Coupled Micromechanical Model of Moisture-Induced Damage in Asphalt Mixtures

The combined effect of moisture and mechanical loading on asphalt mixtures has been recognized as one of the main causes of premature deterioration of flexible pavements. This paper presents a micromechanical model of moisture-induced damage in asphalt mixtures. The model couples the effect of moisture diffusion and mechanical loading to quantify the level of damage within the mixtures. The mechanical properties of the materials are defined as a function of the amount of moisture content. The cohesive zone modeling technique is used to simulate adhesive damage at the aggregate-mastic interfaces. Damage is evaluated based on the location and time for crack initiation and propagation at the aggregate-mastic interfaces and on the level of strains and stresses within the bulk of the mastic. Results show that micromechanical models provide a better understanding of moisture damage mechanisms in asphalt mixtures and can guide the development of continuum damage models.