Developing Technologies and Procedures to Reduce Tracking and Achieve Uniform and Accurate Tack Coat Application

The tack coat bond is known to affect the longevity of asphalt pavements. Proper interlayer bonding prevents successive pavement layers from acting independently of one another and creating non-uniform stress and strain profiles in the pavement structure. Poor bonding between pavement layers can result in various pavement failures such as slippage cracking, debonding, and early fatigue cracking, all of which contribute to a reduced pavement fatigue life. Tack coat application rate and uniformity (that can be achieved by uniform tack coat application and by avoiding/minimizing tracking) are two major factors that control the performance of the tack coat bonding and longevity of the pavement structure. In this study, a wireless scale system (OreTackRate) that can be controlled from a tablet computer was developed to measure tack coat application rate accuracy and uniformity. The developed wireless scale system was recommended to be implemented during construction to validate application rate accuracy and uniformity. In addition, a distributor truck certification process was developed and presented in this study. The developed scale system can also be used to determine whether the applied tack coat is cured at any time point during construction. Residual tack coat application rate can also be measured using OreTackRate during construction. Implementation of all these tests, procedures, and technologies is expected to improve the tack coat uniformity during construction and improve the overall longevity of the pavement structure.