Pyrolysed cork-geopolymer composites: A novel and sustainable EMI shielding building material

In this investigation, and for the first time, pyrolysed sustainable cork was used to produce waste-based geopolymer-cork composites with enhanced electromagnetic interference (EMI) shielding properties. The influence of the pyrolysed cork amount and the geopolymer porosity on the EMI shielding ability of the composites was studied. The maximum total shielding effectiveness (SET) values achieved by these novel building materials (−13.8 to −15.9 dB) are equal to any other reported geopolymer microwave (MW) absorbers over the X-band, despite containing much lower carbon content. In addition, our composites were produced using an industrial waste (biomass fly ash) as raw material and recycled wine stoppers as a carbon source (2.5–3.75 wt%). This strategy is different from those implemented in the only other reported MW absorbing geopolymers, which used standard commercial chemical precursors, and the added carbon component is also a non-renewable commercial product, added in much greater quantities (10× more). Therefore, our approach not only decreases the consumption of virgin raw materials (e.g. kaolin), but also enhances the global sustainability of the construction sector.