Synergistic Effect and Mechanism of Nanomaterial Compounded with Sustainable Lignin for Aging Resistance of Asphalt

TiO 2 and ZnO can alleviate the direct UV attack toward asphalt by absorbing UV, but this process can generate the free radical and may accelerate aging indirectly. Abundant and renewable lignin could trap the free radical and is therefore considered a useful antiaging agent. In this study, to enhance the resistance of asphalt against thermal and UV oxidation comprehensively, lignin was blended in with TiO 2 /ZnO at a mass ratio of 5:3 to prepare composites (3T5L and 3Z5L). Then, the rheological properties and chemical structure of various modified ES70# before and after TFOT and UV aging were studied. The modification mechanism was obtained by SEM, TEM, UV–vis, XPS VB and photocatalytic activity tests. The results showed that 3T5L and 3Z5L improve the shear deformation resistance of asphalt while they slightly influence low-temperature brittleness. Meanwhile, 3T5L and 3Z5L significantly slow down the aging degree of ES70# because of its synergetic effect, especially for 3Z5L. Furthermore, the synergetic effect is explained that lignin and nanomaterials provide a lower free radical generation and lower UV aging state for each other to exert their strong resistance to thermal- and UV-oxidative aging, respectively. Overall, nanomaterials compounded with lignin show promise for eco-friendly antiaging asphalt with economic benefits.