A

Abrasion resistance – How well a concrete surface or decorative coating resists being worn away by friction or rubbing.

Abrasive blasting – Propelling an abrasive medium (such as sand or steel shot) at high velocity against concrete to roughen, clean, or profile the surface in preparation for decorative coatings or overlays. Methods include sandblasting, shot blasting, bead blasting, and sand brushing.

Acetone – Common solvent. Often used as a carrier for solvent based sealers. Considered an exempt solvent from VOC regulations.

Acid etching – Application of muriatic or phosphoric acid to clean or profile a concrete surface. Used as an alternative to abrasive blasting for surface preparation.

Acid stain – (or chemical stain) A stain containing inorganic salts dissolved in an acidic, water-based solution that reacts chemically with the minerals in hardened concrete to produce permanent, transparent color that will not peel or flake. Gives concrete an attractive variegated or marbleized appearance. Colors tend to be earth tones, such as tans, browns, reddish browns, and greens. (Also see polymer stain).

Admixture – An ingredient in concrete other than water, cement, and aggregate used to modify the properties of concrete in its freshly mixed, setting, or hardened states. May be added to concrete at the batch plant or on the job site. Prepackaged admixtures are available for convenient job site addition, giving contractors the ability to modify the concrete they receive when necessary, such as extending the amount of time available for decorative stamping.

Aggregate – A granular material such as sand, rock, crushed stone, gravel, or other particles added to concrete to improve its structural performance. (Also see decorative aggregate.)

Air entrainment – Adding an air-entraining admixture to fresh concrete to cause the development of microscopic air bubbles. Helps to improve the freeze-thaw resistance and durability of hardened concrete.

Antiquing – A color layering technique for giving decorative concrete surfaces an aged or mottled appearance.

B

Blistering – The formation of blisters in toppings or coatings and the loss of adhesion with the underlying substrate. On concrete surfaces, this is often caused by moisture or moisture vapor transmission problems.

Bond – The degree of adhesion or grip of a material (such as coatings, toppings, repair mortars, or sealers) to an existing surface.

Bonding agent – An adhesive agent used to increase the adherence of coatings or toppings to the existing surface. Also used to bond new concrete to old. Also known as a primer.

Broom finish – Surface texture obtained by pushing a broom over freshly placed concrete.

Build – The wet or dry thickness of a coating or topping. (Also see high-build coating

Bush hammer – A percussive hammer with rows of pyramid-shaped points used to roughen or profile a concrete surface.

C

Cast in place – Concrete placed and finished in its final location.

Concrete replacement – (or supplementary cementitious material) a material used in concrete as a partial replacement for cement. Includes pozzolans, fly ash, and granulated blast furnace slag. Can have positive effects on decorative concrete by improving finish ability, reducing permeability, and reducing efflorescence.

Chalking – Loose, powdery substance caused by deterioration of a concrete surface or degradation of a coating or overlay.

Coating system – A complete system requiring a number of coats of material to be applied separately in a predetermined order and at prescribed intervals to allow for sufficient drying and curing. May include a primer, one or more intermediate coats, and a topcoat.

Compressive strength – The maximum compressive stress concrete or cementitious overlay materials are capable of sustaining, expressed as pounds per square inch (psi).

Color chips – Plastic chips, available in various colors and sizes, for broadcasting onto freshly placed epoxy resin flooring systems, such as epoxy terrazzo, to produce multicolored effects.

Color layering – Applying layers of color to achieve variegated or faux finish effects, such as antiquing or marbleizing. For example. A dry-shake color hardener may serve as the base color, accented by a pigmented powdered or liquid release agent, followed by additional accenting with acid stains, dyes, or tints.

Consistency – The ability of fresh concrete to flow. The usual measure of consistency is slump.

Control (or contraction) joint – Sawed or tooled groove in a concrete slab used to regulate the location of cracking.

Coverage rate – The area that a specified volume of coating will cover to a specified thickness upon drying.

Crack stitching – A method of repairing cracks that involves drilling holes on both sides of the crack and grouting in wire or U-shaped metal strips that span the crack.

