Effects of lab-prepared soybean oil-based rejuvenator on high reclaimed asphalt pavement content asphalt mixtures

The growing emphasis on sustainability in pavement engineering has increased the utilization of Reclaimed Asphalt Pavement (RAP) in asphalt mixtures. However, high RAP content often results in stiffness and reduced performance due to the aging of bitumen. To address this, rejuvenators are commonly applied to ameliorate the performance of high RAP mixtures. This study evaluates the effectiveness of a lab-prepared soybean oil-based rejuvenator in blended bitumen and asphalt mixtures containing 50%RAP. The rejuvenator was synthesized through a controlled process and blended with aged bitumen. Laboratory tests were conducted including the Dynamic Shear Rheometer (DSR), Fourier Transform Infrared Spectroscopy (FTIR), Indirect Tensile Rutting Test (IDEAL-RT) and Indirect Tensile Cracking Test (IDEAL-CT). Results indicate that the soybean oil-based rejuvenator restores the rheological properties of aged bitumen, significantly enhancing in cracking resistance while effectively maintaining rutting resistance. FTIR analysis provided clear evidence of chemical interactions between the rejuvenator and the aged bitumen, specifically showing a reduction in carbonyl and sulfoxide functional group intensities. These findings suggest that lab-prepared soybean oil-based rejuvenators offer a sustainable and effective solution for improving the performance of high-RAP asphalt mixtures.