Thesis Defence: Crack Mitigation and Contaminant Immobilization in Bentonite Clay with Sustainable Amendments

Sharon Kumar Injamala, supervised by Dr. Sumi Siddiqua, will defend their thesis titled “Crack Mitigation and Contaminant Immobilization in Bentonite Clay with Sustainable Amendments” in partial fulfillment of the requirements for the degree of Master of Applied Science in Civil Engineering.

An abstract for Sharon Kumar Injamala’s thesis is included below.

Defences are open to all members of the campus community as well as the general public. Please email sumi.siddiqua@ubc.ca to receive the Zoom link for this defence.

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ABSTRACT

Desiccation cracks in landfill liners pose several problems that can significantly impact the performance and environmental safety of landfills. This study introduces two different sustainable stabilizing materials to minimize the cracking properties and improve the geotechnical properties of bentonite for its application in landfill liner systems. One of those sustainable stabilizing materials is biochar, which has been widely used to improve soil quality, restore soil, and store atmospheric carbon dioxide, whereas the other material is a biopolymer, which helps in the polymerization of clays and has gained significant interest due to sustainability characteristics. Three different percentages of biochar (5%, 15%, 25%) of size less than 0.075 mm and three different percentages of biopolymer (0%, 2%, 4%) are mixed with bentonite clay followed by investigating their volumetric shrinkage behavior, compaction, and compressive strength characteristics. The desiccation cracking is assessed with the help of ImageJ analysis in terms of Crack Intensity Factor (CIF) and Crack Density Factor (CDF). The microstructure analysis using a Scanning electron microscope (SEM) is carried out to visualize how the composite materials interact when mixed. Finally, the adsorption studies are conducted, to determine the effect of biochar and biopolymer on the adsorption behavior of bentonite. It was observed that the compaction and compressive strength values recorded the highest at biochar (5%) and biopolymer (4%). Further, the biochar-amended bentonite portrayed improved adsorption behavior, volumetric shrinkage, and crack resistance in terms of CDF and CIF. The results indicate that biochar and biopolymer can be added as a sustainable amendment to the high-swelling bentonite clay to improve its geotechnical properties for its application as a landfill liner material.