Ceramics-Silikáty 49, (3) 195 - 204 (2005)

Owing to their high strength and predominantly amorphous microstructure the materials on the basis of latent hydraulic active substances activated by alkalis (fly ash, slag) represent a transition between traditional inorganic binders and ceramics and, therefore, they are included into the group of so-called "chemically bonded ceramics". The products being formed during the alkaline activation of fly ashes exhibit their amorphous character with minority crystalline phases. The materials prepared on the basis of fly ashes activated by alkalis exhibit an excellent resistance to the corrosive action of salt solutions, they possess high values of strength and a good frost resistance; furthermore, they can withstand the exposure to temperatures of up to about 600°C. There is a substantial difference in the corrosion of geopolymer by sulfate solutions and that of the materials on the basis of Portland cement.