Ceramics-Silikáty 43, (3) 111 - 116 (1999)

Alkaline activation (brought about by the effect of NaOH and Na₂SiO₃ solutions) is capable of increasing significantly the reactivity of substances with latent hydraulic properties, such as fly-ash or mixtures of fly-ash with blast-furnace slag. The optimum properties (compressive strength of 120 - 170 MPa) were achieved with ash-slag mixtures over the composition range 70 - 50 wt.% fly-ash and 30 - 50 wt.% slag, activated with alkaline activator having a M_S modulus of 0.6 and containing 7 wt.% Na₂O. The microstructure of hardened activated fly-ash and ash-slag mixtures is composed of amorphous hydrates of sodium aluminosilicates and the C-S-H phase.