Enhanced GPR system for Rapid Assessment of Chloride Content in Concrete Bridge Decks

Chloride infiltration into concrete is the major cause of bridge deck damage, and knowledge of the degree of chloride infiltration is needed for decisions related to the type, extent, and timing of preservation and rehabilitation efforts. A new method based on a novel implementation of ground penetrating radar (GPR) was evaluated in Phase 1 of this project. This method demonstrated the feasibility of predicting chloride content using GPR data alone on a small group of bridge decks. By calibrating the GPR data for variations from deck to deck, a single chloride-GPR relationship (or “master-curve”) was obtained for all decks, which showed a reasonable correlation. The Phase II project seeks to improve and implement the methodology demonstrated in Phase I by refining the master curve concept through testing and evaluation of a larger group of decks. The implementation will be using a vehicle mounted 3DGPR system coupled with automation of the data analysis with a developed software application. This system will be able to rapidly scan a deck in 15-30 minutes with minimum traffic interference and produce chloride content statistics and contour maps that can be used by bridge owners to project the remaining deck life and determine appropriate rehabilitation strategies.