Chemical and Performance Characteristics of Rejuvenated Bituminous Materials with High Reclaimed Asphalt Content

Abstract

The present paper aimed at studying the effectiveness of waste vegetable oil (WVO) as rejuvenator in restoring the desired properties of recycled asphalt mixes. The effectiveness of rejuvenators was first evaluated based on aging resistance, rutting, and fatigue performance of rejuvenated bitumen blends of recovered reclaimed asphalt pavement (RAP) bitumen and virgin bitumen. Bitumen was also characterized chemically by conduction thin layer chromatography–flame ionization detector (TLC–FID) analysis and Fourier transform infrared spectroscopy (FTIR) analysis. The rutting and fatigue resistance of asphalt mixes with high RAP content (60% and 90%), and rejuvenator was also evaluated. Comparison of the results of TLC–FID analysis on RAP bitumen and rejuvenated bitumen suggested that the WVO was able to reinstate the lighter fractions of bitumen. Two new peaks were observed in rejuvenated bitumen FTIR absorbance spectrum at 1,744 and 1,160 cm-1. These peaks respectively correspond to C═O and C─ O─ C stretches of saturated fatty acid ester, which is a major component of WVO. Multiple stress creep and recovery test on bitumen and a wheel-tracker test on asphalt mixes suggest that the rutting performance might not be an issue if the rejuvenator dosage selection is based on the target viscosity (at 60°C) or the softening point of the virgin bitumen type that is commonly adopted by the applicable road agency. Rejuvenated bitumen, when evaluated based on a linear amplitude sweep test, has shown inferior fatigue resistance compared to virgin bitumen. Such behavior of rejuvenated bitumen could be attributed to the presence of a high concentration of more reactive unsaturated fatty acids inherited from WVO. However, from indirect tensile fatigue tests on the asphalt mixes, it was found that the fatigue performance of rejuvenated recycled asphalt mixes is satisfactory.