Effect of gradation segregation on low-temperature crack resistance of asphalt pavement using 3D DEM

Abstract

Gradation segregation can have a great influence on the low-temperature crack resistance of asphalt pavement. In this paper, five kinds of AC-20 asphalt mixtures with different degrees of gradation segregation are designed according to the standards put forward by the American NCHRPRReport-441 project report, and numerical models are developed using the DEM to simulate the splitting test. The effect of gradation segregation is analyzed on the low-temperature crack resistance of asphalt pavement from two aspects of macroscopic (mean splitting strength and horizontal tensile stress) and mesoscopic (contact force, displacement and crack). The results show that in the macro level, the coarse aggregate gradation segregation leads to the decrease of the splitting strength and horizontal tensile stress of the mixture, while the fine aggregate gradation segregation leads to the increase of the splitting strength and horizontal tensile stress of the mixture. Moreover, in the meso-level, the coarse aggregate gradation segregation leads to the decrease of the internal contact force, the displacement and the number of cracks, and the fine aggregate gradation segregation leads to the increase of the internal contact force and quantity of the mixture. Furthermore, the macroscopic response caused by segregation is related to the mesoscopic response and coarse aggregate heavy segregation has the greatest influence on macro and meso mechanical parameters and the low-temperature properties of asphalt mixtures. The research results provide a new idea and way to evaluate the low-temperature crack resistance of asphalt pavement based on the meso-level gradation segregation.