| Moist Room | (Concrete Engineering) A room used for storing and curing cementitious test specimens. The atmosphere of this room is maintained at a temperature of 73.4 3.0'F or 23.0*1.7'0 and relative humidity of at least 98 percent. These facilities must be adequate to continually maintain free moisture on the exteriors of test specimens. |
| Non-agitating Unit | (Concrete Engineering) A truck-mounted unit for transporting ready-mixed concrete short distances, not equipped to provide agitation (slow mixing) during delivery. |
| Non-evaporable Water | (Concrete Engineering) The water in concrete which is irremovable by oven drying; chemically combined during cement hydration. |
| Overvibration | (Concrete Engineering) Excessive vibration of freshly mixed concrete during placement-causing segregation. |
| Particle-Size Distribution | (Concrete Engineering) Particle distribution of granular materials among various sizes; for concrete material normally designated as gradation. Usually expressed in terms of cumulative percentages smaller or larger than each of a series of sieve openings or percentages between certain ranges of sieve openings. |
| Peeling | (Concrete Engineering) A process in which thin flakes of matrix or mortar are broken away from concrete surface; caused by adherence of surface mortar-to forms as forms are removed, or to trowel or float in portland cement plaster. |
| Pining | (Concrete Engineering) Development of relatively small cavities in a concrete surface, due to phenomena such as cavitation or corrosion. |
| Plastic | (Concrete Engineering) A condition of freshly mixed concrete. mortar or cement -paste indicating that it is workable and readily re-moldable, is cohesive, and has an ample content of fines and cement but is not over wet. |
| Portland Cement (ASTM C 150) | (Concrete Engineering) The product obtained by pulverizing clinker consisting essentially of hydraulic calcium silicates. |
| Pozzolan (ASTM C 618) | (Concrete Engineering) A siliceous, or siliceous and aluminous material, which in itself possesses little or no cementitious value but will, in a finely divided form, such as a powder or liquid and in the presence of moisture, chemically react with calcium hydroxide at ordinary temperatures to form permanent, insoluble compounds possessing cementitious properties. |