A review of converting woody biomass waste into useful and eco-friendly road materials

Because of abundant reserves and renewable and environmentally friendly properties, the utilization of woody biomass waste in road engineering can alleviate the shortage of fossil fuels and carbon emissions so as to mitigate global climate change and achieve sustainable development of road engineering. This paper synthesizes the state of the art about the strategies of applying five kinds of resources derived from waste woody biomass, including biochar, bio-oil, lignin, wood ash and nanocellulose to road construction. Based on the characteristics analysis of the five materials, it can be concluded that biochar can comprehensively improve the road performance of asphalt and its mixtures, and has the potential of runoff purification; bio-oil can soften asphalt and improve its low-temperature performance, but has negative effects on high-temperature performance; lignin increases the asphalt ageing resistance and can be used as a regenerant, and will improve the overall performance of asphalt mixtures if combined with other modifiers; wood ash can increase subgrade bearing capacity and bring significant environmental benefits; nanocellulose improves the strength of cement mortar, but there is a lack of research on its effects on performance of pavement materials and the interaction mechanism; the lifecycle environmental and economic assessment of woody biomass-modified road materials is not comprehensive. Moreover, prospects were also summarized to show the opportunities for future study, such as the establishment of a database for biomass. This review provides useful insights for the utilization of woody biomass as road materials to achieve waste management and sustainable development.