ACCELERATION MECHANISM OF SLAG REACTION BY INORGANIC ADDITIVES AND IMPACT OF Al₂O₃ IN SLAG ON ITS EFFECT

Abstract

This study investigated mechanism of acceleration of slag reaction by the addition of calcium sulfate （CS） and calcium nitrite （CN） using laboratory-made slags with different Al₂O₃ contents analyzed by XRD, ²⁷Al-MAS NMR and SEM-EDS. In the case of CS addition, the initial reaction of slag was promoted by Ettringite（Et）formation. However, as diffusion of ions would be suppressed by Et and Monosulfate （Ms） formed on the slag surface, the degree of the long-term reaction of slag was almost same as that without CS. On the other hand, in the case of CN addition, NO₂^－ ion increases the solubility of slag and AFm （Ni） nitrite is formed away from the slag surface. As a result, diffusion of ions is not inhibited on the slag surface and the slag reaction ratio can be significantly increased.