Effects of sodium chloride and sodium sulfate on hydration process

被引：8
|
作者：
Cao Y. [1 ]
Guo L. [1 ,2 ,3 ]
Xue X. [1 ]
机构：
[1] School of Materials Science and Engineering, Southeast University, Nanjing
[2] Jiangsu Key Laboratory of Construction Materials, Southeast University, Nanjing
[3] Collaborative Innovation Center for Sustainable Civil Engineering Materials and Structures, Southeast University, Nanjing
来源：
Dongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Southeast University (Natural Science Edition) | 2019年 / 49卷 / 04期
关键词：
Chloride; Hydration kinetics; Hydration products; Sulfate;
D O I：
10.3969/j.issn.1001-0505.2019.04.014
中图分类号：
学科分类号：
摘要：
To investigate the influence of chloride salt and sulfate on the hydration mechanism of cement-based materials, NaCl and Na2SO4 were mixed into cement, and the TAM air microcalorimeter, X-ray diffractometer (XRD), and inductively coupled plasma spectroscopy(ICP) were used to investigate the hydration kinetics of cement and the transformation of hydration products. The results show that both NaCl and Na2SO4can accelerate cement hydration from the hydration heat release rate and the cumulative heat, and the accelerating effect of NaCl is better than that of Na2SO4. The concentration of SO4 2- decreases rapidly during the hydration process, but the Cl- concentration does not decrease until 10 h hydration. When Na2SO4 and NaCl coexist,SO4 2- reacts with C3A prior to Cl-, and NaCl promotes gypsum dissolution and accelerates ettringite formation. From the XRD pattern, it can be found that in the cement slurry mixed with NaCl, Friedel salt is not produced in the early stage of hydration, and only with the conversion of ettringite into monosulfide ettringite (SO4-AFm), Cl- starts to react to form Friedel salt. In addition, the influence of NaCl and Na2SO4 on the hydration mechanism of cement was discussed according to the hydration kinetic curve. During the hydration process, NaCl promotes the NG process, and has a certain weakening effect on the I process, but has little effect on the D process. © 2019, Editorial Department of Journal of Southeast University. All right reserved.
引用
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页码：712 / 719
页数：7
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