Study on the Rheological Optimization and Multiscale Verification of the Asphalt Rejuvenator

The use of Reclaimed Asphalt Pavement (RAP) is a sustainable strategy to conserve natural resources, reduce environmental pollution, and lower construction costs. However, aged asphalt in RAP suffers from oxidation and loss of light fractions, increasing stiffness and brittleness. A key scientific challenge is how to effectively restore the performance of aged asphalt while maintaining cost efficiency. In this study, a novel asphalt rejuvenator was developed to address this issue. The rejuvenator consists of 6% aromatic oil-like materials to replenish light components, 1.52% plasticizer to enhance ductility, and 0.3% modifier A to improve adhesion, with a total dosage of 7.82% by the mass of the aged binder. The rejuvenator meets the requirements of Chinese specifications. The performance evaluation was conducted at both asphalt binder and mixture scales. The results show that the rejuvenator significantly improves low-temperature cracking resistance and medium-temperature fatigue performance of aged binders, although it slightly reduces high-temperature rutting resistance. When applied to asphalt mixtures with 45% RAP, the rejuvenated mixtures exhibited enhanced low-temperature performance. A comparative analysis with commercial rejuvenators confirmed the developed product's competitive performance and economic benefit. This study provides technical insight into rejuvenator design and addresses critical challenges in RAP recycling for sustainable pavement engineering.