In his project titled “Nebraska Balanced Mix Design”, Dr. Hamzeh Haghshenas Fatmehsari worked to develop a preliminary framework for evaluating asphalt mixtures against three main types of distresses, namely rutting, fatigue cracking, and moisture susceptibility. Balanced Mix Design (BMD) is an alternative concept for designing asphalt mixtures that mainly focuses on the performance of mixtures rather than only volumetric analysis.
Dr. Haghshenas and his research team recognize the main goal when designing or improving an asphalt-concrete mixture is to find a blend that is economic and capable of withstanding deformation and cracking in heavy traffic conditions over time. Therefore, different testing methods have been developed to assess these mixtures. This portion of the project focused on the evaluation of asphalt-concrete mixture testing methods. Laboratory performance tests and field tests were conducted on commonly used asphalt mixtures in Nebraska and the testing methods were evaluated for their sensitivity, practicality, cost-effectiveness, and variability using statistical analysis.
For moisture damage resistance tests, no strong correlation was found between well-established and surrogate tests. When evaluating long-term aging methods, the National Center for Asphalt Technology (NCAT) protocol was found to be more severe than National Cooperative Highway Research Program (NCHRP) 09-54, meaning it was better at simulating aging and correlating the actual field aging of asphalt concrete mixtures. Selecting an appropriate long-term aging protocol for the Nebraska BMD will be done after the long-term data analysis in the next phases of the study.
This project was completed with financial support from the US Department of Transportation through the Nebraska Department of Transportation. It was co-authored by graduate research assistant Farzad Yazdipanah and research engineer Dr. Mahdieh Khedmati.
Dr. Hamzeh Haghshenas Fatmehsari was an Adjunct Professor in the Department of Civil and Environmental Engineering at the University of Nebraska-Lincoln and now works as an asphalt binder and mixture laboratory manager at the Federal Highway Administration Turner-Fairbank Highway Research Center. His areas of research and professional interests include chemo-physical and multi-scale characterization of construction materials, mechanistic analysis and design of pavements, and infrastructure sustainability.
