Comprehensive characterisation of lignin-based bio-bitumen as a sustainable paving material

Rising demand, increasing prices, and growing environmental concerns necessitate the exploration of sustainable alternatives in transportation infrastructure. Lignin has shown promise as a partial substitute for petroleum-derived bitumen, but its efficacy needs to be comprehensively assessed. This study investigates the effects of incorporating two types of lignin at dosages of 3 % and 5 %. Thermogravimetric analyser, Fourier-transform infrared spectroscopy, X-ray diffraction, and dynamic shear rheometer were employed to characterise physicochemical properties of lignin and the corresponding modified bitumen. Considering the decomposition of lignin, the mixing temperatures should below 180 °C. The addition of lignin reduced ageing susceptibility, implying lignin may serve both as a partial bitumen replacement and antioxidant. Rheological tests showed minor improvements in rutting resistance and reduced stiffness-controlled critical temperatures, while creep rate-controlled temperatures remained largely unchanged. However, these changes were not statistically significant. Thus, partially replacing petroleum bitumen with bio-sourced lignin is a technically viable and sustainable solution.