Effect of Clay Mineralogy on Permeability Behavior of Compacted Fine-Grained Soils
In compacted fine-grained soils, permeability is very important phenomena, because of its primary usage in clay liners, landfills and road embankments. The Hydraulic conductivity behavior of compacted fine-grained soils is a physico-chemical phenomenon due to the presence of least active to most active clay minerals in different proportions. However, very limited documented test data is provided on the hydraulic conductivity behavior of compacted fine-grained soils with respect to effect of clay mineralogy and placement conditions subjected to various energy levels. In the present experimental study, One dimensional consolidation tests were conducted on two field soils having same liquid limit but different clay mineralogical composition and plasticity characteristics at various placement conditions (95% of optimum on dry and wet side and at optimum) from a seating pressure of 6.25 kPa to 1600 kPa with an increment ratio of one. An attempt has been made to compute the Coefficient of Permeability (K) indirectly by determining the consolidation characteristics like Cv and Mv by five user friendly methods documented in the literature for IS Light and Heavy Compaction energy levels and for different placement conditions. In addition variable head permeability tests were conducted for a pressure ranging from 6.25 kPa to 1600 kPa for loading conditions. Coefficient of Permeability values computed through actual measurements for loading conditions were compared with the estimated values of K using user friendly methods. The Variation of Coefficient of Permeability (K) is uniquely correlated with Coefficient of Consolidation (Cv) for soils having different clay mineralogy and placement conditions for both IS Light and Heavy compaction energy levels. The Variation of K with void ratio (e) showed that, maximum K values were observed on dry of optimum side in relative comparison with the optimum and wet of optimum due to the effect of soil fabric.