Swelling of compacted sand–bentonite mixtures

Based on the concept that the maximum water volume absorbed by montmorillonite per unit volume is constant, the swelling deformation of sand–bentonite mixtures was characterized using the void ratio of montmorillonite, defined as volume ratio of water to montmorillonite. The relationship between the montmorillonite void ratio and vertical pressure at full swelling is independent on the initial compaction condition and sand–bentonite mixing ratio, and is a straight line in log scales. When the vertical pressure is large enough and/or the content of bentonite in the mixture is small, the measured plots deviate from linearity. Using the concept of skeleton void ratio, a method is proposed and verified for predicting the limited vertical pressure over which the measured plots start to deviate from linearity between the montmorillonite void ratio and vertical pressure.