Laboratory Evaluation of the Geogauge and Light Falling Weight Deflectometer as Construction Control Tools

Abstract

The objective of this paper is to assess the potential use of the geogauge and the light falling weight deflectometer (LFWD) as quality control/quality assurance (QC∕QA) devices for testing subgrades, base courses, and compacted soil layers. A comprehensive laboratory experimental program was conducted on compacted layers of silty clay, clayey silt, cement-treated clay, sand, gravel, recycled asphalt pavement, and limestone aggregates. The geogauge, LFWD, static plate load test (PLT), and the dynamic cone penetration (DCP) measurements were acquired for the constructed layers. The geogauge elastic modulus and the LFWD dynamic modulus were correlated with the PLT initial and reloading elastic moduli and with the DCP penetration rates. The results of this study show that the geogauge and the LFWD can be used to calculate the elastic modulus/stiffness characteristics of compacted layers. Whereas the geogauge and the LFWD determined the initial modulus of the cement-treated clay, they did not yield accurate measurements of strength gain with time. Good statistical correlations were found between elastic moduli measured by the devices used in this investigation.