Reclaimed Asphalt Pavement in Asphalt Mixtures: State of the Practice

2011Copeland, AudreyPDFTech Reporthttps://www.fhwa.dot.gov/publications/research/infrastructure/pavements/11021/FHWA-HRT-11-021Reclaimed asphalt pavementsAsphalt mixturesMix designUnited StatesUnited States. Federal Highway Administration. Office of Research, Development, and TechnologyCopeland, AudreyUnited States. Federal Highway Administration. Office of Infrastructure Research and DevelopmentTurner-Fairbank Highway Research CenterFederal Highway AdministrationWith increased demand and limited aggregate and binder supply, hot mix asphalt (HMA) producers discovered that reclaimed asphalt pavement (RAP) is a valuable component in HMA. As a result, there has been renewed interest in increasing the amount of RAP used in HMA. While a number of factors drive the use of RAP in asphalt pavements, the two primary factors are economic savings and environmental benefits. RAP is a useful alternative to virgin materials because it reduces the use of virgin aggregate and the amount of virgin asphalt binder required in the production of HMA. Using RAP greatly reduces the amount of construction debris going into landfills, and it does not deplete nonrenewable natural resources such as virgin aggregate and asphalt binder. Ultimately, recycling asphalt creates a cycle of reuse that optimizes the use of natural resources and sustains the asphalt pavement industry. More widespread use of higher amounts of RAP in asphalt mixtures requires support from State transportation departments and the HMA industry. State transportation departments have expressed concern over the lack of guidance on the use of high percentages of RAP (high RAP) mixtures, as well as the lack of information on their performance. As a result, there is a need for national guidance on best practices when using RAP and documented information about long-term performance of high RAP pavements. The intent of this report is to provide state-of-the-practice information on including higher amounts of RAP in asphalt mixtures. The state of the practice for RAP use across the United States, as well as common challenges for increasing the use of RAP, are identified. Best practices applicable for the use of RAP are presented to identify general parameters that must be considered when developing specifications and to provide information on available resources and best practices for sourcing, processing, stockpiling, testing, designing, evaluating, producing, and placing high RAP mixtures, as well as practices to attain the best performance for high RAP mixtures.79