Heterogeneous numerical modeling of asphalt concrete through use of a biphasic approach: Porous matrix/inclusions

This paper presents a numerical finite element (FE) model used to predict the dynamic modulus of porous asphalt mixes. The material considered is modeled as a biphasic medium composed of granular inclusions with linear elastic properties and a porous matrix of bituminous mastics containing a given percentage of air voids (5–6% for the purpose of this article), exhibiting linear viscoelastic behavior at small strain values. With this heterogeneous numerical model, a custom software (called “MOA”, French acronym for Random Object Modeler) developed in our laboratory has been used to generate random inclusions of various sizes and shapes in order to derive the aggregate skeleton of the particular asphalt mixture model. The chosen aggregate sizes must comply with a specific aggregate grading curve. This model is subjected to a cyclic load at a given frequency. The generalized Maxwell model has been used to determine the viscoelastic behavior of the matrix. The complex modulus and phase angle of the asphalt mixes generated from our numerical approach were compared to those obtained by Qingli Dai [1], resulting in a good agreement. This comparison leads to confirming the feasibility of the proposed heterogeneous numerical procedure. Lastly, localized stress and strain distribution results provide the basis for an interesting discussion on material design optimization in the aim of improving the mechanical properties under study.