Approach to Assess As-Built Moduli of Compacted Foundation Layers Using Intelligent Compaction

The satisfactory performance of well-designed pavement sections hinges on the appropriate compaction of layers in the field, especially compacted geomaterials forming the foundation layers. In-situ spot density tests are standard practice for assessing the compaction effort, even though the mechanistic-empirical design procedures are based on layer moduli. The state of the practice in in-situ density measurements, and more recently modulus measurements, relies on limited in-situ spot testing meant to represent a large area of compacted geomaterial. Intelligent compaction (IC) can be utilized to access the as-built moduli by vibratory rollers across the entire compacted geomaterial area to overcome the limitation of spot density tests. This paper presents an approach to assess the layer-by-layer variation in the as-built moduli. The real-time IC mapping process has proved to be practical, efficient, and robust. The assessment results can be obtained by combining the IC measurement values (ICMV) with limited lightweight deflectometer (LWD) measurements for local calibration and laboratory-based resilient modulus nonlinear parameters. The method's veracity and applicability are demonstrated through comprehensive data from two cells collected during the Minnesota Road Research Facility (MnROAD) reconstruction. The assessment results showed that the local in situ calibration of the ICMVs with the limited LWD modulus is necessary to obtain accurate layer-specific as-built moduli.