Fatigue resistance of aged asphalt binders: An investigation of different analytical methods in linear amplitude sweep test

Abstract

This paper aims to investigate the fatigue resistance of asphalt binders using different analytical methods and fatigue failure criteria with the consideration of various aging conditions. Four different performance grade (PG) binders with and without modifiers were tested by Linear Amplitude Sweep (LAS) test to characterize their fatigue behavior. The fatigue failure strain was determined using three different definitions: peak value of shear stress, peak value of phase angle and the maximum stored pseudo-strain energy. The damage characteristic curves and fatigue life were obtained by two kinds of analytical methods: dissipated energy-based method and pseudo-strain energy-based method. Statistical analysis shows that there is no distinct difference between these three criteria of fatigue failure for aged and unaged asphalt binders. However, for the modified asphalt binders at unaged condition, it is hard to observe the peak value of phase angle or stored pseudo-strain energy. The fatigue life determined by the pseudo-strain energy-based method is slightly higher than that of dissipated energy-based method across the entire loading strain range. In addition, the fatigue resistance of neat asphalt binder tested in this paper is deteriorated at high strain levels but improved at low strain levels and the critical strain level is approximate 4.5%. The effect of aging is asphalt specific and depends on the strain levels from the experimental results.