Cement boards are combinations of cement, glass, aggregate, and fiber reinforcements that are formed into sheets and used as tile backing boards, and to build wall or floors. They can be nailed or screwed to steel or wood studs to create a substrate for vertical tiling. Cement boards can also be attached to plywood horizontally for tile floors, kitchen counters, and backsplashes. These hard, environmentally-stable materials are sometimes used on the exterior of buildings, as a base for exterior plaster systems, or even as the finishing system itself. Typically, cement boards are formed into 4-ft. x 8-ft. or 3-ft. x 5-ft. sheets with a thickness of 1/2-inch or 1/4-inch.
Cement boards differ in terms of bonds and properties. Choices include calcium aluminate and carbon bonds, Portland cement bonds, phosphates, and slag cement. Products with sulfate, sulfur and polymer bonds are also available. Polymer-modified Portland cement provides improved plasticity and water resistance. Polymer cement boards are used with corrosion-resistant tile, brick, or other masonry. Acrylate, epoxy, polyurethane, polyester, and vinyl ester provide additional choices. Cement boards that use specialized or proprietary bond types are also available.
Product specifications for cement boards include dimensional, mechanical, physical, and thermal characteristics. Length, width, and thickness are critical dimensions to consider. With regard to mechanical properties, cement boards differ in terms of compressive strength and modulus of rupture (MOR). Compressive or crushing strength is the maximum compressive load per unit cross-section that cement boards can withstand before mechanical failure or breakage occurs. MOR, flexural strength, or cross-strength is the maximum flexural strength that products can withstand before failure occurs.
Cement boards are used widely in flooring and walls, but have applications beyond the building and construction industry. For example, some cement boards are used in foundry, refractory, metal processing, and other high-temperature applications. Other products are used in glass or ceramics manufacturing, chemical or materials processing, or thermal insulation or fireproofing applications. Structural cement boards are used in the construction of fire-rated floor, roof, and wall assemblies. Structural cement boards are a cost-effective alternative to poured concrete that installs with standard carpentry tools. Refractory cement boards are cement boards that are used for high temperature applications, especially in factories and manufacturing plants.