Practical Evaluation of Bridge Deck Reinforcement Corrosion Using Ground Penetrating Radar, Half-Cell, and Sounding.

Currently many Departments of Transportation rely almost entirely on visual inspections and sounding (chain drag) to assess the condition of bridgedecks. While these techniques have their place, they also have limitations. Several non-destructive techniques which provide a more objective evaluation of condition exist to evaluate reinforced concrete bridge decks. Ground Penetrating Radar (GPR) uses radar waves to provide information about subsurface characteristics, i.e. those items that cannot be seen visually. Thus, this technique shows promise for evaluating what is occurring in bridge decks. The use of GPR on the concrete bridge decks with concreteoverlays has not been standardized. In order to develop a methodology for use of the GPR technique for bridge deck evaluations, the Indiana Department of Transportation has evaluated more than 25 bridge decks over the past two years. These decks were evaluated using a combination of nondestructive (NDE) techniques such as GPR, Half-Cell, and sounding. In this paper,the results from GPR measurements are compared to standardized NDE techniques: half-cell and sounding. Three specific bridges are chosen as examples. The results indicate that all three methods employed can be used to locate deteriorated areas in reinforced concrete bridge decks. Additionally, the GPR technique compared favorably with the half-cell technique in determining the extent of damage on the bridge decks.