Influencia de la adición del BaCO3 sobre la hidratación del cemento portland

Abstract

The effect of incorporation of BaCO₃ in portland cement hydration has been studied. From this study it is inferred that presence of BaCO₃ in cements makes them require a higher quantity of mixing water. However, mechanical resistances do not seem negatively affected, for a formation of carboaluminates by chemical reaction between the barium carbonate and the C₃A of the clinker appears. The BaCO₃ reveals a retardant effect on the setting time, in presence of gypsum as much as in its absence. The BaCO₃ with gypsum reacts as BaSO₄, a salt of a very high stability. The formation of this barium salt inhibits the formation of ettringite in pastes. Finally, the presence of BaCO₃ in cements ensures that no expansive process will occur in sulphatic means either external or internal, for carbonate is going to react with these sulphates and form BaSO₄, preventing thus the formation of expansive ettringite.