Development of a Balanced Mix Design Method in Oregon

Cracking is a common failure mechanism in asphalt concrete pavement structures. It is one of the main reasons for large road maintenance and rehabilitation expenditures, as well as reduced user comfort and increased fuel consumption due to high road roughness. The resistance of the pavement to this distress mechanism is dependent upon the ductility of the asphalt pavement mixture. The use of recycled asphalt materials in asphalt mixtures are also becoming increasingly common. A drawback of this practice is a reduction in ductility of the asphalt mixture, which causes a significant reduction in the fatigue life of the pavement in many cases. In Oregon, asphalt pavements are commonly failing prematurely due to cracking-related distresses, necessitating costly rehabilitation and maintenance at intervals of less than half of the intended design lives in some cases. For this reason, it is necessary to accurately quantify the impact of increasing the recycled asphalt content in asphalt pavement on the structural cracking and rutting resistance of the pavement through use of low-cost and efficient testing procedures that can be implemented easily. ODOT Research Projects SPR785 and SPR797 (Coleri et al. 2017a and Coleri et al. 2017b) constructed the beginnings of a performance-based balanced mix design method for Oregon. It was suggested that semi-circular bend (SCB) and flow number (FN) tests are the most effective cracking and rutting performance tests that can effectively be used for balanced mix design. It was determined that typical flexibility index (Fl), an energy parameter calculated using SCB test results, values for production mixtures (plant-produced) range from 9 to 14. However, more experiments need to be conducted to determine exact threshold for FI that will provide acceptable long-term pavement cracking performance. For highways with high traffic levels (ESALs > 30 million), an FN of 740 was suggested by AASHTO TP79-13 (2013) and used in SPR785 and SPR797 as the threshold value for rutting performance acceptance. However, FI and FN threshold numbers used in these two research projects were not validated using measured field performance or extensive laboratory testing. In addition, mix design strategies suggested in SPR 797 (high RAP mixtures with different binder contents and binder types) were not validated by plant sampling, laboratory testing, and pilot section construction and performance monitoring.


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    • Status: Active
    • Funding: $85000
    • Contract Numbers:

      SPR 801

    • Sponsor Organizations:

      Federal Highway Administration

      1200 New Jersey Avenue, SE
      Washington, DC  United States  20590
    • Managing Organizations:

      Oregon Department of Transportation

      555 13th Street NE
      Salem, OR  United States  97301
    • Project Managers:

      Shippen, Norris

    • Performing Organizations:

      Oregon State University, Corvallis

      101 Kearney Hall
      Corvallis, OR  United States  97331
    • Principal Investigators:

      Coleri, Erdem

    • Start Date: 20171001
    • Expected Completion Date: 20201231
    • Actual Completion Date: 0
    • USDOT Program: Transportation, Planning, Research, and Development

    Subject/Index Terms

    Filing Info

    • Accession Number: 01688093
    • Record Type: Research project
    • Source Agency: Oregon Department of Transportation
    • Contract Numbers: SPR 801
    • Files: RiP, STATEDOT
    • Created Date: Dec 12 2018 4:35PM