Microwave absorption and electromagnetic properties of ultra-high-strength cementitious materials: Influence of basalt powder and underlying mechanism

Abstract

The utilization of basalt powder in ultra-high-strength cementitious materials (UHSCMs) holds significant potential for application in mitigating CO2 emissions and reducing electromagnetic pollution. This study investigated the microwave absorption and electromagnetic properties of UHSCMs incorporating basalt powder, with the silica-fume-based mix as a comparison. A comprehensive multi-scale investigation was conducted to gain an in-depth understanding of the electromagnetic properties of UHSCMs. From the results, the UHSCM with basalt powder was demonstrated to possess improved microwave absorption performance, characterized by a mean reflection loss of −8.22 dB and effective bandwidths of 58.3% (<-7.0 dB) and 26.6% (<-10.0 dB). The enhanced performance of this mixture was attributed to its superior impedance-matching capability and microwave attenuation ability. The dielectric loss peaks within frequency ranges of 7.0–8.5 GHz and 10.0–11.5 GHz were caused by the interfacial polarization of macro pores and gel pores, respectively. The natural resonance, exchange resonance, and eddy current effect were the primary mechanisms of the magnetic loss. CaFeSi2O6 particles from basalt powder contributed to the enhanced natural resonance. In addition, basalt powder had the better market potentials and lower environmental impact as a supplementary cementitious material than silica fume for enhancing microwave absorption of UHSCMs. The finding of this study demonstrated the suitability of adopting basalt powder in UHSCM production with improved greenness and electromagnetic properties.