Electromagnetic Shielding Characteristics of High Performance Fiber Reinforced Cementitious Composites

This study aims to investigate the effect of multi-walled carbon nanotubes (MWCNTs) and steel fibers on the electrical conductivity and electromagnetic shielding effectiveness (SE) of a high-performance, fiber-reinforced cementitious composite (HPFRCC). The electrical conductivity of the 100 MPa HPFRCC with 0.30% MWCNT was 0.093 S/cm and that of the 180 MPa HPFRCC with 0.35% MWCNT and 2.0% steel fiber was 0.0173 S/cm. At 2.0% steel fiber and 0.3% MWCNT contents, the electromagnetic SE values of the HPFRCC were 45.8 dB (horizontal) and 42.1 dB (vertical), which are slightly higher than 37.9 dB (horizontal) at 2.0% steel fiber content or 39.2 dB (horizontal) at 0.3% MWCNT content. The incorporation of steel fibers by 3.0 vol. % did not result in any electrical percolation path in the HPFRCC at the micro level; thus, a high electrical conductivity could not be achieved. At the macro level, the proper dispersion of the steel fibers into the HPFRCC helped reflect and absorb the electromagnetic waves, increasing the electromagnetic SE. The incorporation of steel fibers helped improve the electromagnetic SE regardless of the formation of percolation paths, whereas the incorporation of MWCNTs helped improve the electromagnetic SE only under the condition that percolation paths were formed in the cement matrix.