Innovative porous ceramic matrices from inorganic polymer composites (IPCs): Microstructure and mechanical properties

The thermal performance of pegmatite-based geopolymer composites is investigated. Dense and compact matrix was prepared replacing metakaolin with pegmatite in the range of 70–85 wt% and activate with sodium hydroxide/sodium silicate solution in 1:1 vol ratio. The products of geopolymerization, cured at room temperature for 28 days, were heated at 100, 200, 400, 600, 800, 900, 1000 and 1100 °C with 2 h soaking time. The high values of flexural strength (46–51 MPa) were observed at 1000 °C as the consequences of low porosity (173 mm3/g) and water absorption (4.50–5.62%). The increase of the vitrification at 1100 °C enhanced the liquid phase and develop porosities responsible for reduction of strength. The mechanical properties, microstructural evolution and pore size distribution were found to be influenced by the amount of fine powder of pegmatite (solid solution).