What must be done to milled asphalt surfaces prior to placing tack coat?

Prior to placing tack coat on milled asphalt surfaces, it is essential to clean and prepare the surface to ensure effective adhesion. Milled surfaces can have debris, dust, loose particles, or the remnants of aged asphalt that could prevent the tack coat from bonding properly with the new asphalt layer. Thorough cleaning helps to remove these contaminants, allowing for better connectivity between layers.

By ensuring that the surface is properly prepared, the long-term durability and performance of the road can be significantly improved. A clean, well-prepared surface allows the tack coat to function as intended, enhancing the mechanical bond between the milled surface and the new layer of asphalt, which is crucial for the overall integrity and performance of the roadway.

Other options, like applying a sealant, covering with gravel, or leaving the surface as is, are not effective or appropriate prior to applying a tack coat. These actions could either interfere with the bonding process or be unnecessary for the preparation of the surface.