Performance Evaluation of Asphalt Mixtures Modified with Lignin Powder and Crumb Rubber

The use of biological additives in bitumen presents a promising path toward sustainable development, driven by economic and environmental benefits. These additives can reduce reliance on oil-derived bitumen, a finite and unsustainable resource. This study investigated the potential of lignin, derived from paper industry waste, to enhance asphalt mixture performance. Lignin powders were incorporated into neat asphalt at varying percentages to create lignin-modified asphalt mixtures. By conducting FTIR analysis, we looked into the mixing mechanism and potential interaction of lignin and crumb rubber with bitumen. The analysis revealed no chemical reaction among the samples and indicated similar absorption peaks. Various tests, including the wheel tracking test, semicircular bending test, and four-point beam bending test, were then conducted to evaluate the properties of the mixtures. Results indicated that lignin effectively improved the rutting and fatigue performance of the mixtures. However, no improvement in low-temperature performance of samples was observed. To address this limitation, the study explored the effectiveness of crumb rubber, a well-known additive for improving low-temperature performance in asphalt mixtures, in combination with lignin. Addition of crumb rubber to asphalt mixtures containing lignin modifiers produced composite asphalt mixtures (lignin and crumb rubber-modified asphalt mixtures). The results demonstrated that lignin-modified mixtures containing crumb rubber exhibited significantly better performance at low and moderate temperatures, indicating a synergistic effect between the two additives. This finding suggests that incorporating lignin and crumb rubber into asphalt mixtures could offer a sustainable and high-performing solution for pavement construction, addressing multiple performance challenges and promoting resource conservation.