A viscoelastic damage constitutive model for asphalt mixture under the cyclic loading

Abstract

Taking into consideration the shortcomings of traditional fatigue theory in addressing fatigue cracking distress in asphalt pavement, this paper attempts to investigate the fatigue damage characteristic of asphalt mixture through the fatigue damage theory, which demonstrates fatigue damage’s mechanism, and mainly focuses on the theory’s pivotal content --- the damage constitutive model. First, this paper couples the Burgers viscoelastic model with a modified Chaboche damage model, using classical mechanics of viscoelastic materials as well as strain equivalent principle of damage mechanics, to establish a viscoelastic damage constitutive model that can reflect the effect of cyclic loading or loading frequency on mixture’s stress-strain characteristic. Then, some indirect tensile fatigue tests were conducted to collect the data for strain progress, damage development, and the fatigue life of mixtures under different loading conditions, so as to obtain the value of model parameters that fit these test data. Finally, a comparison of the cumulative strain, damage variable, as well as the fatigue life verified the model’s effectiveness and accuracy. Results showed that the proposed model can better reflect the damage evolution law and stress-strain characteristics of asphalt mixture under the cyclic loading, as well as the effect of loading frequency or load level on mixture’s fatigue damage characteristics. The model is worthy of further application and promotion in the area of fatigue damage research for asphalt pavement.