refractory concrete having a bulk density greater than 100 lb/ft³ (1600 kg/m³).

 

concrete, no-slump — freshly mixed concrete exhibiting a slump of less than 1/4 in. (6 mm).  (See also concrete, zero-slump and concrete, negative-slump.)

 

concrete, pervious – concrete containing little, if any fine aggregate that results in a sufficient voids to allow air and water to easily pass from the surface to underlying layers. History

 

concrete, plain — structural concrete with no reinforcement or with less reinforcement than the minimum amount specified in the applicable building code for reinforced concrete. History

 

concrete, polymer — concrete in which an organic polymer serves as the binder. History

 

concrete, polymer-cement — a mixture comprising hydraulic cement and aggregate combined at the time of mixing with organic monomers or polymers that are dispersed in water. History

 

concrete, polymer-impregnated — a hydrated portland-cement concrete that has been impregnated with a monomer that is subsequently polymerized. History

 

concrete, popcorn — no-fines concrete containing insufficient cement paste to fill voids among the coarse aggregate so that the particles are bound only at points of contact.  (See also concrete, no-fines.)

 

concrete, precast — concrete cast elsewhere than its final position.

 

concrete, prepacked — see concrete, preplaced-aggregate.

 

concrete, preplaced-aggregate — concrete produced by placing coarse aggregate in a form and later injecting a portland cement-sand grout, usually with admixtures, to fill the voids.

 

concrete (mortar, grout), preshrunk —

 

(1) concrete that has been mixed for a short period in a stationary mixer before being transferred to a transit mixer, or

 

(2) grout, mortar, or concrete that has been mixed one to three hours before placing to reduce shrinkage during hardening.

 

concrete, prestressed — structural concrete in which internal stresses have been introduced to reduce potential tensile stresses in concrete resulting from loads. History

 

concrete, pumped — concrete which is transported through hose or pipe by means of a pump.

 

concrete, ready mixed — concrete manufactured for delivery to a purchaser in a fresh state.  (See also  concrete, central-mixed; concrete, shrink-mixed; and concrete, transit-mixed.)

 

concrete, recycled — hardened concrete that has been processed for reuse, usually as aggregate.

 

concrete, refractory — hardened hydraulic-cement concrete that has refractory properties and that is suitable for use at temperatures between 600 and 2400 °F (315 to 1315 °C).

 

concrete, refractory-insulating — refractory concrete having low thermal conductivity.

 

concrete, reinforced — structural concrete reinforced with no less than the minimum amount of prestressing steel or nonprestressed reinforcement as specified in the applicable building code. History

 

concrete, resin — see concrete, polymer (preferred term).

 

concrete, rich — concrete of high cement content.  (See also concrete, lean.)

 

concrete, roller-compacted — concrete compacted by roller compaction; concrete that, in its unhardened state, will support a roller while being compacted.

 

concrete, rubble —

 

1. concrete similar to cyclopean concrete except that small stones (such as one person can handle) are used.

 

2. concrete made with rubble from demolished structures.  (See also concrete, cyclopean.)

 

concrete, sand-lightweight — concrete made with a combination of expanded clay, shale, slag, or slate or sintered fly ash and natural sand; its density is generally between 105 and 120 lb/ft³ (1680 and 1920 kg/m³).

 

concrete, sawdust — concrete in which the aggregate consists mainly of sawdust from wood.

 

concrete, self-consolidating — fresh concrete that can flow around reinforcement and consolidate within formwork under its own weight without vibration and that exhibits no defect due to segregation or bleeding. History

 

concrete (mortar or grout), self-stressing — expansive-cement concrete (mortar or grout) in which expansion, if restrained, induces persistent compressive stresses in the concrete (mortar or grout); also known as chemically prestressed concrete.

 

concrete, shielding — concrete, employed as a biological shield to attenuate or absorb nuclear radiation, usually characterized by high density or high hydrogen (water) content or boron content, having specific radiation attenuation effects.  (See also biological shielding.)

 

concrete, shrink-mixed — ready mixed concrete mixed partially in a stationary mixer and then mixed in a truck mixer.  (See also concrete, preshrunk.)

 

concrete, shrinkage-compensating — concrete containing expansive components usually based on formation of calcium sulfoaluminate (ettringite) in a mixture of calcium aluminate and gypsum.  (See also  cement, expansive.)

 

concrete, siliceous-aggregate — concrete made with normal-density aggregates having constituents composed mainly of silica or silicates.

