GA/KH792 Surface Chemical Co-Modification for Enhancing Performance and Interfacial Properties of PET Fiber-Reinforced Asphalt Mastic

Polyester (PET) fibers are widely used to reinforce asphalt materials; however, their smooth and hydrophobic surfaces limit interfacial bonding and restrict their reinforcing efficiency. This study develops an eco-friendly surface modification method based on the chemical modification of gallic acid (GA) and aminosilane (KH792) to enhance the compatibility between PET fibers and asphalt. Modified fibers with various molar ratios of GA/KH792 were prepared and incorporated into asphalt mastic. Their performance was evaluated using softening point, cone penetration, dynamic shear rheometer (DSR), multiple stress creep recovery (MSCR), linear amplitude sweep (LAS), and bending beam rheometer (BBR) tests, combined with interfacial interaction analysis and scanning electron microscopy (SEM). The results show that surface modification significantly improves the reinforcing effect of PET fibers. In particular, the co-modified fiber with a GA/KH792 ratio of 1:1 exhibits the best performance, with increases of 27% in softening point and 105% in shear strength, as well as notable improvements in rutting resistance, fatigue performance, and temperature stability. Interfacial indices and SEM observations confirm enhanced adhesion, dispersion, and load transfer capacity. However, the improvement in low-temperature performance is limited. Overall, GA/KH792 chemical modification effectively enhances fiber asphalt interfacial interaction and provides a simple and sustainable approach for developing high-performance asphalt materials.