Performance Evaluation of PET and Glass Fiber Modified High Modulus Asphalt Concrete under Simulated Extreme Indian Climates

This study evaluates the mechanical and durability performance of High Modulus Asphalt Concrete (HMAC) modified with Polyethylene Terephthalate (PET) and Glass Fibers using a PMB 70 binder, under temperature and moisture conditions that simulate extreme Indian climates. Fiber dosages ranging from 0.0% to 0.4% by total mix weight were incorporated into Dense Bituminous Macadam (DBM) grade mixes. A series of laboratory tests, including Marshall Stability, Indirect Tensile Strength (ITS), Dynamic Modulus, and Tensile Strength Ratio (TSR), were conducted on specimens prepared at Optimum Binder Content (OBC) and varying fiber contents. Results indicate that the inclusion of 0.3% Glass Fiber improved Marshall Stability by 21.5% and reduced flow values by 14.2%, suggesting enhanced rutting resistance under high-temperature loading. PET Fiber, at 0.3%, yielded a 27.4% increase in ITS at –10°C, indicating improved resistance to low-temperature cracking. Both fiber types enhanced volumetric parameters, with Void Filled with Bitumen (VFB) exceeding 76% in all modified mixes. Moisture susceptibility improved substantially, with TSR values exceeding 85% for both fiber-reinforced mixes, signifying strong adhesion in the presence of water. The Dynamic Modulus of Glass Fiber mixes increased by 17.8% at 25°C compared to the control mix, while PET-modified mixes exhibited better modulus performance at lower frequencies. These findings suggest that Glass Fiber is more effective in improving high-temperature performance and stiffness, whereas PET Fiber excels in enhancing flexibility, crack resistance, and sustainability. The study supports the use of both fibers in region-specific applications, offering improved pavement life and reduced environmental burden.