Interlaminar shear fatigue and damage characteristics of asphalt layer for asphalt overlay on rigid pavement

According to the failure characteristics of asphalt overlay on rigid pavement, a special-purpose test apparatus and method were developed for interlaminar shear fatigue tests to evaluate interlaminar shear fatigue of asphalt overlay on rigid pavement, and an interlaminar shear fatigue equation was determined by analyzing the correlation between fatigue life and shear stress obtained from interlaminar shear fatigue tests. The damage mechanics theory, heat transfer theory and the Finite Element Method (FEM) were adopted to analyze fatigue damage characteristics and cracking mechanism of asphalt layer. The result showed that under repeated traffic loading, the asphalt layer located at the existing transverse joints of the rigid base on the side of traffic loading, is prone to fatigue cracking, and the crack extends upward along the tip due to the tensile stress; thermal fatigue damage occurs mainly on the surface of asphalt overlay, the horizontal tensile stress on the surface of asphalt overlay decreases linearly with the increase of temperature variation times, and the fatigue life of asphalt overlay decreases with the increase of the amplitude of temperature variation; and it is recommended to choose asphalt mixtures with features such as relatively low thermo-contraction character, low modulus and high tensile strength to guarantee the expected cracking resistance and durability of asphalt overlay on rigid pavement.