Pozzolanic properties of calcined clay in geopolymer concrete: A review

The utilization of calcined clays as pozzolanic materials are in demand by many industries as valuable mineral resource mainly in cement industry including geopolymer concrete. This is due to the content of the SiO₂ and Al₂SiO₃ that are very similar to the Portland Cement. Studies on the pozzolanic properties of concrete incorporation with representative samples of the calcined clays would contribute to the sustainability of concrete production. Not only that, the determination of the specification of acceptance criteria for raw clays and calcined products are also need to be taken into account. This paper presents some research finding about pozzolanic properties of calcined clays (metakaolin, illite, montmorillonite) with focus on the effect of calcination temperature on clay, its compressive strength and the geopolymer concrete itself. Metakaolin is a pozzolanic material and can be obtained by the calcination of kaolinitic clay. It is being used very commonly as pozzolanic material in mortar and concrete, and has exhibited considerable influence in enhancing the mechanical and chemical properties of mortar and concrete.