CTRE is an Iowa State University center, administered by the Institute for Transportation.

Address: 2711 S. Loop Drive, Suite 4700, Ames, IA 50010-8664

Phone: 515-294-8103
FAX: 515-294-0467

Website: www.ctre.iastate.edu/

Iowa State University--Becoming the Best

Improving the Foundation Layers for Concrete Pavements

Pavement foundation study reveals non-uniform support conditions

States involved in the pooled fund study and field project locations

Segregation of aggregate base surface following trimming operations

Kuab FWD testing on concrete pavements


Field testing of injected high-density polyurethane foam-stabilized base under concrete pavements


Principal investigators:

Co-principal investigators:

Project status

In progress

Start date: 03/16/09
End date: 12/31/18



Related publications:



About the research


The objective of this research is to improve the construction methods, economic analysis and selection of materials, in situ testing and evaluation, and development of performance-related specifications for the pavement foundation layers. The outcome of this study will be conclusive findings that make pavement foundations more durable, uniform, constructible, and economical.

All aspects of the foundation layers were investigated, including thickness, material properties, permeability, modulus/stiffness, strength, volumetric stability, and durability. Forensic and in situ testing plans were conceived to incorporate measurements using existing and emerging technologies (e.g., intelligent compaction) to evaluate performance-related parameters as opposed to just index- or indirectly related parameter values. Field investigations were conducted at various sites in multiple states.

The results of the study will be compatible with the Mechanistic-Empirical Pavement Design Guide (MEPDG). Evaluating pavement foundation design input parameters at each site provides a link between what is actually constructed and what is assumed during design. There are many inputs to the pavement design related to foundation layers and this project will provide improved guidelines for each of these. The study will benefit greatly from maximizing the wide range of field conditions possible with a study across a variety of soil and climatic conditions.

Detailed and comprehensive field studies were carried out for existing pavement sections that have good and poor performance and also new pavement foundation construction. In situ testing was extensive and involved the current state of practice and emerging testing technologies, including non-destructive methods and intelligent compaction. Comprehensive project reports were submitted from each site summarizing the findings from the field investigations. Further, an interactive open house was conducted at each site to facilitate discussion and review of the field measurements.

The final report generated as part of this project will be a compilation of what we know now and all the new knowledge gained during the course of this study. It will include best construction practices to provide stable and uniform pavement foundations, guideline quality control/quality assurance (QC/QA) testing recommendations, design aids, and suggested improvements to specifications. The results presented in the final report will guide the state-specific studies as part of the Transportation Pooled Fund Study in development of the Manual of Professional Practice for Design, Construction, Testing and Evaluation of Concrete Pavement Foundations.