Bonded Interface Shear Performance of a Double-Layer Asphalt Mixture Based on DIC Technology

Abstract

Abstract To study the effect of water and salt erosion on the bonded interface shear performance of a double-layer asphalt mixture (DLAM), an inclined shear test was conducted on a DLAM using a tack coat as the bonded interface between simulated old asphalt pavement (AC-16) and overlay (SMA-13). First, the inclined shear test of the DLAM before and after freeze–thaw (F–T) cycles was conducted. Second, the digital image correlation (DIC) technique was used to calculate the deformation field to divide the failure of the specimen into meso- and macrocracks and analyze them. According to the results of this study, the shear failure of DLAM under F–T cycles consisted of two stages. In the first stage (three cycles), the interface shear properties decreased due to ice expansion load. In the second stage (after three cycles), the interface shear performance deteriorated, and chlorine salts accelerated the interlayer failure due to the interface debonding of asphalt and aggregate under the combined action of water/salt and vehicle load. The damage factor defined on the basis of the statistical analysis of the strain field by DIC could reflect the deformation of the bonded interface in real time. The damage factor evolution curve was used to compare the interface damage degree caused by water and salt erosion. A method for judging the crack initiation area of mesocracks was proposed by DIC technology, and the correctness of the appearance position of the interface crack was verified by calculation.