Research on the absorbing characteristics of cement matrix composites filled with carbon black-coated expanded polystyrene beads

A new cement matrix composite filled with carbon black-coated expanded polystyrene (EPS) beads was developed. The electromagnetic reflection loss of this composite in the frequency range from 2·6 to 8 GHz was studied experimentally. It was shown that filling with carbon black (CB)-coated EPS beads can improve the reflection loss of plain cement-based materials greatly, and the EPS filler ratio and sample thickness all have remarkable effects on the electromagnetic wave reflection loss of this cement matrix composite material. With a CB-coated EPS filler volume concentration of 80% and sample thickness of 20 mm, the reflection loss can reach −24 dB in the range 2·6-8 GHz and the bandwidth for −10 dB reaches 3 GHz. This composite material still has a relatively low bulk density and can be handled easily.