The surface to be repaired must be structurally sound and clean, as well as free from any dirt, oil, grease, paint, or other contaminants. Use either mechanical means (such as sandblasting or wire brushing) or chemical means (such as a 10% trisodium phosphate solution) to thoroughly clean the area before repair. Smooth surfaces should be roughened by mechanical means or by using a 10% muriatic acid solution.
NOTE: Acid solution must be washed off the surface thoroughly with water. Clean the area to be repaired with potable water, leaving the concrete saturated but free of standing water. Some very porous concretes may require several applications of water to ensure complete saturation.