A fatigue damage model of asphalt mixture considering tensile and compressive modulus decay

In practical asphalt pavement engineering, asphalt mixture experiences both tensile and compressive stresses, and the stress state plays a pivotal role in determining fatigue performance. This study thoroughly explores the fatigue damage characteristics of asphalt mixture, specifically emphasizing a meticulous analysis of the differences between tensile and compressive moduli. Initially, the compressive and tensile moduli of the asphalt mixture were calculated based on the dual modulus theory. Subsequently, differences in tensile and compressive moduli, along with fatigue performance characteristics, were evaluated through indirect tensile tests. Ultimately, a comprehensive fatigue damage model was proposed to ascertain the critical damage degree of the asphalt mixture, integrating both modulus decay and fatigue damage. The findings reveal that decay rates for the tensile modulus were higher than those observed for the compressive modulus. The tensile damage should be considered more in the design of pavement structures. Upon comparing the critical damage degree determined using the traditional modulus decay model with the comprehensive fatigue damage model, it can be deduced that the latter shows favorable applicability. The compressive fatigue modulus can better characterize the fatigue damage behavior. The model proposed in this study integrates modulus decay and fatigue damage information, offering a more comprehensive depiction of asphalt mixture damage behavior during fatigue processes.