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

Abstract

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.

Development on the Rheological Properties and Micromorphology of Active Reagent-Rejuvenated SBS-Modified Asphalt

“…The characteristic peak of OCN at 2245 cm –1 almost disappeared for 6E1.0M, indicating that there was an obvious chemical reaction between HMDI and SBSPAV. Carbamates were formed when OCN reacted with the hydroxyl and carboxyl groups in the broken butadiene segments . The carbamate characteristic peak appeared at 1311 cm –1 (N–C) and 1535 cm –1 (N–H).…”

“…Carbamates were formed when O�C�N reacted with the hydroxyl and carboxyl groups in the broken butadiene segments. 25 The carbamate characteristic peak appeared at 1311 cm −1 (N−C) and 1535 cm −1 (N−H). The hydroxyl characteristic peaks of 6E1.0H at 3100−3400 and 1703 cm −1 disappeared, indicating that there was an obvious chemical reaction between HDE and SBSPAV.…”

Minireview on the Rejuvenation of Aged Styrene–Butadiene–Styrene (SBS) Modified Bitumen: State-of-the-Art and Outlook

“…Additionally, HDI and TDI were detrimental to the workers and environment because of strong toxicity. Therefore, Han et al , designed and developed new reactive chain extension rejuvenators (RCERs) made up of diisocyanate (TDI and HDI) and polyethylene glycol (PEG-400 and PEG-1000), as illustrated in Figure a. Compared with TDI and HDI, RCERs could more efficiently recover the cross-linking network structure of degraded SBS modifiers and thus better recover the physical properties including the resistance to low-temperature cracking and high-temperature rutting because of the long flexible chains in RCERs.…”

“…Molecular structures of reactive rejuvenators: (a) RCERs, reproduced with permission from ref . Copyright 2021 American Chemical Society, and (b) ITLCARs, reproduced with permission from ref .…”

“…Hence, the selection of molecular structures of reactive chemicals is the key to affect the performance of rejuvenated SBS modified bitumen. Furthermore, according to the research conducted by Han et al, − the new reactive chain extension rejuvenators synthesized from small molecule reactive chemicals is one of the effective means to enhance the effectiveness of reconstruction. Similarly, the addition of reactive chemicals with multiple molecular structures can also further enhance the performance through giving play to the characteristics of different reactive chemicals.…”