A review of the influence of clay–brine interactions on the geotechnical properties of Ca-montmorillonitic clayey soils from western Canada

Natural Ca-montmorillonite clay soils or engineered clay barriers in western Canada are often used to contain brine generated from the surface disposal of potash tailings or from drilling activities associated with the oil and gas industry. The performance of these barriers has ranged from excellent to poor. The influence of salt brines on the geotechnical properties of these soils has been recognized as a potentially important factor for some time. It has been well documented in the literature that the behavior of clayey soils is strongly influenced by physicochemical interactions between clay particles and pore-fluid chemistry; consequently, the properties of these soils are sensitive to changes in the electrolyte concentration of the pore fluid. An increase in the concentration of the pore fluid to the levels of a concentrated brine can cause significant changes in the geotechnical properties of the soil. In this paper, the impact of brine contamination on the geotechnical properties of two Ca-montmorillonitic clayey soils of glacial origin from western Canada is reviewed. The influence of clay–brine interactions on the index properties (liquid limit, plastic limit, plastic index, mineralogy, density, grain size, and compaction characteristics), mechanical properties (volume change and shear strength), and hydraulic properties (hydraulic conductivity) is described. A quantitative explanation for the changes that occur in the hydraulic and mechanical properties of these soils as a result of brine permeation is also provided. This explanation relates the changes in pore-fluid chemistry to changes in an effective physicochemical stress state. This approach may be used to predict the changes in hydraulic conductivity, volume, or shear strength of a clayey soil as a result of brine contamination. Key words : clay–brine interactions, diffuse double layer, hydraulic conductivity, soil structure, physicochemical.

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Impact of Particle Sizes, Mineralogy and Pore Fluid Chemistry on the Plasticity of Clayey Soils

Sustainability ◽

10.3390/su132111741 ◽

2021 ◽

Vol 13 (21) ◽

pp. 11741

Author(s):

Jongmuk Won ◽

Junghee Park ◽

Junki Kim ◽

Junbong Jang

Keyword(s):

Particle Size ◽

Shear Strength ◽

Undrained Shear Strength ◽

Ionic Concentration ◽

Pore Fluid ◽

Particle Sizes ◽

Clayey Soils ◽

Fluid Chemistry ◽

Pore Fluid Chemistry ◽

Undrained Shear

The current classification of clayey soils does not entail information of pore fluid chemistry and particle size less than 75 µm. However, the pore fluid chemistry and particle size (at given mineralogy) are critical in the plasticity of clayey soils because of their impact on negative charge density. Therefore, this study extensively discusses the description of clay with respect to mineralogy, particle sizes, and pore fluid chemistry based on liquid and plastic limits of kaolinite, illite, and bentonite, and estimates undrained shear strength from the observed liquid limits. The liquid limits and undrained shear strength estimated from the observed liquid limits as a function of mineralogy (clay type), particle size, and ionic concentration reveal the need of incorporating pore fluid chemistry and particle size into the fines classification system. Furthermore, multiple linear regression models developed in this study demonstrate the importance of particle size and ionic concentration in predicting the liquid limit of clayey soils. This study also discusses the need for a comprehensive understanding of fines classification for proper interpretation of natural phenomena and engineering applications for fine-grained sediments.

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Pore Fluid Chemistry and Aging Effects on Swelling, Shear Strength, and Pore Size Distribution Behavior of Soils

Geoenvironmental Engineering ◽

10.1061/9780784413432.025 ◽

2014 ◽

Author(s):

Emel Çakar ◽

Hasan Firat Pulat ◽

Yeliz Yükselen Aksoy

Keyword(s):

Shear Strength ◽

Pore Size Distribution ◽

Pore Size ◽

Size Distribution ◽

Pore Fluid ◽

Aging Effects ◽

Fluid Chemistry ◽

Pore Fluid Chemistry ◽

Distribution Behavior

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Evaluation of the impact of pore fluid chemistry on the hydromechanical behaviour of clay-based sealing materials

Canadian Geotechnical Journal ◽

10.1139/t10-064 ◽

2011 ◽

Vol 48 (2) ◽

pp. 199-213 ◽

Cited By ~ 64

Author(s):

Sumi Siddiqua ◽

James Blatz ◽

Greg Siemens

Keyword(s):

Hydraulic Conductivity ◽

Pore Fluid ◽

Experimental Program ◽

Dry Density ◽

Analysis And Design ◽

Barrier Materials ◽

Fluid Chemistry ◽

Pore Fluid Chemistry ◽

Swell Potential ◽

The Impact

The results of an experimental program undertaken to evaluate the impact of pore fluid salinity on the hydromechanical performance of light and dense backfill materials are presented. Light and dense backfills are engineered barrier materials that are being examined in the Canadian concept for storage of spent fuel in a deep geological repository. The current research investigates the impact of pore fluid chemistry on the swelling, compressibility, stiffness, and hydraulic conductivity parameters of light and dense backfills that are required as material parameters for analysis and design. In these tests, pore fluid chemistry was selected to represent groundwater within potential host units including granite and limestone rock. Results show that the performance of light backfill is significantly affected by changes in pore fluid chemistry. The swell potential of light backfill decreases with increasing salinity of the solution. The hydraulic conductivity decreases with increasing effective montmorillonite dry density and specimens saturated with saline solution have higher hydraulic conductivity than those saturated with distilled water. Conversely, the behaviour of dense backfill is governed mainly by the crushed granite component and therefore changes to the pore fluid chemistry have relatively little effect. Results of dense backfill tests confirm the material performance as a sealing material.

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