 

concrete, specified compressive strength of (fc') — compressive strength of concrete used in design. History

 

concrete, sprayed — see shotcrete (preferred term).

 

concrete, spun — see concrete, centrifugally cast (preferred term).

 

concrete, structural — plain or reinforced concrete in a member that is part of a structural system required to transfer gravity and /or lateral loads along a load path to the ground. History

 

concrete, structural lightweight — structural concrete made with low-density aggregate; having an air-dry density of not more than 115 lb/ft³ (1850 kg/m³) and a 28 day compressive strength of more than 2500 psi (17.2 MPa).

 

concrete, subaqueous — see concrete, underwater.

 

concrete, terrazzo — marble-aggregate concrete that is cast-in-place or precast and ground smooth for decorative surfacing purposes on floors and walls.

 

concrete, transit-mixed — concrete, the mixing of which is wholly or principally accomplished in a truck mixer.

 

concrete, translucent — a combination of glass and concrete used together in precast and prestressed panels.

 

concrete, truck-mixed — see concrete, transit-mixed.

 

concrete,  underwater — concrete placed underwater by tremie or other means.

 

concrete, unhardened — see concrete, fresh (preferred term).

 

concrete, unreinforced — see concrete, plain.

 

concrete, vacuum — concrete from which excess water and entrapped air are extracted by a vacuum process before hardening occurs.

 

concrete, vermiculite — concrete in which the aggregate consists of exfoliated vermiculite.

 

concrete, vibrated — concrete consolidated by vibration during and after placing.

 

concrete, visual — see concrete, exposed and concrete, architectural.

 

concrete, zero-slump — concrete of stiff or extremely dry consistency showing no measurable slump after removal of the slump cone.  (See also slump; concrete, no-slump; and concrete, negative-slump.)

 

concrete block — see block, concrete.

 

concrete breaker — a compressed-air tool specially designed and constructed to break up concrete.

 

concrete brick — see brick, concrete.

 

concrete cart — see buggy.

 

concrete compressive strength — see strength, concrete compressive.

 

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

 

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

 

concrete flatwork — see flatwork, concrete.

 

concrete masonry unit — see masonry unit, concrete.

 

concrete paver — see paver, concrete. 

 

concrete pile — see pile, cast-in-place and pile, precast.

 

concrete pump — see pump, concrete.

 

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 — see spreader, concrete.

 

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

 

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

 

condensed silica fume — see silica fume (preferred term).

 

conductance, thermal — time rate of heat flow through a unit area of body induced by a unit temperature difference between the body surfaces; the thermal conductance is the reciprocal of the thermal resistance.

 

conductivity, thermal — the property (of a homogeneous body) measured by the ratio of the steady-state heat flux (time-rate of heat flow per unit area) to the temperature.

 

cone —

 

cone, flow —  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 (flow factor) being used as the indication of consistency; also the mold used to prepare a specimen for the flow test.

 

cone, pyrometric — a small, slender, three-sided oblique pyramid made of ceramic or refractory material for use in determining the time-temperature effect of heating and in obtaining the pyrometric cone equivalent (PCE) of refractory material.

 

cone, slump — 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; a cone 6 in. (152 mm) high is used for tests of freshly mixed mortar and stucco.

 

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 — see concrete, confined.

 

confined region — region with transverse reinforcement within beam-column joints.

 

connection, scarf — 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.

 

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

 

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

 

consistency, fluid — the consistency at which a grout will form a nearly level surface without vibration or rodding; the consistency of a grout that has an efflux time of less than 30 seconds from the ASTM C939 flow cone.

 

consistency, normal —

 

(1) the consistency exhibited when a mixture is considered acceptable for the purpose at hand; or

 

(2) the consistency of cement paste satisfying appropriate limits defined in a standard test method (for example, ASTM C187). History

 

consistency, plastic —

 

(1) the consistency at which a mixture subjected to a constant stress undergoes increasing deformation without rupture; or

 

(2) the consistency at which mixture properties satisfy appropriate limits defined in a standard test method. History

 

consistency, wettest stable — the condition of maximum water content at which cement grout and mortar will adhere to a vertical surface without sloughing.

 

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 entrapped air in a fresh cementitious mixture, usually accomplished by inputting mechanical energy. (See also compaction, vibration,  rodding, and tamping.) History

 

construction —

 

construction, alternate-lane — a method of constructing soil-supported concrete roads, runways, building floors, or other paved areas, in which alternate lanes are placed and allowed to harden before the remaining intermediate lanes are placed.

