GPR inspection of concrete bridges

Ground-penetrating-radar (GPR) has become an important method for the non-destructive testing of concrete bridges. Although there are standards and guidelines available today, the quality of results does not only depend on the object inspected but also on the qualification and experience of the team carrying out the radar survey. This situation is unsatisfactory for engineers that have to decide whether a radar survey is suitable to solve their problem.EMPA has been active in the field of non-destructive testing of concrete structures for more than ten years. During this time, procedures for efficient data acquisition, processing interpretation and reporting have been developed. In addition, a large number of concrete structures has been inspected for research and services.In a research project completed in 2005, radar inspections using the EMPA approach were carried out on bridges designated for demolition. Results were laid open before the bridges were taken down. After the demolition radar results were verified with the help of the bridge parts. Thus, the accuracy and reliability of radar surveys was quantified under realistic circumstances.