Utilization of Agricultural Wastes and By-Products in Asphalt: A Critical Review

Innovative utilization of agricultural waste has led to the production of valuable bio-oil, obtained through the pyrolysis of various organic materials such as crop residues and wood chips. Agricultural by-products, such as rice husk ash, sugarcane bagasse ash, palm oil fuel ash, and biomass ash, can be used to modify asphalt binders, enhancing road performance while minimizing waste and conserving resources in the pavement industry. However, the availability of agricultural by-products and wastes depends on local agricultural practices and hence can be used locally rather than globally. This versatile bio-oil, akin to petroleum-based products, offers a solution to both waste reduction and sustainable industry practices. Waste cooking oil, a form of bio-oil, acts as a rejuvenating agent for aged asphalt binders in road construction. The chapter summarizes the benefits and possibilities of using different agricultural by-products and wastes for asphalt modification, giving due importance to the region. Based on the study, a roadmap is provided to advance the state-of-the-art. It is envisioned that this review contributes to environmentally conscious road construction, aligning with the principles of sustainability and efficient resource utilization.