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p.s.i. or psipounds per square inch, a unit measure of pressure.
packing house tilesimilar to quarry tile but usually of greater thickness.
palletizeda system of stacking stone on wooden pallets. stone which comes palletized is easily moved and transported by modern handling equipment. palletized stone generally arrives at the job site in better condition than unpalletized material.
panela finished stone unit used on walls.
paper and wirefar paper and wire mesh (or metal lath) that are used as a hacking; for the installation of tile.
parapet wallthat part of any wall entirely above the roof line.
pargingplastering a cementitious coating of mortar onto a surface, often used for damp-proofing.
parquetryan inlay of stone floors in geometrical or other patterns.
pate dure (hard paste)a french term designating; ceramic whitewares fired at relatively high temperatures. 
pate tendre (soft paste)a french term designating ceramic whitewares fired at relatively low temperatures. 
paversunglazed porcelain or natural clay tile formed by the dust-pressed method and similar to ceramic mosaics in composition and physical properties but relatively thicker with 6 in.- or more of facial area. 
pavingstone used as an exterior wearing surface, as in patios, walkways, driveways, etc. (see flooring).
pedestalin classical architecture, the support for a column or statue, consisting of a base, dado, and cap.
pedimentthe gable end of a roof in classical architecture. located above a horizontal cornice member, it comprises the raking cornices and the tympanum. it is typically triangular, but can also be curved when applied as a decorative element over windows.
peelingsee orangepeel; shivering.
pencil rodreinforcing steel rod with a diameter of y4″.
perforated wallwall containing a considerable number of relatively small openings. often called pierced wall or screen wall.
pergolagarden sturcture formed by two rows of posts or pillars with joists and open framing above, often covered by climbing plants and shading a walkway.
perronsslabs of stone set on other stones serving as steps and arches in gardens.
petalitea lithium mineral of theorical composition li,o – a 120a ‘ 8si02 which transforms on heating to a beta spodurnene-silica solid solution product of very low or nil thermal expansion.
phenocrystin igneous rocks, the relatively large and conspicuous crystals in a finer-grained matrix or ground mass.
pilasteran engaged pier of shallow depth; in classical architecture it follows the height and width of related columns, with similar base and cap.
piloweda tile finish that features softly rounded edges, thus giving the tile a pillowed look.
pinholesimperfections in the surface of a ceramic body or glaze resembling pin pricks. 
pitched stonestone having arris clearly defined; face, however, is roughly cut with pitching chisel used along the line which becomes the arris.
pittedindentations in the finished surface of individtial tiles other than at the corners and edges. these are caused by sharp corners on trowels and other tools of the workmen and are different than manufacturing defects.
pittingdevelopment of relatively small cavities in a surface, due to phenomena such as corrosion or cavitation, or, in concrete, localized disintegration. (see also popout. )
plastera cementitious material or combination of cementitious material and aggregate that, when mixed with a suitable amount of water, forms a plastic mass or paste which when applied to a surface, adheres to it and subsequently hardens, preserving in a rigid state the form or texture imposed during the period of plasticity; also the placed and hardened mixture. (see also stucco.)
plastic crackingcracking that occurs in the surface of fresh concrete soon after it is placed and while it is still plastic.
plastic flowsee creep.
plastic pressingsee pressing, wet.
plasticitya complex property of a material involving a combination of qualities of mobility and magnitude of yield value; that property of freshly mixed cement paste concrete, or mortar which determines its resistance deformation or ease of molding.
plasticizera material that increases plasticity of a cement paste, mortar, or concrete mixture.
plinthsthe lower square part of the base of a column. a square base or a lower block, as of a pedestal. the base block at the juncture of baseboard and trim around an opening.
plucked finishobtained by rough planing the surface of stone, breaking or plucking out small particles to give rough texture.
plumbperpendicular to a true level.
plumb scratchan additional scratch coat that has been applied to obtain a uniform setting bed on a plumb vertical plane.
plutonicapplies to igneous rocks formed beneath the surface of the earth, typically with large crystals owing to the slowness of cooling.
pointingthe filling and tooling of mortar joints with mortar or caulking compounds.
pointing mixmortar with a consistency of stiff paste. the mix is forcibly compressed into the tile joints where it hardens.
pointing trowelthe pointing trowel or pointer is probably the most essential tool in the trade. it comes in sizes ranging from 4″ to 7″ in length, but the 6″ trowel is the most popular. the tilesetter uses this trowel in every phase of the work, especially for straightening tiles on walls and floors, marking floated surfaces, filling; small depressions on float coats, buttering; tiles and trim work, and placing mortar in areas that are too small for the flat trowel. the butt of the handle is used for tapping in tiles that are not on a true plane with the rest of the tilework. the trowel’s flat working surface must be protected. the tilesetter should not use it to pry or chop hardened materials such as concrete or plaster.
