PHENOMENOLOGY STUDY OF HERMES GROUND-PENETRATING RADAR TECHNOLOGY FOR DETECTION AND IDENTIFICATION OF COMMON BRIDGE DECK FEATURES

Abstract

Accurately evaluating the condition of a bridge deck over time and using this information to choose appropriate maintenance techniques has become critical for the efficient allocation of resources to bridge deck maintenance. Tomographic imaging of subsurface bridge deck features using ground penetrating radar (GPR) is one method of addressing this problem that has been pursued through a research program at the Federal Highway Administration (FHWA) Nondestructive Evaluation Validation Center. Prototype GPR systems, developed by Lawrence Livermore National Laboratory (LLNL), have been used in a phenomenology study of several controlled specimens. These specimens were designed with subsurface features that simulate cracks, voids and other common problem phenomena for bridge decks. The specimens have some unique features that make the data collected from them compelling. Results from these phenomenology tests are the primary focus of this paper. Field tests have also been conducted that produced inconsistent results, clarifying the need for system improvements. These improvements are planned for incorporation into a new prototype GPR system currently being developed by LLNL that will be tested by FHWA in the coming year.