Prediction for swelling deformation of fractal-textured bentonite and its sand mixtures in salt solution

• Published in: Clay minerals Vol. 54; no. 2; pp. 161 - 167
• Main Authors: Xiang Guosheng, Xiang Guosheng, Yu Feng, Yu Feng, Xu Yongfu, Xu Yongfu, Fang Yuan, Fang Yuan, Xie Shenghua, Xie Shenghua
• Format: Journal Article
• Language: English
• Published: Middlesex Mineralogical Society 01.06.2019; Cambridge University Press
• Subjects: Bentonite; chemical properties; clastic rocks; clastic sediments; Clay; clay mineralogy; clay minerals; Deformation; Distilled water; expansion; experimental studies; Fractal geometry; geochemistry; Groundwater; Montmorillonite; Montmorillonites; Physical properties; prediction; Predictions; rock, sediment, soil; Saline solutions; Salinity; Sand; Sand & gravel; Saturation; sed rocks, sediments; Sedimentary petrology; sedimentary rocks; sediments; sheet silicates; silicates; Sodium chloride; solution; Surface structure; Swelling; Void ratio; China
• ISSN: 0009-8558; 1471-8030
• DOI: 10.1180/clm.2019.24

Swelling deformation tests of Kunigel bentonite and its sand mixtures were performed in distilled water and NaCl solution. The salinity of NaCl solution has a significant impact on the swelling properties of bentonite, but not on its surface structure. The surface structure was characterized using the fractal dimension Ds. Based on the fractal dimension, a unique curve of the em-pe relationship (em is the void ratio of montmorillonite and pe is the effective stress) at full saturation was introduced to express the swelling deformation of bentonite-sand mixtures. In mixtures with a large bentonite content, the swelling deformation always followed the em-pe relationship. In mixtures with a small bentonite content, when the effective stress reached a threshold, the void ratio of montmorillonite em deviated from the unique em-pe curve due to the appearance of a sand skeleton. The threshold of vertical pressure for mixtures in different solutions and the maximum swelling strains were estimated using the em-pe relationship. The good agreement between estimates and experimental data suggest that the em-pe relationship might be an alternative method for predicting the swelling deformation of bentonite-sand mixtures in salt solution.