Electromagnetic wave absorption properties of cement-based composites filled with graphene nano-platelets and hollow glass microspheres

The cement-based composites made from graphene nano-platelets (GN) and hollow glass microspheres (HGM) were prepared and its electromagnetic waves absorbing properties were researched in this work. Results show that the absorbing properties were improved after the combination of GN and HGM. As the filling ratio of glass microspheres increases, the value of absorption peak and the bandwidth below −5 dB increases at first and decreases afterwards. In addition, several sharp peaks were obtained and the values tend to appear at high frequency. With further increase of GN, the value at absorbing peak decreases and the curves become relatively flatter. When GN is 0.2%, HGM is 40% (vol/vol) and the thickness is 20 mm, materials have the excellent absorbing properties with the average reflectivity loss being −8.2 dB in the range of 2-18 GHz and the bandwidth was 4.4 GHz below −5 dB. The thickness of sample has a significant influence on the absorbing properties. The optimal thickness is 20-30 mm with 40% (vol/vol) HGM and 0.2% (wt/vol) GN combine together.