Cracks, static – Random, non-moving hairline cracks that only affect the concrete surface (also see craze cracks and plastic shrinkage cracks).

Crusting – A condition that occurs when the surface of freshly placed concrete dries too quickly, often due to exposure to direct sun, wind, or high temperatures.

Curing – Action taken to maintain favorable moisture and temperature conditions of freshly placed concrete or cementitious materials during a defined period of time following placement. Helps to ensure adequate hydration and proper hardening.

D

Decorative aggregate – Richly colored natural stones, such as basalts, granite, quartz, or limestone, used to enhance exposed-aggregate concrete or decorative toppings.

Decorative concrete – Concrete that has been enhanced by color, pattern, texture, or a combination of ornamental treatments.

Densifier – A penetrating liquid chemical hardener applied to concrete to help solidify and densify the surface and provide extra protection from water penetration and staining. Often recommended for polished concrete, because hard concrete produces a better polish.

Dry polishing – The method most commonly used for polished concrete. The floor polisher is hooked up to a dust-containment system that vacuums up the dust fromdiamond grinding of the surface. (Also seewet polishing.)

Dry-shake color hardener – A mixture of coloring pigments, cement, aggregates, and surface conditioning agents. Applied as a dry shake to stamped concrete or stamped overlays to produce a colorful, wear-resistant surface.

E

Edger – A tool used on the edges of fresh concrete to provide a clean, finished edge.

Efflorescence – A crystalline deposit of salts (usually white in color) that forms on the concrete surface when soluble calcium hydroxides leach from the concrete and combine with carbon dioxide in the atmosphere. On colored concrete, especially darker tones, these white deposits can be particularly unsightly.

Epoxy injection – A method for sealing or repairing cracks in concrete by low-pressure injection of an epoxy adhesive.

Epoxy resins – Organic chemical bonding systems used in the preparation of protective and decorative coatings for concrete, adhesives for injection of cracked concrete, or as binders in epoxy mortars.

Epoxy terrazzo – A poured-in-place topping for concrete substrates that goes on at a thickness of ¼ to 3/8 inch. The epoxy resin matrix can be pigmented to achieve an unlimited spectrum of colors and is often seeded while still wet with decorative aggregates or color chips.

Exposed aggregate – A decorative surface formed by removing the surface mortar from a concrete slab (either by scrubbing, pressure washing, or abrasive blasting) to expose the underlying aggregates. (Also see surface retarder.)

F

Faux rock – An artificial rock formation sculpted or molded from concrete and then textured and colored to replicate the look and feel of natural rock. Popular applications include waterscapes, zoo exhibits, landscaping, and theme parks. (Also see glass-fiber reinforced concrete.)

Feather edge – To smoothly, seamlessly blend the edge of a topping or repair material into the existing concrete.

Finishing – Leveling, smoothing, compacting, and otherwise treating the surface of newly placed concrete or concrete overlays to produce the desired appearance and service properties.

Floor Polisher – A walk-behind machine used in the production of polished concrete. Most machines are equipped with a planetary drive system large primary polishing head (from 17 to 36 inches in diameter) fitted with three or four smaller satellite heads that hold the diamond abrasives. When the machine is operating, the satellite heads rotate in the opposite direction of the primary head to eliminate linear grinding marks in the floor. (Also see diamond grinding, dry polishing, wet polishing).

Form liner – Material used to line the interior face of formwork in order to impart a smooth or patterned architectural finish.

G

Gauge rake – A tool with an adjustable depth gauge designed for application of high-build coatings or cementitious toppings at a preset, uniform thickness.

Glass-fiber reinforced concrete (GFRC) – A Portland cement – based composite containing glass fibers for reinforcement. Substantially lower in weight than plain concrete, with higher flexural and compressive strengths. Often used in the production of faux rock formations and concrete countertops.

Grinding – A mechanical surface preparation method using rotating abrasive stones or discs to remove thin coatings and mastics or slight flaws and protrusions.

Groover – A tool with a V-shaped bit used to create control joints in plastic concrete.

