Performance characteristics of bio-modified bitumen at laboratory scale: a comprehensive review

The review focuses on the utilization of bio materials for the modification of bitumen, with the aim of achieving enhanced performance, sustainability, environmental and economic benefits as well as utilization of renewable resources, mostly discarded as waste earlier. Amongst various bitumen modifiers which are derived from biological sources, extensive research was observed in the use of four specific bio materials. It includes waste cooking oil, waste wood-based oil, swine manure, and natural rubber. Disposal of these materials is an issue and use of these as bio-modifier for bitumen can be an important sink. Literature suggests that optimized bio-oil addition on bitumen is preferred at 1-20% of bitumen, 200-4000 rpm, mixing time and temperature being 10-40 min and 135 - 150 °C respectively, and also indicate the possibility of using these oils as rejuvenators. Moreover, incorporating these bio materials into bitumen, notable improvements have been observed in terms of decrease in viscosity and softening point of the modified bitumen, while penetration and ductility are observed to increase. The rheological studies of the bio-modified bitumen exhibited significant improvements, especially in terms of fatigue performance. These changes contribute to enhanced pavement performance, durability, and flexibility, which are crucial for the durability of road infrastructure. To corroborate laboratory findings, it is important to assess the usage of bio-modified binders with carbon footprint analyses, and techno-economic evaluations and cradle-to-grave life cycle assessment (LCA). It is envisioned that such wastes to rejuvenate aged binders will promote environmental sustainability by easing use of already depleting natural resource. Various stretches are being developed Worldwide to check the long-term viability.