Wave-Absorbing Properties of Multi-Walled Carbon Nanotubes Reinforced Cement-Based Composites

Multi-walled carbon nanotube (MWCNT)/Portland cement (PC) composites have been prepared to evaluate their electromagnetic wave absorbing properties. The effects of MWCNTs content and sample thickness were discussed in the frequency ranges of 2–18 GHz. Results show that the absorbing properties of cement-based composites are affected by the content of MWCNT and the thickness of the samples. When MWCNTs contents are 0, 0.25, 0.50, 0.75, and 1.00%, absorbing property of sample of 5 mm is unstable due to the resonance absorption. Samples of 10 mm and 15 mm thickness show stable microwave absorbing properties, and a sample of 15 mm thickness has better absorbing property than that of 10 mm. Optimum contents of carbon nanotube (CNT) of 0.75, 0.50, and 0.5% by mass are found in 5, 10, and 15 mm thick samples, respectively. A sample with thickness of 5 mm and 0.50% mass content of CNT has the best absorbing property and the peak is –15.3 dB.