Abstract Investigation of the effect of salt solution on the swelling properties of compacted bentonite is of great importance for evaluation of the properties of behavior of engineering barrier in deep geological repository for disposal of high-level radioactive waste. In the present work, a multitude of swelling deformation tests were performed on sodic bentonite using NaCl, KCl, and CaCl2 solutions. It is revealed from the results that the swelling strains of the tested samples in variety of saline solutions follow the order of NaCl > KCl > CaCl2 at the concentration of 0.1 mol/L (M), whereas the order was NaCl > CaCl2 > KCl at 1.0 M concentration. The fractal em–pe relations for swelling deformation of Na-bentonite in different solutions were estimated, where em is the smectite void ratio at saturation, pe is effective stress incorporating osmotic suction depicting the effects of ionic concentration on swelling. In addition, the effect of the cation exchange is described using the smectite swelling coefficient K. The estimation values fit well with the experimental data. In NaCl solutions, the coefficient K is basically unchanged due to the weak cation exchange reaction. On the contrary, Ca2+ can much easily replace Na+ even at low concentrations and the CaCl2 solution exhibits the highest values of osmotic suction, the swelling coefficient and swelling deformation of the samples in the 0.1 M CaCl2 solution are smaller than that of samples in other 0.1 M solutions. However, at high concentrations, Na+ can be fully replaced by both Ca2+ and K+. The hydration energy of K+ is comparatively lower due to which the swelling coefficient of the samples in the 1.0 M KCl solution significantly decreased thereby resulting in least swelling deformation.

中文翻译：

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Na-膨润土在不同阳离子溶液中的溶胀变形

摘要 研究盐溶液对压实膨润土膨胀性能的影响，对于评价高放废物处置深地质处置库工程屏障的性能具有重要意义。在目前的工作中，使用 NaCl、KCl 和 CaCl2 溶液对钠基膨润土进行了大量溶胀变形试验。结果表明，在0.1 mol/L (M)的浓度下，供试样品在各种盐溶液中的溶胀应变顺序为NaCl > KCl > CaCl2，而浓度为0.1 mol/L (M)时的溶胀应变顺序为NaCl > CaCl2 > KCl。 1.0 M 浓度。估算了钠基膨润土在不同溶液中溶胀变形的分形em-pe关系，其中em为饱和时的蒙脱石空隙率，pe 是结合渗透吸力的有效应力，描述了离子浓度对溶胀的影响。此外，使用蒙脱石溶胀系数 K 描述了阳离子交换的影响。估计值与实验数据非常吻合。在NaCl溶液中，由于阳离子交换反应较弱，系数K基本不变。相反，Ca2+即使在低浓度下也很容易取代Na+，CaCl2溶液的渗透吸力值最高，0.1 M CaCl2溶液中样品的溶胀系数和溶胀变形小于其他0.1 M CaCl2溶液中的样品。 M 解决方案。然而，在高浓度下，Na+ 可以被 Ca2+ 和 K+ 完全替代。