What is the primary purpose of applying tack at the joint face?

• A. Improve cohesion at the joint
• B. Clean the joint area
• C. Reduce temperature
• D. Increase moisture

Answer: (A)

Applying tack at the joint face creates a thin, adhesive film on the surface so the new asphalt can bond to the existing pavement. This tacky layer fills small gaps and provides a cohesive, sticky surface that the hot mix can adhere to as it’s placed, which helps the joint transfer loads smoothly and stay intact under traffic. The result is a continuous pavement with reduced risk of delamination, raveling, or cracking at the joint.

Tack coat isn’t primarily about cleaning the joint, changing the temperature, or increasing moisture. Cleaning and surface prep are done separately, and the tack coat’s main role is to enhance adhesion between layers rather than alter moisture levels or temperature.