Correlating Intelligent Compaction Data to In Situ Soil Compaction Quality Measurements

AbstractIntelligent compaction (IC) technologies yield a large number of data useful for quality control and quality assurance (QC/QA) in the construction of soil subgrade and embankments. A main challenge of using IC technologies for QC/QA is that the empirical relationships between IC data and in situ measurements are not clear, which prevents transportation agencies from developing an equivalent-criteria specification for the use of IC as a QC/QA tool. This paper describes the results from an experimental research study that was conducted for the Indiana Department of Transportation (INDOT) to assess the correlations between IC data and in situ measurements of compaction quality. Instead of a specifically prepared test site, all the data were collected from a section of U.S. Highway 31 that was under construction. Two types of IC data, compaction meter value (CMV) and machine drive power (MDP), were collected along with the corresponding positions of the rollers. In situ measurements were also conducted to independently assess soil compaction, including dynamic cone penetrometer (DCP), falling weight deflectometer (FWD), and lightweight deflectometer (LWD). Averages of the IC measures were obtained from the local areas of the in situ measurements for correlation analysis. The correlation results provide insights for a state highway agency (SHA) to determine how it may rely on IC for QC/QA in soil compaction. Observed correlations confirm the promise of using IC results to substitute traditional in situ measurements in acceptance tests, which can reduce the requirements for inspection staff to perform in situ tests. The results also suggest that the identification of weak areas, rather than determining acceptance, is the most readily attainable application of IC for QC/QA with soils, particularly with respect to CMV.