Creep Instability Rules of Asphalt Mixture Based on Compression-Shear Fatigue Test

The objective of this research is to investigate the deformation instability intrinsic rules about asphalt mixture at high temperature from the shear fatigue damage perspective. Firstly, the shearing strength parameters and the shear stress value in the damaged surface about the test material were determined by conducting unconfined compressive strength tests and uniaxial penetration tests, and then characteristics of the cumulative deformation instability in asphalt mixture at high temperature were obtained using uniaxial compressive dynamic creep tests. In addition, the curves of the creep deformation versus cycles can be obtained under different loading levels, respectively, so that the rheological cycles and the corresponding value as an instability point were defined. Finally, the relationship between the shear stress level and the rheological cycle, namely, the fatigue equation was established by analyzing testing results. The effect of shear fatigue obviously exists during the rutting development process, and the rutting instability in the third stage of the creep curve is the macroscopic phenomena of the cumulative deformation under the shear fatigue effect.