Impacts of Rejuvenator Pretreatment and Marination on Quality Characteristics of Reclaimed Asphalt Pavement

To mitigate the potential cracking performance issues of high reclaimed asphalt pavement (RAP) asphalt mixtures, rejuvenators can be added to restore the rheological and chemical properties of the RAP binder. Traditionally, rejuvenators are pre-blended into the virgin binder before mixing, which may limit the direct interaction between the rejuvenator and RAP. Therefore, alternative methods of adding rejuvenators by pretreating RAP with appropriate marination before mixing with virgin materials should be considered to potentially enhance the rejuvenating effectiveness of these products. In this study, three RAP pretreatment methods (spray-on, emulsified, and foamed rejuvenators) were explored. The effects of each pretreatment method on RAP quality properties were characterized through workability evaluation based on the Dongre Workability Test (DWT), durability assessment based on the Cantabro test, and grayscale image analysis. From these results, the most effective pretreatment method was selected to evaluate the impact of marination on RAP quality via the same characterization techniques. Four marination conditions were evaluated, including 3 and 7 days at 25°C, and 1.5 and 3 h at 135°C. Furthermore, asphalt binders extracted from untreated and pretreated RAP samples at selected marination conditions were tested for rheological and chemical characterization. Test results indicated that RAP quality significantly improved with pretreatment with the rejuvenator, but the degree of improvement varied depending on the rejuvenator dosage and application method, among other factors. Marination also affected the RAP binder properties but did not significantly improve the overall quality characteristics of the RAP in relation to DWT, Cantabro, and grayscale image analysis.