Effect of Kaolin Addition into Metakaolin Geopolymer Composite

Industrially produced metakaolin may contain raw kaolin residues. Therefore, the aim of this work was to determine the influence of kaolin remains in the metakaolin on the final geopolymer quality. A series of mixtures based on metakaolin (Mefisto L05 by CLUZ Nove Straseci, Czech Republic) was prepared with the 0%–50% by weight gradual addition of raw kaolin, and the mechanical strength of the final geopolymer products was tested. It was found that up to a 20% by weight amount of kaolin in metakaolin does not weaken the geopolymer’s performance. Moreover, a geopolymer made of metakaolin with 2%–4% by weight of kaolin showed slightly better mechanical properties than the geopolymers made from metakaolin itself.