Diamond polishing
Diamond polishing of decorative overlays, another technique for finishing decorative concrete, is similar to polishing marble, granite, terrazzo, or concrete. The goal is to bring out the natural beauty of the sand and tiny aggregates, giving a lustre and depth to the product while offering light reflectivity as a bonus.
Once the material is cured according to manufacturer’s recommendations, the grinding, honing, densifying, polishing, and protective waxing process begins. Specialized craftsmen, using planetary grinding equipment, diamond tooling, and high-efficiency-particulate-arrestance (HEPA)-certified dust extractors, are capable of attaining a honed or highly polished surface. Though the surfaces are refined through polishing, they still are capable of providing slip resistance according to building codes. There are a growing number of overlays on the market that cater to this style of flooring.
A distinct advantage of overlays is their lack of large aggregates concrete contains. Diamond-polished overlays offer a true salt and pepper look, which many find very desirable. Canadian design professionals have access to non-profit associations, such as the Concrete Polishing Association of America (CPAA), which offers aid with written specification guides for design professionals wishing to accurately specify required slip resistance, level of shine, distinction of image, clarity, and the type of polish required—whether it is abrasive or topical. These specifications greatly reduce margins for misinterpretation between contractor and specifier.
Advantages of overlay polish are:
- better abrasion resistance than resinous coatings;
- increased light reflectivity;
- a natural look and feel;
- easy, low-cost maintenance;
- the ability to be re-waxed and burnished periodically; and
- the ability to be re-honed and polished.
Nevertheless, overlay polish can be disadvantageous because it can:
- be relatively costly;
- have poor salt resistance; and
- be more porous, resulting in the need to address spills immediately.
Conclusion
Decorative overlays offer a solution for a concrete look and feel when the existing concrete is unable to attain this due to blemishes, cracks, pitting, and necessary repairs. It is a tool for the design professional that can be fashioned in many ways to attain specified requirements. However, it is important to refer to qualified consultants, manufacturers, and craftsmen because overlays are prone to limitations similar to concrete.
Installation requires precision and must be properly planned and staged. There is only one shot at making overlays work perfectly, so any naturally or unnaturally occurring incidents during placement may have an effect on the final product. For these reasons, it is recommended to rely on industry experts experienced with these overlays and types of projects to ensure successful delivery.
Ultimately, the look of concrete or overlays will not satisfy everyone; and whether or not overlays are the correct building material for a given project remains in the domain of personal taste. However, those who work with decorative overlays are often repeat users who enjoy working with these products because they offer an opportunity to create a look and feel totally unique and customizable.
Giovanni Natale is a second-generation cement finisher/contractor with 35 years of industry experience. In his career, he has been responsible for the installation, supervision, and coaching of crews working with concrete repair systems, flatwork, decorative concrete, floor and wall coatings, and carbon-fibre-reinforced polymer (CFRP) systems. More recently, his work with MAPEI has brought him to assist professionals with concrete restoration solutions. He can be reached via e-mail at gnatale@mapei.com.
