Transformation of Biomass Waste into Carbon-Storage Asphalt Pavements: A Circular Economy Pathway toward Net-Zero Infrastructure.

Asphalt pavements are an underexplored platform for carbon management because their production and maintenance are energy intensive over long service lives. Here, we redefine biomass-derived asphalt systems not simply as sustainable additives but as carbon-storage material platforms that enable partial substitution of fossil-derived binders while keeping biogenic carbon in durable infrastructure. We propose a molecular-level framework linking biomass-derived carbon structures with asphalt colloidal fractions, emphasizing how aromaticity, polarity, and functional groups regulate compatibility through π-π interactions, hydrogen bonding, and colloidal stabilization. These mechanisms provide opportunities to tune workability, aging resistance, and temperature adaptability. For example, biochar is more suitable for high-temperature and heavy-traffic pavements because it improves stiffness and rutting resistance. Bio-oil is more suitable for rejuvenation and low-temperature cracking mitigation. Lignin is more suitable for anti-aging modification and partial binder replacement under thermal-oxidative or ultraviolet aging conditions. However, high biomass incorporation remains limited by thermodynamic incompatibility, phase separation, chemical heterogeneity, and reduced molecular mobility, indicating that conventional physical blending is insufficient. From a systems perspective, scalability depends on feedstock availability, supply-chain logistics, and thermochemical conversion pathways that allow controllable tailoring of additive chemistry. Key barriers include feedstock variability, processing sensitivity, storage instability, moisture susceptibility, limited field validation, and the lack of harmonized specifications. We argue that high-content substitution requires molecular design, targeted chemical modification, life-cycle carbon efficiency metrics, and multi-year field validation. This review paper positions biomass-derived asphalt as a pathway for integrating carbon storage with infrastructure performance.