Evaluation of fatigue life of asphalt binders using the time sweep and linear amplitude sweep tests: A literature review

Asphalt binders play a crucial role in the fatigue cracking resistance of asphalt pavement, making the characterization of their fatigue life increasingly important. To evaluate the fatigue life of asphalt binders, two tests have been developed: the time sweep (TS) and the linear amplitude sweep (LAS), both conducted using the dynamic shear rheometer (DSR). Similar to asphalt mixtures, predicting the fatigue life of asphalt binders necessitates the predefinition of fatigue failure criterion and/or fatigue failure definition (failure point). Phenomenological and dissipated energy-based failure criteria are commonly employed to analyze TS test results, while the viscoelastic continuum damage (VECD) model is primarily used to predict fatigue life through the LAS test. Given that the fatigue test temperature significantly impacts the fatigue life of asphalt binders, various methods have been proposed in the literature for selecting the fatigue test temperature.This paper provides a comprehensive review of the fatigue life evaluation of asphalt binders using both TS and LAS tests. It summarizes the different fatigue failure criteria and fatigue failure definitions employed and discusses the selection of fatigue test temperatures. Furthermore, the paper examines the influence of fatigue test conditions, binder chemical composition and/or penetration grade, and bitumen modification on the fatigue life of asphalt binders. Based on the current review, it is recommended to utilize the LAS test on PAV-aged bitumen under strain-controlled conditions to evaluate the fatigue life of asphalt binders. The most relevant failure definition is the peak in stored pseudo-strain energy based on the simplified viscoelastic continuum damage model (S-VECD). Additionally, the authors propose conducting the fatigue test at an intermediate reference temperature for each country or region, depending on its climate zone.