The use of ground penetrating radar to determine corrosion risk potential for steel reinforced exposed concrete bridge decks

The research undertaken for this thesis advances the level of sophistication with which material properties and the risk of corrosion damage in steel reinforced concrete structures can be predicted using Ground Penetrating Radar (GPR). The purpose of this research was to evaluate GPR data from exposed-surface reinforced concrete bridge decks more effectively. The thesis describes relationships between the GPR measurements and condition of the concrete, which are then incorporated into an innovative new process that can be used to estimate the present risk and future timing of corrosion activity within such decks. These predictions of corrosion activity are based on a combination of in-situ nondestructive measurements using GPR and destructive evaluation of drilled core samples. They consist of both material and structural properties of the reinforced deck at each measured bar location including a refined GPR-based estimate of cover depth, water-soluble chloride diffusivity of the concrete, the variation in surface concentration of water-soluble chloride ions on the in-service deck, and the interpreted concentration profile of water-soluble chlorides over the cover depth.; The corrosion risk assessment method presented in this thesis incorporates the positive attributes from current state-of-the-art methods with a stronger, more robust, technical structure. The values predicted by this method permit an analyst to estimate the time at which corrosion should initiate, which will allow for a more effective scheduling procedure for maintenance and repair. The variations in these predicted values over the deck surface are portrayed in the form of contour plots of water-soluble chloride concentrations and remaining time until repairs are required. This is a novel approach, where reinforced concrete decks have been evaluated with respect to corrosion damage in terms with which maintenance engineers are familiar. The result is a more reliable and practical deliverable, which increases the value of the current GPR analyses for the client.