2022 Volume 76 Issue 1 Pages 108-114
In this study, the influence of sodium carbonate and calcium nitrite addition on the hydration and fluidity of blast furnace slag-calcium hydroxide system were investigated. And we also discussed the effect of combination usage of sodium carbonate and calcium nitrite for blast furnace slag-calcium hydroxide system as alkaline additive. The initial reactivity of blast furnace slag-calcium hydroxide system was largely accelerated by adding of sodium carbonate. On the other hand, the initial heat liberation and the reaction rate of blast furnace slag with sodium carbonate was reduced by addition of calcium nitrite and the mass loss of ignition decreased. In this system, the decrease in pH of the liquid phase were confirmed. The properties of quick setting and low flowability of blast furnace slag-calcium hydroxide system with sodium carbonate was improved by addition of calcium nitrite. due to the suppression of initial blast furnace slag reaction. Also, the long-term reactivity of blast furnace slag was also enhanced by the addition of calcium nitrate due to the nitrite AFm formation. From these results, it is considered that the combination usage of sodium carbonate and calcium nitrite as an additive, is effective for the improvement of blast furnace slag reactivity and flowability of paste in blast furnace slag-calcium hydroxide system.
