Title: Electromagnetic Characteristics of Cement Matrix Materials with Carbon Nanotubes

Author(s): I. W. Nam, H. K. Lee, J. B. Sim, and S. M. Choi

Publication: Materials Journal

Volume: 109

Issue: 3

Appears on pages(s): 363-370

Keywords: carbon nanotubes; cement matrix materials; electromagnetic characteristics; shielding effectiveness.

DOI: 10.14359/51683827

Date: 5/1/2012

Abstract:
Electromagnetic (EM) characteristics and the shielding effectiveness (SE) of cement matrix materials fabricated with different contents of multi walled carbon nanotubes (MWNTs) were investigated at a frequency range of 0.1 to 18 GHz in this study. To incorporate MWNTs in the cement matrix materials, MWNTs were mixed with a surfactant in the purified water and then sonicated to set bundled MWNTs apart prior to mixing with fiber-added mortar. The dispersion quality of MWNTs in water was analyzed by ultraviolet-visible near-infrared (UV-vis-NIR) absorption spectra, whereas the dispersion quality of MWNTs in the cement matrix was examined by observation of the fracture surface using a scanning electron microscope (SEM). EM wave SE measurement was conducted using a network analyzer with a coaxial transmission line. The most effective shielding performance in a comprehensive frequency range was attained with the incorporation of 1.5% of MWNTs with respect to the cement content in the matrix. The cement matrix materials displayed improved shielding of EM waves within the X-band, although degradation of EM wave SE resulting from air voids in the materials was observed. In SEM observations, most of the MWNTs were separated and embedded in the cement hydration product. As a result, it can be concluded that the cement matrix materials with MWNTs have noteworthy potential as candidate EM wave shielding materials.