Application of Innovative Tools in Optimizing Risk and Cost of Subgrade QA/QC

During the reconstruction of the Ohio Turnpike, data were collected from construction sites using non-destructive tools. This study was done in two phases: the first one included using the Light Weight Deflectometer (LWD) and Automatic Dynamic Cone Penetrometer (ADCP) to evaluate the subgrade, which was recommended to be stabilized. The second phase included using the Falling Weight Deflectometer (FWD) and Ground Penetration Radar (GPR) to evaluate the structural capacity of the entire pavement. The data generated from these tests were statistically analyzed and compared with traditional measurements to develop QA/QC procedures that optimize risk and cost. This article sheds lights on the first phase of the study, which was mainly concerned with subgrade characterization using LWD and ADCP. The ADCP and LWD data correlated fairly well. Both the ADCP and LWD provide a measure of stiffness, whereby the nuclear density gauge provides a measure of density. In comparison, the LWD seems to be the most promising QA/QC candidate. It was the most cost-effective among the three tests, had the highest rate of production, and was the most reliable.