Lignin as Renewable and Superior Asphalt Binder Modifier

The utilization of lignin for fungible products remains a major challenge for biofuel, pulp and paper industries. We hereby demonstrated the potential of lignin to be used as the asphalt binder modifier, and addressed the challenges in producing high-performance asphalt binder modifiers from lignin. We first demonstrated that Kraft lignin could improve the high temperature performance of asphalt binder, yet compromise the low temperature performance. To address the challenge, we developed both enzyme-mediator-based biological processing and formic acid-based chemical processing to derive lignin fractions to improve the high temperature performance of asphalt binder without compromising its low temperature performance. Moreover, the soluble fraction of biologically processed lignin could improve both high temperature and low temperature performance of asphalt binder, which enabled lignin to serve as a modifier with unique features. We also carried out a thorough characterization of different lignin fractions, and revealed the potential mechanisms for lignin to improve the asphalt binder performance. Overall, the study opened the new avenues for lignin to serve as an exceptional modifier and renewable substitute to improve both high and low temperature performance of asphalt binder. The novel application also transformed lignin waste into a valuable byproduct with market size compatible to biorefinery, pulp and paper industries.