 

construction, cellular — a method of constructing concrete elements in which part of the interior concrete is replaced by voids.

 

construction, composite — 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.

 

construction, structural sandwich — 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.

 

construction joint — see joint, 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 — see splice, contact.

 

containment grouting — see grouting, perimeter.

 

continuous beam — see continuous slab or beam.

 

continuous footing — see footing, continuous.

 

continuous grading — see grading, continuous.

 

continuous mixer — see mixer, continuous.

 

continuous mixing — see mixing, continuous.

 

continuous sampling — see sampling, continuous.

 

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 — see documents, contract.

 

contraction — decrease in either length or volume.  (See also expansion; shrinkage; swelling; volume change; and volume change, autogenous.)

 

contraction, thermal — see thermal contraction.

 

contraction joint — see joint, contraction.

 

contraction-joint grouting — see grouting, contraction-joint.

 

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

 

control joint — see joint, contraction (preferred term).

 

control-joint grouting — see grouting, contraction-joint.

 

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. History

 

conveying hose — see hose, delivery (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.

 

coquina — a type of limestone formed of sea shells in loose or weakly cemented condition, found along present or former shorelines; used as a calcareous raw material in cement manufacture and other industrial operations.

 

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); or

 

(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 sample 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 — see reinforcement, corner.

 

corrosion — destruction of metal by chemical, electrochemical, or electrolytic reaction within its environment. History

 

corrosion, bacterial — 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.

 

corrosion inhibitor — a chemical compound, either liquid or powder, usually intermixed in concrete and sometimes applied to concrete, and that effectively decreases corrosion of steel reinforcement. History

 

cotton mats — see mats, cotton.

 

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); or

 

(3) internal threaded device for joining reinforcing bars with matching threaded ends for the purpose of providing transfer of either axial compression or axial tension or both from one bar to the other.  (See also coupling sleeve, end-bearing sleeve, mechanical connection.)

 

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

 

coupling pin — an insert device used to connect lifts or tiers or formwork scaffolding vertically.

 

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, 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. History

 

cover block — see spacer and spreader (preferred terms).

 

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, diagonal — in a flexural member, an inclined crack caused by shear stress, usually at about 45 degrees to the axis; or a crack in a slab, not parallel to either the lateral or longitudinal directions.

 

crack, hairline — a concrete surface crack with a width so small as to be barely perceptible. History

 

crack, longitudinal — a crack that develops parallel to the length of a member.

 

crack, plastic-shrinkage — surface crack that occurs in concrete prior to initial set. History

 

crack, shrinkage — crack due to restraint of shrinkage.

 

crack, transverse — a crack that crosses the longer dimension of the member. History

   

crack-control reinforcement — see reinforcement, crack-control.

 

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

 

cracking —

 

cracking, diagonal — development of diagonal cracks.  (See also tension, diagonal.)

 

cracking, map —

 

(1) intersecting cracks that extend below the surface of hardened concrete; caused by shrinkage of the drying surface concrete that is restrained by concrete at greater depths where either little or no shrinkage occurs; vary in width from fine and barely visible to open and well-defined; or

 

(2) the chief symptom of chemical reaction between alkalies in cement and mineral constituents in aggregate within hardened concrete; due to differential rate of volume change in different portions of the concrete; cracking is usually random and on a fairly large scale, and in severe instances the cracks may reach a width of 0.50 in. (12.7 mm).  (See also checking, crazing; also known as pattern cracking.)

 

cracking, pattern — see cracks, and cracking, map.

 

cracking, shrinkage — cracking of a structure or member due to failure in tension caused by external or internal restraints as reduction in moisture content develops, carbonation occurs, or both.

 

cracking, stress-corrosion — a cracking process that requires the simultaneous action of a corrodent and sustained tensile stress. (This excludes corrosion-reduced sections that fail by fast fracture; also excludes intercrystalline or transcrystalline corrosion that can disintegrate an alloy without either applied or residual stress).

 

cracking, temperature — 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.

 

cracking load — see load, cracking.

 

cracks —

 

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

 

cracks, D-line — see D-cracks (preferred term.)

 

cracks, pattern — see cracks and cracking, map.

 

craze cracks — see cracks, craze.

 

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

 

creep — time-dependent deformation due to sustained load.  (See also deformation, inelastic.)

 

creep, basic — creep that occurs without migration of moisture to or from the concrete.  (See creep; creep, drying.)

