Glossary of Terms

This glossary is limited to terms that relate to preparation, coatings, resurfacing, repairing, and polishing concrete floor surfaces.

Abrading: (1) Erosion by mechanical or particulate impact; (2) Surface preparation of concrete that is intended to roughen the surface profile of the concrete and remove foreign materials. Methods classified as abrading include mechanical abrasion, water blast cleaning, and abrasive blast cleaning. Abrading methods for concrete are defined in ASTM D 4259.

Abrasive: (1) A material used for wearing away a surface by rubbing; (2) A fine, granulated material used for blast cleaning. Abrasive particles of controlled mesh sizes are propelled by compressed air, water, or centrifugal force to clean and roughen a surface. Blast cleaning abrasives often are simply referred to as metallic or non-metallic and as shot- or grit-like.

Abrasive Blast Cleaning: A surface preparation method that uses an abrasive propelled by air pressure, centrifugal force, or water pressure to clean and usually profile a surface. Stand-off distance, angle of attack, and dwell time are the three most important variables under the control of an operator that can affect the quality and effectiveness of the blast cleaning.

ACI: American Concrete Institute www.concrete.org

Acid Etching: A method of preparing concrete floors for coating. An acid etching solution may be made of diluted hydrochloric acid (5 to 10 percent), diluted phosphoric acid (20 to 25 percent), or, often for environmental reasons, citric acid. These and other acid solutions can clean and remove dirt and other impurities from the concrete as well as provide a surface texture to improve the adhesion of the coating. Residual acid salts formed must be rinsed from the concrete surface before coating application.

Adhesion Test, Tensile (Pull-Off): The method for testing the greatest perpendicular force which an area of coating can withstand before: (1) detaching from the surface (adhesion) or (2) fracturing within a layer of coating or substrate (cohesion). The method can also be used to determine whether a coating will remain intact at a particular applied tensile force. This standard test method is defined in ASTM D 4541.

Aliphatic Polyurethane: These coatings offer excellent resistance to ultraviolet light.

Ambient Conditions: The weather conditions including air temperature, relative humidity, dew point, wind velocity, and air temperature at a specific place and time or time period. These conditions are generally monitored on the job site.

Aromatic Polyurethane: These coatings offer excellent chemical and heat resistance, but yellow and chalk in direct sunlight.

ASTM: American Society For Testing And Materials

ASTM Standard: A document (specification, test method, guide, practice, etc.) developed and established by the consensus principals of ASTM, a not-for-profit organization that develops standards for products, materials, systems, and services.

Blushing: Film defect which appears as a milky opalescence as the film dries. It is generally caused by rapid evaporation, moisture, or incompatibility. This can affect adhesion of any subsequent coat if not properly removed.

Broadcast: To hand toss a decorative aggregate, or other dry material in a uniform layer over fresh coatings to add color or traction. (Also see seeding.)

Bug Holes: Small regular or irregular cavities, usually not exceeding 15 mm in diameter, resulting from entrapment or air bubbles in the surface of formed concrete during placement and compaction.

Calcium Chloride Vapor Emission Test: An ASTM test used to measure the volume of moisture vapor released from a concrete substrate over time (typically 24 hours). Too much moisture emitted from a slab can affect the performance and bonding of overlays, coatings, and sealers. Moisture vapor test kits are available that include small containers of preweighed, unhydrated calcium chloride.

Cementitious: A material containing Portland Cement as one of its components or having cement-like properties.

Coating System: A protective film consisting of one or more coats, applied in a predetermined order by prescribed methods. A coating system description in a specification may include surface preparation and quality control requirements.

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

Construction Joints: Joints formed when one slab pour ends and another begins and are usually found at column lines.

Control Joints: Saw-cut joints designed to control slab cracking and minimize random cracking.

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

Crack Chasing: Routing out cracks in concrete with a saw or angle grinder before filling with a repair material.

Curing: The process by which a coating changes from a liquid state into a dry, stable, solid protective film.

Curing Agent: An additive component, sometime called a hardener that helps a coating film or concrete cure by chemical reaction.

Curing Compound: A liquid that, when applied to the surface of newly placed concrete, forms a membrane on the concrete or penetrates the concrete to retard the evaporation of water.

Delaminate: a separation of a coating or topping from a substrate or the layers of a coating from each other due to poor adhesion.

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.

