Concrete and paving glossary - P

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Parging

Portland cement plaster applied over masonry to make it less permeable to water.

Particle-size distribution

Particle distribution of granular materials among various sizes; for concrete material normally designated as gradation. It is 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.

Paver, paving

Materials, typically masonry, that are laid down to make a firm, even surface.

Paving forms

Heavy duty metal forms used in the placement of concrete for concrete roadways, commercial driveways, intersection entrance and exit ramps, and airport work. See apron.

Paving machine

A self-propelled piece of construction equipment that forms and finishes concrete simultaneously. See slip form.

Pea gravel

Portion of concrete aggregate passing the 1/2" sieve and retained on a No. 4 sieve.

Peeling

A process in which thin flakes of matrix or mortar are broken away from the concrete surface. It is caused by adherence of surface mortar to forms as forms are removed, or to trowel or float in Portland cement plaster. See concrete, forming, float, trowel, and Portland cement.

Pining

The development of relatively small cavities in a concrete surface due to phenomena such as cavitation or corrosion.

Pitch

The amount of angle or slope used in concrete flatwork to disperse water. See slope.

Pitch-in

A curb and gutter profile designed to accept water into the flow-line of the gutter. It is also referred to as wet-curb. See flow-line and pitch-out.

Pitch-out

A curb and gutter profile designed to direct water away form the curb. It is also known as a dry-curb or spill-out curb. See flow-line and pitch-in.

Placement

The process of placing and consolidating concrete. A quantity of concrete placed and finished during a continuous operation. Also, inappropriately referred to as pouring. See placing.

Placing

The physical insertion of the concrete mixture into the final location avoiding segregation of the mixture materials and compaction can be achieved. The deposition, distribution, and consolidation of freshly mixed concrete in the place where it is to harden. Also, inappropriately referred to as pouring. See compaction and placement.

Plain concrete

Concrete either without reinforcement, or reinforced only for shrinkage or temperature changes. See shrinkage.

Plant mix

A mixture of aggregate and asphalt cement or liquid asphalt, prepared in a central or traveling mechanical mixer. Any mixture produced at a mixing plant. See agitator truck, central plant, concrete transporting, and ready-mixed concrete.

Plastic consistency

Condition in which concrete, mortar, or cement paste will sustain deformation continuously in any direction without rupture.

Plasticity

Property of freshly mixed concrete, cement paste or mortar which determines its ease of molding or resistance to deformation.

Plasticizer

An agent used to increase the fluidity of fresh cement with the same cement/water ratio improving the workability and placement of the cement. Same as a superplasticizer.

Pocket

See stake pocket.

Polyethylene

A thermoplastic widely used in sheet form for vapor retarders, moisture barriers, and temporary construction coverings. See Visqueen.

Portland cement

A special synthetic blend of limestone and clay used to make concrete which is generally believed to be stronger, more durable, and more consistent than concrete made from natural cement. Portland cement is made by mixing calcareous material, like limestone, with silica, alumina, and iron oxide-containing materials. These materials are burned together and the resulting product, or admixture, is ground up to form Portland cement. See cement and concrete.

Posttensioning

A method of pre-stressing reinforced concrete in which tendons are tensioned after the concrete has hardened. See pre-tensioning.

Pour

To cast concrete. A pour is an increment of concrete casting carried out without interruption. See casting.

Power float

See rotary float.

Pozzolano (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 cementitious properties.

Pre-cast concrete

Concrete forms cast into permanent shapes using reusable forms at a plant, then transported as fully cured structural units to the actual construction job site. See cast-in-place concrete.

Pre-mixed concrete

The same as ready-mixed concrete.

Pre-placed aggregate

Coarse aggregate placed in a form, with Portland cement grout injected later. See aggregate and Portland cement.

Pre-placed 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.

Pre-stressed concrete

Concrete that has already been subjected to compression increasing its ability to withstand tension and stress without the need for steel reinforcement. Concrete in which internal stresses of such magnitude and distribution are introduced that the tensile stresses resulting from the service loads are counteracted to a desired degree. In reinforced concrete, the pre-stress is commonly introduced by tensioning the tendons. See reinforced concrete.

Pre-stressed concrete wire

Steel wire with a very high tensile strength, used in pre-stressed concrete. The wire is initially stressed close to its tensile strength. Then some of this load is transferred to the concrete, by chemical bond or mechanical anchors, to compress the concrete. See pre-stressed concrete.

Pre-tensioning

The compressing of concrete in a structural member by pouring the concrete for the member around stretched high-strength steel strands, curing the concrete, and releasing the external tensioning force on the strands. See posttensioning.

Proportioning

The 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.

Pump mix

Special concrete used in a concrete pump. Generally, the mix has smaller rock aggregate than regular concrete mix. See aggregate.

Punched for dowel forms

Metal concrete placement forms with dowel holes punched into them to hold either solid dowels or rebar to reinforce the concrete placement. See dowels, rebar, reinforced concrete, and paving forms.

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