Sodium Carboxymethyl Cellulose-Enhanced GCLs in Freshwater Reservoirs

Abstract

Biopolymers that are environmentally friendly organic products are increasingly used in geotechnical applications instead of synthetic polymers and other chemical additives. Cellulose is a biopolymer that is obtained from the cell walls of plants. In order to evaluate its effect on internal erosion, triaxial permeability tests were performed on a sodium carboxymethyl cellulose-enhanced geosynthetic clay liner (GCL) with Ca bentonite that was placed over a coarse gravel with an average grain diameter of 2.5 cm and permeated with tap water. Furthermore, unconfined compression tests were conducted on the cellulose-added bentonite component of the GCL in order to evaluate the mechanical effect of sodium carboxymethyl cellulose addition to the GCL on internal erosion. Test results indicated that 2% cellulose addition by dry weight maintained sufficient hydraulic and mechanical performances with almost 2.5 orders of magnitude decrease in permeability and 10 times increase in unconfined compressive strength. However, cellulose addition had only a slight enhancement against internal erosion. All the tested GCLs resisted against internal erosion up to a hydraulic head of 25 m. But 30 m hydraulic head resulted in internal erosion for the GCLs enhanced with up to a content of 2% cellulose.