Polymer-enhanced soil mixtures for potential use as covers or liners in landfill systems

The use of polymers can change the specific properties of natural soils. This study analyses the interaction between a natural fine sand, a clayey soil and anionic polyacrylamide (APAM). The laboratory results show that APAM, a superabsorbent polymer, increases the plasticity and the capacity of water absorption of the clay–APAM and sand–clay–APAM compacted composites. Free swelling and swelling pressure also increase with the addition of APAM. The sand–clay–APAM composite shows a higher unconfined compressive strength and a slight reduction in hydraulic conductivity. Microstructural analysis confirms the aggregation capacity of APAM and a reduction in the accumulated pore volume, which minimise liquid infiltration and soil erosion. Results demonstrate that the clay–APAM and sand–clay–APAM composites can be effective as liners and covers, respectively, in a landfill system.