Time domain reflection technique for microwave non destructive testing of Steel Fiber Reinforced Concrete

Preliminary results of a time domain reflection approach for the non-destructive testing of Steel Fiber Reinforced Concrete (SFRC) are presented in this paper. An open-ended epoxy-filled waveguide and a reflector plate located behind the material sample are used to measure its effective permittivity. An electromagnetic model based on the Maxwell-Garnett approach for dielectric mixtures is used to relate the effective permittivity of SFRC to its fiber dosage. Agreement with the expected dosage figures is obtained. Time domain results are compared with frequency domain results obtained in previous experiments. Conclusions regarding the suitability of this method are derived.