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
These CSP surface profiles are vital to the performance of coating, cementitious, and aggregate systems. More systems and applications fail because of poor surface preparation than from any other cause. All unsound concrete must be removed, leaving sound, clean, and suitably roughened surfaces. For any overlay installation or surface coating, what constitutes "suitable roughness" should be specified using ICRI's Concrete Surface Profiles (CSP). This is a series of nine roughness levels ranging from acid etched to heavy scarification.
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