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

The abundant lignin can capture the (& BULL;)OHand O-& BULL;(2) (-) produced byTiO(2)/ZnO under UV, synergistically improving the agingresistance of asphalt. TiO2 and ZnO can alleviate the direct UV attacktowardasphalt by absorbing UV, but this process can generate the free radicaland may accelerate aging indirectly. Abundant and renewable lignincould trap the free radical and is therefore considered a useful antiagingagent. In this study, to enhance the resistance of asphalt againstthermal and UV oxidation comprehensively, lignin was blended in withTiO(2)/ZnO at a mass ratio of 5:3 to prepare composites (3T5Land 3Z5L). Then, the rheological properties and chemical structureof various modified ES70# before and after TFOT and UV aging werestudied. The modification mechanism was obtained by SEM, TEM, UV-vis,XPS VB and photocatalytic activity tests. The results showed that3T5L and 3Z5L improve the shear deformation resistance of asphaltwhile they slightly influence low-temperature brittleness. Meanwhile,3T5L and 3Z5L significantly slow down the aging degree of ES70# becauseof its synergetic effect, especially for 3Z5L. Furthermore, the synergeticeffect is explained that lignin and nanomaterials provide a lowerfree radical generation and lower UV aging state for each other toexert their strong resistance to thermal- and UV-oxidative aging,respectively. Overall, nanomaterials compounded with lignin show promisefor eco-friendly antiaging asphalt with economic benefits.