Swelling Behavior of Sand–Bentonite Mixtures

Abstract: In this study, the swelling behavior of sand-bentonite mixtures and pure bentonite is investigated by considering different factors, such as bentonite content in the mixture, specimen preparation method by applying different compactive efforts, and various effective stress levels. Compaction tests were performed on the specimens of the sand–bentonite mixtures with 10% and 20% bentonite contents, and pure bentonite. The maximum dry density and optimum water content of the specimens with 20% bentonite are higher than those of the specimens with 10% bentonite. Pure bentonite specimens have a lower maximum dry density and higher optimum water content compared to sand-bentonite mixtures. Specimens of the swelling tests were prepared at the optimum water content values of the mixtures. Up to a vertical effective stress of 25 kPa, the mixtures showed swelling behavior. Under the effective vertical stresses of 50 and 100 kPa, the specimens behaved in the compression side. It was seen that the application of either 10 or 25 blows by means of compactive effort in pure bentonite specimens had a negligible effect on the swelling behavior