Volume Change and Hydraulic Conductivity of Soil-Bentonite Mixture

The aim of this study was to estimate volume change and hydraulic conductivity and to collect suction data for UKM (University Kebangsaan Malaysia) soil - bentonite mixture. This mixture is proposed as a barrier material in waste containment systems. Tests were performed on UKM soil mixed with different bentonite contents (0%, 5%, 10% and 20%). It was found that with the addition of bentonite, both shrinkage and swelling strains increased. Insignificant cracks appeared at 0% and 5% bentonite content. However, significant cracks appeared in UKM soil after mixing with 10% and 20% bentonite contents. The results also showed that bentonite decreases the hydraulic conductivity of UKM soil significantly. The results from tested samples after 1 to 4 drying cycles showed that the largest rise in soil hydraulic conductivity occurred at first or second drying. Soil water characteristic curves (SWCC) were developed for compacted soil samples (with and without bentonite) using pressure membrane apparatus. The relative locations of SWCC plots were higher for the soil samples mixed with bentonite.