新型缓凝剂对建筑石膏性能的影响及机理研究

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。

Effects of a New Retarder on Building Gypsum and Its Mechanism

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.