Characterizing Fatigue Failure Behavior of Modified Asphalt Binders from Linear Amplitude Sweep Test

Abstract

The fatigue characteristics of asphalt binder contributes to the fatigue resistance of asphalt concrete and pavements. The linear amplitude sweep (LAS) test (AASHTO TP 101) has been developed as the accelerated testing procedure for fatigue specification of asphalt binders in the United States. Recently a newly energy-based fatigue failure definition and unified failure criterion have been proposed for improving the LAS procedure and data interpreting. However, these new improvements need more verification and calibration on more materials with different modifiers for distinguishing the fatigue performance. In this paper, the improved LAS testing procedure was applied on totally two neat asphalt binders and six modified asphalt binders, which covered the high modulus asphalt binders (HMABs), SBS modified binder, high viscosity (HV) binder and crumb rubber (CR) modified binder. Based on the simplified-viscoelastic continuum damage (S-VECD) modeling approach, three material properties of linear viscoelastic property, damage characteristic curve and failure criterion were characterized for fatigue life prediction of all tested binders. Test results indicates that the CR binder demonstrated the highest failure strain followed by the SBS and compound SBS+HV binders, HMABs and neat binders. Further results of predictive fatigue life also verified the best fatigue life of CR binder followed by SBS+HV binders, SBS binder and HMABs. The HV additives to SBS binder was found to linearly increase the binder fatigue lives and the HMAB-RA showed better fatigue performance than HMAB-PR. Generally, the fatigue life ranking determined from the multiple-loading rates of LAS tests is consistent to the failure strain results and thus, the failure strain identified from the standard LAS-5 test could be used as a fatigue performance parameter.