Sealing and Volume Change Behaviour of Gellan Gum Amended Granular Bentonite Under Extreme Chemical Loading for Landfill Applications

Geosynththetic clay liners (GCLs) having granular bentonite (GB) are widely used as lining system in waste containment facilities. Significant increase of several folds in hydraulic conductivity has been observed by several researchers in presence of high concentration salt solutions in leachate due to loss in osmotic potential. The second-generation GCLs having polymer amended bentonites are being explored for liner applications under extreme salt environment by several researchers. A biopolymer, gellan gum, was explored in this study to use as amendment of the GB present in GCLs to improve its sealing ability. The liner system is also subjected to the mechanical stresses due to the waste load. The performance of liner under the influence of chemical and mechanical loading needs to be understood before using them for long term. In this study, the GB and gellan gum amended GB were compacted at a density of 1.2 Mg/m3. The sealing and volume change behaviour of these samples were evaluated with different commonly available salts (i.e. NaCl and KCl) in leachate. The results showed the influence of pore fluids, gellan gum amendment on sealing, and volume change behaviour. Mechanism influencing the sealing and volume change behaviour will be presented.