NDE for corrosion detection in reinforced concrete structures – a benchmark approach

Corrosion of steel reinforcements is the main cause of damage and early failure of reinforced concrete structures in civil engineering, leading to enormous costs for inspection, maintenance, restoration and replacement of the infrastructure worldwide. Conventional methods for detecting corrosion are based on electrochemical techniques such as half-cell potential and linear polarization. These methods can be affected by a number of factors and require direct contact with the concrete. To overcome difficulties with conventional inspection techniques a benchmark project using and evaluating state-of-the-art NDE methods is set up at FHWA’s Turner-Fairbank Highway Research Center. The aim is to devise a test protocol for structural health monitoring (and asset management) of concrete structures by performing periodic baseline NDE surveys. For this a typical bridge deck specimen is cast, corroded and cyclic loaded. The benchmark project incorporates the latest developments in NDE inspection methodologies. A special focus lies on the promising technique of time-resolved thermography with induction heating combined with 3-D microwave imaging—a research cosponsored by the US National Research Council NRC.