Effects of Reactive Chain Extension Rejuvenation Systems on the Viscosity–Temperature Characteristics, Rheological Properties, and Morphology of Aged Styrene–Butadiene–Styrene-Modified Bitumen

In this study, the reactive chain extension rejuvenators (RCERs) and aromatic hydrocarbon oil (AHO) were applied to construct the reactive chain extension rejuvenation systems (RCERs-AHO), and the effect of RCERs-AHO on the viscosity–temperature characteristics, rheological properties, and morphology of aged styrene–butadiene–styrene (SBS)-modified bitumen (ASMB) was thoroughly studied. Meanwhile, the rejuvenation effect of RCERs-AHO and TDI/HDI-AHO (toluene-2, 4-diisocyanate/hexamethylene diisocyanate and AHO) on ASMB was compared. The results indicated that the RCERs-AHO were more effective in restoring the viscosity of ASMB compared with TDI/HDI-AHO. The critical temperatures of the rutting factor at G*/sinδ = 1.0 kPa of rejuvenated SBS-modified bitumen (RSMB) regenerated by RCERs-AHO were higher than those of RSMB rejuvenated by TDI/HDI-AHO, revealing that RCERs-AHO could better increase the high-temperature rutting resistance of RSMB. Also, the low-temperature cracking resistance of RSMB was obviously enhanced by RCERs-AHO in comparison with TDI/HDI-AHO. The results of the average recovery rate of RSMB revealed that RCERs-AHO could better enhance the deformation recovery ability of RSMB. In addition, fluorescence morphology images clearly indicated that RCERs-AHO could better reconstruct the cross-linking structures of aged SBS compared with TDI/HDI-AHO. The comprehensive analysis of the research results showed that RCERs-AHO could efficiently restore the performances of ASMB to the level of fresh SBS-modified bitumen, and the rejuvenation ability of RCERs-AHO was more obviously excellent than TDI/HDI-AHO.