Unveiling the composite rejuvenator efficacy on performance improvement of asphalt binder including high RAP contents

Since the incompatibility between crumb rubber (CR) and reclaimed asphalt binder (RAB) can cause sedimentation and limit its application, this study employed waste cooking oil (WCO) to pre-treat CR particles at different CR/WCO ratios, and assessed its impact on performance of asphalt binders including 30 % and 50 % RABs. Anti-aging and rejuvenation potentials of corresponding composite rejuvenators in binder blends were explored by Fourier transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC) tests, while the performance of corresponding binder blends was evaluated by bending beam rheometer (BBR), linear amplitude sweep (LAS), and multiple stress creep recovery (MSCR) tests. Furthermore, correlation analyses were performed to explore the relationships between the chemical and rheological parameters with a significance level below 0.05. The results confirmed the rejuvenation efficacy of composite rejuvenators in high RAB, and improvement in the critical low temperature of binder blends to a higher performance grade (PG) level compared to the non-treated CR modified binder. In addition, the fatigue cracking resistance was improved at the strain levels higher than 4 % in LAS test. However, the pre-swelled CR fairly compromised the rutting performance of binder blends compared to non-treated CR, its performance was still better than virgin binder. The correlation analysis suggested that it is possible to use chemical parameters as indicators for evaluating certain rheological properties. •Utilizing composite rejuvenator compensates the loss of performance in binder blends including high RAB.•Modification mechanism of the CR and rejuvenation efficacy of pre-treated CR were investigated.•The rheological performance of rejuvenated binder blends was highly influenced by the CR/WCO ratio.•PDI obtained from GPC and ether index derived from FTIR were good chemical indicators in identifying the rejuvenated RAB.