Microwave thermoreflectometry for detection of rebar corrosion

Jane W. Maclachlan Spicer; Robert Osiander; Leonard C. Aamodt; Robert B. Givens

doi:10.1117/12.300111

31 March 1998 Microwave thermoreflectometry for detection of rebar corrosion

Jane W. Maclachlan Spicer, Robert Osiander, Leonard C. Aamodt, Robert B. Givens

Proceedings Volume 3400, Structural Materials Technology III: An NDT Conference; (1998) https://doi.org/10.1117/12.300111
Event: Non-Destructive Evaluation Techniques for Aging Infrastructure and Manufacturing, 1998, San Antonio, TX, United States

Abstract

A microwave-based approach under development for detecting corrosion of rebar is described. The rebar inside the concrete is heated with an induction heater and then the surface temperature of the rebar inside the concrete is probed using a microwave reflectance method. This is in contrast to infrared thermographic approaches which monitor the surface temperature of the concrete and are dependent on waiting for considerable lengths of time for heat flow from the rebar to the concrete surface. Results will be presented for a series of test specimens produced by deliberately corroding rebar inside concrete in the laboratory. Microwave thermoreflectance measurements made in a 5 second measurement time are compared with conventional thermographic measurements of the temperature distribution at the concrete surface which require a 10 minute measurement time. Theoretical results are also presented of the predicted temperature versus time curves expected for rebar inside concrete with and without air defects at the rebar-concrete interface. These results predict that a rebar-concrete interface could be distinguished from a rebar-air interface with only 1 second of heating. The theoretical results further show that the presence of an air layer of finite thickness between rebar and concrete after about 2 seconds could be detected with a 2 second heating time.

Citation Download Citation

Jane W. Maclachlan Spicer, Robert Osiander, Leonard C. Aamodt, and Robert B. Givens "Microwave thermoreflectometry for detection of rebar corrosion", Proc. SPIE 3400, Structural Materials Technology III: An NDT Conference, (31 March 1998); https://doi.org/10.1117/12.300111

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