Concrete walls reinforced with rebars have poor shielding effectiveness for telecommunication frequencies (frequencies above 0.5 GHz). An effective method to increase the shielding effectiveness of the walls is to increase the complex permittivity of the concrete. This can be done by mixing in thin filaments of a material with high conductivity. One such material is carbon. In this paper the Maxwell Garnett mixing rule is used to model a concrete material with carbon filaments. The shielding effectiveness computed with the mixing rule is found to agree with previously published measurement results.
"Modeling Shielding Effectiveness for Composite Walls of Concrete and Carbon Filaments," Progress In Electromagnetics Research M,
Vol. 28, 15-25, 2013. doi:10.2528/PIERM12112004
1. Dalke, R., C. Holloway, P. McKenna, M. Johansson, and A. Ali, "Effects of reinforced concrete structures on RF communications," IEEE Transactions on Electromagnetic Compatibility, Vol. 42, No. 4, 486-496, Nov. 2000. doi:10.1109/15.902318
2. Guan, H., S. Liu, Y. Duan, and J. Cheng, "Cement based electromagnetic shielding and absorbing building materials," Cement and Concrete Composites, Vol. 28, No. 5, 468-474, 2006. doi:10.1016/j.cemconcomp.2005.12.004
3. Wen, S. and D. D. L. Chung, "Electromagnetic interference shielding reaching 70 dB in steel fiber cement," Cement and Concrete Research, Vol. 34, No. 2, 329-332, 2004. doi:10.1016/j.cemconres.2003.08.014
4. Fu, X. and D. D. L. Chung, "Submicron carbon filament cement-matrix composites for electromagnetic interference shielding," Cement and Concrete Research, Vol. 26, No. 10, 1467-1472, 1996. doi:10.1016/0008-8846(96)00146-9
5. Cao, J. and D. D. L. Chung, "Colloidal graphite as an admixture in cement and as a coating on cement for electromagnetic interference shielding," Cement and Concrete Research, Vol. 33, No. 11, 1737-1740, 2003. doi:10.1016/S0008-8846(03)00152-2
6. Chiou, J.-M., Q. Zheng, and D. Chung, "Electromagnetic interference shielding by carbon fibre reinforced cement," Composites, Vol. 20, No. 4, 379-381, 1989. doi:10.1016/0010-4361(89)90663-0
7. Cao, J. and D. D. L. Chung, "Use of fly ash as an admixture for electromagnetic interference shielding," Cement and Concrete Research, Vol. 34, No. 10, 1889-1892, 2004. doi:10.1016/j.cemconres.2004.02.003
8. Roqueta, G., B. Monsalve, S. Blanch, J. Romeu, and L. Jofre, "Microwave dielectric properties inspection of fiber-reinforced civil structures," IEEE Antennas and Propagation Society International Symposium, AP-S 2008, 1-4, Jul. 2008.
9. Koledintseva, M. Y., J. L. Drewniak, R. E. DuBroff, K. N. Rozanov, and B. Archambeault, "Modeling of shielding composite materials and structures for microwave frequencies," Progress In Electromagnetics Research B, Vol. 15, 197-215, 2009. doi:10.2528/PIERB09050410
10. Sihvola, A., Electromagnetic Mixing Formulas and Applications, The Institution of Electrical Engineers, 1999. doi:10.1049/PBEW047E
11. Robert, A., "Dielectric permittivity of concrete between 50MHz and 1 GHz and GPR measurements for building materials evaluation," Journal of Applied Geophysics, Vol. 40, No. 1-3, 89-94, 1998. doi:10.1016/S0926-9851(98)00009-3
12. Ogunsola, A., U. Reggiani, and L. Sandrolini, "Modelling shielding properties of concrete," 17th International Zurich Symposium on Electromagnetic Compatibility 2006, EMC-Zurich 2006, 34-37, Feb. 27-Mar. 3, 2006.
13. Lagarkov, A. N. and A. K. Sarychev, "Electromagnetic properties of composites containing elongated conducting inclusions," Phys. Rev. B, Vol. 53, No. 10, 6318-6336, Mar. 1996. doi:10.1103/PhysRevB.53.6318