Changes in hydraulic conductivity of sand-bentonite mixtures accompanied by alkaline alteration
Changes in hydraulic conductivity of sand-bentonite mixtures accompanied by alkaline alteration
复制标题
碱蚀作用下砂-膨润土混合物水力传导率的变化
DOI：
10.1180/claymin.2013.048.2.18
复制
发表时间：
2013
期刊：
影响因子：
1.5
通讯作者：
T. Tanaka
中科院分区：
文献类型：
--
作者：
T. Yamaguchi;T. Sawaguchi;Manabu Tsukada;M. Kadowaki;T. Tanaka
摘要放射性废物处置库中水泥基材料引起的高碱性环境可能会改变膨润土缓冲材料的主要成分蒙脱石，并可能导致缓冲材料的物理和/或化学性能恶化。该劣化可能导致缓冲器的水力传导性的变化。然而，经验数据的水力传导率的变化是稀缺的，主要是因为压实的缓冲材料，砂膨润土混合物，是非常缓慢的变化。在这项研究中，进行了实验室实验，以观察砂-膨润土混合物的水力传导率的变化，伴随着它们的碱性蚀变，在80-90ºC下使用NaOH基溶液。系列-1多步蚀变/水传导实验导致水力传导率在200天内增加一个数量级。系列-2单步蚀变/水传导实验表明，蒙脱石含量随时间的推移而减少，并导致水力传导率在67天内增加了30倍。系列-3同时蚀变/导水实验也表明，在150天的时间内，导水率增加了30倍。结果表明，膨润土缓冲剂的碱性化可以提高渗透系数。本研究中获得的数据可用于验证将用于评估变更的代码。
Abstract Highly alkaline environments induced by cementitious materials in radioactive waste repositories are likely to alter montmorillonite, the main constituent of bentonite buffer materials, and are likely to cause the physical and/or chemical properties of the buffer materials to deteriorate. The deterioration may cause variation in hydraulic conductivity of the buffer. However, empirical data on the variation of hydraulic conductivity are scarce, mainly because the alteration of compacted buffer materials, sand-bentonite mixtures, is extremely slow. In this study, laboratory experiments were performed to observe changes in hydraulic conductivity of sand-bentonite mixtures, accompanied by their alkaline alteration, using NaOH-based solutions at 80-90ºC. Series-1 multi-step alteration/water conduction experiments resulted in an increase in the hydraulic conductivity by one order of magnitude over a 200 day period. Series-2 single step alteration/water conduction experiments revealed a decrease in the montmorillonite contents with time and a resulting increase in the hydraulic conductivity by 30 times over the 67 day period. Series-3 simultaneous alteration/water conduction experiment also demonstrated an increase in the hydraulic conductivity by 30 times over the 150 day period. The results proved that the alkaline alteration of the bentonite buffer can increase the hydraulic conductivity. The data obtained in this study are useful for verification of the code that will be used for assessing the alteration.