Investigation on the electromagnetic wave absorption properties of foamed cement-based materials

To prevent the electromagnetic pollution of the architectural space, the foamed cement-based materials with high electromagnetic wave (EMW) absorption performance and wide effective absorption bandwidth (the reflectivity less than-10 dB) was fabricated in this study. EMW absorption performance of foamed cement-based materials was investigated, and the mechanism of EMW transmission and attenuation were analyzed. The results show that porosity, sample thickness, and pore size have remarkable effects on the EMW absorption perfor-mance. With the porosity of 61.5 %, the thickness of 40 mm, and the mean pore diameter of 301 mu m, the effective absorption bandwidth reaches 12.7 GHz in the range of 2-18 GHz. The excellent EMW absorption capacity of foamed cement-based materials is mainly due to the introduction of pores, which improve the impedance matching properties and increase scattering and multiple scattering as well as coherent attenuation. Foamed cement-based materials with high EMW absorption performance, low bulk density, and cost can be deemed an ideal candidate for EMW absorption in engineering.