Temperature Dependencies of the Permittivities and Microwave Shielding Effectiveness of a Carbon-containing Electrically Conductive Concrete

Conductive concrete is a construction material that can be utilized for a number of applications: in particular, electromagnetic shielding. In this research, the microwave shielding effectiveness of a carbon containing electrically conductive concrete was determined from both the real and the imaginary permittivities. Also, the permittivities and the shielding effectiveness of a normal concrete were determined for comparison purposes. It was shown that the permittivities of the conductive concrete were significantly higher than those of the normal concrete. The shielding abilities of both of the concretes were determined as a function of concrete thickness and temperature, and the conductive concrete had a superior shielding effectiveness. For the normal concrete, at room temperature and a frequency of 912 MHz, a shielding effectiveness of 30 dB was achieved for a thickness of about 400 cm. For the conductive concrete, under the same conditions, a thickness of only about 3 cm was required to achieve the same shielding effectiveness.