Durability assessment of lignin-based asphalt for sustainable road construction

The scarcity and changing quality of conventional fossil-based asphalt binders have spurred the search for sustainable alternatives for binder in road construction. Lignin, a renewable binder derived from lignocellulosic biomass, shows promise as a substitute for bitumen. The current study evaluates the durability and performance of lignin-based asphalt constructed as a Stone Mastic Asphalt (SMA) surface layer in demonstration roads and conducted within the CHAPLIN TKI project. The aim of CHAPLIN TKI was to advance lignin-based asphalt technology to Technological Readiness Level (TRL)-6 by assessing existing demonstration roads. Asphalt core samples from these roads were evaluated to determine the expected lifespan of lignin based asphalt. Preliminary findings suggest a slightly shorter lifespan, approximately 1.5 years, for lignin asphalt compared to conventional bitumen asphalt, based on the trends observed in the selected data sets. The paper discusses the methods used for durability assessment, including rheological and chemical evaluations, as well as binder morphology characterization. At the asphalt level, the susceptibility to freeze-thaw cycles were evaluated, along with the influence of density on strength properties. Microscopy results from thin asphalt sections show that lignin is well distributed in the bitumen phase, with some lignin present as intrinsic particles. The research conducted within the CHAPLIN TKI project offers promising outcome for the use of lignin-based asphalt, but further investigation and long-term monitoring of road sections are necessary. This study contributes to the development of sustainable alternatives to traditional bitumen binders, addressing challenges faced by the asphalt industry.