Electromagnetic wave absorption enhancement of carbon black/gypsum based composites filled with expanded perlite

The electromagnetic (EM) wave absorbing carbon black (CB)/gypsum based composites with high wave absorption properties and wide effective bandwidth were prepared by filling expanded perlite (EP) simply. The influences of CB contents, EP volume concentration, EP particle size, and thickness of samples on EM wave absorption were investigated, and the absorption mechanisms were analyzed as well. The results indicate that the wave absorption of the composites can be remarkably enhanced, due to the improvement of impedance matching as well as the single and multiple scattering and refractions caused by EP particles. The reflectivity is lower than 10 dB in the frequency ranges of 2-3, 5-6.5 and 8-18 GHz for the sample with 3% CB, when the EP volume concentration and sample thickness are 40 vol% and 20 mm, respectively, with the EP diameter of 1 mm. The prepared composites with low cost and high efficiency can be considered as a promising candidate used in construction engineering for EM wave absorption. (C) 2016 Elsevier Ltd. All rights reserved.