Seismic Approach to Quality Management of HMA (MnDOT Contract No 1034287)
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In January 2020, the Minnesota Department of Transportation (MnDOT) launched a project funded by National Road Research Alliance (NRRA) that builds such a system that one can routinely use in the field for the quality management of Hot Mix Asphalt (HMA) pavement by using a seismic method. The project produced a 2D receiver-array system consisting of four (4) 1D MEMS microphone arrays arranged transversely so that a certain width of pavement (e.g., 4 ft) can be measured simultaneously. The system can be easily harnessed on a simple apparatus on the back of a car−for example, a bicycle rack. The survey vehicle can travel at a 10-30 MPH speed making a high-density rolling measurement, for example, one measurement every 2 ft. The on-board GPS and IR sensors record the location and temperature data, respectively, for geo-referencing and temperature-referencing of the final results of the velocity (Vs) and thickness (H). The dedicated software package installed on the on-board laptop computer analyzes incoming data in a fully automated mode to display the results on the computer screen almost in real time.
It was a 2-year project in which Park Seismic LLC (PSL) participated as the prime contractor and Norrfee Tech AB (NTA) participated as the subcontractor. PSL built the software package while oversighting the entire project. NTA built all the hardware components while providing technical consultations. NTA previously built the 48-channel system used in Bjurström and Ryden (2017) and Ryden et al. (2019) (Starkhammar et al., 2007). A dedicated web site in PSL home page provides details about all aspects of this project (parkseismic.com/HMA-Project.html). For example, the original project proposal, awarded contract, scope of the work, and the technical advisory panel (TAP) members are posted. The project progress had been updated every month at the site during the project execution.
The completed system was delivered to MnDOT Materials Lab in St Paul, MN, on June 10, 2022. Principal Investigator (PI) (Choon Park) and a staff (Jin Park) from Park Seismic LLC assembled the system during the morning of June 15. PI presented about technical, operational, and maintenance aspects of the system in the afternoon. Topics covered can be found in the presentation file (Appendix I of the final report). On the following day (June 16), field demonstration surveys were conducted at MnROAD Low Volume Road (LVR) in Otsego, MN, by two Park Seismic participants and MnDOT personnel. A video illustration of the demo survey is posted on YouTube. A separate summary report of all three demo surveys is presented in Appendix II of the final report.