Experimental and numerical analyses on the fracture characteristics of cement-asphalt mastic-aggregate interface

Abstract

The stiffness and failure properties of cement-asphalt mastic-aggregate (C-AM-A) interface are among the most important factors affecting the performance of pouring semi-flexible pavement materials (SFP). Therefore, determining the characteristics of C-AM-A interface are essential for guiding the design of SFP from the perspective of interface enhancement. In this study, the failure characteristics of C-AM-A interfaces are examined experimentally and numerically. Firstly, the effects of temperature and the proportion of cement substituting limestone filler on the bonding strength of C-AM-A interface are analyzed via pull-off tests. Then, an innovative test method based on a three-point bending test of C-AM-A beam is proposed to investigate the influence of test temperature and asphalt mastic type on the fracture characteristics of the C-AM-A interface. Finally, based on the cohesive surface techniques, numerical modeling of C-AM-A beam under three-point bending was applied to study the effect of cohesive parameters on the interfacial fracture characteristics. The results show that the interface bonding strength decreased significantly with the increase of temperature. Using cement as a filler improves the bonding strength, fracture strength, stiffness and fracture energy of C-AM-A interface as compared to the case when limestone filler is used. As the temperature increases from −10 °C to 20 °C, the failure mode of the C-AM-A interface first alters from adhesive failure to mixed failure mode, and then to cohesive failure. It suggests that enhancing the adhesion of C-AM-A interface is more advantageous for improving the fracture resistance at low temperatures, while increasing the interface cohesion is more important at relatively high temperatures. The laboratory test methods, the numerical model and methodology developed in this study are useful to study the failure behavior of C-AM-A interface and optimize the performance of SFP from the perspective of interface enhancement.