Water retention curves of untreated and hyper clay geosynthetic clay liners

Abstract

Bentonite clay is widely used as a hydraulic barrier in geosynthetic clay liners (GCLs) due to its low hydraulic conductivity, but in an aggressive environment, such as interaction with electrolytic solutions and higher temperature variations and number of wet and dry cycles, the performance of bentonite deteriorates. Polymerised bentonite clay (hyper clay) has shown better performance than untreated bentonite under these conditions, possibly due to better water retention, thus highlighting the need to investigate the water retention capacity. Therefore, the water retention behaviour of hyper clay GCLs was studied and compared with that of untreated clay GCLs. This paper presents the soil water retention curves of untreated bentonite GCL and hyper clay GCLs treated with 8% carboxymethylcellulose measured by filter paper tests. Different electrolytic solutions were used as permeation fluids along with deionised water to represent a more aggressive environment. The results showed that a hyper clay GCL has 7% higher water retention capacity near the air entry value than an untreated clay GCL in deionised water. In other words, a hyper clay GCL can be considered a potential alternative to conventional bentonite GCLs due to its improved water retention capacity.