Design Guide for Improved Quality of Roadway Subgrades and Subbases (TR-525)

Project Details
STATUS

Completed

START DATE

01/01/05

END DATE

09/30/08

RESEARCH CENTERS InTrans, CEER, CTRE, PROSPER
SPONSORS

Iowa Highway Research Board

Researchers
Principal Investigator
Vern Schaefer

Interim Director, CEER

Co-Principal Investigator
Larry Stevens

SUDAS Director

Co-Principal Investigator
Halil Ceylan

Director, PROSPER

Co-Principal Investigator
David White

Geotechnical Engineer

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.

TOP