A micromechanical based three-dimensional DEM approach to characterize the complex modulus of asphalt mixtures

Abstract

Asphalt mixture is a typical particulate system whose mechanical performance can be modeled based on the particle interactions (contacts) at microscale. Once calibrated microscopically, the model can be used to predict the macroscopic properties based on the same contact mechanisms. The effect of individual component on the performance of the mixture can also be captured by the calibrated micromechanical model. In this paper, a three-dimensional DEM approach is developed to model the complex modulus of asphalt mixtures. Complex modulus is a crucial viscoelastic material property which describes the stress and strain responses of asphalt mixtures and has been incorporated into the DARWin-ME mechanistic empirical pavement design program to guide pavement design. The model is found to be successful in predicting both the dynamic modulus and the phase angle of a conventional dense graded asphalt mixture over wide ranges of temperatures and frequencies. The nonlinear behavior of the phase angle at high temperature is also captured. The effect of the key model parameters on the dynamic modulus and the phase angle are evaluated which contributes to the fundamental understanding of the material mechanical properties and provides meaningful guidance for the design and modeling of asphalt mixtures.