Dew Point: The temperature at which air becomes saturated with water, that is, when the air is at 100 percent relative humidity. Below this temperature, moisture will condense and produce dew or fog. As air is cooled, the amount of water vapor it can hold decreases. Expressed another way, the point where the actual water vapor pressure becomes equal to the saturation water vapor pressure; any further cooling beyond this point normally results in the condensation of moisture.

Diamond grind: a method of preparing a concrete surface using a planetary head diamond grinder fitted with diamond-segmented abrasive discs. Often it is used after shot blasting to smooth out shot blast lines and to complete surface preparation.

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: Flooring epoxies consist of two parts, a resin and a hardener. Good quality epoxies are 100% solids, no solvents. Epoxies typically are used as a primer and build coat. They are also used as the binder resin in most resurfacer systems. (See Urethane vs. Epoxy comparison)

Expansion Joint: an isolation joint intended to allow independent movement between adjoining concrete pads.

Fibers: Tiny filaments made of polypropylene, polyolefin, nylon, polyethylene, polyester, or acrylic used alone or in conjunction with rebar or welded wire mesh to reinforce concrete.

Film Thickness: the depth of the film when wet (wet film thickness) and the final depth when dry (dry film thickness) usually expressed in mils (0.001 inch).

Fish Eyes: Imperfections in the concrete coating caused by contaminants such as oil and silicone.

HEPA: Commonly used abbreviation for high efficiency particulate air filters; encompasses specifications and testing requirements set for air filters by the U.S. Department of Energy. (www.eh.doe.gov/hepa)

High Build Coating: A protective or decorative coating that produces a thick film (usually greater than 10 mils) in a single coat.

IAQ: Stands for indoor air quality

Integral Color: a coloring agent premixed into fresh cementitious toppings before application.

Green Concrete: Concrete that has set but not appreciably hardened.

Green Seal: An independent, non-profit organization that strives to achieve a healthier and cleaner environment by identifying and promoting products and services that cause less toxic pollution and waste, conserve resources and habitats, and minimize global warming and ozone depletion. (www.greenseal.org)

Laitance: A thin layer of fine, loosely bonded particles on a concrete surface caused by an upward movement of water. Laitance must be removed before application of a coating.

LEED: Acronym for Leadership in Energy and Environmental Design. A Green Building Rating System^® created and implemented by the U.S. Green Building Council. (www.usgbc.org)

Moisture Vapor Emission Rate: Measurement of moisture vapor movement through a concrete slab. ASTM F 1869 describes how this is accomplished by absorbing moisture on anhydrous calcium chloride.

Mil: A measurement equal to 1/1,000 (0.001) inch. Commonly used to denote coating thickness.

Moisture Vapor Transmission Rate: Rate of movement of moisture vapor through a membrane.

NFSI: National Floor Safety Institute (www.nfsi.org), a non-profit organization with a mission to aid in the prevention of slip-and-fall accidents through education, training and research. Conducts laboratory and field testing to determine walkway materials, floor maintenance products and coatings that have achieved safety benefits worthy of NFSI certification.

NSF International A non-profit, non-governmental organization established as a world leader in standards development, product certification, education, and risk-management for public health and safety, with a focus on food, water, indoor air, and the environment. (www.nsf.org)

Orange Peel Finish: Coatings can be applied with a textured, orange peel finish to provide some slip resistance.

Overlay: A bonded layer of material, ranging from ¼ inch to 1 inch or more in thickness, placed on existing concrete surfaces to level or restore.

PCA: Portland Cement Association www.cement.org

pH Neutral: Chemicals that are neither acidic nor alkaline are pH neutral. On the pH scale, low pH corresponds to high hydrogen ion concentration, and high pH corresponds to low hydrogen ion concentration. A substance that when added to water increases the concentration of hydrogen ions (lowers the pH) is called an acid. A substance that reduces the concentration of hydrogen ions (raises the pH) is called a base.

Primer: The first coat of material applied to a concrete surface to improve bonding or adherence of subsequent coats.

Profile: The act of preparing a concrete surface to achieve the necessary degree of roughness.

Sacrificial coating: A final floor finish designed to protect the sealer or topcoat from wear.

Sawcutting: Using a concrete saw with abrasive blades or disks to cut joints into hardened concrete.

Scarify: A method of mechanically preparing concrete for coating or removing existing coatings. Uses rotary impact cutters held at a right angle to the surface.

