Ceramics-Silikáty 50 (4) 208-215 (2006)

Microstructure of geopolymer materials based on fly ash

F. Škvára, L. Kopecký, J. Němeček, Z. Bittnar

Geopolymer prepared by brown coal fly ash alkali activation contains mainly structures of the types AlQ⁴(4Si)and SiQ⁴(3Al) and SiQ⁴(2-3Al). Any presence of the temporary phase with different composition was not found between geopolymer and aggregate as it is at the concretes from Portland cement. Geopolymer composition is almost the same in the close nearness even in the geopolymer matrix. Elastic modulus evaluated for the mixed geopolymeric and C–S–H phase by means of nanoindentation was found to be E= 36.1 ± 5.1 GPa. Such result is comparable (a little bit higher) to ordinary Porland cement pastes.

Keywords: Geopolymer, Fly ash, Microstructure