Activation of gypsum anhydrite-slag mixtures

Abstract Gypsum anhydrite-slag mixtures were produced by blending anhydrite with granulated blast furnace slag, Ca(OH)2 and small amounts of Na2 SO4 · 10H2O and FeSO4 · 7H2O as activators. A mechanism of conversion of anhydrite into gypsum through transient double salts in presence of activators is suggested. Activation of granulated slag with the gypsum anhydrite and Ca(OH)2 to form ettringite and tobermorite has been discussed. The correlation between gain in strength and hydration products is reported.