Technical performance of lignin-modified bitumen and organic bitumen as binders for asphalt considering environmental criteria

Biomass-derived kraft lignin and organic bitumen have emerged as promising low-carbon alternatives to conventional petroleum-based bitumen, particularly in innovative “BioPave” applications. This study investigates the rheological behavior and environmental impact of lignin-modified bitumen and organic bitumen (natural asphalt blended with bio-oil) through a comparative analysis with conventional base bitumen. To achieve this, the chemical compositions of all bitumen samples, in both unaged and aged conditions, was first characterized using Fourier Transform Infrared (FTIR) spectroscopy to assess molecular structural changes due to oxidation. Subsequently, rheological properties were evaluated using dynamic shear rheometer (DSR) testing, focusing on the effects of aging on viscoelastic behavior. Furthermore, the environmental performances of the conventional and lignin-modified bitumen alternatives were assessed through Life Cycle Assessment (LCA) and compared with producer-specific environmental data for the organic bitumen. The results show that both bio-bitumen variants exhibit higher stiffness and improved rutting resistance, meeting heavy traffic requirements up to 70°C, with lignin-modified bitumen demonstrating superior aging resistance. LCA results indicate that organic bitumen reduces climate change impacts by nearly 50%, while lignin-modified bitumen achieves a 9.4% reduction. However, increased impacts in land use and resource consumption highlight the need for optimized biomass sourcing strategies. Overall, bio-bitumen presents a viable lower-carbon alternative with enhanced mechanical performance, though further research is required to optimize long-term durability and economic feasibility for practical implementation in road construction.