BACKGROUND

The overall durability of a pavement structure is strongly tied to the retention of the desired amount of tack on the pavement layer surface during construction or rehabilitation as well as the bonding quality of the tack between pavement layers. The interlayer bond, in turn, is dependent on the quality of the tack coat material. Over the last few decades, there have been several developments in tack coat materials and their application. For example, the use of non-tracking materials and specialized application equipment have gained much attention in the pavement industry.

Producers have developed various tack coat materials and often approached highway agencies for product approval, and agencies and producers have developed a range of laboratory tests to evaluate the characteristics of the tack coat materials and qualify their use. Research was needed to revisit recently developed methods and produce a specification that defines the test methods, parameters, and thresholds that are indicative of performance.

OBJECTIVE

The objective of this research was to produce a specification with related laboratory test methods for tack coat materials that allows prediction of their performance over a range of environments, pavement types, and construction methods. The research considered test methods for tack coat characteristics related to bonding, tracking, and durability.