Classified as a cationic, Tack Coat is a light application of Bitumen Emulsion between layers of hot mix asphalt designed to create a strong adhesive bond without slippage. Heavier applications can be used under porous layers or around patches where it also acts as a sealing layer. Without the use of Tack Coat, asphalt layers on the road can separate, reducing the structural integrity of the road and also allowing water to penetrate the structure.