Experimental investigation of electromagnetic interference shielding effectiveness of concrete block incorporated with carbon fiber and carbon nanotube

High conducting metal such as Mu-metal, aluminum and silver are commonly used as shielding material which prevents electromagnetic radiation by reflection. However, metal material exhibit various disadvantages such as heavy weight, high cost, poor corrosion resistance and poor processing. Over these few decades, non-metal materials such as carbon black (CB), carbon fiber (CF) and carbon nanotube (CNT) are gaining popularity as they are corrosion resistant, have high tensile strength, are light weight, have low cost and design flexibility. The use of EMI shielding in commercial and military application has rapidly increased and are widely used. Therefore, the objective of this study is to investigate the EMI shielding effectiveness (SE) of nonmetal materials used in concrete block via experimental methods. There are two materials used in the study, namely carbon fiber and multiwalled carbon nanotube (MWCNT). The EMI SE of carbon fiber was studied with respect to their orientation at the same layer of material while MWCNT was examined by different weightage percentage. The EMI SE measurement was conducted using Vector Network Analyzer (VNA) in the frequency range of 2.4 GHz to 4.2 GHz. The results show
that CF sample with perpendicularly orientation of CF (0⁰/90⁰/ 0⁰/ 90⁰/ 0⁰) has higher EMI SE than other CF samples with EMI SE of -40.26 dB at 4.02 GHz with improvement of 15.71 % compared to reference sample. Meanwhile, it is found that CNT sample with 2.0 wt% of
MWCNT has higher EMI SE compared to the sample with 1.5 wt% and 1.8 wt% of MWCNT. This sample obtained the highest EMI SE of -40.78 dB at 3.45 GHz with improvement of 17.23% compared to reference sample. The compressive strength test of concrete block was also conducted using compressive strength machine. It was observed that, all concrete blocks passed the strength test according to the grade 30 concrete mixture standard that is adjudged to be safe for application in building construction.