R-value see resistance, thermal.
raft foundation see foundation, raft.
rail-steel reinforcement see reinforcement, rail-steel.
rake classifier machine for separating coarse and fine particles of granular material temporarily suspended in water; the coarse particles settle to the bottom of a vessel and are scraped up an incline by a set of blades, the fine particles remaining in suspension to be carried over the edge of the classifier.
raker a sloping brace for a shore head.
raked joint see joint, raked.
raker pile see pile, batter (preferred term).
raking pile see pile, batter (preferred term).
ramming a form of heavy tamping of concrete, grout, or the like by means of a blunt tool forcibly applied. (See also pack, dry; punning; and tamping.)
random ashlar see masonry, ashlar (preferred term).
ranger see wale (preferred term).
ratio, A/F the molar or mass ratio of aluminum oxide (Al2O3) to iron oxide (Fe2O3), as in portland cement.
ratio, aggregate-cement the ratio of cement to total aggregate, either by mass or volume.
ratio, Poissons the absolute value of the ratio of transverse (lateral) strain to the corresponding axial (longitudinal) strain resulting from uniformly distributed axial stress below the proportional limit of the material; the value will average about 0.2 for concrete and 0.25 for most metals.
raveling the wearing away of the concrete surface caused by the dislodging of aggregate particles. History
raw mix blend of raw materials, ground to desired fineness, correctly proportioned, and blended ready for burning; such as that used in the manufacture of cement clinker.
Rayleigh wave an ultrasonic surface wave in which the particle motion is elliptical and effective penetration is approximately one wavelength.
reaction, alkali-aggregate chemical reaction in either mortar or concrete between alkalies (sodium and potassium) from portland cement or other sources and certain constituents of some aggregates; under certain conditions, deleterious expansion of concrete or mortar may result.
reaction, alkali-carbonate rock the reaction between the alkalies (sodium and potassium) in portland cement and certain carbonate rocks, particularly calcitic dolomite and dolomitic limestones, present in some aggregates; the products of the reaction may cause abnormal expansion and cracking of concrete in service.
reaction, alkali-silica the reaction between the alkalies (sodium and potassium) in portland cement and certain siliceous rocks or minerals, such as opaline chert, strained quartz, and acidic volcanic glass, present in some aggregates; the products of the reaction may cause abnormal expansion and cracking of concrete in service.
reaction, endothermic a chemical reaction that occurs with the absorption of heat.
reaction, exothermic a chemical reaction that occurs with the evolution of heat.
reaction, pozzolanic see pozzolan.
reaction, subgrade see contact pressure and coefficient of subgrade reaction.
reactive aggregate see aggregate, reactive.
reactive silica material several types of materials that react at high temperatures with portland cement or lime during autoclaving, includes pulverized silica, natural pozzolan, and fly ash.
reactivity (of aggregate), alkali susceptibility of aggregate to alkali-aggregate reaction.
ready mixed concrete see concrete, ready mixed.
rebar colloquial term for reinforcing bar. (See also reinforcement.)
rebound shotcrete materials, or wet shotcrete, that bounces away from the surface against which the shotcrete is being projected. History
rebound hammer see hammer, rebound.
recycled concrete see concrete, recycled.
reference standards standardized mandatory language documents of a technical society, organization, or association, including the building codes of local or state authorities, which are referenced in the contract documents. History
refractories materials, usually nonmetallic, used to withstand high temperatures.
refractoriness in refractories, the property of being resistant to softening or deformation at high temperatures.
refractory resistant to high temperatures.
refractory, castable a packaged, dry mixture of hydraulic cement, generally calcium-aluminate cement, and specially selected and proportioned refractory aggregates that, when mixed with water, will produce refractory concrete or mortar.
refractory, neutral a refractory that is resistant to chemical attack by either acidic or basic substances.
refractory aggregate see aggregate, refractory.
refractory concrete see concrete, refractory.
refractory-insulating concrete see concrete, refractory-insulating.
reglet a groove in a wall to receive flashing.
regulated-set cement see cement, regulated-set.
rehabilitation the process of repairing or modifying a structure to a desired useful condition. (See also preservation, repair, and restoration.)
reinforced concrete see concrete, reinforced.
reinforced masonry see masonry, reinforced.
reinforcement bars, wires, strands, fibers, or other slender elements that are embedded in a matrix such that they act together to resist forces. History
reinforcement, auxiliary in a prestressed member, any reinforcement in addition to that participating in the prestressing function.
