Numerical study of particle size distribution effect on the failure of asphalt mixtures using discrete element method

This study aims to numerically investigate the effect of particle size distribution (PSD) of asphalt mixtures on their load carrying capacity measured in three point bending test. Discrete element method (DEM) is employed as the numerical framework to simulate asphalt mixtures. The PSD feature of asphalt mixtures is replicated in DEM by an assembly of polydisperse particles with identical gradation. A cohesive damage-plasticity model characterising the fracturing processes of binder matrix within the materials is also incorporated in the inter-particle contacts to collectively model their macro-behaviour. This discrete-based modelling approach is validated to capture well the mechanical response of asphalt mixtures in three point bending test. It is then applied to investigate the PSD effects, in which numerous simulations of three point bending test are conducted and material PSD is varied while other model parameters remain constant. The influence of PSD on material load carrying capacity obtained from the simulations is discussed and interpreted via further micromechanical analysis on numerical specimens.