Effects of the ductility and brittle point of modified asphalt on the freeze-break behavior of asphalt concrete: A 3D-mesoscopic damage FE model

Abstract

Hydraulic asphalt concrete is widely used in pumped storage power stations and other anti-seepage engineering. The low-temperature freeze-break of asphalt mixtures is a rather complex phenomenon significantly affected by the ductility (at 5℃) and the brittle point of asphalt binder. In order to achieve better crack resistance at low temperatures, the influence of ductility and brittle point on low-temperature fracture becomes a major problem. This paper firstly proposes an effective modulus equation of asphalt mortar, which accounts for ductility and brittle point of modified asphalts as dominant factors. Then, a three-dimensional (3D) mesoscale finite element (FE) model, which considers this equation and the damage evolution of the asphalt mixture from linear viscoelastic (LVE) to elastic-brittle due to cooling, is established through an aggregate random placement procedure to simulate the freeze-break behavior of asphalt concrete samples in the thermal stress restrained specimen test (TSRST). The numerical simulation results of thermal stress are in good agreement with the previously published TSRST thermal stress data, and this verifies that our model is effective. Furthermore, the proposed model can predict the freeze-break temperature of asphalt mixture with good accuracy, and well describe the mesoscale thermal stress, strain, and damage distributions.