 

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

 

creep, nonrecoverable — the residual or nonreversible deformation remaining in hardened concrete after removal of sustained load.

 

crimped wire — see wire, crimped.

 

critical saturation — see saturation, critical.

 

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

 

cross joint — see joint, cross.

 

cross section — a plane through a body perpendicular to a given axis of the body; a drawing showing such a plane.

 

cross-tee — a light-gage metal member resembling an upside-down “tee” used to support the abutting ends of formboards in insulating concrete roof constructions.

 

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.  (See also strip, wrecking.)

 

crushed gravel — see gravel, crushed.

 

crushed stone — see stone, crushed.

 

crusher —

 

crusher, primary — a heavy crusher suitable for the first stage in a process of size reduction of rock, slag, or the like.

 

crusher, secondary — a crusher used for the second stage in a process of size reduction of aggregate and the like.  (See also crusher, primary.)

 

crusher-run aggregate — see aggregate, crusher-run.

 

C/S — the molar or mass ratio, whichever is specified, of calcium oxide (CaO) to silicon dioxide (SiO₂); usually of binder materials cured in an autoclave.

 

cube strength — see strength, cube.

 

cubical piece (of aggregate) — one in which length, breadth, and thickness are approximately equal.

 

cumulative batching — see batching, cumulative.

 

curb form — a retainer or mold used in conjunction with a curb tool to give the necessary shape and finish to a concrete curb.

 

curb tool — a tool used to give the desired finish and shape to the exposed surfaces of a concrete curb.

 

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.  (See ACI 308.)

 

curing, adiabatic — the maintenance of adiabatic conditions in concrete or mortar during the curing period.

 

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

 

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

 

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

 

curing, final — 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. History

 

curing, fog —

 

(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); and

 

(2) application of atomized water to concrete, stucco, mortar, or plaster.

 

curing, high-pressure steam — see curing, autoclave (preferred term).

 

curing, initial — deliberate action taken between placement and final finishing of concrete to reduce the loss of water from the surface of the concrete. History

 

curing, internal — supplying water throughout a freshly placed cementitious mixture using reservoirs, via pre-wetted lightweight aggregates, that readily release water as needed for hydration or to replace moisture lost through evaporation or self-desiccation. History

 

curing, low-pressure steam — see curing, atmospheric-pressure steam.

 

curing, mass — adiabatic curing in sealed containers.

 

curing, membrane — a process that involves either liquid sealing compound (for example bituminous and paraffinic emulsions, coal tar cut-backs, pigmented and non pigmented resin suspensions, or suspension of wax and drying oil) or nonliquid protective coating (for example, sheet plastics or “waterproof” paper), both of which types function as a film to restrict evaporation of mixing water from concrete surfaces.

 

curing, moist-air — curing in air of not less than 95% relative humidity at atmospheric pressure and normally at a temperature approximating 73 °F (23 °C).

 

curing, single-stage — autoclave curing process in which precast concrete products are put on metal pallets for autoclaving and remain there until stacked for delivery or yard storage.

 

curing, standard — exposure of test specimens to specified conditions of moisture and temperature.  (See also curing, fog.)

 

curing, steam — curing of concrete, mortar, grout, or neat-cement paste in water vapor at atmospheric or higher pressures and at temperatures between about 100 and 420 °F (40 and 215 °C).  (See also curing, atmospheric-pressure steam; curing, autoclave; curing, single-stage; and curing, two-stage.)

 

curing, two-stage — a process in which concrete products are cured in low-pressure steam, stacked, and then autoclaved.

 

curing agent — see agent, curing.  History

 

curing blanket — see blanket, curing.

 

curing compound — see compound, curing.

 

curing cycle — see cycle, autoclave and steam-curing cycle.

 

curing delay — see period, presteaming (preferred term).

 

curing kiln — see curing, autoclave.

 

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.) History

 

curtain grouting — see grouting, curtain.

 

curtain reinforcement — see reinforcement, curtain.

 

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

 

curve, grading — 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.

 

cutting screed — see screed, cutting.

 

cycle, autoclave — the time interval between the start of the temperature-rise period and the end of the blowdown period; also, a schedule of the time and temperature-pressure conditions of periods which make up the cycle.

 

cyclopean concrete — see concrete, cyclopean.

 

cylinder strength — see strength, concrete compressive and strength, splitting tensile.

 

cylinders, field-cured — test cylinders that are left at the jobsite 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.