Utilization of biomass waste to produce phenol-rich bio-oil for enhancing the long-term aging resistance of rejuvenated bitumen

This study evaluated the long-term antioxidant performance of bio-oils produced via thermochemical liquefaction (HTL) as bio-rejuvenators for secondary aged bitumen binders. Five types of bio-oils were prepared from different biomass sources using sulfuric acid as a catalyst and polyols as liquefaction solvents. Subsequently, these bio-oils were added to aged bitumen and subjected to secondary aging to test their antioxidant effectiveness. Various tests, including gas chromatography–mass spectrometry (GC–MS), attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR), and gel permeation chromatography (GPC), were conducted to assess the chemical composition of the bio-oils. The results demonstrated that bio-oils contain substantial amounts of phenolic compounds, which exhibit antioxidant properties. The rheological testing showed that phenolic-rich bio-rejuvenators can be added to bitumen to increase the phase angle (δ) and decrease the complex modulus (G*). Additionally, some of these bio-rejuvenators improve secondary-aged bitumen’s fatigue performance and low-temperature cracking resistance while also recovering strain recovery (R) and non-recoverable creep compliance (J_nr). The chemical test showed that the carbonyl index, molecular weight, and polydispersity index of secondary-aged bitumen all decrease with the addition of bio-rejuvenators. Furthermore, the correlation analysis between the quantification of phenols in bio-oils and the rheological and chemical indices of bitumen subjected to secondary aging with added bio-rejuvenators shows a significant positive correlation between phenolic compound content and the antioxidant effects on the rheological and chemical properties of secondary-aged asphalt.