Birim alana gelen bentonit kütle miktarının yapay hazırlanmış geosentetik kil örtülerin (Y-GKÖ) hidrasyon ve hidrolik iletkenliklerine etkisi

This study investigates the effect of mass per unit area (MPUA) of bentonites on the hydration and hydraulic performances of artificially prepared geosynthetic clay liners (A-GCLs). For this purpose, polymer treated GCL (P-GCL) and sodium GCL (Na-GCL) prepared with different MPUAs were used. They were hydrated over compacted silty sand for 7 and 30 days. When the MPUAs of GCLs were increased, final water contents decreased. Longer hydration duration resulted in higher water contents of GCLs. Hydrated GCLs over subsoil were subjected to hydraulic conductivity tests. In the first set, hydraulic conductivity tests were conducted under high hydraulic gradients. In the second set, hydraulic gradients were gradually increased from lower to higher hydraulic gradients. In the tests under higher hydraulic gradients, P-GCL had lower hydraulic conductivity when compared to Na-GCL. The final hydraulic conductivities of GCLs with high MPUAs were around 1.0×10-11 m/s. However, GCLs with the MPUA of 3.0 kg/m2 had greater permeability (i.e. 1.0×10-6 m/s) regardless of hydration duration. This can be attributed to the fact that the bentonite cannot fill the gap formed by the bundle of fibers even after swelling and that the bentonite particles might have not been distributed homogeneously in the GCL. As a result of Rhodamine tracer dye test, it was seen that bundle of fibers induced pore in the GCL caused high permeability. On the other hand, in the tests initiated from lower hydraulic gradient, lower hydraulic conductivity values were obtained for Na-GCLs prepared with 3.0, 4.0 and 5.0 kg/m2 even if hydraulic gradient was further increased. Like Na-GCL, P-GCL with MPUA of 3.0 kg/m2 had lower hydraulic conductivity under hydraulic gradient of 20.