Sustainable asphalt with bio-binders: a review on materials, processing methods, performance, and practical applications

This study presents a detailed review of biomass-derived binders for asphalt pavement applications, focusing on biomass sources, biomass-to-bio-binder processing techniques, bio-asphalt mixture, field performance, and life cycle assessment. Bio-binders produced from various waste sources, including waste oils, animal waste, and agricultural residues, are systematically analysed. Their effects on characteristics of petroleum binders, including rheological, chemical, and thermal properties, are discussed. The review also compares asphalt mixtures using different percentages of bio-binders, evaluating how blending ratios influence the mixture performance characteristics using laboratory tests, including rutting, moisture susceptibility, and fatigue performance. While field applications are still limited, existing studies are evaluated to provide insight into practical feasibility and challenges. Differences in performance between various resources and bio-binder ratios are highlighted, along with critical issues related to compatibility, long-term durability, cost, and environmental trade-offs. This study serves as a benchmark that will guide researchers in using biomass alternatives in sustainable pavement engineering.