Random generation of asphalt mixture mesostructure and thermal–mechanical coupling analysis at low temperature

Abstract To further study the damage mechanism of asphalt mixture during ice crystal frost heaving force and to provide reference and suggestions for the prevention and research of frost damage of asphalt pavement in severe cold areas. Taking AC-13 asphalt mixture as an example, this study uses Matlab to establish a random delivery model of irregular aggregates and uses ANSYS to conduct a thermal–mechanical coupling analysis of asphalt mixtures with different porosity and temperatures. Results show that the numerical model can be used for the microstructure analysis of asphalt mixtures. Moreover, in a low temperature environment of −5 °C to −25 °C, the moisture in the void will freeze sharply within 60 s and eventually reach the same temperature value as the matrix. In the three-way constrained displacement field, the frost heave force generated by ice crystals causes the largest and most obvious deformation on the surface of the specimen. In addition, due to the interaction of the aggregate surface, the asphalt components are reorganized. Under the extreme condition of −25 °C, the stress value in the bonding surface reaches the maximum 33.07 MPa, which is three times that of asphalt mortar under the same conditions. It shows that under the same strain, the bonding surface reaches the allowable stress earlier than the asphalt mortar and fails. Therefore, this study not only provides a quantitative expression for the frost heave damage of ice crystals but also reveals the influence of ice crystals on the macroscopic properties of asphalt mixture from a meso level.