Electromagnetic properties and mechanisms of multiwalled carbon nanotubes modified cementitious composites

The effects of different types and contents of multiwalled carbon nanotubes (MWCNTs) on the electromagnetic wave absorption and shielding properties of cementitious composites as well as their mechanisms were investigated in this paper. Experimental results show that the electromagnetic properties of cementitious composites are improved with the increase of MWCNTs content and size. Besides, MWCNTs is more effective in enhancing the electromagnetic wave absorption performance of cementitious composites. The cementitious composite containing 0.8% of carboxylated MWCNTs with larger tube diameter achieves the best electromagnetic wave absorption property with a minimum reflectivity of 36 dB, which is 4.3 times that of cementitious composites without MWCNTs. The incorporation of 0.8% untreated MWCNTs with larger tube diameter and tube length endows cementitious composites a maximum electromagnetic wave shielding effectiveness of 3.3 dB, which is 27% higher than that of control samples. The electromagnetic wave absorption properties of cementitious composites with MWCNTs are dominated by dielectric loss rather than magnetic loss, and the electromagnetic wave shielding properties are dominated by reflection. (C) 2019 Elsevier Ltd. All rights reserved.