Few building surfaces are subject to more wear and tear yet are as prominently visible as floors. In the quest to create durable, long-lasting and appealing floor surfaces, concrete has often been used as the base material whether on grade or an elevated slab. Final finishes have commonly ranged from any number of flooring materials placed on top of it to simply sealing or painting the concrete. However, recent advances in the technology of cement-based concrete overlays have given rise to a new option that is growing in popularity. Essentially, a properly formulated cement and aggregate mix can be used as a thin (approximately 3/8-inch-thick) layer placed on top of a new or existing concrete floor slab (repaired as needed). In fact, the technology is available such that it is now possible to design and specify a concrete overlayment of this type in a full range of colors, patterns, and with various aggregates to simulate other materials such as terrazzo. In all, concrete flooring overlayments offer an option to create finished flooring that enhances any interior design, provides a durable, long-lasting surface, and requires minimal maintenance.

Advances in Cement and Concrete Products

In order to understand the nature of concrete flooring overlayments and the repair of an existing underlayment, it is worth delving first into the nature of different advanced cement and concrete products. Most architects are familiar with portland cement as a common basis for concrete products and mortars of all types. The Portland Cement Association, the trade organization for America’s cement manufacturers, points out that concrete is formed when portland cement is mixed with water to create a paste that binds with sand or rock (also called aggregate) and hardens all of the materials together. Portland cement as a product is manufactured through a closely controlled chemical combination of calcium, silicon, aluminum, iron and other ingredients. Common materials used to manufacture cement include limestone, shells, and chalk or marl combined with shale, clay, slate, blast furnace slag, silica sand, and iron ore. These ingredients, when heated at high temperatures form a rock-like substance that is ground into the fine powder that we commonly think of as cement.

Photo courtesy of CTS Cement Manufacturing Corporation

Advances in cement and concrete products allow for very attractive floor finishes to be created with polished concrete overlays that are suitable for a wide range of building types.