Feasibility and Sustainable Performance of RAP Mixtures with Low-Viscosity Binder and Castor Wax–Corn Oil Rejuvenators

Abstract

The utilization of Recycled Asphalt Pavement (RAP) mixtures in pavement construction is an environmentally friendly approach that promotes sustainable development by reducing energy consumption and material waste. However, the high cost of conventional rejuvenators limits the widespread use of RAP mixtures. In this study, a novel approach is proposed to enhance the performance of RAP mixtures by incorporating a combination of high-penetration asphalt binder and rejuvenators, namely Castor wax and Corn oil. The newly developed rejuvenator consists of 8.5% Castor wax oil, 3% Corn oil, 3% fatty acid amine surfactant, 0.2% additive, and 79.8% water. The test results demonstrate that the modified mixture exhibits superior properties compared with conventional RAP mixtures. The Multiple Stress Creep Recovery test results showed a 20% reduction in cumulative strain rate for the RAP mixture with the new rejuvenators compared with that for the conventional ones. Furthermore, the Tensile Strength Ratio test indicated a notable 9.47% improvement in the rejuvenated RAP mixture’s resistance to moisture-induced damage compared with the conventional mixture. Evaluation of viscoelastic behaviors revealed a slight reduction in dynamic modulus for the rejuvenated binder, but a significant improvement in elastic behavior. In terms of rutting resistance, the Hamburg wheel tracking rut depths of the rejuvenated binder were significantly lower, representing reductions of 21.83% for specific binder compositions. Additionally, the absence of the stripping phenomenon further confirmed the superior moisture resistance of the modified mixture. The rejuvenated binder exhibited a remarkable 28.55% increase in fatigue load cycles to failure compared with the reference RAP binder, demonstrating substantial resistance to fatigue cracking. These quantitative comparisons not only confirm the superior performance of the modified mixture over conventional RAP mixtures, but also highlight the potential cost savings achieved through the utilization of Castor wax and Corn oil rejuvenators.