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

Biomass-derived kraft lignin and organic bitumen are promising low-carbon alternatives to conventional petroleum-based bitumen, particularly for innovative “BioPave” applications. This study compares the rheological behavior and environmental impacts of lignin-modified bitumen and organic bitumen (natural asphalt blended with bio-oil) against conventional bitumen. Chemical compositions under unaged and aged conditions were analyzed using FTIR spectroscopy to evaluate oxidation-induced molecular changes. Rheological performance was assessed via dynamic shear rheometer (DSR) tests, focusing on aging effects on viscoelasticity. 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. Results show both bio-bitumen variants offer higher stiffness and rutting resistance up to 70 °C, with lignin-modified bitumen showing superior aging resistance. LCA indicates that organic bitumen reduces climate change impact by nearly 50 %, and lignin-modified bitumen by 9.4 %. However, increased land use and resource consumption underscore the need for improved biomass sourcing strategies. Overall, bio-bitumen offers a viable, lower-carbon alternative with enhanced mechanical properties, though further work is needed to optimize its long-term durability and economic viability for widespread road use. • A comparison was conducted between organic, lignin-modified, and Petro-bitumen. • A 100 % bio-based binder was benchmarked for the first time against Petro-bitumen. • A cradle-to-gate LCA was performed to quantify impacts of bio-based binders.