Optimized composition, structure, and property of a low-carbon bio-rejuvenator for aged asphalt

Catalytic liquefaction of waste wood and waste tire rubber was conducted to produce bio-oil under varying experimental conditions, including liquefaction temperature, retention time, solvent type, and catalyst type. Subsequently, a bio-oil-activated waste tire rubber rejuvenator, referred to as a bio-rejuvenator (BRR), was synthesized by adjusting the bio-oil content and optimizing microwave treatment parameters. The microwave activation and structure-property regulation mechanisms of BRR were elucidated. The results indicated that the highest bio-oil yield and aromatic content were achieved under the following conditions: a waste wood-to-waste tire rubber ratio of 6:4, a liquefaction temperature of 200 °C, a residence time of 0.5 h, dichloromethane as the solvent, and Al 2 O 3 as the catalyst. Liquefaction temperature had the most significant effect on the structure and properties of bio-oil, followed by solvent and catalyst type, and finally residence time. The flash point, aromatics content, and saturates content of BRR are 375–462 °C, 20.1–21.8 %, and 16.4–17.9 %, respectively, which meet the road application standards. BRR containing 15–35 % bio-oil met the performance requirements for a rejuvenator. The microwave activation mechanism revealed that microwaves can break the S-S and C-S bonds in waste tire rubber, increasing molecular flexibility. The -OH and C O groups in bio-oil can then react with the broken S-S or C-S bonds, forming BRR. The structure-property regulation mechanism of BRR indicates that waste wood contributes to higher aromatic and oxygen content, whereas waste tire rubber increases carbon content and reduces oxygen content. Bio-oil acts as a source of aromatics and saturates, helping to compatibilize the waste tire rubber, soften it, and reduce the viscosity of BRR. • Co-liquefaction of waste wood and waste tire rubber was carried out. • The bio-rejuvenator was synthesized by fine-tuning the bio-oil content and preparation parameters. • The regulation of structure-property relationships of bio-rejuvenator were elucidated. • Oxygen species (O*) present in waste wood can oxidize sulfides to elemental sulfur.