Method for attenuation assessment of GPR data from concrete bridge decks

Abstract

Ground penetrating radar (GPR) is a well-accepted technology for condition assessment of concrete bridge decks. Such assessment has been mainly based on the measurement of attenuation of a signal reflected from the top rebar mat. Recently, a new approach for GPR data interpretation has been proposed, which is based on the correlation analysis of time-series GPR data. Motivated by that same research, the current paper presents an alternative method for performing the GPR attenuation analysis. In this method, instead of requiring time-series or baseline data, semi-simulated waveforms are developed and employed in a correlation analysis. With only one reflection retained from direct coupling, these waveforms mimic A-scans collected on a completely deteriorated bridge deck. The obtained results are then plotted in a form of contour maps of correlation coefficients, in which a higher value coefficient indicates more deteriorated concrete. The method was validated through its implementation on three bare concrete bridge decks. The condition maps from the proposed GPR correlation analysis correlate well to those obtained using the conventional GPR amplitude approach, and condition maps from several other nondestructive evaluation (NDE) techniques. However, in comparison to the conventional amplitude analysis, the proposed method provides a better description of the overall deterioration of bridge decks.