AbstractThe waste of scrap rubber and asphalt mixtures brings a serious problem of environmental pollution and resource waste, which is inconsistent with the principles of sustainable development and a circular economy. A waste-utilizing rejuvenator was developed using scrap rubber, waste engine oil (WEO), aromatic furfural oil (AFO), and antiaging agent, among others, in this investigation. This work aims to explore the influence of the rejuvenator on properties of recycled asphalt binders. The recycling effect of the rejuvenator was first evaluated by conventional tests, followed by the characterization of saturate (S), aromatic (A), resin (R), and asphaltene (A) fractions and colloidal structures. Subsequently, the evaluation indicators were optimized by gray relational analysis (GRA). Finally, the viscosity composition characteristics were analyzed by the composite viscosity theory. The results indicated that the rejuvenator can significantly restore the consistency, workability, and low-temperature flexibility of aged asphalt binders, and a rejuvenator content of 8%–12% is acceptable. The rejuvenator can effectively replenish the components lost during the aging process. Hence, SARA fractions in the aged asphalt binder are balanced and the colloidal structure is restabilized. Penetration, ductility, and viscosity are recommended as evaluation indicators according to GRA, and the percentage change of SARA fractions is worth noting. The modified model can accurately predict the viscosity of recycled asphalt binders at 65°C and 85°C because it considers the difference in viscosity between the rejuvenator and the aged asphalt binder. This provides the possibility to design the composition of recycled asphalt binders.

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