Fatigue Damage Characteristics Considering the Difference of Tensile-Compression Modulus for Asphalt Mixture

Abstract

Abstract In order to reveal the difference and correlation of tensile modulus, compressive modulus, and flexural modulus, the four-point bending fatigue test is used on two kinds of asphalt mixtures—rock asphalt modified asphalt mixture and styrene butadiene styrene block copolymer modified asphalt mixture, were conducted using closed-loop test system. The fatigue damage variable was defined by the modulus attenuation based on the theory of damage mechanics, and the modulus attenuation equation was deduced. Under the same conditions, the initial value and the critical value of the tensile modulus were less than those of the compressive modulus, but the critical damage value and the attenuation slope of the tensile modulus were larger than those of the compressive modulus. The attenuation models of the tensile and compressive modulus of the asphalt mixture during the bending fatigue test were established. Based on the fatigue test results, a new concept of design and analysis was developed, in which the corresponding modulus and its evolution law is chosen according to its actual stress state at each point of asphalt pavement. The results indicate that under the bending fatigue stress state, there exists great differences between the attenuation law of the modulus of tension and compression for asphalt mixture and that the attenuation rate of tensile modulus is greater than that of compressive. Therefore, the tensile zone results in greater damage; the pavement structure of the tensile zone is damaged, which should be given more attention.