Concrete is prepped by Grinding or by chemicals. There are times where both are needed to obtain the proper end results for the best finish, depending on what product or surface is desired.
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 847-827-0830 or visit www.icri.org.