Investigation on low-temperature cracking characteristics of asphalt mixtures: A virtual thermal stress restrained specimen test approach

Abstract

In order to characterize the effects of aggregate characteristics on the low-temperature cracking characteristics of asphalt mixtures, a virtual approach for the thermal stress restrained specimen test (TSRST) was established based on the discrete element method (DEM) and the simulation software particle flow code in two-dimension (PFC2D). A two-dimensional (2D) virtual specimen was established according to the random generation algorithm. The meso contact parameters between each phase in materials at different temperatures were determined through laboratory tests. The internal thermal stress curve of the specimen and the meso mechanism of crack propagation were analyzed during the virtual test, and the reliability of the virtual test was confirmed by the results of laboratory tests. Finally, the effects of aggregate properties on the low-temperature crack resistance of asphalt mixtures were analyzed. The results of the virtual test and the laboratory test are highly consistent, which proves that the virtual TSRST can be used as a reliable method to evaluate the low-temperature crack resistance of asphalt mixtures. The damage of the specimen can be divided into three stages: crack initiation, stable propagation, and unstable propagation. The asphalt mixture with less aggregate content, coarser gradation and smaller flat ratio has better low-temperature crack resistance.