The interaction mechanism and rejuvenation effect of crumb rubber and waste cooking oil blends

With the rapid increase in the production of reclaimed asphalt pavement (RAP), asphalt pavement rejuvenation technology has attracted significant research attention. To improve the performance of recycled asphalt pavement mixtures, the rejuvenators are usually needed. A waste rubber/oil (WRO) rejuvenator was self-developed by mixing crumb rubber (CR) with waste cooking oil (WCO) at high temperature. However, the chemical dynamic interaction process between WCO and CR, and the effect of reaction time on the rejuvenation properties of the WRO rejuvenators still remained unclear. Therefore, in this study, the functional group and molecular weight of WRO rejuvenators with different reaction times and various WRO rejuvenated asphalts were studied by Fourier transform infrared spectroscopy and gel permeation chromatography, respectively. The rheological properties of various WRO rejuvenated asphalts were also tested using dynamic shear rheometer and bending beam rheometer. The result indicated the occurrence of complex depolymerization and recombination reactions of the polymers released from CR. WRO with higher rubber content exhibited higher polymer concentration. The WRO rejuvenator with a longer reaction time provided more viscous supplement and less elastic retention to the aged asphalt. As the reaction time of the WRO rejuvenator increased, the WRO rejuvenated asphalt showed less resistance to ageing, and the concentration of large molecules and sulfoxide function group in WRO rejuvenated asphalt was reduced. Based on the results, the recommended reaction time of WRO is 0.5 h.