H

High-build coating – A protective or decorative coating that produces a thick film (usually greater than 10 mils) in a single coat.

High-pressure water blasting – A process for cleaning or roughening concrete surfaces using a stream of water delivered at high pressure.

High-volume low-pressure (HVLP) sprayer – A spraying device that applies high-solids paints and coatings at low pressure and low velocity, to reduce overspray.

Hopper gun – A gravity-fed system for spray application of coatings or toppings. The material is placed in a hopper attached to a spray gun, which is powered by an air compressor. Often used to apply spray-down systems.

Hover Trowel – A patented lightweight power trowel developed specifically for precision finishing of epoxy, polymer modified, and cementations overlay systems.

I

Integral color – A coloring agent premixed into fresh concrete or cementitious toppings before placement.

Iron oxide – An inorganic pigment often used to color decorative coatings and toppings.

J

Joint (control, expansion, or isolation) – Formed, sawed, or tooled groove in a concrete slab used to regulate the location of cracking (control joint) or to allow expansion or movement of adjoining structures. In decorative concrete, joints can also double as delineating design elements in a pattern.

Joint filler – A compressible material used to fill a joint to prevent the infiltration of debris.

L

Laitance – A thin layer of fine, loosely bonded particles on the surface of fresh concrete, caused by the upward movement of water. Laitance must be removed before application of a decorative coating or topping.

M

Marbleize – To give concrete surfaces the look and gloss of marble, through a combination of color layering and finishing techniques.

Masking – Covering select areas of a concrete surface with an adhesive stencil, tape, or other medium before applying a decorative treatment that will affect only the exposed areas.

Material safety data sheet (MSDS) – Information sheets containing pertinent chemical ingredients, product handling and safety guidelines.

Membrane – Formed over a concrete surface to provide protection and enhance color. Typically, clear plastic like acrylic, polyurethane, or epoxy.

Micro topping – An ultra-thin polymer-based decorative topping, generally less than ¼-inch total thickness. Typically applied by trowel or squeegee and given a texture or smooth finish. Pigments can be incorporated into the mix or broadcast onto the surface for a marbleized appearance. (Also see skim coat.)

Mix design – Specific proportions of ingredients (cement, aggregates, water, and admixtures) used to produce concrete suited for a particular set of job conditions.

Mixing station – A designated work area outfitted with all the equipment and supplies needed to mix materials properly and efficiently.

N

Notched-squeegee – A rubber squeegee with notches or serrations on one or both edges. Used for smooth and consistent spreading of epoxy resin products or other low-viscosity coatings.

O

Opacity – The ability of a coating to hide the color of the underlying surface. See translucent.

Overlay – A bonded layer of material, ranging from ¼ to 1 inch or more in thickness, placed on existing concrete surfaces to beautify, level, or restore. (Also see polymer-modified overlay, self-leveling overlay.)

P

Patterned concrete – See stamped concrete

Penetrating sealer – A sealer with the ability to penetrate into the concrete surface to increase water repellency and resist stains. Often used on decorative concrete to provide invisible protection without changing the surface appearance.

Permeability – The degree to which a membrane or coating will allow the passage or penetration of a liquid or gas.

Pigment – A finely ground natural or synthetic particle adding color and opacity to a coating or topping.

Pinholing – A defect in a coating characterized by pinhead-sized holes that expose the underlying substrate.

Plastic – A condition of freshly mixed concrete indicating that it is workable and readily moldable.

Plastic shrinkage cracks – Irregular cracks that occur in the surface of fresh concrete soon after it is placed and while it is still plastic.

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

Platform tools – Rigid stamps made of plastic or metal that leave deep grooves in freshly stamped concrete, which can later be grouted or left open.

Polished concrete – A high-gloss finish attained by using special floor polishers fitted with diamond-impregnated abrasive disks (similar to sandpaper) to grind down surfaces to the desired degree of shine and smoothness. The resulting surface is very low-maintenance and can be stained to replicate the look of polished stone. (Also see dry polishing, wet polishing, diamond grinding.)

