Experimental study to evaluate soil water retention curve of HYPER clay geosynthetic clay liner

Abstract

Geosynthetic clay liners are widely used as hydraulic barrier due to their low hydraulic conductivity but bentonite in the liners loses its effectiveness due to significant thermal fluxes by both diurnal and seasonal heating and cooling cycles. Modified sodium carboxy methyl cellulose-based bentonite clay (HYPER clay) has shown better hydraulic performance in both situations. A possible reason for this improved performance of HYPER clay based geosynthetic clay liner is the improvement in the suction under changing thermal conditions. Thus, the relationship between soil suction and moisture content, also called the soil water retention curve, needs to be estimated. Therefore, we investigated the soil-water retention curve of the HYPER clay based geosynthetic clay liner and compared it with the untreated clay based geosynthetic clay liner. The article presents the suction test results on wetting path conducted on geosynthetic clay liner prototypes containing HYPER and untreated clay assessed by the contact filter paper method and the relative humidity sensor. The results showed that the geosynthetic clay liner containing HYPER clay has a high volumetric water content and thus, high water retention compared to untreated bentonite at a given suction value. In other words, the HYPER clay can be considered as a potential alternative to conventional bentonite due to its improved water retention capacity.