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WESTERN REGIONAL
SUPERPAVE CENTER
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Implementation of The Superpave Binder Grading System in Nevada In the early 1990s, the Nevada DOT sponsored research efforts to assess the feasibility of implementing the Superpave PG binder grading system under Nevada’s conditions. The research effort graded a large number of asphalt binders used on NDOT’s projects using the Superpave PG grading system. Because NDOT uses polymer-modified binders extensively, the PG grades showed that the majority of the binders will provide less than satisfactory performance. The long term performance monitoring of these projects, however, showed an opposite trend. The field performance monitoring also showed that polymer-modification is necessary to ensure good long term performance in both the southern and northern regions of the state. With these information, NDOT recently modified the Superpave PG binder grading system to better suite polymer-modified binders that have successfully been used in Nevada. The modified Superpave PG binder grading system is being used in the southern part of the state with planned implementation in the north in the near future. Field sections have been constructed using binders specified with the modified grading system on I-15 in southern Nevada. The performance of these sections are being monitored and will be used to make future modifications as needed Available Information: Download Report: Design and Construction of NDOT PG-Special Test Sections Implementation of Superpave Mix Design and Analysis Procedures In the mid 1990s, NDOT funded extensive research efforts to implement the Superpave mix design and analysis procedures on HMA projects throughout Nevada. The efforts are still continuing up to this date with great advancements on learning about the long term performance of Superpave designed mixtures under Nevada’s loading and environmental conditions. These efforts included the construction of several field test sections and the monitoring of their long term performance. Up to date, a total of eight Superpave designed HMA mixtures have been constructed throughout the state. The performance of these sections have been evaluated through extensive laboratory testing programs and field performance. The resistance of the Superpave mixtures to rutting, fatigue, and low temperature cracking were evaluated in the laboratory using Superpave recommended performance tests on laboratory prepared samples and field samples. The recommendations of the laboratory testing programs were also checked against the performance of the mixtures under actual field conditions. The performance of the earlier sections indicated that the current Superpave Volumetric Mix Design method needs some modifications in order to be successful under Nevada’s conditions. These modifications included the following: Eliminate the Restricted Zone requirement on aggregate gradation. Include a minimum requirement on Hveem stability. Verify potential performance using the Asphalt Pavement Analyzer (APA) Include a minimum dry tensile strength of 65 psi on Hveem compacted samples at optimum. Include a minimum tensile strength ratio of 70% on Hveem compacted samples at optimum. In 2001, NDOT constructed one Superpave section with the above modifications and three additional sections are planned for the 2002 construction season. Each Superpave section is coupled with a Hveem designed section on the same project. The properties of the two mixtures will be evaluated in the laboratory and their field performance will be monitored. The data generated from this research will be used to support the implementation of the Superpave system in Nevada. Available Information: Download Report: Design and Construction of NDOT Test Sections on Interstate 80 Download Report: Performance of Superpave and Hveem Sections in Nevada, Volume IV Download Report: Design And
Construction
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