Complex modulus modeling of asphalt concrete mixes using the Non-Smooth Contact Dynamics method

Abstract

Asphalt mixtures are complex multiphase materials showing a viscoelastic behavior. To assess the mechanical response of these materials, a typical practice is to perform a complex modulus test. An alternative to laboratory characterization is to simulate numerically this test by means of a discrete approach. These approaches are able to reproduce the mechanical performances of asphalt mixtures, but are still time-consuming. In this paper, the complex modulus test is reproduced numerically for a viscoelastic granular material by means of 3D Non-Smooth Contact Dynamics simulations. A viscoelastic phase surrounding the rigid particles is simulated by a contact model acting between them. This contact law was implemented in the LMGC90 software, based on the Burger’s model. The developed contact model handles larger time step lengths to reduce the computational time. Experimental and numerical testing campaigns were conducted for the complex modulus test on trapezoidal samples in a 2PB configuration. The numerical model was able to reproduce the mechanical performances obtained during experimental tests, regarding the material properties such as the complex modulus norm and the associate phase angle. The proposed model can be used to simulate the mechanical response of road structures under traffic loading concerning rutting, crack propagation and fatigue damage.