Stress–Strain–Strength Behavior of Hydraulic Asphalt Concrete at Different Bitumen Grades

The stress–strain–strength behavior of hydraulic asphalt concrete is critical to the safety of the high asphalt concrete core. To study the effect of bitumen grade on the stress–strain–strength behavior of hydraulic asphalt concrete, uniaxial compression tests, direct tension tests, bending tests, and triaxial compression tests were conducted. The variation patterns of mechanical performance indicators and stress–strain curves of hydraulic asphalt concrete with bitumen grades A70, A90, and A110 were analyzed. The elastic modulus expression of asphalt concrete based on nonlinear failure criteria were proposed. Considering potential issues associated with asphalt concrete core, the selection of bitumen grades was discussed. The results indicate that increasing the bitumen grade enhances the tensile, compressive, bending, and shear deformation properties of hydraulic asphalt concrete, and makes it exhibit more pronounced ductile behavior. However, the strength and modulus decrease. The use of higher-grade bitumen reduces the dilatancy of hydraulic asphalt concrete. As the bitumen grade increases, the nonlinear property of the shear strength of hydraulic asphalt concrete becomes more significant. An elastic modulus expression based on nonlinear failure criterion accurately describes the deviatoric stress–axial strain relationship for hydraulic asphalt concrete of different bitumen grades. When the strength of hydraulic asphalt concrete meets these requirements, it is advisable to select higher-grade bitumen to enhance the safety of the core.