Foamed concrete composites: Mn–Zn ferrite/carbon fiber synergy enhances electromagnetic wave absorption performance

In order to achieve multi-functional integration of materials and reduce electromagnetic pollution in the building environment, this paper uses foam concrete as a base, combined with magnetic loss absorbing material Mn–Zn ferrite (MZF) and resistance absorbing material carbon fiber to prepare a composite material with outstanding electromagnetic wave (EMW) absorption performance. The EMW absorption performance and mechanisms of the composites in the 0.2–5 GHz frequency range were studied, and the mechanical properties, hydration products, aperture parameters, and conductivity of the composites were analyzed. The results demonstrate that the magnetic loss of MZF in composites primarily comes from eddy current loss, domain wall resonance loss, and natural resonance loss. The combination of MZF and carbon fiber not only synergizes the electromagnetic loss capability, but also improves the impedance matching of the composite material, significantly enhancing the EMW absorption effect. The minimum reflection loss of the composite material in the tested frequency band is −28.75 dB (2.10 GHz, thickness 10 mm) and the effective absorption bandwidth is 1.46 GHz (2.29–3.75 GHz) at a thickness of 5.8 mm.