Heterogeneous numerical modeling of fatigue damage for asphalt mixtures through complex mechanical impedances

Asphalt mixes, also known as bituminous concrete and asphalt concrete (AC), which are one of the most widely used materials in pavement engineering, are complex, multi-scale composite materials. AC is a heterogeneous material composed of a bituminous matrix and aggregates featuring viscoelastic and elastic behavior, respectively. Fatigue under cyclic loading of this material is one of the main pavement degradation phenomena. Under cyclic loading, the viscoelastic behavior of this material converts part of the energy brought by the loading into dissipated energy due to the viscous effects of the bituminous matrix. It is a heat source that leads to the increase of temperature during phase I of fatigue (self-heating). The second part of the energy is restituted and is the growth driving force of the damage. This work deals with a new thermodynamic approach to describe rheological models applied to viscoelastic materials under mechanical cyclic loading. The dissipation and the energy-released rate are determined based on an electromechanical analogy to simulate damage growth and the temperature increase. Both thermal and mechanical aspects and their coupling are taken into account leading to complete constitutive modeling to simulate the decrease of the AC complex modulus. Using the image processing technique, a heterogeneous microstructure is used to model the AC.