Advancements in bio-asphalt binders: production, physico-chemical characterization, optimization, performance, and sustainability perspectives

Bio-asphalt binders are rapidly emerging as sustainable alternatives to conventional petroleum-based asphalt in flexible pavements. Derived from biomass through processes such as pyrolysis and hydrothermal liquefaction, bio-asphalts can function as replacements, modifiers, or rejuvenators for aged asphalt. Their performance depends heavily on source material, production conditions, and chemical modification. While bio-asphalts offer environmental advantages, such as reducing emissions by up to 50%, they also present challenges, including lower thermal stability and reduced moisture resistance. This review highlights thermochemical conversion pathways, chemical interactions, molecular dynamics simulations, and optimization strategies to enhance the performance of bio-asphalt. Findings emphasize the importance of tailored modification techniques, such as catalyst-assisted hydrothermal liquefaction or heat pretreatment, to improve compatibility and durability. Optimization methods, such as orthogonal design and fatty acid profiling via gas chromatography-mass spectrometry, have shown promise in guiding material formulation and predicting low-temperature behavior. The integration of artificial intelligence and machine learning models for performance prediction, along with life cycle assessment and life cycle cost analysis, demonstrates the environmental and economic viability of bio-asphalt. Overall, advancing bio-asphalt technology requires a comprehensive understanding of production parameters, chemical structure, and performance behavior to support circular economy goals and sustainable pavement design.