Neat Cement-Paste A mixture of water and hydraulic cement, both before and after setting and hardening.
No-Fines Concrete A concrete mixture in which only the coarse
gradation (3/8' to 3/4' normally) of aggregate issued.
Non-agitating Unit A truck-mounted unit for transporting ready-mixed
concrete short distances, not equipped to provide agitation (slow
mixing) during delivery.
Non-evaporable Water The water in concrete which is irremovable by
oven drying; chemically combined during cement hydration.
Ottawa Sand A sand used as a standard in testing hydraulic cements
by means of mortar test specimens. Sand is produced by processing
silica rock particles obtained by hydraulic mining of the orthoquartzite
situated in open-pit deposits near Ottawa, Illinois; naturally rounded
grains of nearly pure quartz.
Overvibration Excessive vibration of freshly mixed concrete during placement-causing segregation.
Particle-Size Distribution 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.
Pea Gravel Portion of concrete aggregate passing the 3/8' sieve and
retained on a No.4 sieve.
Peeling 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
Pining Development of relatively small cavities in a concrete
surface, due to phenomena such as cavitation or corrosion.
Plane of Weakness 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.
Plastic 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
Plastic Consistency Condition in which concrete, mortar, or cement
paste will sustain deformation continuously in any direction without
Plasticity Property of freshly mixed concrete, cement paste or
mortar which determines its ease of molding or resistance to
Plasticizer A material that increases the workability or consistency of a concrete mixture, mortar or cement paste.
Porosity The ratio of the volume of voids in the material to the
total volume of the material, including the voids, usually expressed as
Portland Blast- slag Cement Furnace (ASTM C 595) The product
obtained by intimately intergrinding or an intimate and uniform blending
a mixture of granulated blast furnace slag and portland-cement clinker
Portland Cement (ASTM C 150) the product obtained by pulverizing
clinker consisting essentially of hydraulic calcium silicates.
Portland-Pozzolan Cement (ASTM C 595) The product obtained by
intimately intergrinding a mixture of portland-cement clinker and
pozzolan, or an intimate and uniform blend of portland cement and fine
Post-tensioning A method of prestressing concrete in which the
tendons are tensioned after the concrete has hardened.
Pozzolan (ASTM C 618) 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
Precast A concrete unit, structure or member that is cast and cured
in an area other than its final position or place.
Preplaced Concrete 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.
Proportioning Selection of proportions of material for concrete to
make the most economical use of available materials to manufacture
concrete of the required strength, placeability, and durability,
Prestressed Concrete Concrete in which stresses have been introduced which are opposite in sense to those that the structural member will be expected to carry during its use.
Pretensioning 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) 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
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