不同类型缓凝剂对建筑石膏的缓凝作用

Retarding Action of Various Retarders on Setting and Hardening Characteristics of Gypsum

研究了麦蛋白水解液石膏缓凝剂、柠檬酸、六偏磷酸钠对脱硫石膏的凝结时间、强度损失等的影响,同时也对不同水化环境pH值条件下的缓凝作用的凝结硬化特征进行了分析,并结合XRD和SEM对建筑石膏强度损失的原因和缓凝剂的缓凝机理进行了分析。对比结果表明:凝结时间相近的情况下,麦蛋白水解液对石膏的强度影响最小,而六偏磷酸钠影响最大;麦蛋白水解液对pH值环境适用范围最广,有良好的适应性,并在弱碱条件下缓凝效果最佳,而柠檬酸和六偏磷酸钠分别在酸性和中性条件下缓凝效果最佳;麦蛋白水解液对二水石膏晶体形貌基本没有影响,而六偏磷酸钠和柠檬酸使明显而完整的二水石膏针片状晶体减少。

The effect of hydrolyzed wheat protein retarder, citric acid retarder and sodium hexametaphosphate on the setting time and the strength loss of FGD gypsum was investigated and the retarding action on the setting and hardening characteristics at different pH was also discussed. Furthermore, the retarding mechanism and the influence of various properties on the hardened gypsum plaster was investigated in detail by SEM and XRD. The results indicated that the hydrolyzed wheat protein retarder for plaster had better retarding effect, low strength loss and less influence on the crystal morphology of dihydrate gypsum.