Broadband electromagnetic wave absorbing performance by designing the foam structure and double-layer for cement-based composites containing MWCNTs

This work fabricated foamed cement-based composites with different densities, MWCNTs content, and double-layer design with different layer combinations. Not only were the EMW-absorbing performance and mechanism of these composites investigated, but the mechanical properties were also examined. Single-layer composites' optimum EMW absorption performance showed an effective absorption bandwidth (EAB) of 9.76 GHz and RLmin of −13.6 dB. Compared to the single-layer samples, the double-layer samples showed the wider EAB of 12.7 GHz, RLmin of −32.9 dB at the same thickness, furthermore EAB of 14 GHz, and lower RLmin of −47.3 dB at 30 mm thickness. Attributing to the specific porous system and the internal micro conductive network, a synergistic effect of improved impedance matching characteristic and superior EMW attenuation of the double-layer composite was achieved.