Synergistic effects of carbon black and steel fibers on electromagnetic wave shielding and mechanical properties of graphite/cement composites

Abstract This study is focused to develop a broadband and high-efficiency electromagnetic (EM) shielding cement composites by the application of different scales conductive fillers , such as graphite, carbon black (CB) and steel fiber . The synergistic effect of CB and steel fibers addition on the EM wave shielding/absorbing characteristics and mechanical properties of cement matrix with 10 % graphite by weight to cement was examined. The results reveal that the shielding properties can be visibly enhanced by the addition of CB and steel fibers, and the maximum shielding efficiency (SE) of 73.7 dB and average SE of 59.3 dB of the graphite/cement composite with 1 % CB and 30 % steel fibers (by weight of cement) can be obtained, and the bandwidth for SE > 50 dB reaches 14 GHz (4–18 GHz). In addition, the EM wave absorption capacity is also acceptable, the reflection loss of the graphite/cement composite contains 2 % CB and 10 % steel fibers can be lower than −5 dB in 6–18 GHz. Thus, the developed cement-based composite can better solve the issue of EM pollution due to the excellent shielding and absorption properties , avoiding the secondary pollution caused by completely reflective shielding. Furthermore, the mechanical properties which can meet the requirements of conventional engineering applications was achieved, the maximum flexure and compressive strength exceed 10 MPa and 40 MPa, respectively.