Phenol-rich bio-oils as free-radical scavengers to hinder oxidative aging in asphalt binder

This study examined the capability of phenol-rich bio-oils to improve the durability of bituminous composites by hindering oxidative aging in asphalt binder. Bio-oils derived from six wood-based bio-sources were introduced to asphalt binder, each specimen was then exposed to thermal aging. A chemical aging index was measured using Fourier-transform infrared spectroscopy, and a rheological aging index was measured using a dynamic shear rheometer. The results of the study showed that all phenol-rich bio-oils reduced the extent of aging in bio-modified binder, however, the bio-oils’ efficacy against aging varied, partly based on the content of their phenolic compounds. Computational modeling showed that the efficacy of each bio-oil is also affected by the molecular structures of its phenolic compounds, electron-donor substituents in the phenolic compound structure promote its antioxidant activity. The study outcomes show that using phenol-rich bio-oils can enhance the durability of asphalt binder while promoting a carbon-negative built environment.