In highway construction, the nuclear density gauge (NDG) is the industry standard for measuring soil density and moisture. They are widely used at state transportation agencies, however, because of their reliance on radiation, NDGs are expensive to maintain and have unique storage requirements. Operators must also earn specialized certifications and adhere to rigorous safety protocols. Equipment manufacturers have developed several non-nuclear density gauges which are more user friendly, however, their accuracy has sometimes not equaled NDGs. This comparative study evaluated the performance of the eGauge (a relatively new device) to NDGs. Over 100 soil density and moisture measurements were collected from nine field sites throughout Kentucky. At sites characterized by silt/clay and shale or stabilized clay, NDGs and the soil density eGauge produced statistically similar soil density readings, while significant differences were observed for clays and full depth reclamation (FDR). Across all sites, 82.5% of the NDG and eGauge density readings were within +/- 5% of one another. For soil moisture, readings from NDGs and the eGauge were compared to samples dried in an oven laboratory. At sites characterized by silt/clay and shale, the NDGs, eGauge, and lab samples yielded significantly different measurements, while at sites with clay the eGauge measures differed significantly from those acquired via NDGs and the lab samples. No significant differences were noted for stabilized clays. Based on raw data, 88.2% of NDG and 48.0% of eGauge soil moisture readings were within +/- 5 percentage points of the corresponding lab measurement. For most soil types, the eGauge produces sufficiently accurate readings for field use, although further study of clays and FDR is needed.

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