Estimation of mechanical and hydraulic parameters of bentonite-soil mixtures in oedometer condition with index properties

A large amount of bentonite slurry is dumped as construction waste in fill banks around the world. In order to reuse them, it is important to determine the mechanical and hydraulic parameters of bentonite-soil mixtures containing different montmorillonite contents. The establishment of these parameters with index properties is an efficient and simple way. Despite the proposal of some correlations to estimate the compression and swelling indices for kaolinite or illite-dominated soils (KIDSs) with relatively low liquid limits, they are unsuitable for bentonite-soil mixtures dominated by montmorillonite. Besides, no correlation was given for predicting the parameters in the non-linear creep function as well. In this study, the results of the Atterberg limits, oedometer, and scanning electron microscope (SEM) tests on five mixtures with different montmorillonite contents from 5 to 35% were presented. Compression and swelling indices creep coefficient as well as the non-linear creep parameters and hydraulic conductivity of bentonite-soil mixtures were obtained. Several correlations were put forward to estimate the mechanical parameters with Atterberg limit indices. The proposed correlations were further verified using the data collected from literature, which can well estimate the mechanical parameters of soils with a liquid limit of above 50%. In addition, a simplified model with a homogenization approach was developed to estimate hydraulic conductivity with reasonable accuracy, which is easier to be adopted in practical engineering.