Evaluating the Rheological and Aging Characteristics of Plastic-Modified Asphalt Binders Incorporating Reactive Elastomeric Terpolymer

This study investigates the rheological behavior and aging characteristics of plastic-modified asphalt binders incorporating two Reactive Elastomeric Terpolymer (RET) stabilizers with different melt flow indices (MFI). A comprehensive experimental program was conducted with performance-grade asphalt (PG) 58-28 as the control binder to assess the effect of RETs on the performance of plastic-modified binders. Separation index and fluorescence microscopy were used to evaluate storage stability, while rheological behavior was analyzed using black space diagrams and performance grading. Aging effects were examined using low-temperature grade, stress dissipation capacity (ΔT _c ), and Linear Amplitude Sweep testing. In addition, rutting resistance was assessed under higher stress levels by conducting the Multiple Stress Creep Recovery test. The results showed that RET stabilizers improved the storage stability of plastic-modified binders, with the higher MFI stabilizer being more effective. Black space analysis revealed the formation of elastomeric networks and morphological complexity because of RETs, with RET B (lower MFI) exhibiting higher stiffness and lower phase angles, indicating improved rutting resistance. RETs also enhanced high-temperature PG by four grades and restored low-temperature PG, mitigating the reduction caused by plastics. Although ΔT _c values degraded with plastic addition, stabilizers improved ΔT _c , indicating enhanced resistance to low-temperature cracking. Moreover, RET stabilizers enhanced fatigue life by 660%–1,200% compared with plastic-modified binders. Under extended aging, RET-modified binders showed slightly greater ΔT _c and fatigue life reductions but still outperformed other binders. The combination of 2% plastic + RET B provided superior rutting resistance, reducing nonrecoverable creep compliance by 70% and increasing recovery by 3,000%. The results emphasize the potential of RETs in developing high-performance binders.