Multiple performance evaluation of asphalt binders modified with micronized polyethylene terephthalate (PET), polyphosphoric acid (PPA) and ethylene–methyl acrylate–glycidyl methacrylate (EMA-GMA)

Recycled polyethylene terephthalate (PET) has been investigated as an asphalt modifier, although compatibility, storage stability, and performance optimization remain challenges. This study evaluated a ternary modification strategy combining micronized PET, ethylene–methyl acrylate–glycidyl methacrylate (EMA-GMA), and polyphosphoric acid (PPA) to improve the physical and rheological properties of asphalt binders. A control binder (AB 50/70, PG 64-22) was modified using three formulations: M1 (1.80% EMA-GMA + 0.30% PET + 0.15% PPA), M2 (1.26% EMA-GMA + 0.21% PET + 0.15% PPA), and M3 (0.90% EMA-GMA + 0.15% PET + 0.15% PPA). Physical, chemical, storage-stability, and rheological characterization included penetration, softening point, rotational viscosity, Performance Grade, Multiple Stress Creep Recovery (MSCR), and Linear Amplitude Sweep (LAS) tests. The ternary modification increased the softening point by up to approximately 34% and elastic recovery from 0% for the control to 86% for M1. Viscosity remained below 3 Pa s at 135 °C. M1 reduced Jnr at 3.2 kPa from 4.51 to 0.43 kPa −1 , meeting the binder classification for extremely heavy traffic. LAS indicated intermediate fatigue performance for M1 (BFF = 1.42), whereas the SBS-modified reference binder showed superior performance (BFF = 1.48). M1 also exhibited an Aging Index approximately 22.7% lower than the control after short-term RTFO aging. Overall, M1 provided the most favorable binder-scale balance among rutting resistance, fatigue damage resistance, storage stability, and short-term aging response.