reinforcement, axle-steel either plain or deformed reinforcing bars rolled from axle steel.
reinforcement, cold-drawn wire steel wire made from rods that have been hot rolled from billets, cold-drawn through a die; for concrete reinforcement of diameter not less than 0.080 in. (2 mm) nor greater than 0.625 in. (16 mm).
reinforcement, cold-worked steel steel bars or wires that have been rolled, twisted, or drawn at normal ambient temperatures.
reinforcement, compression reinforcement designed to carry compressive stresses. (See also stress.)
reinforcement, corner metal reinforcement for plaster at reentrant corners to provide continuity between two intersecting planes; or concrete reinforcement used at wall intersections or near corners of square or rectangular openings in walls, slabs, or beams.
reinforcement, crack-control reinforcement in concrete construction designed to minimize opening of cracks, often effective in limiting them to uniformly distributed small cracks.
reinforcement, curtain a mat of orthogonal reinforcing steel in a member such as a wall; known as a double curtain (of reinforcement) when a mat is at each face.
reinforcement, deformed metal bars, wire, or fabric with a manufactured pattern of surface ridges that provide a locking anchorage with surrounding concrete.
reinforcement, distribution-bar small diameter bars, usually at right angles to the main reinforcement, intended to spread a concentrated load on a slab and to prevent cracking.
reinforcement, dowel-bar see dowel.
reinforcement, edge-bar tension steel sometimes used to strengthen otherwise inadequate edges in a slab without resorting to edge thickening.
reinforcement, expanded-metal fabric see lath, expanded-metal.
reinforcement, four-way a system of reinforcement in flat-slab construction comprising bands of bars parallel to two adjacent edges and also to both diagonals of a rectangular slab.
reinforcement, heavy-edge wire-fabric reinforcement for highway pavement slabs having one to four edge wires heavier than the other longitudinal wires.
reinforcement, helical steel reinforcement of hot-rolled bar or cold-drawn wire fabricated into a helix (more commonly known as spiral reinforcement).
reinforcement, high-strength see steel, high-strength.
reinforcement, hoop a one-piece closed tie or continuously wound tie not less than No. 3 in size, the ends of which have a standard 135 degree bend with a ten-bar diameter extension, which encloses the longitudinal reinforcement.
reinforcement, lateral transverse reinforcement, usually applied to ties, hoops, and spirals in columns or column-like members.
reinforcement, longitudinal reinforcement parallel to the length of a concrete member or pavement.
reinforcement, mesh see fabric, welded-wire and reinforcement, welded-wire fabric.
reinforcement, negative steel reinforcement for negative moment.
reinforcement, nonprestressed reinforcing steel, not subjected to either pretensioning or post-tensioning.
reinforcement, nonstructural see reinforcement, temperature.
reinforcement, positive reinforcement for positive moment.
reinforcement, rail-steel reinforcing bars hot-rolled from standard T-section rails.
reinforcement, shear reinforcement designed to resist shear or diagonal tension stresses. (See also dowel.) History
reinforcement, shrinkage reinforcement designed to resist shrinkage stresses in concrete.
reinforcement, spiral continuously wound reinforcement in the form of a cylindrical helix. (See also reinforcement, helical.)
reinforcement, temperature reinforcement designed to carry stresses resulting from temperature changes; also the minimum reinforcement for areas of members that are not subjected to primary stresses or necessarily to temperature stresses.
reinforcement, tension reinforcement designed to carry tensile stresses such as those in the bottom of a simple beam.
reinforcement, transverse reinforcement at right angles to the longitudinal reinforcement.
reinforcement, twin-twisted bar two bars of the same nominal diameter twisted together.
reinforcement, two-way reinforcement arranged in bands of bars at right angles to each other.
reinforcement, web reinforcement placed in a concrete member to resist shear and diagonal tension.
reinforcement, welded reinforcement joined together by welding.
reinforcement, welded-wire fabric welded-wire fabric in either sheets or rolls, used to reinforce concrete.
reinforcement, woven-wire see fabric, welded-wire (preferred term).
reinforcement displacement movement of reinforcing steel from its specified position in the forms.
reinforcement ratio ratio of the effective area of the reinforcement to the effective area of the concrete at any section of a structural member. (See also percentage of reinforcement.)