Polyaspartic – An aliphatic polyurea coating that is very fast-curing and that can be applied to concrete over a wide range of temperatures. Seamless polyaspartic floors are typically applied in two or three coats with embedded vinyl or quartz chips to form a highly stain- and abrasion-resistant coating.

Polymer-modified overlay – A cement-based overlay with polymer resins added to improve performance, wear resistance, and aesthetic qualities. Overlay manufacturers use different types of polymer resins, often blending them to produce proprietary products with unique characteristics. Many of todays decorative overlays use acrylics or vinyl blends because these resins provide excellent bond strength and UV resistance.

Polymer stain – An acrylic-urethane based stain available in a broader palette of colors than acid stains. Very low in volatile organic compounds, with workability characteristics similar to latex paint. Can be applied to concrete surfaces by brush, roller, sponge, cloth, or commercial sprayer.

Pot life – The length of time a material is useful after its original package is opened or a catalyst is added.

Profile – The act of preparing a concrete surface to achieve the necessary degree of roughness (also see concrete surface profile).

Portland cement – A hydraulic product that sets and hardens when it chemically interacts with water. Made by burning a mixture of limestone and clay or similar materials. (Also see white cement.)

Pozzolan – A siliceous and aluminous material that, in the presence of moisture, chemically reacts with calcium hydroxide to form compounds possessing cementitious properties. (Also see cement replacement).

Primer – The first coat of material applied to a concrete surface to improve bonding or adherence of subsequent coats. See also bond coat.

Pump-up sprayer – An airless sprayer often used to apply sealers and liquid release agents.

R

Ready-mixed concrete – Concrete thats batched or mixed at a central plant before delivery to the job site for placement.

Rebar (or reinforcing bars) – Ribbed steel bars installed in cast-in-place concrete to provide flexural strength. Rebar come in various diameters and strength grades.

Reflection cracking – The occurrence of cracks in overlays and toppings that coincide with the location of existing cracks in the substrate.

Reinforced concrete – Concrete construction that has steel rebar or welded wire mesh embedded in it to provide greater tolerance to tension and flexural stress.

Release agent – A powder or liquid parting agent applied to stamping mats or texturing skins before stamping to keep the mats from sticking to fresh overlay or concrete surfaces.

Rustication strip – A strip made of wood, polystyrene, or plastic thats fastened to forms or form liners to impart architectural details to grime.

S

Salt finish – A textured, decorative finish obtained by broadcasting rock salt onto fresh concrete and then using a roller or float to press the salt particles into the surface. After the concrete sets, the salt is washed away to reveal a speckled pattern of shallow indentations.

Sample (or sample board) – A small (generally 2×2-foot) representation of a decorative concrete installation, used as a selling tool or to experiment with various decorative treatments and techniques for applying materials.

Sandblast stenciling – A technique for patterning existing concrete surfaces by applying resilient adhesive stencils followed by sandblasting to lightly remove concrete in only the exposed areas. (Also see stenciled concrete.)

Sandblasting – A method of abrading or profiling a surface with a stream of sand ejected from a nozzle at high speed by compressed air. (Also see abrasive blasting.)

Sealer – Solvent- or liquid-based material used to protect and enhance the appearance of decorative concrete. (Also see film-forming sealer and penetrating sealer.)

Seeding – Broadcasting decorative aggregates on the surface of freshly placed concrete or toppings.

Segregation – The separation of the components of wet concrete caused by excessive handling or vibration.

Self-leveling overlay – A flowable, polymer-modified cementitious topping with the ability to self-level without troweling. Used to smooth and level existing concrete surfaces. Can also be enhanced by staining, dying, or saw cutting.

Set – The condition reached by concrete when plasticity is lost, usually measured in terms of resistance to penetration or deformation. Initial set refers to concrete that has reached first stiffening. Final set occurs when concrete attains full rigidity.

Setting – The chemical reaction that occurs after the addition of water to a cementitious mixture, resulting in a gradual development of rigidity.

Shotblasting – An abrasive blasting method using round iron shot to clean and profile concrete surfaces.

