Shear Deformation Behavior of a Double-Layer Asphalt Mixture Based on the Virtual Simulation of a Uniaxial Penetration Test

Abstract

This paper aims to clarify the shear deformation behavior of double-layer asphalt mixtures using the virtual uniaxial penetration test (UPT) with a discrete element method. For this purpose, asphalt mixtures with two different nominal maximum aggregate sizes were designed for the preparation of double-layer wheel tracking test specimens. Then, the cylindrical cores were prepared from the specimens and were cut for capturing the longitudinal profile images. These images were used to reconstruct a two-dimensional discrete element model (DEM) of the uniaxial penetration test specimen. The results indicate that the shear deformation behavior of the asphalt mixtures showed corresponding changes under the virtual loading. The tensile and compressive stress were distributed unevenly within the upper layer after the test, and both coarse aggregates and asphalt mortars bore a greater shear stress. Therefore, cracks were more likely to occur in the upper layer, leading to the failure of the specimens. This process enhanced the bonding between the asphalt mortars and the mineral aggregates. The aggregate particles in the upper layer moved more vertically, while those in the lower layer generally moved more laterally under the virtual loading. This behavior reveals the rutting mechanism of asphalt pavement.

A Unified Strength Model of Asphalt Mixture Considering Temperature Effect

“…3. The product of the maximum penetration pressure obtained from the test and the strength parameter is the maximum shear stress τ max of the asphalt mixture specimen (Kou et al, 2020):…”

“…The uniaxial penetration test is easy to operate, the equipment is simple, and the stress mode of the specimen is consistent with the pavement. It can effectively evaluate the anti-shear property of asphalt mixture (Kou et al, 2020). Therefore, a uniaxial penetration test is adopted to test the anti-shear property of asphalt mixture in this study at different temperatures.…”