The effect of sodium chloride on the dissolution of calcium silicate hydrate gels.
The effect of sodium chloride on the dissolution of calcium silicate hydrate gels.
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DOI：
10.1016/j.wasman.2006.01.022
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发表时间：
2006
期刊：
影响因子：
8.1
通讯作者：
J. Hill;A. W. Harris;M. Manning;A. Chambers;S. Swanton
中科院分区：
文献类型：
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作者：
J. Hill;A. W. Harris;M. Manning;A. Chambers;S. Swanton
在联合王国，水泥基材料将广泛用于放射性材料的长期管理。应用之一可能是Nirex参考拱顶回填（NRVB），作为深层地质处置库内的工程屏障。NRVB提供碱性条件，通过控制一些关键放射性核素的溶解度，增强吸附和最大限度地减少钢容器的腐蚀，提供强大的化学屏障。了解C-S-H凝胶在适当条件下（例如，盐水地下水）的测试是必要的，以证明化学性质随时间的预期演变，并提供足够的水泥来缓冲所需时间内的孔隙水条件。本文研究了C-S-H凝胶在氯化钠溶液中的溶解行为以及钙硅比（C/S）、温度和阳离子类型对溶解行为的影响。与在25°C下制备的样品相比，在45°C下平衡的样品观察到钙浓度和pH值的降低。盐阳离子类型对C-S-H凝胶溶解的盐浓度依赖性的影响进行了研究，通过添加锂或氯化钾代替氯化钠用于C/S为1.0和1.8的凝胶。在C/S为1.0的情况下，对于不同的盐，记录到溶解的钙浓度随着离子强度的增加而类似地增加。然而，在C/S为1.8时，在锂的存在下观察到异常高的钙浓度。
The use of cement based materials will be widespread in the long-term management of radioactive materials in the United Kingdom. One of the applications could be the Nirex reference vault backfill (NRVB) as an engineered barrier within a deep geological repository. NRVB confers alkaline conditions, which would provide a robust chemical barrier through the control of the solubility of some key radionuclides, enhanced sorption and minimised corrosion of steel containers. An understanding of the dissolution of C–S–H gels in cement under the appropriate conditions (e.g., saline groundwaters) is necessary to demonstrate the expected evolution of the chemistry over time and to provide sufficient cement to buffer the porewater conditions for the required time. A programme of experimental work has been undertaken to investigate C–S–H gel dissolution behaviour in sodium chloride solutions and the effect of calcium/silicon ratio (C/S), temperature and cation type on this behaviour. Reductions in calcium concentration and pH values were observed with samples equilibrated at 45°C compared to those prepared at 25°C. The effect of salt cation type on salt-concentration dependence of the dissolution of C–S–H gels was investigated by the addition of lithium or potassium chloride in place of sodium chloride for gels with a C/S of 1.0 and 1.8. With a C/S of 1.0, similar increases in dissolved calcium concentration with increasing ionic strength were recorded for the different salts. However, at a C/S of 1.8, anomalously high calcium concentrations were observed in the presence of lithium.