Multiscale model for predicting freeze-thaw damage in asphalt mixtures

Freeze-thaw cycles in combination with long-term moisture exposure and traffic is a major threat to the performance of asphalt pavements. To enable characterisation and understanding of the damage process, this paper presents a new thermodynamics-based multiscale model of freeze-thaw damage in asphalt mixtures which also accounts for the damage due to moisture and traffic. The developed model consists of a microscale and a macroscale and is thereby able to account for the effect of the different microscale material components on the homogenous macroscale damage development. Additionally, the model is able to account for the acceleration of freeze-thaw damage which occurs when moisture infiltrates a damaged pavement with an increased effective air void content between freeze-thaw cycles. The novelty of the model lies in the ability to simulate the in-time acceleration of damage, the combined deteriorating effect of freeze-thaw cycles, moisture and traffic, as well as the coupling of the two scales to enable accurate predictions and understanding of the damage evolution. These features are demonstrated through a set of parametric examples which demonstrate the importance of including the effect of long-term moisture exposure and freeze-thaw cycles as well as the coupling between the different damage modes.