Ceramsite containing iron oxide and its use as functional aggregate in microwave absorbing cement-based materials

Electromagnetic (EM) wave absorbing cement-based composite has promising applications in protecting civil and military buildings from electromagnetic interferences. A new idea of preparing EM wave absorbing cement-based composite is proposed by using ceramsite containing iron oxide as EM wave absorbing functional aggregate. The ceramsite was synthesized by adding 10 wt% Fe 3 O 4 into clay and sintering at 1 200 °C, which shows obvious dielectric and magnetic loss properties for electromagnetic wave. The maximum reflection loss (RL) of the concrete specimens prepared with the ceramsite is between -10.2—10.7 dB (corresponding to absorption greater than 90% EM energy) in the bandwidth of 8-18 GHz. In addition, the compressive strength at 28 days age of the concrete is 46 MPa, showing the potentiality of being used as structural components in buildings.