Waste Tire Pyrolysis and Distillation for Designing Effective Asphalt Rejuvenators

The pyrolysis of waste tires presents a sustainable strategy to convert polymeric waste into functional pyro-oil asphalt rejuvenators. However, the chemical complexity and variability of pyro-oils have hindered consistent performance and predictive control. In this study, we develop optimized pyro-rejuvenators (PRs) aimed at restoring the self-healing properties of aged asphalt binders. Employing response surface methodology (RSM), we determined ideal pyrolysis conditions for producing PRs from Passenger Car Waste Tires (PCWT) and Haul Truck Waste Tires (HTWT). The optimum PRs were obtained from the 160–200 °C distillation fractions of pyro-oils produced at pyrolysis temperatures of 450 °C (PCWT) and 470 °C (HTWT). These rejuvenators feature a high content (>95%) of monoaromatics and alkenes coupled with low viscosity (<10 cP). Notably, PRs derived from PCWT and HTWT enhanced the healing index of aged bitumen by 26.6% and 45.3%, respectively, compared to natural recovery. This performance improvement strongly correlates with the limonene and cymene concentrations in the PRs. These findings advance the development of pyro-rejuvenators that not only restore the self-healing capacity of asphalt binders but also demonstrate the promise of sustainable tire-derived additives as key enablers of a circular economy.