Improving hydraulic performance and durability of sandwich clay liner using super-absorbent polymer

The hydraulic performance and durability of geosynthetic clay liner containing various amounts of sodium polyacrylate polymer are experimentally studied. Sodium polyacrylate, generally known as a super-absorbent polymer, is a polymeric material with a potential of high water absorbance due to its chemical structure. In this study, sodium polyacrylate powder is used as a partial replacement of bentonite as much as 3%, 5% and 7% by the weight of bentonite. For comparison, the hydraulic performance of geosynthetic clay liner without super-absorbent polymer is also experimented. Atterberg limits, free swell index, hydraulic conductivity, self-healing capacity and wet/dry cycle tests are conducted in order to assess how super-absorbent polymer can affect the performance of geosynthetic clay liners as landfill liners and covers. The results show that the hydraulic conductivity and self-healing capacity of geosynthetic clay liner are relatively enhanced by super-absorbent polymer inclusion. The results of wet/dry cycle test show that using super-absorbent polymer as a partial replacement of bentonite considerably improves the durability of geosynthetic clay liner against wet/dry cycles. Geosynthetic clay liner containing super-absorbent polymer shows a negligible increase in hydraulic conductivity while there is a noticeable increase in hydraulic conductivity of specimen without super-absorbent polymer after 10 cycles of wetting and drying.