Skim coat – An overlay layer applied very thinly with a squeegee or trowel. (Also see micro topping.)

Solvent – Liquid typically used as a carrier for sealers and curing compounds.

Spray-down system – A decorative overlay applied as a splatter coat or a knock-down finish to a thickness of about 1/8 inch. Often used in conjunction with paper or adhesive stencils. Available precolored or can be integrally colored during mixing.

Splatter coat – A coating or topping applied by splattering it onto the surface, typically by dipping a brush into the material and then flicking it.

Stamped concrete – Concrete flatwork that is patterned with platform tools, stamping mats, or seamless texturing skins to resemble materials such as brick, slate, stone, tile, and wood planking. (Also see vertical stamped concrete.)

Stamped overlay – Similar to conventional stamped concrete, but can be applied to existing concrete. A cementitious topping is applied at a thickness of ¼ to ¾ inch and then stamped to mimic brick, slate, and natural stone. Color options include dry-shake color hardeners, colored liquid or powdered release agents, acid stains, dyes, and tinted sealers.

Stamping mats – Rigid or semi-flexible polyurethane tools for imprinting stone, slate, brick, and other patterns in stamped concrete surfaces. Stamping mats usually imprint a shallower pattern than platform tools.

Static cracks – Random, non-moving hairline cracks that only affect the concrete surface (also see craze cracks and plastic shrinkage cracks).

Strike off – To level off freshly placed concrete to the correct elevation.

Substrate – An existing concrete surface that receives an overlay, decorative or protective coating, repair procedure, or other resurfacing treatment.

Surface preparation – Preparing concrete surfaces prior to resurfacing or application of a decorative coating to remove contaminants and minor defects or to obtain the necessary degree of roughness for adequate bonding. (Also see abrasive blasting, acid etching, and grinding.)

T

Tack – The stickiness or adhesiveness of a material.

Tamper (or pounder) – A handheld impact tool used to firmly press stamping mats or texturing skins into fresh concrete to ensure a complete imprint.

Technical data sheet – Contains important specifications and manufacturer guidelines for product usage. Includes such data as coverage rates, recommended applications, product limitations, surface preparation guidelines, mix ratios and required mixing times, pot life, application procedures, cure times, performance data, and precautions.

Texture roller – A cylindrical tool similar in appearance to a paint roller used to impart a stonelike texture to stenciled concrete. It is rolled over the stencil and the fresh concrete to texture only the exposed surfaces.

Texturing – Giving concrete or overlay surfaces a texture without leaving deep pattern lines.

Texturing skins – Flexible skins for adding seamless textures to concrete surfaces. Generally thinner and more pliable than stamping mats. Often used to texture slab perimeters and vertical faces, such as stair risers. Can also be used to fix blemishes from nonuniform stamping.

Trowel finish – The smooth or lightly textured surface finish obtained by troweling.

Translucent – A type of finish were the coating has some level of transparency.

V

Vertical stamped concrete – A decorative finish for walls and other vertical surfaces using a lightweight cementitious overlay formulated to be applied at thicknesses of up to 3 inches without sagging. While the overlay is still plastic, it can be stamped or hand carved to produce deep-relief stone or masonry wall textures. After the material dries, acid stains or dyes can be sprayed or sponged onto the surface to give it the multi-toned look of natural stone.

Viscosity – A measure of the fluidity of a liquid material. The more viscosity a material such as a sealer or coating has, the less it flows.

W

Water-cement ratio – The ratio of the amount of water to the amount of cement in a concrete mixture. The key to producing high-quality decorative concrete is to keep the water-cement ratio as low as possible without sacrificing workability.

Water plug – A hydraulic cement used to fill cracks and to prevent the migration of moisture.

White cement – A portland cement with a low iron content that hydrates to a white paste. Often used in integrally colored concrete to produce pure, bright color tones, especially pastels.

Workability – The ease with which concrete or other cementitious materials can be mixed, placed, and finished.

Working time – The amount of time available for placing and finishing a cement-based material before it begins to set. Often depends on the ambient temperature and substrate temperature.