Uniform fatigue characterization of high modulus asphalt mixtures under three-dimensional stress state. (7th November 2022) - Liu, Biao
Highlights: The Desai three-dimensional strength criterion was improved by including the effects of loading velocities. A new approach for fatigue characterization under three-dimensional stress state was proposed. The fatigue life values obtained under distinct stress states were uniformly characterized. Abstract: To improve the durability of asphalt pavement, high modulus asphalt mixtures were developed and widely utilized to construct heavy trafficked pavements to resist rutting. Except for rutting, serving under repeated heavy loads, pavements with high modulus asphalt mixtures are also vulnerable to fatigue cracking. To prevent fatigue cracking, the fatigue resistance of high modulus asphalt mixtures is a crucial indicator for pavement structural design and checking computations, which is generally obtained by laboratory tests. However, the current test methods are generally based on maximum tensile stress or strain theory and neglecting the effects of loading velocities, so the fatigue resistance obtained cannot match that under actual pavement serving conditions. Moreover, the fatigue performance of high modulus asphalt mixtures obtained by different test methods are quite different, which caused random and disunity when selecting fatigue parameters for pavement structural design. Therefore, the objective of this paper is to accurately and uniformly characterize the fatigue resistance of high modulus asphalt mixtures. To this end, the indirect tensile, direct tensile, unconfined compressive strength and fatigue tests of high modulus asphalt mixtures were implemented under distinct loading velocities. Based on the Desai yield criterion, the strength yield surfaces under diverse loading velocities and the fatigue path of high modulus asphalt mixtures in three-dimensional stress state were established. Finally, the fatigue life values of high modulus asphalt mixtures obtained under distinct test methods and loading velocities were uniformly characterized by the relationship between fatigue life and equivalent stress ratio Δ, which was N f = Δ - 5.42 . With the uniform characterizing model, the disunity of fatigue parameters can be eliminated, and the fatigue resistances of high modulus asphalt mixtures under three-dimensional stress states and different loading velocities can be evaluated.