Effect of tackcoat type on shear stiffness modulus at interface of asphalt concrete sample under variation of testing normal pressure and temperature

Abstract

In asphalt pavement construction, the quality of the bonding layer greatly affects the bonding ability between the two layers of asphalt concrete. The interface shear stiffness modulus (K) is one of the essential parameters for evaluating the interlayer stiffness of the asphalt layer. Currently, many types of tack coat materials are used to improve interface bonding ability and stiffness. Each type of tack coat material affects the adhesion quality. This study was conducted on two-layer asphalt concrete samples, using 3 types of tack coat materials (CRS-1, CSS-1, CRS-1P) with the same application rate of 0.5 l/m2, tested. The test was conducted under 3 different normal pressure levels (0, 0.2, 0.6MPa) and 2 experimental temperature levels (25, 60^oC). The result shows that with the increasing temperature from 25^oC to 60^oC, the average shear stiffness modulus decreases significantly when using different types of tack coat. Among them, CRS-1P decreased the least and CSS-1 decreased the most. Tack coat material has significant effect on K modulus. Also, the influence of other factors on the interlayer shear stiffness modulus is different. In particular, the experimental temperature is the the most influent factor on the K.