Study on basic properties and rejuvenation mechanism of wood tar-based rejuvenated asphalt

This study conducted a laboratory investigation to assess the effects and rejuvenation mechanism of wood tar-based rejuvenator (WTR) on the properties of aged 70# base asphalt and styrene-butadiene-styrene (SBS) modified asphalt, using a commercial rejuvenator RA-102 as a reference. The conventional physical properties (penetration, ductility, softening point, and viscosity), high and low temperature rheological properties, composition, chemical characteristics, and microscopic characteristics of asphalt under different aging states were tested. The results show that WTR and RA-102 rejuvenator can enhance the penetration, ductility, phase angle δ, and creep rate (m-value) of aged asphalts, but reduce their softening point, viscosity, complex modulus G*, and creep stiffness (S-value). Meanwhile, both rejuvenators can reduce the stiffness and increase the proportion of viscous components of aged asphalt, making the values of △T_c and the continuous low-temperature grade controlled by the m-value and approach those of the original asphalt. Notably, the joint modification effects of wood tar and bamboo fiber make wood tar-based rejuvenated asphalt (WTRA) have better high-temperature performance but slightly lower low-temperature performance than RA-102 rejuvenated asphalt. The WTR primarily rejuvenates aged asphalt through physical blending by replenishing light components, reducing gel index I_C value, and improving microstructural uniformity via the mitigation of wax crystal aggregation and the optimization of bee structure distribution. The results of grey correlation analysis reveal that the rejuvenation of aged asphalt performance by WTR is driven by synergistic changes in composition, chemical structure, and microscopic features, where the regulation of composition and colloidal structure play a dominant role. Overall, WTR demonstrates strong potential as a sustainable and effective rejuvenator for aged asphalt.