relative humidity the ratio of the quantity of water vapor actually present to the amount present in a saturated atmosphere at a given temperature; expressed as a percentage.
release agent see agent, release.
release, partial release into a prestressed-concrete member of a portion of the total prestress initially held wholly in the prestressed reinforcement.
remoldability the readiness with which freshly mixed concrete responds to a remolding effort such as jigging or vibration, causing it to reshape its mass around reinforcement and to conform to the shape of the form. (See also flow.)
remolding test see test, remolding
render to apply a coat of mortar by a trowel or float.
repair to replace or correct deteriorated, damaged, or faulty materials, components, or elements of a structure. (See also preservation, rehabilitation, and restoration.) History
repair, structural increasing the load-carrying capacity of a structural component beyond its current capacity or restoring a damaged structural component to its original design capacity. History
repair system the combination of materials and techniques used in the repair of a structure. History
repeatability variability among replicate test results obtained on the same material within a single laboratory by one operator; a quantity that will be exceeded in only about 5% of the repetitions by the difference, taken in absolute value, of two randomly selected test results obtained in the same laboratory on a given material; in use of the term, variable factors should be specified. History
repost see reshore.
reproducibility variability among replicate test results obtained on the same material in different laboratories; a quantity that will be exceeded in only about 5% of the repetitions by the difference, taken in absolute value, of two single test results made on the same material in two different, randomly selected laboratories; in use of the term, variable factors should be specified. History
required strength see strength, required.
resetting (of forms) setting of forms separately for each successive lift of a wall to avoid offsets at construction joints.
reshore a temporary support placed against the bottom of a slab or other structural member immediately after the forms and original shores have been removed. History
residual deformation see creep, nonrecoverable.
residual strength, test specimen strength in the post-peak load region of a static load-deflection curve.
resilience the work done per unit volume of a material in producing strain.
resin generally a thermosetting polymer used as the matrix and binder in FRP composites. History
resin, acrylic one of a group of thermoplastic resins formed by polymerizing the esters or amides of acrylic acid used to make polymer-modified concrete and polymer concretes; also used in concrete construction as a bonding agent, surface sealer, or an integral concrete component.
resin, epoxy a class of organic chemical bonding systems used in the preparation of special coatings or adhesives for concrete or as binders in epoxy-resin mortars, concretes, and fiber reinforced polymer composites. History
resin, phenolic a class of synthetic, oil-soluble resins (plastics) produced as condensation products of phenol, substituted phenols and formaldehyde, or some similar aldehyde that may be used in paints for concrete.
resin, polystyrene synthetic resins, varying from colorless to yellow, formed by the polymerization of styrene on heating with or without catalysts, that may be used in paints for concrete, or for making sculptured molds, or as insulation.
resin concrete see concrete, polymer (preferred term).
resin mortar see concrete, polymer.
resistance refractory aggregate see aggregate, refractory.
resistance, abrasion ability of a surface to resist being worn away by rubbing and friction.
resistance, fire the property of a material or assembly to withstand fire or give protection from it; as applied to elements of buildings, it is characterized by the ability to confine a fire or, when exposed to fire, to continue to perform a given structural function, or both.
resistance, penetration the resistance, usually expressed in pounds per square inch (psi) or megapascals (MPa), of either mortar or cement paste to penetration by a plunger or needle under standard conditions, such as to determine time of setting.
resistance, skid a measure of the frictional characteristics of a surface.
resistance, sulfate ability of concrete or mortar to withstand sulfate attack. (See also sulfate attack.)
resistance, thermal the reciprocal of thermal conductance expressed by the symbol R.
restoration the process of reestablishing the materials, form, and appearance of a structure to those of a particular era of the structure. (See also preservation, rehabilitation, and repair.)
restraint (of concrete) restriction of free movement of fresh or hardened concrete following completion of placing in formwork or molds or within an otherwise confined space; restraint can be internal or external and may act in one or more directions.
retardation reduction in the rate of either hardening, setting, or both, that is, an increase in the time required to reach time of initial and final setting or to develop early strength of fresh concrete, mortar, or grout. (See also retarder.)
retarder an admixture that delays the setting of cement paste, and of mixtures, such as mortar or concrete, containing cement. (See also admixture, retarding.)
retarder, surface a retarder applied to the contact surface of a form or to the surface of newly placed concrete, to delay setting of the cement, to facilitate construction joint cleanup, or to facilitate production of exposed-aggregate finish.
