Engineering behavior of sand-bentonite mixtures and the influence of particle size of sand

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Sand-bentonite mixtures are playing a greater role as geotechnical barrier materials in waste disposal schemes around the world. Therefore, a comprehensive understanding on the engineering behavior of a geotechnical barrier becomes a necessity. Literature review indicated a host of variables influencing the engineering behavior of a barrier to various degrees, including and not limited to mixing water content, compaction effort, mineralogy of the soil, size and shape of particles, interactions among the soil particles, interactions with water, interactions with any other pore fluid that may exist in the soil, pH, temperature, cation exchange capacity and concentration of cations in the soil pore fluid. Upon scrutiny, it has been observed that most of the studies conducted were primarily focusing on the role of bentonite in the sand-bentonite mixture. Studies highlighting the contributions of sand particle size, sand gradation etc. were very few, though sand formed the major component in most of the sand-bentonite mixtures being employed around the world. This study sheds some light on the influence of sand particle size and sand composition on the engineering characteristics of sand-bentonite mixtures with varying bentonite proportions.In the current study, locally available sand has been washed and sieved for different particles sizes (fine sand and medium sand). Two commercially available bentonites with different swelling capabilities were used in the study. Fine sand-bentonite (FS-B), medium sand-bentonite (MS-B) and fines sand-medium sand-bentonite (FS-MS-B) mixtures were made with bentonite proportion varying from 10 to 50 percent by dry weight in the mix. These mixes were tested for Atterberg limits, standard compaction characteristics, consolidation characteristics, hydraulic characteristics, unconfined compressive strength behavior and shrinkage characteristics.
supervisor: Anil Kumar Mishra