煅烧制度对高岭土的结构特征及胶凝活性的影响

Effect of Calcination Regime on Microstructure and Cementitious Activity of Kaolin

采用DTA-TG,IR,XRD,SEM等分析手段研究了不同煅烧制度下高岭土的结构变化,分析了偏高岭土胶凝活性产生的原因,并以水玻璃激发偏高岭土制成地聚合物材料.结果表明:高岭土在600℃煅烧6h或者在700～900℃煅烧2h以上,可形成偏高岭土,它是一种结晶度很差的过渡相,保持了高岭土的层片状结构,但片状和管状晶体尺寸变小,结块增加,其胶凝活性较好.

DTA-TG,IR,XRD and SEM were used to study crystalline change and microstructure of kaolin.Results shows Longyan kaolin lost part of hydroxyl after calcination at 600 ℃ for 6 h or 700-900 ℃ for 2 h to form metakaolin which is a transient phase with unstable crystalline.Metakaolin has layered structure like kaolin with smaller size and lump formation.The principle of cementitious activity of metakaolin was discussed,and then geopolymers were made with sodium silicate as activator,the results of 3d compression strength indicate that metakaolin shows good cementitious activity after calcination at 600 ℃ for 6 h or 700-900 ℃ for 2 h.