A thermodynamics-based model for freeze-thaw damage in asphalt mixtures

Damage due to freeze-thaw cycles is a major problem for asphalt mixtures. Considering the complexity of the damage process in asphalt mixtures, characterization of the process and its effect on the material behavior is not straightforward. This paper therefore develops a thermodynamics-based model which includes viscoelasticity, damage due to freeze-thaw cycles, and temperature dependent damage due to external forces which affects the elastic strain energy. Furthermore, the model couples the freeze-thaw damage and the damage due to external forces in order to capture the aggravating effect that they have on each other in reality. The freeze-thaw damage evolution is in the model dependent on the number of freeze-thaw cycles and the duration of the freezing in each cycle. The novelty of the model, the freeze-thaw damage and its coupling to the elastic energy damage, is highlighted through numerical examples. It is shown that the model is capable of simulating an increase of the freeze-thaw damage through several freeze-thaw cycles and a realistic deteriorating effect on the material properties which is consistent with reported results from previous studies. Furthermore, the effect of coupling the two damages is illustrated by comparing the effect of the resulting damage to an uncoupled case. (C) 2020 The Authors. Published by Elsevier Ltd.