Corrosion detection in reinforced concrete using induction heating and infrared thermography

A novel non-destructive technique of corrosion detection in reinforced concrete based on a combination of induction heating (IH) and infrared thermography was investigated. The technique is based on the principle that corrosion products have poor heat conductivity, and they inhibit the diffusion of heat that is generated in the reinforcing bar due to IH. Corrosion can thus be detected by determining the temperature profiles on the surface of concrete. Small idealized reinforced concrete specimens were employed, and the impressed current method was used to generate corrosion. The influences of rebar diameter, cover depth, corrosion amount, and heating time on the temperature distribution on the concrete surface were investigated. It was found that the proposed techniques worked well and greater the extent of corrosion, smaller was the temperature rise on the concrete surface. A more advanced state of corrosion also led to a higher temperature rise in the rebar itself. The technique worked particularly well when either the diameter of the rebar was large or when the cover depth was small.