Field performance of RAS test sections and laboratory investigation of impact of rejuvenators on engineering properties of RAP/RAS mixes.

PDFTech ReportFHWA/TX-14/0-6614-3Project 0-6614Pavement designRecycled materialsField testsLaboratory testsAsphalt pavementsBenefit cost analysisCrackingMix designReclaimed asphalt pavementsPavement performanceTexasTexas. Dept. of Transportation. Research and Technology Implementation OfficeIm, SoohyokZhou, FujieTexas A&M Transportation InstituteUnited States. Federal Highway AdministrationUS Transportation CollectionIn the last several years, recycled asphalt shingles (RAS), in addition to reclaimed asphalt pavement (RAP),have been widely used in Texas. The use of RAS can significantly reduce the cost of asphalt mixtures, conserveenergy, and protect the environment. However, one of the major concerns is poor cracking resistance of RAS mixesdue to super stiff asphalt binder in the RAS. This research focused on field performance of RAS test sections andthe benefit of using rejuvenators in improving cracking resistance of RAS(/RAP) mixes. In addition, a simple costanalysis was performed to investigate the cost-benefits of using rejuvenators. It was found that both increasingdesign density (leading to higher virgin binder content) and using soft virgin binders (e.g. PGXX-28) can improvecracking resistance. With respect to improving cracking resistance of RAS mixes, the three rejuvenators evaluatedin this research are all effective. Furthermore, the incorporation of rejuvenators also improved the moisturesusceptibility and rutting resistance of the mixtures containing recycled materials. Apparently, additional tests andanalyses are necessary. Specifically, field test sections with different types of rejuvenators should be constructedfor further evaluation.Additionally, the observed field performance indicated that cracking performance is influenced by manyfactors, such as traffic, climate, existing pavement conditions for asphalt overlays, and pavement structure and layerthickness. It is extremely difficult to propose a single cracking requirement for all applications. There is a need todevelop a RAP/RAS mix design and performance evaluation system for project-specific service conditions,including traffic, climate, existing pavement conditions, etc