How do you ensure proper bond between a surface layer and underlying asphalt?

Applying a tack coat before placing a new layer of asphalt is critical for ensuring proper bond between the surface layer and the underlying asphalt. A tack coat is a sticky, thin layer of asphalt emulsion that enhances the adhesion of the newly laid asphalt to the existing surface. When this coat is applied, it penetrates the surface texture of the underlying layer, creating a stronger bond that helps resist the potential for slippage or separation during the performance of the pavement.

Using a heavier aggregate in the surface layer does not directly contribute to the bonding process but may affect the surface friction and durability. Adding additional layers of asphalt could lead to an increase in weight and thickness, but without proper bonding, the layers could still separate under load. Increasing the temperature of the underlying layer is not a common practice and could lead to issues like asphalt flow or instability rather than enhancing adhesion between layers. Overall, the application of a tack coat is the most effective and accepted method for achieving a reliable bond in asphalt paving.