Study of shear strength and gradation optimization of asphalt mixture based on uniaxial penetration numerical test

Abstract

Improving the shear strength is an effective way to improve the high-temperature performance of asphalt mixtures. In this study, we conducted numerical tests of uniaxial penetration of asphalt mixture to analyze the influencing factors of shear strength and shear cracking mechanism of asphalt mixture. Moreover, the stress transfer paths during cracking and the effect of voids on shear cracking behavior were also explored. Finally, a strong interlock skeleton-dense gradation with high temperature resistance of AC-20 mixture was proposed based on the shear strength. The results show that an appropriate increase in asphalt content, an increase in aggregate roughness, and a decrease in the void ratio improve the shear strength of the asphalt mixture. The shear cracking process is influenced by the combination of shear stress, tensile stress, and microcracks. Shear cracks are spread around and below the specimen in a “V” shape. The expansion and penetration of micro cracks are caused by the stress concentration phenomena brought on by the existence of voids, which also reduces the shear strength of the structure. The high-temperature performance of the AC-20 mix with strong interlock skeleton-dense gradation was improved by about 27%.