In Situ Modulus Measurement Using Automated Plate Load Testing for Statewide Mechanistic-Empirical Design Calibration

In the new AASHTOWare™ Pavement Mechanistic Empirical (ME) Design guide, resilient modulus (Mr) values for the pavement foundation layers are used in both rigid and flexible pavement design, yet in situ Mr values have not been directly measured as part the current statewide ME calibration process. To date, the ME calibration process for foundation input parameters has relied upon on limited and time-consuming laboratory testing and adopting conservative values based on historical numbers and empiricism. The next big step forward in Iowa’s ME pavement design optimization and reliability on foundation input parameters will be realized through collecting in situ and direct measurements of Mr for a wide range of typical subgrade and subbase materials used in the foundation layers. Innovations in automated plate load testing (APLT) to directly measure the in situ stress-dependent Mr now makes modulus measurement direct and rapid. This technology has been proven in recent years on several projects and is ready for deployment statewide to assist with the statewide calibration. (TASK 1) – Project Management: Within one month of starting work on this project, a Technical Advisory Committee (TAC) will be established. The TAC will provide technical advice throughout the project and review information and reports. The TAC will consist of a group of 4 to 6 Iowa Department of Transportation (IDOT) representatives, preferably from the districts where the projects will be selected for field testing. The project management task will be carried out throughout the project. In addition to establishing the TAC, other ongoing efforts will be completed throughout the duration of the study. This includes the following activities: (1) Discuss potential field project opportunities, (2) Provide quarterly updates to IHRB, (3) Conduct conference calls with TAC, and (4) Project Tracking. Deliverables: Quarterly updates, project tracking, minutes from TAC conference calls. (TASK 2) – Project Selection and Field Testing: The research team will coordinate with the IDOT Construction and Soils Design group and the District offices to select the 10 to 12 project sites for field testing. Projects will be selected to be representative of the soil and projects conditions statewide including compacted aggregate base layers with virgin aggregates and recycled aggregates, compacted select subgrade soils, compacted special backfill materials, and stabilized layers (e.g., fly ash, cement, and geosynthetics). Once the projects are identified, the research team will travel to the selected sites for in-situ testing. The in-situ testing area will include sampling from test sections of about 500 ft to 1000 ft long. At each site, testing includes six to eight 1,100 cycle multi-stress sequence in situ Mr test with 12 in. diameter plate and a layered-kit so that can provide stress-dependent Mr values for composite Mr as well as base and subgrade layer Mr values, and two 30 in. diameter static plate load test to determine k-values. In addition, DCP tests will be conducted at each APLT location. A bulk sample of the materials from each site will be obtained for laboratory characterization/classification. Deliverables: Test results, photos and maps, memo report. (TASK 3) – Assess Results and Develop Recommendations: This task will involve combining all the data reports, summarizing the key findings and observations, and provide guidance for IDOT to use the values in design depending on the project materials. Deliverables: Final Report, Tech Brief, and Presentation.

  • Supplemental Notes:
    • Contract to Performing Organization has not yet been awarded.


  • English


  • Status: Active
  • Funding: $125000
  • Contract Numbers:


  • Sponsor Organizations:

    Iowa Department of Transportation

    800 Lincoln Way
    Ames, IA  United States  50010
  • Project Managers:

    Brakke, Chris

  • Principal Investigators:

    White, David

  • Start Date: 20171005
  • Expected Completion Date: 20190531
  • Actual Completion Date: 0

Subject/Index Terms

Filing Info

  • Accession Number: 01648494
  • Record Type: Research project
  • Source Agency: Iowa Department of Transportation
  • Contract Numbers: ST-003
  • Files: RIP, STATEDOT
  • Created Date: Oct 16 2017 3:13PM