Absorbing Properties of Cement Mortar Filled with Porous Aggregates

The absorbing properties of cement mortar filled with porous aggregates,such as expanded polystyrene,expanded perlite and shale,were investigated.The results show that porous aggregates can improve the impedance matching characteristic of the composites,and attenuate the electromagnetic wave by mulitple scattering and reflection.The filling ratio,the type and the size of porous aggregates all had effects on the absorbing properties.Among the aggregates used,the expanded polystyrene(EPS) had a su-perior ability to improve the absorbing properties of cement composite.When the filling ratio of EPS with the size of 2 mm to cement was 1:1 in volume,the lowest reflectivity of-18 dB was obtained at 4.5 GHz and the bandwidth less than-10 dB was 8.1 GHz.