Na_2C_2O_4对硬石膏水化硬化的影响及作用机理  

Influence of Na_2C_2O_4 on hydration and hardening of anhydrite and its action mechanism

作　　者：彭家惠[1,2] 张建新[2] 陈明凤[2] 瞿金东[2] 李青[2] 

机构地区：[1]重庆大学国家镁合金材料工程技术研究中心,重庆400044 [2]重庆大学材料科学与工程学院,重庆400045

出　　处：《浙江大学学报（工学版）》2009年第7期1322-1326,共5页Journal of Zhejiang University：Engineering Science

基　　金：国家自然科学基金资助项目(50572126)

摘　　要：研究了草酸钠对硬石膏水化进程、硬化体显微结构与强度、液相离子浓度与二水石膏析晶过饱和度的影响,从二水石膏晶体成核与生长的角度探讨了草酸钠的作用机理.草酸钠使硬石膏水化率提高,水化热集中,水化潜伏期缩短,水化进程加快;草酸钠使二水石膏晶体细化,硬化体结构致密,强度提高,是硬石膏水化活性的高效激发剂.草酸钠作用机理归纳为:草酸钠与硬石膏反应形成草酸钙沉淀与可溶硫酸盐,使液相SO42-浓度大幅提高;提高二水石膏析晶过饱和度,使二水石膏临界晶核半径减小,晶体成核与生长速率加快;草酸钠促进硬石膏溶解.The influence of sodium oxalate on anhydrite hydration process and crystal morphology of its dihydrate products was studied by determination of the hydration rate, hydration temperature and ion concentration in the liquid phase of anhydrite in combination with the investigation of the microstrueture of the hardened paste. The activation mechanism of sodium oxalate was analyzed from the standpoint of the crystal growth of gypsum. The addition of Na2 C2O4 increased the hydration rate of anhydrite, concentrated the hydration heat, shortened the hydration latency period, and accelerated the hydration process, accordingly leading to the refinement of gypsum crystal,the compactness of hardened gypsum paste, and the increases of its strength, so it was a highly efficient activator of anhydrite hydration. The activating mechanism of sodium oxalate could be summarized as follows： sodium oxalate reacted with anhydrite, and calcium oxalate precipitation and soluble sulfate salt were then formed, which increased the SO4^2- concentration in the liquid phase, and increasing the supersaturation degree of gypsum crystallization decreased the critical nucleus radius of dehydrate gypsum, and it accelerated the crystal nucleation and growth, and sodium oxalate accelerated the dissolution of anhydrite.

关 键 词：硬石膏 草酸钠 激发剂 水化硬化 

分 类 号：TU522.09[建筑科学—建筑技术科学]