不同缓凝剂的缓凝效果及其对水泥水化的影响

The retarding effect of different retarders and their influence on cement hydration

在相同配合比和成型条件下,测试了羟基乙叉二磷酸、氨基三亚甲基磷酸、葡萄糖酸钠、六偏磷酸纳、柠檬酸等5种缓凝剂对水泥净浆凝结时间和抗压、抗折强度的影响,并通过XRD、SEM等分析研究其对水泥水化的影响。结果表明:羟基乙叉二磷酸的缓凝效果最佳,同时其7、14 d胶砂抗压、抗折强度相比空白组有所提高,对净浆流动度和砂浆减水率无不良影响;羟基乙叉二磷酸的缓凝作用主要是抑制水化产物AFt和AFm的产生,延缓水泥的水化速率,延长水化时间和凝结时间。

Under the same mixing ratio and molding conditions,the effects of five retarders,including hydroxyethylidenediphos-phoric acid,amino trimethylene phosphoric acid,sodium gluconate,sodium hexametaphosphate,and citric acid,on the setting time,compressive and flexural strength of cement pastehas been tested,and its influence on cement hydration are studied by XRD,SEM and other analytical methods.The results show that the retardation effect of hydroxyethylidenediphosphoric acid is the best,and the compressive/flexural strengths of 7 and 14 d are improved compared with the blank group,and there is no adverse effect on the fluidity of the pure slurry and the water reducing rate of cement mortar.The retardation effect of hydroxyethylidenediphosphoric acid is mainly to inhibit the production of hydration products AFt and AFm,delay the hydration rate of cement,prolong the hydra-tion time,and prolong the setting time.