Abstract
This study modified a neat asphalt binder of PG 58-28 grade using in situ grown iron oxide particles. Particle contents of 0.25, 0.5, and 1.0 wt% improved the performance grades to PG 64-28, PG 70-28, and PG 82-28, respectively. The particles enhanced high-temperature properties while maintaining low-temperature performance. At 70 °C, the rutting parameter of the unaged binder increased from 0.33 kPa to 4.29 kPa with 1.0 wt% iron oxide. Multiple Stress Creep Recovery at 58 °C and 3.2 kPa stress showed recovery rising from 0.3% to 65.2% for the 1.0 wt% binder. Recovered particles exhibited polycrystalline γ-iron oxide structure with average size 2–9 μm, depending on content. Unlike ex situ mixing based modification, no particle aggregation was observed. Overall, in situ grown iron oxide particles substantially improved binder performance and outperformed most additives reported in the literature, including nanoparticles..