Yongping Hu, Sayyed Mahdi Hejazi, Dady Jal Patel, Hebah Jahan, Derya Kaya Özdemir, Yike Yin, Gordon Airey, Anand Sreeram
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. • Two types of lignin were used to partially replace petroleum-derived bitumen. • Lignin reduced bitumen hardening during ageing but had limited effect on relaxation properties. • Lignin acted mainly as a potential substitute for bitumen rather than a strong antioxidant. • Prolonged ageing revealed limited or adverse antioxidation effects of lignin.