ELECTROMAGNETIC PROPERTIES OF CONCRETE AT MICROWAVE FREQUENCY RANGE
Electromagnetic properties of hardened concrete specimens are measured over a microwave frequency range from 0.1 GHz to 20 GHz. The experimentally obtained values provide information about the behavior of concrete as a material in its interaction with electromagnetic waves. In addition to the frequency variation, the effect of different moisture contents on the electromagnetic properties are studied. Properties of mortar specimens and constituents of concrete--that is, coarse aggregates, sand, and cement--are also measured. An open-ended coaxial probe method is used for the measurement of real and imaginary parts of complex permittivity of concrete. The physical significance of the measured data in nondestructive testing, including penetration depth and detectability, is discussed and demonstrated through radar measurement results. The results of this research work will serve as a basis in applying wideband microwave imaging techniques for nondestructive testing of concrete using radar.