Investigation of the adhesive and cohesive properties of asphalt, mastic, and mortar in porous asphalt mixtures

Abstract

The adhesive and cohesive properties of asphalt, mastic, and mortar in the same porous asphalt (PA) mixture essentially control the durability and failure mechanism of PA mixtures. A typical PA mixture with three types of asphalt was investigated, and the corresponding asphalt, mastic, and mortar were also designed. Binder bond strength (BBS) test was used to evaluate the adhesion and cohesion (Ad/Co) of the asphalt, and a modified BBS test was developed to evaluate the Ad/Co of the mastic and the mortar. The influences of asphalt properties, temperature, and moisture damage on the Ad/Co of the asphalt, mastic, and mortar were evaluated. In addition, indirect tensile tests and Cantabro loss tests were performed to investigate the relationships between the durability and indirect tensile strength (ITS) of the mixture and the Ad/Co of binder. The results indicate that the cohesive strength of asphalt, mastic, and mortar increases with the increasing dynamic viscosity of asphalt. The failure type of the asphalt changes from adhesive to cohesive failure, while the failure types of the mastic and mortar change from cohesive to adhesive failure with the increasing temperature. Adhesive failure was observed in asphalt under wet conditions, and the failure type of the mastic and mortar changed from cohesive to adhesive failure with increasing moisture damage. The Ad/Co of mortar has the potential to predict and evaluate the ITS and the durability of PA mixtures. Finally, the adhesive and cohesive failure mechanisms of PA mixture are discussed under different temperature and moisture damage.