Design Guide for Improved Quality of Roadway Subgrades and Subbases (TR-525)
Iowa SUDAS, which develops specifications and guidance for urban construction
- Larry Stevens
- Halil Ceylan, 515-294-8051, email@example.com (project list)
- David White, 515-294-1463, firstname.lastname@example.org (project list)
Start date: 01/01/05
End date: 09/30/08
Report: September 2008, Final Report: Design Guide for Improved Quality of Roadway Subgrades and Subbases (TR-525) 2.7 mb (*pdf)
Related publications: Tech Transfer Summary: Design Guide for Subgrades and Subbases 285 kb *pdf (Tech transfer summary) September 2008
*To read pdf files, you may need to download the free Adobe Acrobat Reader.
Sponsor(s):Iowa Highway Research Board
About the research
The performance of a pavement depends on the quality of its subgrade and subbase layers; these foundational layers play a key role in mitigating the effects of climate and the stresses generated by traffic. Therefore, building a stable subgrade and a properly drained subbase is vital for constructing an effective and long lasting pavement system. This manual has been developed to help Iowa highway engineers improve the design, construction, and testing of a pavement system's subgrade and subbase layers, thereby extending pavement life. The manual synthesizes current and previous research conducted in Iowa and other states into a practical geotechnical design guide (proposed as Chapter 6 of the SUDAS Design Manual) and construction specifications (proposed as Section 2010 of the SUDAS Standard Specifications) for subgrades and subbases. Topics covered include the important characteristics of Iowa soils, the key parameters and field properties of optimum foundations, embankment construction, geotechnical treatments, drainage systems, and field testing tools, among others.