Concrete Surface PreparationIf you plan to overlay or restore existing concrete, proper surface preparation is essential to achieving good results
Preparing concrete surfaces for coatings, overlays, stains or repair materials is a time-consuming task that many contractors perform begrudgingly or are tempted to overlook altogether. But if you've ever skipped this essential first step in the process, you undoubtedly learned the hard way how critical it is to the success of the job.
Concrete surfaces are prepared prior to resurfacing concrete to look like plain concrete again or to be upgraded to a decorative finish. Today polymers can be applied as thin as 1/8 " or up to 3/4" thick and stamped, producing a surface that looks just like a normal stamped concrete surface.
Surfaces are also prepared prior to various floor-coating installations in industrial, commercial, and institutional applications. The most important characteristic for resurfacing materials or floor coatings is the texture of the concrete. This section offers an overview of the steps required for surface preparation as well as an introduction to the machinery that is used.
What's a Concrete Surface Profile, or CSP?
For proper bonding of concrete overlays and coatings, it's important to give surface the correct concrete surface profile, or CSP. To help contractors make this assessment, the International Concrete Repair Institute has developed benchmark guidelines for CSP-a measure of the average distance from the peaks of the surface to the valleys. They range from CSP 1 (nearly flat) to CSP 9 (very rough). As a general rule, the thicker the overlay or topping, the more aggressive the profile needs to be. A skim coat, for example, may require a light CSP of 2 to 4. For thicker self-leveling or polymer overlays, acceptable profiles generally range from CSP 4 to 6. Achieving surface profiles in the higher ranges often requires roughening by shotblasting or scarifying.
For a copy of ICRI's technical guide, "Selecting and Specifying Concrete Surface Preparation for Sealers, Coatings, and Polymer Overlays," call 651-366-6095 or visit www.icri.org.