While the research and development of the SUPERPAVE asphalt mixture design and analysis system did address the use of polymer modified asphalt binders in the specification of material performance properties, no recommendations or procedural guidelines were given for the use of recycled materials. The use of recycled asphalt pavements (RAP) in new paving mixtures is not an innovative idea. RAP has been called one of the most recycled materials in the world, and its use in paving mixtures has been shown to have environmental, economic and performance benefits. In this study, four different RAP stockpiles were sampled and the characteristics of each RAP material were investigated in terms of binder content, aggregate gradation and the rheologic characteristics of the reclaimed RAP binder. The reclaimed RAP binders were blended with several different virgin performance graded binders in order to determine how RAP binder concentration affected the stiffness and performance grade of the RAP -- virgin binder blends. Recommendations were made on how to select virgin binder grade andor RAP concentration combinations to fulfill a project's binder grading requirements. The effects of RAP were also investigated in terms mixture design, and recommendations were made with regards to material handling and specimen fabrication procedures. Asphalt concrete mixtures containing RAP were characterized in terms of stiffness and resistance to plastic strain using SUPERPAVE testing methods, and the results of these tests were compared to those of virgin material mixtures. Assuming a simulated pavement cross section and traffic loading, the results of this performance testing were used in performance prediction models to estimate how pavements constructed with RAP would perform compared to those made from 100% virgin materials. The predicted performance of pavements containing up to 40% RAP (by weight) was found to be similar or slightly better than that of virgin material pavements.

TRB's National Cooperative Highway Research Program (NCHRP) Report 752: Improved Mix Design, Evaluation, and Materials Management Practices for Hot Mix Asphalt with High Reclaimed Asphalt Pavement Content describes proposed revisions to the American Association of State Highway and Transportation Officials (AASHTO) R 35, Superpave Volumetric Design for Hot Mix Asphalt, and AASHTO M 323, Superpave Volumetric Mix Design, to accommodate the design of asphalt mixtures with high reclaimed asphalt pavement contents.