Effectiveness of Ground Penetrating Radar in Predicting Deck Repair Quantities

Abstract

Ground penetrating radar (GPR) was examined as an alternative or supplement to visual inspection methods for predicting reinforced concrete bridge deck repairs. Visual inspection has frequently resulted in grossly inaccurate estimates of repairs causing large maintenance cost overruns. GPR-predicted deteriorations were compared to deterioration detected using the chain drag and half-cell potential methods on 24 asphalt covered reinforced concrete decks exhibiting a broad spectrum of deterioration levels. The differences among the deterioration quantities resulting from these surveys were normalized for comparison with respect to the deterioration area and deck size. Large proportions of all decks surveyed containing less than 10% and more than 50% deterioration of the total deck surface area (as measured by chain drag) exhibited significant differences between the GPR and both ground-truth survey quantities. Insignificant differences between GPR predictions and the ground-truth results were observed for six out of seven decks exhibiting deterioration levels between 10 and 50% (by chain drag). It is concluded from this investigation that a combination of visual inspection and GPR inspection surveys for all decks can improve repair estimates and reduce the occurrence of gross underestimates of repair quantities.