Condition assessment of concrete structures using a new analysis method: Ground-penetrating radar computer-assisted visual interpretation

Many transportation authorities in the United States and Canada require condition assessments of concrete bridge decks and roadways as part of scheduled rehabilitation and maintenance programs. Nondestructive test (NDT) methods and laboratory studies are commonly used by engineering consultants to perform these evaluations. Amongst typical NDT methods, ground-penetrating radar (GPR) is one of the best suited to accomplish this task. Unfortunately, reported test results are oftentimes ambiguous, due to the current numerical analysis approach to evaluate the data. This paper describes some of the shortcomings of numerical analysis of GPR profiles and it introduces an alternative method developed by the authors. Several examples of actual field investigations are described, where the computer-assisted visual interpretation of GPR profiles was used to validate and eventually improve this new analysis approach. The authors’ project experiences on several structures indicate that mapping defects by visual identification of corrosion-induced anomalies in concrete is a much more accurate way of mapping defects. The results obtained from the field applications suggest that use of the computer-assisted visual interpretation of GPR data is an efficient and reliable approach that can be used by experienced GPR analysts.