retarding admixture see admixture, retarding.
retemper to add water and remix a cementitious mixture to restore workability to a condition in which the mixture is placeable or usable. (See also temper.) History
reveal (n.) the vertical surface forming the side of an opening in a wall, as for a window or door; depth of exposure of aggregate in an exposed aggregate finish. (See also exposed-aggregate finish.)
revibration one or more applications of vibration to fresh concrete after completion of placing and initial consolidation but preceding initial setting of the concrete.
revolving-blade (or paddle) mixer see mixer, open-top.
rheology the science dealing with flow of materials, including studies of deformation of hardened concrete, the handling and placing of freshly mixed concrete, and the behavior of slurries, pastes, and the like.
rib one of a number of parallel structural members backing sheathing; the portion of a T-beam which projects below the slab; in deformed reinforcing bars, the deformations or the longitudinal parting ridge.
ribbed panel see panel, ribbed.
ribbed slab see panel, ribbed.
ribbon a narrow strip of wood or other material used in formwork.
ribbon loading see loading, ribbon.
rich concrete see concrete, rich.
rich mixture a concrete mixture containing a high proportion of cement.
rider cap see cap, pile.
rigid frame see frame, rigid.
rigid pavement see pavement, rigid.
rigidity, flexural a measure of stiffness of a member, indicated by the product of modulus of elasticity and moment of inertia divided by the length of the member.
ring, air perforated manifold in nozzle of wet-mix shotcrete equipment through which high pressure air is introduced into the material flow.
ring, proving a device for calibrating load indicators of testing machines, consisting of a calibrated elastic ring and a mechanism or device for indicating the magnitude of deformation under load.
rock pocket a porous, mortar-deficient portion of hardened concrete consisting primarily of coarse aggregate and open voids; caused by leakage of mortar from the form, separation (segregation) during placement, or insufficient consolidation. (See also honeycomb.)
1) a tool that is used as a straightedge or screed to provide a uniform and even surface across a plaster coat usually by trimming to a ground or dot;
2) a tool used as a guide for a scoring (combed) finish or similar repeating pattern finish; or
3) a sharp-edged cutting screed used to trim shotcrete to forms or ground wires. (See also screed.) History
rod, dowel see dowel (preferred term).
rod, pencil plain metal rod of about 1/4 in. (6 mm) diameter.
rod, tamping a straight steel rod of circular cross-section and having one or both ends rounded to a hemispherical tip.
rod, tie see tie, form and tieback.
rodability the susceptibility of fresh concrete or mortar to consolidation by means of a tamping rod.
rod buster (colloquial) one who installs reinforcement for concrete.
rodding consolidation of concrete by means of a tamping rod. (See also rod, rodability, and tamping.)
rodding, dry in measurement of the mass per unit volume of coarse aggregates, the process of consolidating dry material in a calibrated container by rodding under standardized conditions.
rod mill see mill, rod.
roller-compacted concrete see concrete, roller-compacted.
roller compaction a process for compacting concrete using a roller, often a vibratory roller.
rolling the use of heavy metal or stone rollers on terrazzo topping to extract excess matrix.
Roman cement see cement, Roman.
roof, barrel-vault a thin concrete roof in the form of a part of a cylinder.
roof insulation see insulation, roof.
room, fog see moist room (preferred term).
Rosiwal method see linear-traverse method.
rotary float (also called power float) see float, rotary.
rotary kiln see kiln, rotary.
rough grind the initial operation in which coarse abrasives are used to reduce the projecting stone chips in hardened terrazzo down to a level surface.
rout to deepen and widen a crack to prepare it for patching or sealing.
rub brick see brick, rubbing (preferred term).
rubbing brick see brick, rubbing.
rubbed finish see finish, rubbed.
rubber set see set, false (preferred term).
rubble rough stones of irregular shape and size, broken from larger masses by geological processes or by quarrying; concrete reduced to irregular fragments, as by demolition or natural catastrophe.
rubble concrete see concrete, rubble.
runway decking over area of concrete placement, usually of movable panels and supports, on which buggies of concrete travel to points of placement.
rupture modulus see modulus of rupture.
rupture strength see modulus of rupture.
rustic or washed finish see finish, rustic or washed.
rustication a groove in a concrete surface.
rustication strip see strip, rustication.
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