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Shear Strength Behavior of Bentonite Modified by Tetramethylammonium Cations
Abstract Over the past decades, bentonite exchanged with quaternary ammonium cations to form organobentonite has gained increasing attention. Due to its high sorption capacity for organic contaminants and low friction angles, organobentonite has many applications, including in the areas of contaminant site remediation, landfill clay liners, and as a pipe jacking lubricant and drilling mud. Although many properties of organobentonites have been studied in detail, such as sorption capacity, swelling, and hydraulic conductivity, little data are available on the strength of this engineered clay. This study presents the results of the shear strength behavior of tetramethylammonium cations exchanged bentonite (TMA-bentonite) as a function of organic loading. TMA-bentonites had higher shear strength and higher hydraulic conductivity than the unmodified bentonites. The initial shear modulus increased with the amount of TMA loaded on the bentonite surfaces, i.e. as the organic loading was increased. The tested samples were normally to lightly overconsolidated, but always exhibited peak behavior and positive pore pressures in the stress strain curve. This study sets the stage for further investigation of more complicated organic cations, such as tetramethylammonium (TEA) and hexdecyltrimethylammonium (HDTMA).
Shear Strength Behavior of Bentonite Modified by Tetramethylammonium Cations
Abstract Over the past decades, bentonite exchanged with quaternary ammonium cations to form organobentonite has gained increasing attention. Due to its high sorption capacity for organic contaminants and low friction angles, organobentonite has many applications, including in the areas of contaminant site remediation, landfill clay liners, and as a pipe jacking lubricant and drilling mud. Although many properties of organobentonites have been studied in detail, such as sorption capacity, swelling, and hydraulic conductivity, little data are available on the strength of this engineered clay. This study presents the results of the shear strength behavior of tetramethylammonium cations exchanged bentonite (TMA-bentonite) as a function of organic loading. TMA-bentonites had higher shear strength and higher hydraulic conductivity than the unmodified bentonites. The initial shear modulus increased with the amount of TMA loaded on the bentonite surfaces, i.e. as the organic loading was increased. The tested samples were normally to lightly overconsolidated, but always exhibited peak behavior and positive pore pressures in the stress strain curve. This study sets the stage for further investigation of more complicated organic cations, such as tetramethylammonium (TEA) and hexdecyltrimethylammonium (HDTMA).
Shear Strength Behavior of Bentonite Modified by Tetramethylammonium Cations
Bate, Bate (author) / Burns, Susan E. (author)
Advances in Environmental Geotechnics ; 543-548
2010-01-01
6 pages
Article/Chapter (Book)
Electronic Resource
English
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