Ever scratch your head when your pool building contractor is tossing around the terms of the trade? Here’s a handy Glossary of Pool Terms (along with pictures) so that you can keep up with him next time.

Acid washing. The cleansing of the existing pool or spa surface, through controlled dissolution of the material on a cementitious coating’s surface to remove efflorescence, soil or unwanted stains.

Admix. Any material, other than the cement, aggregate, sand, and/or water, that is added to the mix design, whether as a pre-blend or as an individual constituent added at the job site.

Aggregate. The sand , rock or stone portion of the mix design

Bond (Adhesion). The ability of a hardened cementitious coat to hold together with the substrate or to a previous coat by molecular forces, interlocking action or both.

Bond (Chemical). The ability to hold together by chemical process, whether by adhesive or cohesive bond.

Bond (Mechanical). The ability of a plaster coat to embed with or lock together with a plaster undercoat or a substrate.

Swimming Pool Bond FailureBond Failure. 1. The failure of the cementitious coating to hold together. 2. The failure of the cementitious coating to remain adhered to the underlying substrate or to another coat.

Pool Calcium Nodule or Blister




Calcium Nodule or Blister. A slang term used to refer to a calcium carbonate formation on the surface of a finish coat resulting from the percolation of water that is capable of leaching cement compounds from voids, bond failures, cracks or a weak sub-boundary layer in the cementitious coating, which is then precipitated onto the surface.

Cement (Polymer-Modified). Mortar and concrete made with portland cement has been a popular construction material in the world for the past 170 years or more. However, cement mortar and concrete have some disadvantages such as delayed hardening, low tensile strength, large drying shrinkage and low chemical resistance. To reduce these disadvantages, polymers have been utilized as an additive. Polymer-modified or polymer cement mortar (PCM) and concrete (PCC) are the materials which are made by partially replacing the cement hydrate binders of conventional cement mortar or concrete, with polymers.

Cement (Portland). A hydraulic cement (hardens and sets by chemical interaction with water) that is made by fusing certain eath materials though pyro-processing to form hydraulic crystalline compounds, mostly calcium silicates and aluminum silicates. These compounds are pulverized to a fine powder and a small amount of calcium sulfate is added to control the set.

Check Cracking. Also known as “chicken wire cracks” or “crazing.” 1. The common random crack pattern of a plaster surface that generally self-heals through the ongoing hydration and curing process. 2. Small cracks associated with the shrinkage from moisture loss and consolidation within a cementitious coating during set. 3. Small shallow cracks at closely spaced but irregular intervals on the surface of a plaster.

Chip-Off. For pools or spas that have already been resurfaced. If this second or third surface has begun to develop “hollow spots” or delamination areas, it needs to be chipped-off and removed.

Compaction or Consolidation. The process of inducing a closer arrangement of the solid particles in freshly mixed concrete or mortar, during placement by the reduction of voids; usually by vibration, centrifugation, rodding, tamping, or some combination of these actions.

Coping. The capstone on top of the bond beam which finishes the edge around a pool or spa.  It may be pre-cast concrete or brick.  On vinyl liner pools pre-fabricated coping is usually part of an integrated system for the wall, vinyl liner, and deck.

Curing (plaster). The act or process by which the cementitious surface coating continues hydration. Curing is typically done by immersing the cementitious coating in water as soon as possible after final set. This process continues for approximately 28 days.

Pool DelaminationDelamination. This is also known as “bond failure.” The separation within a material or composition and/or the separation between two coats of cementitious material. This situation is often seen on pools that have been resurfaced and a Bond Coat was not installed.

Etching DeteriorationEtching Deterioration. 1. The physical or chemical removal of the material from the surface of the plaster. 2. The visible pitting or eating away of the surface of the plaster due to chemical or physical processes. 3. Any chemical or physical action on a surface that is capable of removing or dissolving away elements or compounds of that surface.

Pool EfflorescenceEfflorescence. Soluble salts, predominantly calcium Hydroxide, which migrate in presence of moisture, from within a cementitious product to the surface of the cementitious product, followed by the precipitation and carbonation of the soluble salts onto the surface.

