Experimental study of soda lignin powder as an asphalt modifier for a sustainable pavement material

•Potentiality of utilizing soda lignin as an asphalt modifier by incorporating in different amounts were investigated.•Enhanced rutting and fatigue performance were achieved after modification as compared to base asphalt.•Lignin modified asphalts showed great thermal storage stability for all dosages of lignin content.•No apparent formation of new functional groups in the infrared spectra even after heating at high temperature. In recent years, lignin has been receiving more coverage as an asphalt modifier because of its wide variety of sources, low price, renewability, and potential to improve the performance of asphalt pavement. This research aims to develop lignin-modified asphalt by adding soda lignin powder in different proportions to overcome some drawbacks of traditional modified asphalt. A series of tests, including empirical, viscosity, rutting, fatigue, cracking, storage stability, and chemical tests, were performed to determine the influence of soda lignin on asphalt binder. Test results revealed that the addition of lignin helps to reduce the temperature sensitivity of the asphalt by increasing its hardness and decreasing its ductility. At the same time, the incorporation of soda lignin powder also increased the viscosity of base asphalt with the increase in lignin content. Furthermore, rheological performance test results revealed that the addition of soda lignin significantly enhanced the rutting resistance and fatigue performance for all the dosages incorporated. And also, a slight reduction in low-temperature cracking performance was observed. In addition, the storage stability test result depicted that the dispersion of lignin powder in asphalt was comparatively uniform and stable, indicating excellent thermal storage stability for all the lignin amounts incorporated. Moreover, chemical test results suggest that the soda lignin and bitumen can be mixed physically without new chemicals.