Evaluation of Overlay Tester Test Procedure to Identify Fatigue Cracking Prone Asphalt Mixtures

US Transportation Collection2019PDFTech ReportBennert, ThomasHaas, EdwinEricson, ChristopherWass Jr, EdRutgers University. Center for Advanced Infrastructure and TransportationUnited States. Department of Transportation. Office of the Assistant Secretary for Research and TechnologyUnited States. Department of Transportation. University Transportation Centers (UTC) ProgramNew Jersey. Dept. of TransportationUnited States. Department of Transportation. Federal Highway AdministrationRutgers University. Center for Advanced Infrastructure and TransportationUnited StatesAsphalt mixturesBend testsBituminous bindersCores (Specimens)Evaluation and assessmentFatigue crackingOverlays (Pavements)Recycled materialsTest proceduresWarm mix paving mixturesOverlay TesterSCB Flexibility IndexGlover-Rowe ParameterLoss TangentFatigue CrackingRecycled AsphaltWarm Mix AsphaltCAIT-UTC-NC57DTRT13-G-UTC28Final Report, August 2018 to September 2019Fatigue cracking is a major problem on asphalt pavements and airfields. Design and production procedures continually result in lean asphalt mixtures, while the use of recycled asphalt pavement (RAP) and recycled asphalt shingles (RAS) increases the relative stiffness and aged condition of the asphalt mixture, significantly decreasing the material's flexibility and natural ability to withstand crack initiation and propagation. The literature has shown that the Overlay Tester is a test method that can identify cracking prone asphalt mixtures and is highly sensitive to recycled asphalt, asphalt content, polymer modification, and asphalt mixture volumetrics. The purpose of the study is to evaluate the Overlay Tester using field cores from the recently completed Federal Highway Administration (FHWA) Accelerated Loading Facility (ALF) Sustainability study. The study comprised of 10 different test lanes, each produced to the same target volumetrics, while varying recycled asphalt contents, base asphalt binder grades, and the addition of warm mix asphalt technologies. Each lane was trafficked until fatigue cracking failure, and therefore, provided an excellent means to compare field and laboratory performance. The results of the study showed that the Overlay Tester, as well as the Semi-Circular Bend (SCB) Flexibility test, are test methods capable of discriminating between \u201cGood\u201d and \u201cPoor\u201d fatigue cracking performing asphalt mixtures. The general ranking of performance from both test methods were shown to compare well with the field performance. Additionally, asphalt binder testing, performed on recovered asphalt binder from the top \ubd - \ube\u201d of the asphalt surface, correlated very well with the measured cracking performance of the FHWA ALF. The Loss Tangent\ub2, Glover-Rowe Parameter, and DTc parameter showed excellent to good agreement to the Number of Cycles to 1st Crack at the ALF. Ultimately, the research study provided asphalt mixture and binder test methods capable of capturing the fatigue cracking performance in asphalt mixture produced with varying amounts of recycled asphalt binders, PG grades, and warm mix asphalt technologies.110