Bio-bitumen development from rice husk bio-oil: Mechanical performance optimisation, cradle-to-gate LCA, and rural biomass valorisation

The research paper concentrates on the use of bio-oil produced through the pyrolysis of rice husk as a green substitute to enhance the characteristics of conventional binders that are based on petroleum. This paper explored the preparation of five bio-oil modified bitumens (BOMBS) VR1, VR2, VR3, VR4, and VR5 at different concentrations of rice husk bio-oil (RHBO) between the range of 5 wt. per cent to 25 wt. per cent. Triplicate measurements ( n = 3) and one-way ANOVA ( p < 0.05) confirm that bio-oil significantly enhances the rheological behavior of bitumen, with lower concentrations (5–10%) increasing binder softness and low-temperature flexibility, and higher dosages (20–25%) increasing stiffness, softening point and high-temperature stability. A 15% bio-oil mixture is a moderate climatic solution. Cradle-to-gate LCA under a zero-allocation scenario for vacuum residue showed bio-bitumen reduces CO₂ emissions by 41.7% relative to conventional bitumen in the base case, with a minimum 28% reduction confirmed under conservative sensitivity assumptions, and valorises rural agricultural and refinery waste. The cradle-to-gate LCA indicates that the global warming potential could be reduced by 41.7–72.8% over conventional asphalt under a zero-allocation scenario, and more savings can be achieved in regions with higher grid emission factors. Results indicate that specific formulations should be used in various climatic conditions, and further durability research is necessary. The work makes progress on sustainable pavement materials by means of effective valorization of the waste and limiting emissions. Since rice husk is a major rural biomass residue in developing countries, the bio-oil pathway presented here provides a sustainable, decentralised valorisation approach that can support rural waste management and low-carbon infrastructure development.