Abstract The hydro-mechanical properties of the buffer material play an important role in the design of deep geological repositories. This paper presents the effect of various electrolyte concentrations on swelling pressure, consolidation characteristics and hydraulic conductivity of two different Indian bentonites. Constant volume swelling pressure tests on compacted bentonite specimens as well as consolidation tests on saturated bentonite specimens were carried out by supplying 0, 0.1, 0.5 and 1.0 N NaCl and CaCl2 solutions. The change in morphology and microstructure of bentonite specimens were examined by Scanning Electron Microscope (SEM) and XRD analysis. The hydraulic conductivity was calculated based on consolidation test results. At a dry density of 1.4 Mg/m3 both swelling pressure and hydraulic conductivity of divalent bentonite were found to be approximately 2.9 and 7.3 times higher than that of monovalent bentonite when saturated with deionized water. The electrolyte solutions altered the morphology, microstructure and hydro-mechanical properties of the monovalent bentonite significantly; however, the effect was found to be negligible for divalent bentonite. An empirical equation is proposed to predict the hydraulic conductivity of the bentonites. A good correlation between experimental and predicted hydraulic conductivity of bentonites is obtained. The divalent bentonite was found to be better suitable engineered barrier material in the electrolyte environment, whereas monovalent bentonite was found preferable at low salinity conditions.

中文翻译：

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电解质浓度对两种印度膨润土膨胀压力、固结特性和导水率的影响

摘要 缓冲材料的水力学特性在深部地质处置库的设计中起着重要作用。本文介绍了不同电解质浓度对两种不同印度膨润土的膨胀压力、固结特性和水力传导率的影响。通过提供 0、0.1、0.5 和 1.0 N NaCl 和 CaCl2 溶液，对压实的膨润土试样进行恒体积膨胀压力试验以及对饱和膨润土试样进行固结试验。通过扫描电子显微镜 (SEM) 和 XRD 分析检查了膨润土试样的形貌和微观结构的变化。根据固结试验结果计算水力传导率。干密度为 1。发现当用去离子水饱和时，二价膨润土的 4 Mg/m3 膨胀压力和水力传导率比一价膨润土高约 2.9 倍和 7.3 倍。电解质溶液显着改变了单价膨润土的形貌、微观结构和水力学性能；然而，发现二价膨润土的影响可以忽略不计。提出了一个经验方程来预测膨润土的水力传导率。获得了膨润土的实验和预测的水力传导率之间的良好相关性。发现二价膨润土在电解质环境中是更合适的工程阻隔材料，而发现在低盐度条件下优选单价膨润土。用去离子水饱和时比一价膨润土高3倍。电解质溶液显着改变了单价膨润土的形貌、微观结构和水力学性能；然而，发现二价膨润土的影响可以忽略不计。提出了一个经验方程来预测膨润土的水力传导率。获得了膨润土的实验和预测的水力传导率之间的良好相关性。发现二价膨润土在电解质环境中是更合适的工程阻隔材料，而发现在低盐度条件下优选单价膨润土。用去离子水饱和时比一价膨润土高3倍。电解质溶液显着改变了单价膨润土的形貌、微观结构和水力学性能；然而，发现二价膨润土的影响可以忽略不计。提出了一个经验方程来预测膨润土的水力传导率。获得了膨润土的实验和预测的水力传导率之间的良好相关性。发现二价膨润土在电解质环境中是更合适的工程阻隔材料，而发现在低盐度条件下优选单价膨润土。一价膨润土的微观结构和水力学性能显着；然而，发现二价膨润土的影响可以忽略不计。提出了一个经验方程来预测膨润土的水力传导率。获得了膨润土的实验和预测的水力传导率之间的良好相关性。发现二价膨润土在电解质环境中是更合适的工程阻隔材料，而发现在低盐度条件下优选单价膨润土。一价膨润土的微观结构和水力学性能显着；然而，发现二价膨润土的影响可以忽略不计。提出了一个经验方程来预测膨润土的水力传导率。获得了膨润土的实验和预测的水力传导率之间的良好相关性。发现二价膨润土在电解质环境中是更合适的工程阻隔材料，而发现在低盐度条件下优选单价膨润土。