Investigating moisture susceptibility of lignin modified asphalt binders with natural aggregates using surface free energy analysis

Pavement deterioration due to moisture damage (MD), primarily caused by poor bitumen or binder-aggregate adhesion, poses significant challenges to road infrastructure. This study investigates the potential of lignin, a sustainable biopolymer, to improve the MD resistance of bitumen. Bitumen was modified with sodium lignosulfonate at varying concentrations (5%, 10%, and 15%) and subjected to short-term aging. Surface free energy (SFE) analysis was conducted on base and lignin modified bitumen to assess their compatibility with four different aggregates. The results indicate that lignin modification enhances the MD resistance of bitumen up to a 10% dosage, beyond that cohesion within the binder is compromised. Basalt exhibited the highest improvement in energy ratio (ER) with the 10% lignin-modified bitumen, suggesting enhanced adhesion. Granite, limestone and quartzite showed promising adhesion characteristics under dry conditions. This study demonstrates the potential of lignin as a modifier to improve bitumen performance and provides valuable insights into bitumen-aggregate compatibility. The ER values can serve as a predictive tool for highway agencies to select suitable binder-aggregate combinations for improved pavement durability.