缓凝剂对高贝利特硫铝酸盐水泥水化和性能的影响

高贝利特硫铝酸盐(HB-CSA)水泥是一种具有低收缩特性的新型低碳水泥。针对该种水泥凝结硬化不易控制的问题,系统研究了氨基三亚甲基膦酸(ATMP)和葡萄糖酸钠(SG)对HB-CSA水泥水化和凝结硬化的影响。采用等温量热仪、X射线衍射仪和扫描电子显微镜分析了缓凝剂在HB-CSA水泥中的作用机理。结果表明:ATMP可以显著延缓HB-CSA水泥水化进程,延长凝结时间,提高HB-CSA水泥的中后期强度;而SG仅表现出有限的作用。两种缓凝剂与聚羧酸减水剂(PCE)复配可以延迟HB-CSA水泥水化放热速率,抑制钙矾石等早期水化产物的形成,且不同种缓凝剂会使钙矾石呈现出不同的形貌。

Effects of Retarders on Hydration and Properties of High-Belite Calcium Sulphoaluminate Cement

High-belite calcium sulphoaluminate (HB-CSA) cement is a new type of low-carbon cement with low shrinkage characteristics. Aiming at the problem that the setting and hardening of HB-CSA cement is difficult to control, the effects of two retarders, aminotri methylenephosphonic acid (ATMP) and sodium gluconate (SG), on the hydration and retardation response of HB-CSA cement were investigated. Each of the retarder compounded has a different effect on the early-age hydrate assemblage, as shown by quantitative X-ray diffraction, thermal conductivity isothermal calorimeter, scanning electron microscopy. The results show that ATMP significantly retards hydration of HB-CSA cement, prolongs the setting time, and improves HB-CSA cement mid-late strength, while the retardation effect of SG is limited. The combination of two retarders with PCE delays the hydration heat release rate differently to inhibit the early hydration product (ettringite)-forming reaction. Furthermore, the morphology of ettringite is altered depending on the type of retarder used.