Meso-scale analysis on shear failure characteristics of asphalt

Meso-scale analysis on shear failure characteristics of asphalt–aggregate interface

Qiu, Xin

The bonding properties of asphalt–aggregate interface affect failure behaviors of asphalt mixtures. The objective of this study was to explore the shear failure characteristics of asphalt–aggregate interface by researching the interface shear strength and the continuous shear failure process. First, the oblique shear tests were conducted to investigate the interface shear strength under the influences of surface roughness, binder aging, loading rate, and aggregate type. Second, the direct shear tests were implemented to explore the continuous failure characteristics of the interface in terms of load–displacement curves. The interface bond-slip constitutive relation was established as a piecewise linear cohesive zone model. Finally, the grey relational analysis (GRA) was conducted to identify and prioritize the correlation between the applied experimental conditions and the interface bond-slip model parameters. The study results indicate that the improvement of surface roughness and loading rate could induce higher interface shear strength and a basalt aggregate with less silica has greater resistance to interface shear damage than a granite aggregate due to its stronger adhesion to binder. The interface shear resistance energy could benefit from higher surface roughness and normal stress level. Although binder aging could increase the interface shear strength, it imposes an adverse impact on the interface shear resistance energy. The established bond-slip constitutive model of the asphalt–aggregate interface could represent a three-stage evolutionary process of the interface shear failure. By performing the GRA, the binder aging condition would be the most significant factor affecting the interface shear performance when compared with the surface roughness and the normal stress.