Fatigue Properties of Asphalt Mixtures at Broad Stress Ratio Conditions with Improved S−N Model

AbstractThe applicability of the Sigmoidal Function to describe the fatigue law of asphalt mixtures at broad stress ratio conditions was examined. This application aimed to avoid the inaccessibility of the segment function. It also sought to address the inadequacy of traditional S−N fatigue equation in analyzing the fatigue characteristics of asphalt mixtures at broad stress ratio conditions. The asphalt mixture gradation and the optimum asphalt aggregate ratio were determined with raw material testing and mixture proportion design. Fatigue tests of the asphalt mixtures were performed at broad stress ratio conditions with Material Test System −810, and results were fitted by the Sigmoidal Function. An improved S−N fatigue model was established with the Sigmoidal Function at broad stress ratio conditions. This improved model, as well as conventional models, can predict the fatigue life of asphalt mixtures. The estimated results were then compared. The improved S−N fatigue model based on the Sigmoidal Funct...