Enhancing Biomass Value Chain by Utilizing Biochar as A Free Radical Scavenger to Delay Ultraviolet Aging of Bituminous Composites Used in Outdoor Construction

摘要

This study examines the merits of using biochar to delay aging in construction while promoting the economic viability of biofuel production and enhancing the biomass value chain. Biochar residue from pyrolysis of biomass to biofuel was introduced to neat asphalt and rubberized asphalt binders. The study results showed biochar can delay oxidation and UV-induced aging at binder and mixture level as evidenced by lowering rheological and chemical aging indexes. The rheological aging index was measured based on the change in crossover modulus due to aging, and the chemical aging index was measured based on the change in carbonyl and sulfoxide functional groups due to aging. Four types of aging were examined including oxidation and UV aging at the binder level as well as aging and weathering at the mixture level. In terms of oxidation aging, biochar was more effective for rubberized asphalt, while in the case of UV aging, neat asphalt appeared to benefit more than rubberized asphalt from the presence of biochar. The latter can be attributed to the role of biochar as a UV-light blockage and free radical scavenger. Rubberized asphalt inherently contains carbon black which enhances the internal resistance against UV aging, hence the role of biochar was not as significant in rubberized asphalt compared to that of the neat asphalt. However, in the case of oxidation aging, biochar noticeably improved the rubberized asphalt compared to neat asphalt. The study outcomes provide a simultaneous solution to promote resource conservation and enhance aging resistance of bituminous composites. Biochar, carbonaceous particles, made from biowaste can be used as a free radical scavenger to delay ultraviolet aging of bituminous composites. Therefore, this study promotes sustainability by creating applications for biochar while increasing pavement durability by delaying asphalt aging.