Multifunctional ultra-lightweight engineered cementitious composites (ECC) for electromagnetic interference shielding

This study developed the multifunctional ultra-lightweight engineered cementitious composite (ULW-ECC) by integrating conductive fillers to achieve effective electromagnetic interference (EMI) shielding capabilities, outstanding mechanical properties and thermal insulation. The mechanical performance, electrical conductivity, EMI shielding effectiveness (SE), and microstructure were analysed. Initially, the effects of the carbon fibre (CF) content and the pre-heating temperature of CF on EMI SE of the matrix (named: ULW-CC) without polyethylene (PE) fibre were tested. Then, CFs (0.5 and 1.0 vol%) with seven lengths (1–20 mm) were respectively incorporated into ULW-ECC to study EMI SE. The EMI SE of ULW-ECC incorporating powder calcined petroleum coke (CPC) was compared with that of CF. Experimental results demonstrated that the incorporation of conductive fillers improved the strength, conductivity, and EMI SE. Both the conductivity and EMI SE of ULW-CC and ULW-ECC increased with the dosage of conductive filler. EMI SE was enhanced with increased electrical conductivity, and pre-heating CF at 300 °C further improved the EMI SE. In ULW-ECC, 9-mm CF showed the highest EMI SE and conductivity. The conductivity and EMI SE of ULW-ECC were lower than those of ULW-CC at the same CF dosage due to the negative impact of PE fibre dispersion on the conductive network of CFs. The mixing method of CF in ULW-ECC affected the EMI SE. The EMI SE of ULW-ECC incorporating powder CPC was much lower than that incorporating CF, but hybridization of CPC and CF significantly enhanced EMI SE.