2011 Volume 65 Issue 1 Pages 33-39
The cement industry is a major generator of CO2 gas by cement production. Replacing cement by blast-furnace slag is an effective method for reducing CO2 gas exhaust. In this study we investigated the reaction and the microstructure of hydrated products when used high volume blast-furnace slag. We analyzed products produced from Blast-Furnace Slag（BFS）-Anhydrate（CS）-Ordinary Portland Cement（OPC）and lime stone powder（LSP）. The hydration reaction and immobilization mechanism of Cr（Ⅵ）in this type of cement were analyzed by X-ray diffraction and Scanning Electron Microscope, and when chemical analysis at water solution was determined by inductively-coupled plasma optical emission spectrometry. The mainly hydrated cement products are ettringite, monosulfate, and Ca（OH）2. When the cement immobilizes Cr（Ⅵ）, monosulfate is usually formed. However, by adding LSP to the samples it changes monosulfate to monocarbonate or hemicarbonate. Monocarbonate and hemicarbonate has not revealed the ability to immobilize Cr（Ⅵ）. We propose that hemicarbonate has sufficient space to incorporate Cr（Ⅵ）ions into its structure more so than that of monocarbonate.
