Tack Coat of road

Tack coat is a single coat, low viscosity liquid bituminous binder applied to the exit road surface to ensure good bonding between the surface and the bituminous overlay. The rate of application of taking coat should be controlled so that the film thickness does not become more than that required. Self-propelled or towed bitumen sprayers can be used for applying tack coat. The surface on which the tack coat should be free from dust or dirt. For emulsion bitumen, the tack coat should be allowed to cure by evaporation until the time a new layer is laid over it.