Subsurface Defect Detection in FRP Bridge Decks Using Ground Penetrating Radar

Abstract

While Ground Penetrating Radar (GPR) has been widely used for defect detection in concrete bridge decks and pavements, its use has not been explored for Fiber Reinforced Polymer (FRP) bridge decks. This paper presents the results from an experimental study that investigated the use of GPR for subsurface defect detection in FRP bridge decks. Several FRP bridge deck specimens were cast with embedded subsurface defects (air‐ and water‐filled) of varying planar sizes and thicknesses. These decks were then tested using a GPR system with 2.0 GHz air‐launched and 1.5 GHz ground‐coupled antennas. Results from both antennas have been compared. Both antennas had problems in detecting air‐filled defects but could detect water‐filled defects. Moreover, it was found that because of its closer proximity (ground‐coupling) and higher energy input into the bridge deck, the ground‐coupled antenna could detect smaller defect sizes (water‐filled) much better compared to the air‐launched antenna.