Effectiveness of Different Categories of Rejuvenators in Recycled Asphalt Mixtures

Abstract

The work presented in this article aimed at studying the effectiveness of different rejuvenators to restore the desired properties of asphalt mixes with a high content of reclaimed asphalt pavement (RAP) material. Five different rejuvenators, waste engine oil (WEO), a commercial product (derived from waste lubrication engine oil), tallow, waste vegetable oil (WVO), and crude tall oil, which can be broadly categorized into three different categories [paraffinic oils (POs), fatty acids (FAs), and tall oils], were considered for this research study. The effectiveness of rejuvenators was first evaluated based on rutting and fatigue performance of rejuvenated bitumen blends of recovered RAP bitumen and virgin bitumen. Then the rutting and fatigue resistance of asphalt mixes with high RAP content (approximately 60%) and rejuvenator was evaluated. The test results suggest that rutting of asphalt mixes due to excessive softening of the rejuvenated bitumen should not be an issue if the target dosage of rejuvenator is determined based on the softening point value or viscosity (at 60°C) test results. It was found that the WEO of the paraffinic oil category was least effective in improving the fatigue resistance of asphalt mixes. Rejuvenators of the FA category, i.e., WVO and tallow, were found to be more effective at improving the fatigue damage resistance of asphalt mixes. Crude tallow has resulted in materials with inferior rutting resistance and fatigue resistance comparable to that of the virgin control mix.