Reliability Analysis of Ground-Penetrating Radar for the Detection of Subsurface Delamination

Abstract

This article reports on research to experimentally analyze the reliability of ground-coupled ground-penetrating radar (GPR) for the detection and imaging of subsurface delamination in concrete. Experimental studies were conducted that included a RC deck mock-up with synthetic delamination targets and two highway bridge decks. Both of the bridge decks had areas of delamination as determined through sounding, infrared thermography, and some limited physical sampling. Receiver operating characteristics (ROC) analysis was used to evaluate the reliability of GPR when implemented using the procedure described in the current ASTM standard that employs signal reflections from uppermost steel bars. The overall results indicate that GPR had limited ability to detect and image areas of delamination in concrete using the aforementioned ASTM procedure. After almost four decades of implementation of GPR for the condition assessment of concrete bridge decks, confusion remains regarding the ability of GPR to directly detect areas of delamination. The findings from this research should make an important contribution to clarifying this issue to improve decision making for maintenance and repair when considering GPR as a condition assessment tool.