| 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. |
| Plane of Weakness | (Concrete Engineering) The plane along which a structure under stress will tend to fracture; may exist because of the nature of the structure and its loading, by accident, or by design. |
| Plasticity | (Concrete Engineering) Property of freshly mixed concrete, cement paste or mortar which determines its ease of molding or resistance to deformation. |
| 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. |
| Preplaced Concrete | (Concrete Engineering) Concrete manufactured by placing clean, graded coarse aggregate in a form and later injecting a portland cement-sand grout under pressure, to fill the voids. |
| Pretensioning | (Concrete Engineering) A method of prestressing reinforced concrete in which the steel is stressed before the concrete has hardened and restrained from gaining its unstressed position by bond to the concrete. |
| Pumping (of Pavements) | (Concrete Engineering) The ejection of a mixture of water and solid materials such as clay or silt along cracks, transverse or longitudinal joints, and along pavement edges caused by downward slab movement due to the passage of heavy loads, machinery or equipment over the pavement after free water has accumulated in or on the subbase, subgrade or basecourse. |
| Rock Pocket | (Concrete Engineering) Area or portion of hardened concrete which is deficient in mortar and consisting primarily of coarse aggregate and open voids; caused by insufficient consolidation or separation during placement, or both; by leakage from form. |
| Sacking | (Concrete Engineering) Removing or alleviating defects on a concrete surface by applying a mixture of sand and cement to the moistened surface and rubbing with a coarse material such as burlap. |