Investigating impacts of warm-mix asphalt technologies and high reclaimed asphalt pavement binder content on rutting and fatigue performance of asphalt binder through MSCR and LAS tests

Abstract

Abstract The combined use of warm-mix asphalt (WMA) technologies and high percentages of reclaimed asphalt pavement (RAP) has become increasingly prevalent in asphalt paving industry due to its promising environmental and economic benefits; however, there remain significant concerns about the performance of WMA-high RAP mixtures. This study was focused on a laboratory investigation that evaluated the effects of two typical WMA additives, i.e., the wax based R and surfactant based M, and various high percentages (from 30% to 70%) of artificial RAP binder on the rutting and fatigue performance of asphalt binders through the recently developed multiple stress creep and recovery (MSCR) and linear amplitude sweep (LAS) tests, respectively. Five asphalt mixtures with different WMA technologies and RAP contents were used to verify the findings from the binder tests through the rutting and flexural fatigue tests. The results showed that the virgin binder always yielded the poorest rutting and fatigue performance. Both RAP binder and M improved the rutting resistance and traffic loading grades of the binders; R remarkably lowered the binder rutting performance, but this impact could be alleviated by properly increasing the RAP binder content. The inclusion of RAP binder enhanced the fatigue resistance of the binders, and so did R and M under most combinations of RAP contents and strain amplitudes. Generally, R performed better than M in improving the binder fatigue resistance. Besides, the LAS predicted results from the dissipated energy based approach generated slightly more conservative predictions than those from the pseudo strain energy based approach. Finally, most of the results for the mixtures exhibited similar trends to those for the binders, but M had different effects on the fatigue performance of the mixtures and binders.