Effect of Different Long-Term Aging Conditions on Cracking Resistance of Polymer-Modified Asphalt Binder and Mixes

Abstract

Long-term aging of asphalt binder plays a major role in fatigue cracking resistance of asphalt mixes. With the use of polymer-modified binder (PMB) with different polymer concentrations, aging susceptibility of asphalt mixes becomes an interesting area to explore. This study evaluated four types of asphalt mixes prepared with PMB, subjected to compacted mix aging (CMA) (85°C, 5 days) and loose mix aging (LMA) (85°C, 8 days). The aged asphalt mixes were tested for their resistance to cracking using the indirect tensile asphalt cracking test (IDEAL-CT). Furthermore, aged binders were extracted from long-term-aged loose and compacted mixes, and their fatigue resistance was examined using the Superpave fatigue factor (|G*|·sinδ), linear amplitude sweep (LAS) test, and binder yield energy test (BYET) parameters. The results indicated that both asphalt binder and mixes exhibit better cracking resistance in CMA conditions compared to LMA conditions. Mixes prepared using PMB with higher polymer content performed better in cracking resistance and were less sensitive to aging. Furthermore, to evaluate the effect of rheology of aged binder on fatigue cracking resistance of mixes, binder fatigue parameters were correlated to cracking index (CTindex) and postpeak slope (|m75|) of mixtures. Other than the yield energy parameter of BYET, a good correlation was observed between binder fatigue and mix fatigue parameters. Outcomes of this study will potentially help to understand the relationship between mixture cracking parameter and standard binder fatigue parameters and their aging sensitivity.