Physical Properties Enhancement of Bitumen via Hybrid Modification Using Cellulose and Glass Powder

This study investigates the effects of hybrid modification with cellulose fibers and glass powder on the physical and rheological properties of paving-grade bitumen. Various concentrations of cellulose (1%, 3%, 5%, 7%, and 10%) and glass powder (3% and 5%) were incorporated individually and in combination to evaluate their influence on penetration, softening point, viscosity at 135°C, and ductility at 25°C. The results showed that increasing additive content led to a consistent decrease in penetration and ductility, indicating an increase in binder stiffness. Simultaneously, the softening point and viscosity increased, reflecting improved resistance to high-temperature deformation. The hybrid combinations—particularly the mixture of 5% cellulose and 3% glass powder—offered the most balanced performance, enhancing thermal stability while maintaining acceptable flexibility. The findings suggest that hybrid modification can significantly improve bitumen performance, especially for applications requiring enhanced rutting resistance and thermal durability, while maintaining adequate ductility.