Electromagnetic shielding enhancement in cement composites: a comparative study of mechanically and thermally recycled carbon fibers

Abstract The recycling of carbon fibers that have reached the end of their service life and their reintegration into new applications hold significant importance from an environmental and sustainable perspective. In this study, the aim is to enhance the electromagnetic wave shielding properties of cement-based composites by incorporating mechanically and thermally recycled and ball-milled carbon fibers at volumetric ratios of 1%, 2%, and 3%. Electromagnetic tests are conducted in the X-band frequency range (8–12.5 GHz), commonly preferred for microwave applications. The obtained results demonstrate an improvement in the SE A (absorption loss )and SE T (total power loss) values of the composite with the use of recycled fibers. This improvement is particularly more pronounced in composites containing thermally recycled fibers. The enhanced performance is attributed to the electrical conductivity imparted by carbon fibers. At a frequency of 11.9 GHz, the SE T value increased from 8.5 dB for the control sample to 9.2 dB for composites with 3% mechanically recycled fibers and up to 19 dB for composites with 3% thermally recycled fibers. These findings indicate that using recycled carbon fibers enhances the electromagnetic wave shielding properties, with thermal recycling contributing more significantly to this enhancement.