Tack coats and prime coats

Tack coats: The asphalt pavement is needed to be bonded to the layer under it. This is done by spraying on to the surface of the underlying layer, a thin coating of asphalt is provided to bind the layers together. This thin coating of asphalt is termed as tack coating. These tack coatings are used to bind the cement concrete base or old brick and stone pavements with the asphalt layers.

Prime coats: The asphalt pavement is treatment is to be placed on a granular base, it is allowable to treat the top surface of the base by spraying on liquid asphalt that will penetrate the base. This treatment is called prime coat. It is implemented to serve as a transition from the granular material to the asphalt layer and to bind them together.

The prime coat and tack coat are different according to the usage of asphalt in it.