新型缓凝剂对建筑石膏性能的影响及机理研究

Effects of a New Retarder on Building Gypsum and Its Mechanism

研究了一种新型缓凝剂—羟基羧酸化合物(KH-PT),对建筑石膏的凝结时间2、8 d强度等性能的影响,并通过无极电阻率测定仪、扫描电镜等测试手段进行了水化进程、晶体形貌变化的研究。结果表明,建筑石膏的凝结时间随着改性剂掺量的增加而延长,在改性剂掺量为0.05%时,不但对建筑石膏具有一定的缓凝效果,而且可使建筑石膏的强度有一定量的增加,在参量为0.10%时,即可使建筑石膏的初凝时间达到近1 h,并随改性剂掺量的增加,建筑石膏水化电阻率的突变段会向后延迟,水化稳定电阻率值也随着减小,而晶体的形貌则随之变粗大,长径比减小。

We studied the effect of a new kind of retarder, hydroxy carboxyl compound （KH-PT）, on setting time and 28-d strength of building gypsum. We used a non-contacting electrical resistance device and a scanning electric microscope to study the change of the hydration process and the crystal morphology of the gypsum. The results indicate the following： With increasing addition of new retarder, gypsum setting time extends. A new retarder content of 0.05% not only affects gypsum setting but also enhances gypsum strength. At a retarder content of 0. 10%, the retarding effect is quite good with the setting time nearly reaching 1 hour. With increased new retarder content, the abrupt change stage of hydration resistivity of building gypsum is delayed, the resistivity stabilization stage decreases, the crystal enlarges, and the ratio of length to diameter decreases.