A dem generalized kelvin contact model for predicting stiffness of asphalt mixtures

Abstract

This paper presents the development of a three-dimensional micromechanical model based on the Laguerre-Voronoi diagrams of the grain structure to study the viscoelastic behaviour of asphalt mastic with the use of the discrete element method (DEM). Usually, the DEM models of asphalt mastics adopt a Burger's contact model to reproduce the known viscoelastic behaviour. A generalized Kelvin chain model (GK) was developed within a particle model (PM) framework in order to obtain a better agreement in the determination of dynamic properties of mastics. Numerical cyclic tests under a frequency range varying from 10 to 0.10 Hz were implemented to analyse the dynamic response. The parameters of the DEM model are determined from macroscale material properties, which are obtained by fitting lab-based dynamic modulus and phase angle results. The influence of the parameters defining the contact models on the dynamic response was investigated. An iterative procedure was derived to convert the macroscale properties into calibrated contact parameters of the proposed model. Simulation tests show a good correlation between the numerical results obtained with the GK contact model and the experimental data when compared with the agreement obtained with the Burger's model.