A micromechanical model of freeze-thaw damage in asphalt mixtures

Freeze-thaw damage in asphalt pavements is a complex phenomenon dependent on many parameters such as moisture infiltration, temperature and mechanical properties of the asphalt constituents as well as the interface between them. As a first step in creating a comprehensive multiscale model including all of these parameters, a micromechanical model has been developed. This model couples the infiltration of moisture and the associated damage, the expansion caused by the water inside the air voids freezing, and the mechanical damage. The expansion of the air voids is implemented by applying a volumetric expansion in the air voids dependent on the temperature. The cohesive damage in the mastic and adhesive damage in the mastic-aggregate interface are included by implementing an energy-based damage model and the cohesive zone model, respectively. To show the capabilities of the model, the effect of different parameters (the number of freeze-thaw cycles, the gradation of the microstructure, and the freezing time) was investigated through simulations. From the analyses it was concluded that the model was capable of capturing the deteriorating effect of an increasing number of freeze-thaw cycles, and was sensitive to the freezing time in the freeze-thaw cycles.