A novel reactive warm-mix rejuvenator and its effects of synergistic rejuvenation and temperature reduction on aged SBS modified bitumen.

Synchronous rejuvenation of colloidal structure of bitumen and crosslinking structure of Styrene-butadiene-styrene (SBS) polymer is of great significance for high-quality cycling and reusing aged SBS modified bitumen (SMB) mixture. In this study, a novel reactive warm-mix rejuvenator (RWR) was developed by using 56.4% rubber oil, 24.5% epoxy-terminated polybutadiene ether (ETPBE), 13.8% cardanol (CA), 3.2% modified polyethylene (PE) wax and 2.1% antiaging agent based on uniform design method. Before the RWR preparation, Fourier transform infrared spectroscopy (FTIR) tests were conducted to investigate the repairing effects of ETPBE and CA on fracture crosslinking structure for aged SBS that had been subjected to coupling effect of multiple aging factors. After the optimum technical parameters of rejuvenated SMB were determined, physical properties, high- and low-temperature performances, and fatigue resistance of rejuvenated SMB as well as its molecular structure and microstructure surface were investigated to evaluate the synchronous rejuvenation of RWR on aged SMB. Additionally, warm-mix effect of RWR on construction temperatures of rejuvenated SMB was analyzed through rotational plate viscosity test. Results indicate that both ETPBE and CA can react with oxygen-containing groups in broken molecular chains of aged SBS with the catalysis of 0.1% triethanolamine, which is conducive to reconnecting the fractured SBS polymer segments. RWR is able to regulate the bitumen components and repair the broken SBS molecular chains for aged SMB, which facilitates the reconstruction of crosslinking structure and promotes the surface roughness for rejuvenated SMB. Physical properties, low-temperature rheological performance and fatigue resistance of aged SMB were successfully restored by using the RWR. Considering high-temperature performance of rejuvenated SMB, 12% was recommended as an optimum RWR content to mix with aged SMB at around 155 ℃ for 15 min, which enables rejuvenated SMB to achieve a balanced performance. Compared with construction temperatures of original SMB, mixing and compaction temperatures of rejuvenated SMB using the RWR can be reduced by 29 ℃ and 28 ℃, respectively. This developed RWR is promising to fully regenerate the performances of aged SMB and reduce the construction temperatures in reuse of aged SMB mixtures. • A novel reactive warm-mix rejuvenator was developed through uniform design method. • Degraded crosslinking structure of aged SBS polymer can be repaired by using the RWR. • The RWR can successfully restore performances of aged SBS modified bitumen. • The RWR is able to significantly reduce construction temperatures for rejuvenated SBS modified bitumen. [ABSTRACT FROM AUTHOR]