Jalal Fazal E, Li Xiaoyue, Onyelowe Kennedy
Interdisciplinary Research Center for Construction and Building Materials, King Fahd University of Petroleum & Minerals, Dhahran, 31261, Saudi Arabia.
State Key Laboratory of Internet of Things for Smart City, University of Macau, Macao, SAR, China.
Sci Rep. 2025 Jul 29;15(1):27628. doi: 10.1038/s41598-025-10052-8.
This study quantifies the complex impact of saline solution on the swelling behaviour of compacted bentonite or montmorillonite clay. The influence mechanisms can be divided into macroscopic mechanical action and microscopic chemical reaction, depending on the altered minerals in the bentonite. A fractal adsorption model has been introduced to depict the void ratio of montmorillonite in different saline solutions at a steady swelling state with a uniform power function. In the formulated model, the osmotic suction of saline solution (π) and vertical load (p) were classified as the macroscopic mechanical actions and were embodied by total effective stress (p), while the microscopic chemical reactions that fundamentally transform the composition of bentonite were reflected by the swelling coefficient (C). A calculated method for the swelling coefficients has been formulated in this study, as the fractal adsorption theory is combined with the diffused double layer theory in deionized water, that has been further validated using swelling experimental data for different bentonites (Commercial bentonite, GMZ24-200 bentonite, and GMZ-07 bentonite) in NaCl, NaSO, and CaCl salt solutions. These three types of bentonite are representative materials planned for future nuclear waste disposal projects, making their experimental data both relevant and significant. Finally, this study suggests that the proposed fractal adsorption model is a practical tool for explaining the chemical effects on bentonite swelling at both macroscopic and microscopic levels.
本研究量化了盐溶液对压实膨润土或蒙脱石黏土膨胀行为的复杂影响。根据膨润土中矿物的变化情况，其影响机制可分为宏观力学作用和微观化学反应。引入了分形吸附模型，以统一幂函数描述蒙脱石在不同盐溶液中稳定膨胀状态下的孔隙率。在建立的模型中，盐溶液的渗透吸力（π）和垂直荷载（p）被归类为宏观力学作用，并由总有效应力（p）体现，而从根本上改变膨润土成分的微观化学反应则由膨胀系数（C）反映。本研究制定了膨胀系数的计算方法，因为分形吸附理论与去离子水中的扩散双电层理论相结合，并利用不同膨润土（商业膨润土、GMZ24 - 200膨润土和GMZ - 07膨润土）在NaCl、NaSO和CaCl盐溶液中的膨胀实验数据进一步验证。这三种膨润土是未来核废料处置项目计划使用的代表性材料，因此它们的实验数据既相关又重要。最后，本研究表明，所提出的分形吸附模型是从宏观和微观层面解释化学作用对膨润土膨胀影响的实用工具。