poisson’s ratiothe ratio of transverse (lateral) strain to the corresponding axial (longitudinal) strain resulting from uniformly distributed axial stress below the proportional limit of the material; the value will average about 0.2 for concrete and 0.25 for most metals.
polished finishthe finest and smoothest finish available in stone characterized by a gloss or reflective property. generally only possible on hard, dense materials.
polychrome decorationa multicolor decoration. 
polyethylenea thermoplastic high-molecular-weight organic compound used in formulating protective coatings or, in sheet form, as a protective cover for concrete surfaces during the curing period, or to provide a temporary enclosure for construction operations.
popoutthe breaking away of small portions of a concrete surface due to internal pressure which leaves a shallow, typically conical, depression.
porcelaina glazed or unglazed vitreous ceramic white,.vare used for technical purposes. this term designates such products as electrical, chemical, mechanical, structural, and thermal wares when they are vitreous. (see also, alumina porcelain; cordierite porcelain; forsterite porcelain; steatite porcelain; titania porcelain; and zircon porcelain.) 
porcelain processthe method of producing glazed ware by which a ceraunic body and glaze are matured together in the same firing operation. 
porcelain tilea ceramic mosaic tile or paver that is generally made by the dust-pressed method, of a composition resulting in a tile that is dense, finegrained, and smooth with sharply formed face, usually impervious. colors of the porcelain type are usually of a clear, luminous type or granular blend thereof. 
porphyryan igneous rock in which relatively large and conspicuous crystals (phenocrysts) are set in a matrix of finer crystals.
porticoa porch formed by a roof suported with columns, similar to a temple front.
post-tensioninga method of prestressing reinforced concrete in which tendons are tensioned after the concrete has hardened.
pot lifethe period of time during which a material maintains its workable properties after it has been mixed.
potteryall fired ceramic wares that contain clay when formed, except technical, structural and refractory products. 
pozzolana siliceous or siliceous and aluminous material, which in itself possesses little or no cementitious value but will, in finely divided form and in the presence of moisture, chemically react with calcium hydroxide at ordinary temperatures to form compounds possessing cementitious properties.
precasta concrete member that is cast and cured in other than its final position; the process of placing and finishing precast concrete.
precast concreteconcrete cast elsewhere than its final position.
prefloatthe term used to describe mortar that has been placed and allowed to harden prior to bonding tile to it with thin-set materials.
pregrouted tilea surface unit consisting of an assembly of ceramic tile bonded together at their edges by a material, generally elastomeric, which seals the joints completely. such material (grout) may fill the joint completely, or partially and may cover all, a portion or none of the back surfaces of the tiles in the sheets. the perimeter of these factory pregrouted sheets may include the entire, or part of the joint between the sheets or none at all. the term edgebonded tile is sometimes used to designate a particular type of pregrouted tile sheets having the front and back surfaces completely exposed.
pressingsee pressing, dry; pressing, hot; pressing, wet.
pressing, dryforming ceramic ware in dies from powdered or granular material by direct pressure. 
pressing, hota jiggering process wherein a heated profile tool or plunger is employed.
pressing, wetforming ceramic ware in dies from a plastic body by direct pressure. 
pressure relieving jointan open horizontal joint below the supporting angle or hanger located at approximately every floor line and not over 15 feet (4.6 m) apart horizontally and every 20 to 30 feet (6 to 9m) vertically to prevent the weight from being transmitted to the masonry below. these joints are to be caulked with a resilient non-staining material to prevent moisture penetration.
prestressed concreteconcrete 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 prestress is commonly introduced by tensioning the tendons.
pretensioninga method of prestressing reinforced concrete in which the tendons are tensioned before the concrete has hardened.
primary claya clay which remains geologically at its site of formation. 
processsee process, dry; process, wet.
process, drythe method of preparation of a ceramic body wherein the constituents are blended dry, following which liquid may be added as required for subsequent processing. 
process, wetthe method of preparation of a ceramic body wherein the constituents are blended in sufficient liquid to produce a fluid suspension for use as such or for subsequent processing. 
processingthe work involved in transforming building stone from quarry blocks to cut or finished stone. this includes primary sawing into slabs. it may also include both hand and mechanical techniques such as sawing, drilling, grinding, honing, polishing, and carving.
projectionsthis refers to the pulling out of stones in a wall to give an effect of ruggedness. the amount of each stone is pulled out can vary between fi and 11/2 inches (1.3 to 3.8cm). stones are either pulled out at the same degree at both ends or sometimes one end is pulled out, leaving the other end flush with the majority of veneer.
pumiceand exceptionally cellular, glassy lava resembling a solid froth.
pumped concreteconcrete which is transported through hose or pipe by means of a pump.
puresee neat cement.
pure coata thin coat of pure portland cement which is used to bond tile to mortar.
pyrophyllitea hydrated aluminum silicate mineral of the theoretical composition a12 03 – 4si 02 – h2 o, having physical properities in the raw state resembling mineral talc.