Novel rejuvenators for sustainable recycling of aged SBS modified bitumen: Performance evaluation and reactive mechanism analysis

The performance of aged styrene-butadiene-styrene (SBS) modified bitumen (SMB) is jointly dominated by the aging of bitumen and degradation of SBS crosslinking network structure. Despite some epoxy reactive rejuvenators which can re-crosslink SBS fragments are able to reconstruct the SBS cross-linking network compared with conventional rejuvenator, the performance of aged SMB regenerated by existing epoxy reactive reactants is unbalanced achieving good low temperature performance by sacrificing high temperature performance. In order to further improve the comprehensive road performance of regenerated SMB, a novel reactive rejuvenator was proposed and assessed in this study aiming at effectively improving the high temperature performance of regenerated SMB. The restoration effectiveness of the reactive rejuvenators was evaluated and compared by the physical properties, rheological properties and FTIR of rejuvenated SMB. The physical and rheological experimental results show that 2,2'-[1,3-phenylenebis (oxymethylene)] dioxirane (RDGE) and 1,6-hexanediol diglycidyl ether (HDDGE) are beneficial to high and low temperature performance of regenerated SMB, respectively, and their composite action can complement each other. Compared with N, N-dimthylbenzylamine (BDMA), 3,6,9,12-tetraazatetradecane-1,14-diamine (PEHA) with crosslinking effect can excellently make up for the disadvantages of epoxy rejuvenator, which has better and balanced recovery effect in consideration of both low and high temperature properties of regenerated SMB. The reactive rejuvenator containing PEHA and RDGE can further alleviate high temperature performance loss of regenerated SMB by an appropriate mix ratio. The changes of chemical functional groups of FTIR and fluorescence microscope directly prove that a novel recovery reaction for degraded SBS network structure via the introduction of PEHA (a kind of polybasic primary amines) is conducive to balancing high and low temperature performance of regenerated SMB.