Novel Methods for Adding Rejuvenators in Asphalt Mixtures with High Recycled Binder Ratios

US Transportation Collection2022PDFTech ReportYin, FanLangan, MariahMoraes, RaquelChen, ChenAuburn University. National Center for Asphalt TechnologyNational Road Research AllianceMinnesota Department of TransportationMinnesota. Department of TransportationUnited StatesAsphalt mixturesFatigue strengthFoamed asphaltPavement performanceReclaimed asphalt pavementsRecycled materialsRejuvenatorsWorkabilityFoaming agentsEmulsionsBlendingImage analysisPavement crackingResistance testsNRRA202202(c) 1036333 (wo) 1Final Report (January 2021 to June 2022)The overall objective of this study was to explore three novel rejuvenator application methods using the emulsion and foaming technologies and determine their impacts on the workability and long-term cracking resistance of high-reclaimed asphalt pavement (RAP) asphalt mixtures. To that end, a comprehensive experimental plan was developed, which consisted of four supplementary experiments focusing on rejuvenator characterization, foaming measurements of rejuvenators and rejuvenated asphalt binders, RAP pretreatment and marination evaluations, and mixture performance testing, respectively. Test results indicated that adding rejuvenators for RAP pretreatment improved the overall quality characteristics of RAP. Among the three rejuvenator application methods evaluated for RAP pretreatment, the emulsion method was found more effective than the spray-on and foaming methods. Marinating the pretreated RAP had a notable impact on the rheological and chemical properties of the extracted RAP binders, but it did not significantly affect the workability, appearance, and color consistency of RAP. Adding rejuvenators, in general, improved the workability and cracking resistance of high-RAP mixtures, although the improvement in mixture performance test results, in some cases, was not statistically significant. Among the different rejuvenator application methods, pre-blending the rejuvenator into the virgin binder (with or without foaming) provided slightly better or equivalent rejuvenating effectiveness and thus, mixture performance properties, than adding the rejuvenator for RAP pretreatment. Based on the findings of the study, it was recommended that asphalt contractors continue to use the pre-blending method of adding rejuvenators for the design and production of high-RAP mixtures due to performance and ease of operation considerations.140