偏高岭土矿渣基地聚合物缓凝剂的性能研究

以自主研发的缓凝剂BCH对偏高岭土-矿渣基地聚合物浆体凝结时间进行调节;利用反应热分析、化学结合水量测定和微观形貌观察等方法对BCH的缓凝效果进行验证.结果表明:缓凝剂BCH能有效延缓地聚合物浆体的反应速率,且对其硬化体抗压强度有一定增强作用.当BCH掺量为5.0%(质量分数)时,缓凝效果最佳,地聚合物浆体20℃和80℃的初凝时间分别比未掺BCH的增加了20.4倍和13.7倍;80℃养护3d和28d的地聚合物硬化体抗压强度分别比未掺BCH的提高了12.28%和5.80%;在20℃和50℃下碱激发反应放热峰出现时间较未掺BCH的明显延迟,放热峰强度显著降低;80℃时碱激发反应主要发生在4.0～6.0h时间段,较未掺BCH的反应时间段(0.2～1.0h)滞后;80℃碱激发反应1.0h后,反应产物浆体不凝结,产物颗粒表面覆盖黏附物,而未掺BCH的碱激发反应产物为连续致密的硬化体.

Study of Retarder Properties for Metakaolin Slag Geopolymer

A retarder BCH developed from independent research was used to adjust the setting time of metakaolin-slag geopolymer paste.Analysis of reaction heat,measurement of chemically combined water content and micro-morphology analysis were used to verify the retarding effect of BCH.Results show that BCH can be used to effectively decrease the reaction rate of geopolymer paste and improve the compressive strength of solidified products.BCH has the best retarding efficiency with addition of 5.0%(by mass).At 20 ℃ and 80 ℃ the initial setting time is prolonged by 20.4 and 13.7 times that without the retarder respectively.At 80 ℃ the compressive strength at 3 d and 28 d is improved by 12.28% and 5.80% respectively.Alkali activated reaction at 20 ℃ and 50 ℃ has late and lower exothermal peak than that without BCH.Alkali activated reaction at 80 ℃ takes place during the period of 4.0~6.0 h and is later than that without BCH(for 0.2~1.0 h).When reacted at 80 ℃ for 1.0 h,the paste does not set,the product is covered with a layer of slurry,whereas the product of alkali activated reaction without BCH is compact solid.