Why Is Prime Coat Applied?

The prime coat is basically designed to harden or toughen the base surface, to provide adhesion between the base and the asphaltic courses, to coat and bond loose aggregate particles, and to waterproof the surface of the base.

Where is prime coat applied?

A prime coat is a coating applied directly to a prepared base before additional layers of support or coating. Prime coat asphalt preparation is a vital element, as it directly affects the shear strength of the final asphalt product.

Why are prime coats and tack coats used?

Prime functions as a protector from rain for both types of bases. A prime coat should not be confused with a tack coat. Tack is an adhesive for gluing two asphalt layers together. A subgrade or rock base is not a single component.