obsidian—a natural volcanic glass of relatively low water content; usually of rhyolite composition. (See also perlite.) offset—an abrupt change in alignment or dimension, either horizontally or vertically; a horizontal ledge occurring along a change in wall thickness of the wall above. offset bend—an intentional distortion from the normal…
nailable concrete—see concrete, nailable. nailer—a strip of wood or other fitting attached to or set in concrete, or attached to steel, to facilitate making nailed connections. natural air-drying—the process of drying cured concrete masonry units without any special equipment (for example, the drying that occurs in a covered…
macadam, cement-bound—a road consisting of crushed stone, crushed slag, or gravel and either a grout or mortar filler; formed by rolling a base of stone, slag, or gravel to a compacted mass having an even surface, and then rolling in the cementitious filler. machine, finishing—a power-operated machine used…
lacing—horizontal bracing between shoring members. lagging—heavy sheathing used as in underground work to withstand earth pressure. (See also sheathing.) laitance—a weak layer of cement and aggregate fines either: (1) carried by bleeding to the surface or to internal cavities of freshly placed concrete; or (2) separated from the…
kaolin—a rock, generally white, consisting primarily of clay minerals of the kaolinite group, composed principally of hydrous aluminum silicate of low iron content, used as raw material in the manufacture of white cement. kaolinite—a common clay mineral having the general formula Al2(Si2O5)(OH4), the primary constituent of kaolin. Keene’s…
ignition loss—see loss on ignition (preferred term). ilmenite—a mineral, iron titanate (FeTiO3), which in pure or impure form is commonly used as aggregate in high-density concrete. impact—instantaneous contact of a moving body with another body, either moving or at rest. impact breakers—see concrete breakers, impact. impact echo—a nondestructive…
hacking—the roughening of a surface by striking with a tool. hairline crack—see crack, hairline. hairpin—the wedge used to tighten some types of form ties; a hairpin-shaped anchor set in place while concrete is unhardened; a light hairpin-shaped reinforcing bar used for shear reinforcement in beams, tie reinforcement in…
gage length—in cement testing, the nominal length between the innermost ends of metal studs that are molded into a test specimen with the axis of the stud in each end of the test specimen coincident with the longitudinal axis of the test specimen and with each other. galvanic…
fabric, welded-wire—a series of longitudinal and transverse wires arranged approximately at right angles to each other and welded together at all points of intersection. fabric, woven-wire—a prefabricated steel reinforcement composed of cold-drawn steel wires mechanically twisted together to form hexagonally shaped openings. face, pilaster—the form for the front…
early ages (of concrete)—the period following the time of final setting during which properties are changing rapidly and heat evolution is important; for concrete made with Type I cement stored moist at 73 F (23 C), it is the first 72 h. early stiffening—see stiffening, early. earth pigments—the…
damage, abrasion—wearing away of a surface by rubbing and friction. (See also damage, cavitation and erosion.) damage, cavitation—pitting of concrete caused by implosion, that is, the collapse of vapor bubbles in flowing water which form in areas of low pressure and collapse as they enter areas of higher…
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 approximately 73 F (23 C) and at least 95% relative humidity. (See also moist room.) cable—see tendon (preferred…
backer rod—a flexible, compressible rod placed in a joint to reduce the depth of sealant and improve its shape factor; it also serves to support the sealant against sagging and indentation. backpack grouting—see grouting, backpack. back plastering—plaster applied to one face of a lath system following application and…
abrasion damage—surface deterioration caused by rubbing and friction against the surface. abrasive—any hard, strong substance, such as rocks, sand, water, or minerals, that will cut, scour, pit, erode, or polish another substance. abrasive blasting—a process for roughening, cleaning, or finishing a surface by propelling an abrasive medium at…
