Electromagnetic shielding of aged cement-paste with biochar and PVC in C-band

Polyvinyl chloride (PVC) deriving from waste electrical and electronic equipment can be used in conjunction of biochar as filler to produce cement-paste thus reducing the environmental impact of PVC. Even if the presence of PVC and biochar worsen the mechanical properties, the shielding effectiveness of the resulting cement-paste is greater compared to plain cement and it can be used for non-structural applications as screen or substrate. In this work, the shielding properties of Portland cement filled with lignine biochar and PVC in various percentages are analyzed. The scattering parameters (Sij) of samples with 4mm thickness are measured in rectangular waveguide in C-band. From the measured transmission coefficient (S21) the shielding effectiveness (SE) of the samples is derived. The addition of biochar and PVC increased the shielding effectiveness and is found to be a suitable candidate for filling cement-based composites. In the frequency range 6-8 GHz, composites samples of thickness 4mm with 10 wt.% of biochar and 6% of PVC (with respect to 100 g of cement) provide a shielding effectiveness value of almost 15 dB and 10 dB after 1 and 30 months ageing in ambient conditions, respectively.