Study on shielding properties of cement-based composites doping carbon materials

The cement-based composite shielding materials was made of cement and shielding mediums, such as graphite, carbon black, carbon fiber, nano-carbon-tube et al, which were dispersed by different method. The effects of these shielding mediums on shielding properties were studied and the relationships of the content of carbon fiber and nano-carbon-tube between shielding effectiveness were also discussed. The conductivity of cement-based composite materials and the uniformity distribution of shielding medium were characterized by four-point probe meter and electron probe X-ray microanalyzer. The results indicated that the electric performance of cement-based composites doped carbon fiber were better than the specimens doped nano-carbon-tube, graphite and carbon black. When the content of carbon fiber reached 5vol.%, the shielding property of specimen was best in 100 kHz-1.5 GHz frequency range, the average shielding effectiveness was about 37dB and the maximum shielding effectiveness was 40 dB.