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 storage area).
natural cement—see cement, natural.
natural frequency—the frequency at which a system that has been moved from its resting position will oscillate about the position if there are no disturbing forces.
natural pozzolan—see pozzolan, natural.
natural sand—see sand, natural.
neat cement grout—see grout, neat-cement.
neat cement paste—see cement paste, neat.
neat line—a line defining the proposed or specified limits of an excavation or structure.
neat plaster—see plaster, neat.
necking—the localized and permanent reduction of crosssectional area of a test specimen of metal; due to stretching produced by applied tensile load.
needle, Gillmore—a device used in determining time of setting of hydraulic cement.
needle, Vicat—a weighted needle for determining time of setting of hydraulic cements.
needle scaling—a surface preparation method in which the surface is impacted with the pointed tips of a bundle of steel rods contained by a steel tube and pulsed by compressed air.
negative catalyst—see catalyst, negative.
negative moment—see moment, negative.
negative reinforcement—see reinforcement, negative.
negative side waterproofing—applying waterproofing to the side of a structural element opposite the one subjected to hydrostatic pressure.
negative-slump concrete—see concrete, negative-slump.
neoprene—an elastomer, polychloroprene, formed by adding hydrogen chloride to monovinylacetylene.
net cross-sectional area (of masonry)—the gross crosssectional area of a section of masonry minus the area of cavities, cells, or cored spaces.
net mixing water—see water, mixing.
neutral axis—see axis, neutral.
neutral refractory—see refractory, neutral.
Nicol prism—a system of two optically clear crystals of calcite (“Iceland spar”) used in producing plane-polarized light.
nip—the seizing of stone between either the jaws or the rolls of a crusher.
no-fines concrete—see concrete, no-fines.
nominal flexural strength—see strength, nominal flexural.
nominal maximum size (of aggregate)—in specifications for and in descriptions of aggregate, the smallest sieve opening through which the entire amount of the aggregate is permitted to pass. (See also maximum size [of aggregate].)
nominal mixture—the proportions of the constituents of a proposed concrete mixture.
nominal shear strength—see strength, nominal shear.
nominal size—see nominal maximum size (of aggregate).
nominal strength—see strength, nominal.
nonagitating unit—a truck-mounted container for transporting central-mixed concrete, not equipped to provide agitation (slow mixing) during delivery.
nonair-entrained concrete—see concrete, nonair-entrained.
nonbearing wall—see wall, nonbearing.
noncombustible—any material that neither ignites nor supports combustion in air when exposed to fire.
nonconcordant tendons—see tendons, nonconcordant.
nondestructive testing(NDT)—examination of materials and structures in ways that do not impair future usefulness and serviceability in order to detect, locate, and measure discontinuities, defects, and other imperfections to assess integrity, properties, and uniformity, and to measure geometrical characteristics.
nondestructive evaluation (NDE)—condition evaluation conducted with nondestructive methods.
nonevaporable water—see water, nonevaporable.
nonferrous—relating to metals other than iron; not containing or including iron.
nonprestressed reinforcement—see reinforcement, nonprestressed.
nonrecoverable creep—see creep, nonrecoverable.
nonreversible deformation—see creep, nonrecoverable (preferred term).
nonsimultaneous prestressing—see prestressing, nonsimultaneous.
nonslip concrete—see concrete, nonslip.
nonstaining cement—see cement, nonstaining.
nonstructural reinforcement—see reinforcement, temperature.
nontilting mixer—see mixer, nontilting.
normal cement—see cement, normal.
normal consistency—see consistency, normal.
normal portland cement—see cement, normal.
normal stress—see stress, normal.
normalweight aggregate—see aggregate, normalweight.
normalweight concrete—see concrete, normalweight.
normalweight refractory concrete—see concrete, normalweight refractory.
no-slump concrete—see concrete, no-slump.
nozzle—an open-ended metal or rubber tip attached to the discharge end of a heavy thick-walled rubber hose from which a continuous stream of shotcrete is ejected at high velocity.
nozzle body—a device at the end of a shotcrete delivery hose that contains a regulating valve and a manifold for adding water or air to the shotcrete mixture.
nozzle liner—a replaceable rubber lining placed inside the nozzle tip toprevent abrasion protection of the interior surface of the nozzle.
nozzle operator—the technician who manipulates the nozzle and controls placement of the shotcrete; in the case of dry-mix shotcrete, the technician also controls the water content of the shotcrete.
nozzle velocity—the velocity (speed) at which shotcrete is ejected from the nozzle.