The self-sealing behaviors of compacted Na- and Ca-bentonite–sand mixtures were investigated by conducting swelling–permeability tests with specimens containing three types of technological voids. The technological voids, including an upper gap, a surrounding gap, and a center hole of the specimens at 0.03–17.65% of the total cell volume, were sealed by the swelling of the specimen. The vertical and lateral pressures became steady during the experiments, resulting in equal equilibrium pressure in the surrounding gap. The unequal equilibrium pressure in the vertical and lateral directions was measured when the upper gap and center hole were set. The lateral pressure tended to be higher than the vertical pressure. The residual compaction pressure likely explains the higher equilibrium lateral pressure. The coefficient of permeability depended on the average effective montmorillonite dry density in both Na- and Ca-bentonite–sand mixtures. This study proposed an effective Na-montmorillonite dry density, focusing on the high swelling potential of montmorillonite with exchangeable Na ions. The effective Na-montmorillonite dry density of the specimen, including the swollen part, exhibited a unique relation with the permeability after self-sealing, despite the different ionic types of bentonite. Under fully saturated condition, the distribution of water content throughout the specimen after self-sealing suggested that the dry density of the swollen part was lower than the initial specimen part, despite the presence of steady state pressures. It is most likely that the density distribution remained after self-sealing if external factors, including changeable boundary conditions and pore water chemistry, are not considered. Although the specimen after self-sealing exhibited the potential for heterogeneous density, its permeability was approximately evaluated by using the average effective Na-montmorillonite dry density.

压实的钠膨润土和钙膨润土-砂混合物的自密封性能是通过对包含三种类型技术空洞的标本进行溶胀-渗透性试验来研究的。样品的膨胀将技术空隙（包括上部间隙，周围间隙和样品的中心孔占总细胞体积的0.03-17.65％）密封住。在实验过程中，垂直和横向压力趋于稳定，从而导致周围间隙中的平衡压力相等。当设定上间隙和中心孔时，在垂直和横向方向上测量不平衡压力。横向压力倾向于高于垂直压力。残余压实压力可能解释了较高的平衡侧向压力。渗透系数取决于钠膨润土和钙膨润土-砂混合物中蒙脱土的平均有效干密度。这项研究提出了一种有效的钠蒙脱石干密度，重点在于具有可交换钠离子的蒙脱石的高溶胀潜力。尽管膨润土的离子类型不同，但样品的有效Na-蒙脱土干密度（包括溶胀的部分）与自密封后的渗透性具有独特的关系。在完全饱和的条件下，自密封后整个样品中的水分分布表明，尽管存在稳态压力，但溶胀部分的干密度低于初始样品部分。如果有外部因素，则很可能在自密封后仍保持密度分布，包括可变的边界条件和孔隙水化学性质，均未考虑在内。尽管自密封后的样品具有潜在的不均一密度，但其渗透率可以通过使用平均有效钠蒙脱土干密度进行近似评估。