Institute for Transportation

About the research

A full description of the project is available on the Federal Highway Administration pooled fund study website.

CEER team members are involved in the project to provide expertise with compaction monitoring technologies, conduct in-situ testing on field project sites using the Geotechnical Mobile Lab and open houses on field project sites to disseminate project findings, and provide training to agency and industry participants.

About the research

The NCHRP Project 21-09, “Intelligent Soil Compaction Systems,” was undertaken to investigate intelligent soil compaction (IC) systems and to develop generic specifications for the application of IC in quality assurance (QA) of soil and aggregate base material compaction. The term intelligent soil compaction systems was defined to include (1) continuous assessment of mechanistic soil properties (e.g., stiffness, modulus) through roller vibration monitoring; (2) automatic feedback control of vibration amplitude and frequency; and (3) an integrated global positioning system to provide a complete geographic information system-based record of the earthwork site. An equally important term is roller-integrated continuous compaction control—defined by IC components (1) and (3).

Roller-integrated continuous compaction control (CCC) technology was initiated in Europe in the 1970s and has been used in European practice for nearly 20 years. The first European specification for roller integrated CCC was developed in Austria in 1990. Today, four European countries have soil compaction QA specifications using roller-integrated CCC (Austria, Germany, Sweden, and Switzerland) and U.S. states are beginning to implement pilot specifications (e.g., Minnesota). In European specifications the use of automatic feedback control IC rollers is permitted during compaction but not during QA because the roller measurement values (MVs) can be strongly influenced by varying amplitude and frequency. The dependence of roller MVs on frequency and amplitude in particular was verified in this study and further determined to be quite complex and difficult to predict. Accordingly, the recommended specifications developed here allow IC during compaction but do not permit the use of automatic feedback control IC during roller-based QA.

The following are the key items covered in this project:

• Recommended Specifications for Roller Integrated CCC in Earthwork QA
• Fundamentals of Roller Measurement Systems
• Relationship Between Roller-Measured Stiffness and In Situ Stress-Strain-Modulus Behavior
• Evaluation of Automatic Feedback Control-Based Intelligent Compaction
• Correlation of Roller Measurement Values to Spot-Test Measurements
• Case Study Implementations of Recommended Specifications