Intelligent Soil Compaction: Geostatistical Data Analysis and Construction Specifications

Intelligent compaction rollers, which use onboard sensors to measure soil compaction characteristics in real time, have been demonstrated or specified on Mn/DOT construction projects for several years. In 2006, two projects were built using new intelligent compaction specifications adapted from standard earthwork and embankment specifications. The new specifications, the underlying rationale and experience to date are discussed. Intelligent compaction provides a large amount of quantitative compaction data that can be used in three important ways: in real-time to guide the compaction effort, over the course of the project for quality control and quality assurance, and as an archive record of the pavement foundation construction. Geostatistical methods have been used to investigate the spatial characteristics of the compaction data from several projects, with the goal of using these techniques to guide the quality assurance process. Preliminary results show that geostatistics transforms massive amounts of intelligent compaction data into meaningful summary statistics that can be used to judge the adequacy of the compaction. Geostatistics-based visualization can also aid the on-site engineer in focusing limited testing resources on likely problem areas. Used together, intelligent compaction rollers, specifications and geostatistics offer the promise of reducing maintenance costs and increasing pavement life by helping project personnel find and fix subgrade compaction problems before pavement placement.