Electromagnetic wave absorption properties of helical carbon fibers and expanded glass beads filled cement-based composites

The cement based composites for electromagnetic (EM) wave absorption were prepared by introducing helical carbon fibers (HCF) and expanded glass beads (EGB), and the influences of HCF mass fraction, EGB volume fraction, and sample thickness on the EM reflection loss were investigated in 2-18 GHz. Results indicate that the EM wave absorption performance increases at first and then decreases with the increase of HCF mass fraction. And the values of absorption peaks and effective bandwidth below −10 dB increase monotonically with the increase of EGB volume fraction. The cement based composites with 2 wt% HCF, 60 vol% EGB, and 20 mm thickness exhibits optimal EM wave absorption performance. The minimum reflection loss can be −17.8 dB and the effective bandwidth for −10 dB reaches 13 GHz. The high EM absorbing capacity and wide effective bandwidth can be attributed to the unique chiral structure of HCF and low permittivity of EGB.