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Title |
Study on Improvement in Electromagnetic Interference Shielding Effectiveness of Ultra-High Performance Concrete (UHPC) / Carbon Nanotube (CNT) Composites
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Authors |
정명준(Myungjun Jung) ; 이영순(Young-soon Lee) ; 홍성걸(Sung-Gul Hong) |
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DOI |
https://doi.org/10.4334/JKCI.2019.31.1.069 |
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Keywords |
초고성능 콘크리트 ; 탄소나노튜브 ; 전도성 콘크리트 ; 전자파 차폐 ; 전자기 커플링 ultra-high performance concrete (UHPC) ; carbon nanotubes (CNTs) ; conductive concrete ; electromagnetic interference (EMI) ; shielding effectiveness ; electromagnetic coupling |
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Abstract |
In this study, to evaluate the electromagnetic shielding effect of UHPC/CNT composites by the content of CNTs, electromagnetic shielding effectiveness (SE) test was performed based on MIL-STD-188-125-1 using specimens similar to actual size of exterior material. Then, experimental results were verified by applying Antenna theory of Schelkunoff. As the CNT contents increased, the SE at the same frequencies increased. However, contrary to the theory, the SE in the magnetic field was decreased with increase in frequency regardless of content of CNTs. The reason was due to the electromagnetic coupling effect and proved by using formula. Percolation threshold of CNT used in this experiment was 0.8∼1 wt.% of cement. In this case, the SE was maximized while maintaining the compressive strength and workability at levels similar to reference proportion. The SE when considering the electromagnetic coupling effect in the magnetic field was 18 dB at 10 kHz. And the SE in the plane wave (1 GHz) was about 22 dB. In conclusion, this composite could be used as a shielding material.
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