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Quantifying Bridge Deck Corrosion with Ground Penetrating Radar

N. MARTINO, R. BIRKEN, K. MASER, M. WANG

Abstract


Throughout the life cycle of a bridge deck the most expensive part to maintain is the deck. The deck is replaced at least once and rehabilitated many times. However, the deck is the most important part of the bridge because it carries the traffic yet it is also exposed to harsh elements like deicing salts during the winter months. These deicing salts penetrate through the concrete and cause the reinforcing steel to corrode. The results of corrosion are cracks, delaminations and spalls. Current inspection methods, like visual inspection and chain drag, used to determine the deterioration condition of reinforced concrete bridge decks do not provide enough quantitative information about the deck. Nondestructive evaluation techniques like ground penetrating radar (GPR) have the ability to accurately and efficiently assess the internal composition of the deck by rapidly scanning over the surface at highway speeds. Previous research has shown that the electromagnetic signals emitted from GPR antennas are attenuated, or their amplitude is reduced when corrosion of the reinforcing steel is present. However, it is not completely clear how the various components of corrosion (i.e. cracking, rust or chloride) contribute to the signal attenuation at the rebar level. This research seeks to break down each component of corrosion individually and by using computational modeling, investigate the signal attenuation at the rebar level. In addition to previous literature, pieces of a highly corroded bridge deck once in-service were used to understand the physical effects of rebar corrosion.

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