ELECTROMAGNETIC PROPERTIES OF CONCRETE AT MICROWAVE FREQUENCY-RANGE

Electromagnetic properties of hardened concrete specimens are measured over a microwave frequency range from 0.1 to 20 GHZ. The experimental ly obtained values provide information about the behavior of concrete as a material in its interaction with electromagnetic waves. In additi on to the frequency variation, the effect of different moisture conten ts on the electromagnetic properties are studied. Properties of mortar specimens and constituents of concrete-that is, coarse aggregates, sa nd, and cement-are also measured. An open-ended coaxial probe method i s used for the measurement of real and imaginary parts of complex perm ittivity of concrete. The physical significance of the measured data i n 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 wideba nd microwave imaging techniques for nondestructive testing of concrete using radar.