Nondestructive corrosion detection in concrete through integrated heat induction and IR thermography

Abstract

A novel integrated system of electromagnetic heat induction and infrared (IR) thermography is proposed for nondestructive detection of steel corrosion in reinforced concrete (RC) structures, by taking advantage of the difference in thermal characteristics of corroded and non-corroded steel. This paper presents a proof-of-concept experimental study. An inductive heater was employed to remotely heat the steel rebar from concrete surface, and an IR camera was applied to measure IR intensity at the concrete surface. Bare rebar and concrete specimens with different cover depths were fabricated, and induced with different levels of corrosion through an accelerated corrosion process. IR thermography was recorded during the specimen heating and cooling periods. The test results reveal a clear correlation between the extent of corrosion and the IR thermal characteristics. More corroded specimens exhibit higher peak IR intensities and faster rates of heating than those of less corroded specimens. As the concrete cover depth increases, however, it becomes less efficient to heat the rebar and more difficult to identify the difference between corroded and non-corroded specimens using the IR camera. This study demonstrates a potential application of the integration of heat induction and IR thermography for nondestructive detection of rebar corrosion in concrete structure.