Electromagnetic interference shielding reaching 70 dB in steel fiber cement

An electromagnetic interference (EMI) shielding effectiveness of 70 dB at 1.5 GHz has been attained in cement paste that contains 0.72 vol.% stainless steel fibers of diameter 8 lint and length 6 mm. The shielding is primarily by reflection. The material exhibits electrical resistivity 16 Omega cm. The presence of sand essentially does not affect the shielding effectiveness. The fibers remain effective in the presence of steel rebars. For comparison, the shielding effectiveness of a solid piece of stainless steel is 78 dB at 1.5 GHz. (C) 2003 Elsevier Ltd. All rights reserved.