Unified Strength Models of an Asphalt Mixture under Different Temperatures and Three-Dimensional Stresses

The goal of this paper is to reveal the influence of temperatures on the triaxial strength of asphalt mixtures. The triaxial compression and triaxial tensile tests, as well as plane tensile and compression/axial tensile tests, which were developed by the self-developed triaxial test equipment to carry out the complex stress state under different temperatures (5 degrees C, 10 degrees C, 15 degrees C, 20 degrees C, and 25 degrees C), were performed on the asphalt mixture. The ultimate failure strength of the material shows that the temperature and stress state significantly affect the triaxial strength characteristics of the asphalt mixture, and the three-dimensional strength decreases by the increase in temperature. Under the triaxial compression and triaxial tensile stress state, the resistance of the octahedral shear stress increases with the hydrostatic stress. A three-dimensional strength calculation model is established based on the influence of temperature and characterization by the tensile meridian, compression meridian, and failure strength envelope. It reveals the change of failure strength envelope with increasing temperatures and decreasing hydrostatic stress under complex stress state. It provides experimental and theoretical references to the design of asphalt pavement structure of different temperature conditions according to the three-dimensional stress state.