Scratch coat: A base coat used to improve the rigidity and/or bonding of subsequent topcoats.

Seeding: Broadcasting aggregates on the surface of freshly placed concrete floor toppings

Semi-Rigid Joint Fillers: Function is to protect joint edges from damage inflicted by hard wheel impact and/or heavy loads. To achieve this filler must be somewhat "stiff". Stiffness is defined using Shore A Hardness. According to ACI and PCA, a minimum hardness of Shore A80 (comparable to very hard rubber) is required. (Note: Since hardness readings were established in the 1960-70 era, criteria for joint fillers will need to expand its description to include compressive resistance, etc. to accommodate heavier vehicles carrying heavier loads.) Due to the stiffness, semi-rigid filler cannot expand significantly in a side-to-side (lateral) manner. If it were flexible enough to expand, it would deflect under load, and thus not provide joint edge protection. Furthermore, semi-rigid epoxies will separate or "split." When filler separation occurs it is neither a failure nor a defect. It is designed for this purpose. When joints open beyond a filler's expansion capability, fillers separate. They may separate adhesively at their bond with the concrete. Or they may separate cohesively (internally). See www.metzgermcquire.com "Joint Filler Separation: Causes and Corrections" for further information.

Shore Hardness: the relative hardness of a material is measured by using "duromete gauge," the most common being a Shore durometer gauge. There is a needle at the bottom of the gauge, which is pressed against the material to be tested. The Shore A gauge has a dull needle used to measure the hardness of rubberlike materials.

Shot blasting: An abrasive blasting method using round iron shot to clean and profile concrete surfaces.

Spalling: The chipping or fragmenting of a surface or surface coating or joint edge caused for example by hard wheel impact and/or the loads imposed.

Substrate: An existing concrete surface that receive an overly, decorative or protective coating, repair procedure, or other resurfacing treatment.

Surface Profile: The roughened surface that results from abrasive blast cleaning. Surface profile is simply the texture of the cleaned surface.

Tack: The stickiness or adhesiveness of a material.

Urethane vs. Epoxy:

Urethane (Polyurethane): An exceptionally hard, wear-resistant coating typically used as a topcoat.

Benefits:
• Urethane coatings are noted for their overall balance of high performance properties
• Excellent toughness, flexibility, high impact resistance, and tensile strength.
• Excellent abrasion and resistance to a wide variety of chemicals, solvents, and stains.
• Aliphatic urethanes offer excellent UV stability.

Benefits:
• Enhances the surface of concrete
• Restores damaged concrete
• Has some chemical resistance to oils, salt, etc.
• Is a non-porous surface unlike concrete
• Good for low traffic areas or where spills are not a problem

Limitations:

• Epoxies wear three times faster than urethanes
• Epoxies are usually coated with urethane for better wear and chemical resistance
• Poor UV stability. Epoxies yellow over time.

UV Stable Coatings: Resist yellowing from ultra-violet light. For example, Tennant Eco-TCU^TM, Eco-DFS and Eco-DQS are ten times more resistant to ultra violet light than standard epoxy systems.

Vapor Barrier: Traditionally specified to minimize moisture inflow through concrete that is in contact with water or water vapor from a high water table. Vapor barriers are used to protect floor coverings that might be damaged from moisture moving upward through the concrete slab. Polyethylene sheeting is the most common vapor barrier material. A 4- to 6-mil thick polyethylene sheet is typically placed on a compacted subgrade or on a sand layer spread over the subgrade. Thicker, stronger sheeting materials resist punctures better during construction. See Hanley-Wood, LLC "Moisture Problems in Concrete Floors - Analysis and Prevention" www.wocbookstore.com for further information.

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.

Volatile Organic Compounds (VOCs): Organic chemicals/gasses that are released from certain solids or liquids. Concrete coatings, sealers, or cleaning materials that are solvent-based generally have higher VOC contents than water-based materials. Reducing VOC's reduces the potential ill-effects they may have on occupants in indoor spaces.

Sources used for glossary:

Society of Protective Coatings :: Protective Coating Glossary	Website
Concrete Network :: Glossary of Decorative Concrete Terms	Website
Tennant Company :: Glossary of Terms	Website
Metzger & McQuire :: Joint Filler Separation	Website
Hanley Wood LLC (World of Concrete Bookstore) :: Moisture Problems in Concrete Floors	Website