Quantitative Evaluation of Select Materials in Subgrade Alternatives

Wisconsin Department of Transportation (WisDOT) has had a statewide policy in place for approximately 20 years where a select materials layer should be included beneath the pavement section in areas deemed difficult for subgrade construction. These areas are well-distributed throughout the state and notably include subgrades comprising silty soils, silty clay soils, soft clay soils, soils with high organic content, and other soils with a history of problems for construction. The WisDOT Facilities Development Manual (FDM) identifies and maps areas where problematic subgrade soils predominate in the form of Standard Inclusion Areas and warrant the design and application of a select materials layer. Ten select materials alternatives are provided in the FDM 11-5 and are assumed to provide an equivalent level of subgrade improvement. While the FDM provides 10 “equivalent” options, there is uncertainty regarding the true equivalency of each alternative. There is an urgent need to systematically and quantitatively evaluate the equivalency of alternative materials and options to address this limitation. Doing so will (1) provide cost savings by mitigating expenses and limited availability of select materials in many locations of the state, (2) provide designers with the confidence that alternatives will effectively perform, (3) reduce energy consumption and transportation emissions (e.g., long hauling distances) by more frequent use of locally sourced materials, and (4) foster sustainable development with beneficial use of alternatives including industrial by-products and recycled materials.

Language

• English

Project

• Status: Proposed
• Sponsor Organizations:

  Michigan State University, East Lansing

  East Lansing, MI  United States  48824
• Start Date: 20261002
• Expected Completion Date: 0
• Actual Completion Date: 0

Subject/Index Terms

• TRT Terms: Alternatives analysis; Materials selection; Pavement subgrade
• Subject Areas: Highways; Materials; Pavements;

Filing Info

• Accession Number: 01979818
• Record Type: Research project
• Source Agency: Wisconsin Department of Transportation
• Files: RIP, STATEDOT
• Created Date: Feb 18 2026 11:37AM