EFFECT OF COMBINED USE OF GYPSUM AND CALCIUM NITRITE ON THE HYDRATION REACTIVITY OF BLAST FURNACE SLAG ADDED A SMALL AMOUNT OF CALCIUM HYDROXIDE

Abstract

It is known that the reaction of blast furnace slag （BFS） changes greatly depending on the amount of calcium hydroxide （CH） and gypsum （Gyp） added, but there is no study of the changes when used in combination with an accelerator. In this study, the effect of the combined use of Gyp and calcium nitrite （CN） on the hydration reactivity of BFS by changing the amount of the CH addition was investigated. As a result, the following findings were obtained for the reaction control of BFS. In the range of CH 0.5 to 1％, which is a very small amount, the promoting effect of CN alone was not exhibited, and a remarkable effect was obtained by adding Gyp. On the other hand, in the range of CH5 to 10％, the amount of CN added affected the reaction promotion of BFS, and the effect of promoting CN was suppressed when Gyp was excessively added.