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Resilient and Dynamic Modulus Testing For M-E Pavement Design

This project was originally funded with Principal Investigator (PI) Dr. Soonkie Nam, with Dr. Bret Lingwall as co-PI serving in a support role. The project began in late 2015, and the project was turned over to Dr. Lingwall as PI when Dr. Nam left SDSMT in August of 2017. Due to insurmountable equipment malfunctions, none of the dynamic modulus or flow number tests performed by the research team are reliable for use by SDDOT. The results are skewed by large temperature swings in the equipment. Despite many attempts to repair, the device continues to pump heat into test specimens. As a result, the team has agreed that the project be terminated. This report serves, by the mutual agreement reached on December 20th, 2019 at the in-person meeting in the Geotechnical Engineering Laboratory at The South Dakota School of Mines and Technology (SDSMT) (and confirmed in follow-up communications) to summarize the work performed and close-out the research project SDDOT 2014-21. Since the development of the American Association of State Highway and Transportation Officials (AASHTO)’s empirical pavement design guide in 1972, this methodology has become the standard in pavement design, updated with only a few revisions. These design guides were simple with relatively few design inputs and have been used for decades by state and local agencies alike. However, over time it has become clear that the several factors that affect pavement performance such as climate, mix design, traffic volume, vehicle loads, and vehicle specifications are not well constrained in these methods, as the performance of the designed pavement systems no longer meet users’ expectations. The need to develop a new design guide better suited to the requirements of today’s transportation network resulted in a new concept of pavement design developed under the National Cooperative Highway Research Program (NCHRP) Project 1-37A (2004), known as the Mechanical Empirical Pavement Design Guide (MEPDG). This new framework includes both mechanistic and empirical analyses and incorporates significant improvements, providing more accurate evaluation of pavement performance and supporting more economical combinations of pavement materials. However, due to the complex calculations in the MEPDG methodology, which takes into account both mechanistic and empirical components, new test methods and equipment are required, as well as new software for the associated analyses. This software is an essential element of all pavement performance evaluations performed using MEPDG methodology. It consists of a set of hierarchical input systems with three levels based on the accuracy of the input parameters; these input parameters are essential and key factors that affect the reliability of the analysis. Among these, dynamic modulus and flow number are critical in terms of the material properties of the asphalt mixtures used to predict permanent deformation. Therefore, in order to design and predict pavement systems according to this new design methodology, obtaining reliable data for these input parameters is the most critical part of the entire process. In this study, the research team obtained representative asphalt mixtures from the South Dakota Department of Transportation (SDDOT), prepared compacted specimens using a Superpave gyratory compactor and conducted a series of dynamic modulus tests and repeated load triaxial tests using a Simple Performance Tester (SPT). The results of these tests were analyzed to determine the essential properties, specifically the dynamic modulus and flow number, of asphalt mixtures with SD design specifications. In addition, statistical analyses were performed with the ultimate goal of developing a South Dakota Asphalt Material Database (SDAMD) for future MEPDG applications. Unfortunately, mechanical and instrument errors with the SPT were revealed near the end of testing that brought the results of all tested specimens into question. Therefore, no productive or usable data was developed by this project despite vast amounts of time and effort expended.

Language

  • English

Media Info

  • Media Type: Digital/other
  • Edition: Final Report
  • Features: Figures; Photos; References; Tables;
  • Pagination: 35p

Subject/Index Terms

Filing Info

  • Accession Number: 01883475
  • Record Type: Publication
  • Report/Paper Numbers: SD2014-21-F
  • Contract Numbers: 311247
  • Files: NTL, TRIS, ATRI, USDOT, STATEDOT
  • Created Date: May 25 2023 1:51PM