Aggregate distribution influence on the indirect tensile test of asphalt mixtures using the discrete element method

Abstract

The purpose of this study is to investigate the effect of horizontal aggregate distribution, i.e. aggregate distribution in horizontal cross sections, on the indirect tensile (IDT) test of asphalt mixtures. An index of aggregate homogeneity, used to evaluate the aggregate distribution in a two-dimensional (2D) cross section, was comprehensively described; the horizontal aggregate distribution was evaluated by the index. A microstructure-based discrete element model for predicting the IDT test results was established by a discrete element program called particle flow code in two dimensions (PFC2D). Based on this model and by loading horizontal cross sections of asphalt mixtures along different directions, the effects of horizontal aggregate distribution on the splitting strength and maximum horizontal stress with regard to an IDT test were numerically simulated by means of the discrete element method; the obtained results were verified by performing an actual IDT test. Results reveal that the splitting strengths and maximum horizontal stresses in the IDT test exhibit anisotropy. Furthermore, it is revealed that there is an insignificant correlation between the horizontal aggregate distributions and the average splitting strengths and average maximum horizontal stresses, as well as a significant correlation between the horizontal aggregate distributions and the variations in the splitting strengths and maximum horizontal stresses.