LAUSR

Abstract To improve physical and mechanical properties of geopolymer, an attempt to incorporate zircon-ZrSiO4 with aluminum silicates in the matrix was addressed. Five geoploymer pastes containing different zircon contents were prepared from Egyptian kaolin with alkali activators. XRF, XRD, FTIR and SEM attached with EDX unit were used to investigate raw materials and prepared geopolymer. Bulk density and apparent porosity were tested according to Archimedes principle. Compressive strength of prepared geopolymer was also examined. XRD results indicated that no interconnected phases were formed between added zircon and starting aluminum silicates or alkali activators. The presence of zircon up to 10 g/100 g metakaolin, led to improving the microstructure of prepared geopolymer. Zircon entered between the polysialate networks and formed a rigid microstructure. This consequently returned on compressive strength. The compressive strength was increased with increasing zircon content up to 10 g per100 g metakaolin, and then decreased with higher zircon content. The maximum obtained compressive strength value was 74 MPa for the sample that contains 10 g zircon. Addition of higher amount of zircon (15 g/100 g metakaolin) hinders the progress of geopolymerization reaction to take place and consequently decreases the compressive strength.