Embankment Quality: Phase I and Phase II

Project Investigators

Charles Jahren, Ken Bergeson, David White

Project Schedule

May 1997 to Apr 1998


Iowa Department of Transportation, Iowa Highway Research Board


construction, embankments, soil

Project Description

Iowa has experienced flexible pavement roughness and slope stability problems on some recently constructed projects. It is suspected that the problems may be caused by the use of unsuitable soils and/or improper compaction and compaction moisture content. Sheepsfoot roller walkout is the current acceptance procedure for embankment compaction. This qualitative specification is totally dependent on the experience and judgment of field construction staff.

Rapid methods of field soil classification and improved training are required for field personnel. It is necessary to investigate alternative methods for embankment compaction acceptance and consider them for possible adoption.

The objective of this research is to evaluate the current compaction method and acceptance, to provide suggestions for new compaction procedures, and to recommend methods of testing and acceptance. In addition, current methods of disposal of unsuitable soils within the embankment relative to impact on roughness and slope stability need to evaluated.

The objectives of this, the first phase of the research project, are as follows:

  • Identify embankment failures in Iowa and assess potential causes
  • Investigate rapid practical methods for field identification and classification of soils during construction projects
  • Identify factors that would be needed to obtain high quality embankments and identify factors that would lead to low quality embankments
  • Identify a list of alternative soil embankment acceptance procedures (this list will receive further consideration during Phase II)
  • Evaluate current methods of unsuitable oil disposal It is anticipated that pavement performance will be enhanced when improvements are made to the field soil selection and compaction acceptance processes