Freeze/Thaw. Seasonal weather and temperature changes that can create expansion and shrinkage, which causes stress within the material and can lead to tensile cracking, debonding and delamination.

Floating. In Oregon and Washington high water tables exist in many areas. A pool is essentially a large, concrete boat. If the water weight is removed from the pool and there is a high water table below the pool, the pool may be pushed out the ground.

Gunite. A dry mixture of cement and sand mixed with water at the “gun”; hence the name. A gunite operator “shoots” the pool’s rough shape, then finishers use trowels to smooth it..

Hydration. The chemical reaction between hydraulic cement and water forming new compounds, most of which have strength –producing properties.

Laitance. 1. Fine material carried by excessive bleed water that migrates to the surface of a plaster causing a weak plaster surface. Laitance can be an indicator that a plaster has a high water content, an improper mixture proportioning, or that the plaster surface has been over-tempered using an abnormal amounts of supplemented water. 2. A weak new plaster surface that can be easily scratched off using a coin or other dull object.

Marcite. Older term used for Marblelite plaster

Mottling. 1. The normal variations in a cementtitious material as a result of the ongoing hydration process, which typically lessen or disappear over time. 2. The blotchy appearance across the surface of a cementitious finish, which can have varying shade of color, usually in a random pattern and are typically more pronounced in darker colored finishes.

Pitting. A slang term denoting a form of etching. 2. The early stage of corrosion of the reinforcing steel of a swimming pool. 3. The development of small cavities in the surface of the cementitious coating.

Plaster. A combination of cement, aggregate and water (with or without other admixtures) that when mixed thoroughly, placed properly and finished correctly, form a desired decorative aesthetic pool surface that is maintainable and near water-tight.

Plaster Dust. A slang term used in the pool industry referring to the calcium salts, namely calcium hydroxide, that are released from cementitious materials when submersed in water. If not removed from the water in a timely manner, the dust will react with carbon dioxide or carbonate ions withn the water to form a calcium carbonate precipitate, which adheres immediately to the surface and cannot be easily removed without aggressively sanding or acid washing the surface.

Pool Polishing or SandingPolishing or Sanding. Water driven polishing tools are used in conjunction with 3M diamond dust pads to create a smooth surface, expose aggregate, remove stains or to remove precipitated minerals from the pool surface.

Pop-Off. 1. A delamination of two cementitious surfaces. The upper surface can become raised and then loosens and falls off.

Pozzolan. A siliceous and aluminous material that in a finely divided form and in the presence of moisture, chemically react with calcium hydroxide at ordinary temperatures to form cementitious hydrates. Certain clays, diatomaceous earths, zeolites, volcanic ashes, tuffs, cherts andshales are know to have pozzolanic properties.

Precipitate. 1. The solid material which is formed out of the solution by chemical or physical reaction. 2. In a swimming pool, it is the minerals and/or metals that come out of solution and settle onto the coating’s surface that can adhere, resulting in unsightly stains and roughness.

Rebound. The portion of the material that is deflected and does not adhere to the shell during the application of shotcrete or gunite. 2. Any portion of material during shotcreting or guniting that is considered “dead” or no longer useable and should be removed from the shell.

Replaster or Resurface. Installing a new coat of plaster in an existing pool.

Pool ShellShell. The structure of the swimming pool that is formed by using gunite, shotcrete or concrete, which is either poured, sprayed or packed into a reinforcement network. 2. The substrate onto which the cementitious coating (plaster) is applied.

Shotcrete (DRY). A dry mixture of cement and sand that is mixed with water at the nozzle and sprayed onto a contoured surface, having a reinforcement network in place. When hardened, this forms the shell of the swimming pool.

Structural Movement CrackingStructural Movement Cracking. The cracking of a cementitious coating due to the structural movement of the swimming pool structure or substrate. In most cases, the pool can be pressure grouted to stabilize the structure and/or lift it back into place

Tensile Cracking. The cracking of a cementitious coating associated with bond failure, abnormal shrinkage, or delaminations, whereby the cementitious coating is stressed beyond its ability to hold together or remain bonded.




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