Synergistic effect of MWNT/fly ash incorporation on the EMI shielding/absorbing characteristics of cementitious materials

The present study aims to develop electromagnetic interference (EMI) shielding materials of which the EM wave shielding/absorbing capabilities were enhanced by a synergistic effect of multi-wall carbon nanotube (MWNT) and fly ash (FA) in terms of EM characteristics. The MWNT/FA-added cementitious materials were fabricated with various content ratios of FA and silica fume (SF). SF was incorporated as a dispersion agent of MWNT and EMI shielding effectiveness (SE) of the cementitious materials was assessed in an effort to determine optimum content ratios of FA and SF. The best EMI SE was achieved by the specimen comprised of MWNT 0.6%, SF 20%, and FA 75% (C-FA75-SF20) as exhibiting -8.0 similar to -57.1 dB at a frequency range from 1 to 18 GHz, indicating a synergistic effect of MWNT and FA. The superior EMI SE of the C-FA75-SF20 was assessed by three different tests, i.e., SEM observation, energy-dispersive X-ray spectroscopy analysis, and electrical & electromagnetic properties evaluation. Furthermore, a computational simulation work demonstrated that the experimental EMI SE results of the C-FA75-SF20 correspond to the simulation results. (C) 2016 Elsevier Ltd. All rights reserved.