Ph.D. candidate WU Zihao, jointly trained by Wuhan University of Technology and China Building Materials Academy, Principal Investigator of NEXCEL 2024 Ph.D. project titled 'Preparation and mechanism of carbon black/cement-based electromagnetic wave absorbing materials with multi-mechanism', and his supervisor Prof. JI Zhijiang have published a paper entitled 'Design of microwave absorbing frequency bands and selection criteria for vitreous aggregates in cement-based materials' in 'Construction and Building Materials' (SCI) recently. This research provides theoretical support for the high added-value applications of petroleum-based carbon black and the designability of the microwave absorption frequency band of cement-based materials.
The cement-based wave-absorbing materials exhibit both wave-absorbing capabilities and mechanical load-bearing capacity, presenting broad application prospects in the field of electromagnetic protection engineering. However, the wave-absorbing frequency bands of cement-based materials lack designability, which imposes limitations when protecting specific frequency ranges. In this study, petroleum-based carbon black was utilized as an efficient wave absorption agent, in conjunction with vitreous aggregates, to adjust the wave absorption frequency band. The research investigated the relationship between the aggregates and the wave absorption frequency based on the electromagnetic modification of carbon black and established a responsive pattern of 'aggregate content - particle size - frequency band.' Based on electromagnetic characteristics and electromagnetic wave scattering theory, the research shows that after the modification of carbon black in a resonant cavity, the aggregates adjusted the carbon black threshold, large particle size/high content aggregates dominate high-frequency electromagnetic wave absorption (7-18 GHz), while small particle size/low content aggregates dominate low-frequency electromagnetic loss (1.1-7 GHz). The effective absorption bandwidth has been expanded, reaching a maximum of 12.4 GHz (reflection loss<-7 dB). Effective protection with an electromagnetic wave absorption rate of 80% can be achieved across the frequency band of 1.1-18 GHz; additionally, when the absorption rate exceeds 90%, effective protection is still achievable in the high-frequency band. Finite element simulation was used to visualize and analyze the transmission loss of electromagnetic waves within aggregates of different particle sizes, elucidating the mechanism of collaborative loss between carbon black and aggregates in electromagnetic wave absorption, thus offering insights for programming frequency band design. The work also ensured that the mechanical and thermal insulation properties met application demands at high carbon black content, thereby guaranteeing the high added-value application of carbon black.
Paper Details:
Construction and Building Materials 463 (2025) 140095
https://doi.org/10.1016/j.conbuildmat.2025.140095