What is the liquid that I’ve seen concrete contractors spray on the surface of concrete sidewalks and driveways?
A—The product you refer to is probably a curing agent. Its purpose is to retard the rapid evaporation of the water in the concrete through the surface. Curing is the process of setting or hardening during which the water in the mix helps the chemicals bind together and strengthen. The process is slow, and water is critical. It takes three to seven days for concrete to harden sufficiently to support vehicle traffic, and 28 days to reach it’s full strength. Up to 50% of concrete’s strength can be lost if it is not properly cured. You will sometimes see concrete covered with plastic sheets or wet burlap. These are alternate techniques for keeping the concrete damp while it cures properly.
