Prediction of the hydraulic conductivity of clays using the electric double layer theory

A model to predict the hydraulic conductivity of consolidated clay, simulat ing clay liners compacted wet of optimum, is presented. The concept that cl ays exist as clusters and the electrical double layer theory are used to pr edict the hydraulic conductivity of clays for permeants of known compositio n. The model relates the physical properties of clays, such as its surface area, with the overburden pressure and the concentration of ions in the per meant. The model can be used to predict the hydraulic conductivity of bento nitic clays with monovalent as well as divalent exchangeable cations. The m odel is valid within the range of applicability of the Gouy-Chapman electri c double layer theory. The variation in the number of clay particles per cl uster with the consolidation pressure and concentration of ions in the perm eant has been discussed. The model has been calibrated and verified using p ublished experimental data. However, the model in its present form is valid only for homoionic clays and permeants with the same valency. With an incr ease in concentration of ions in the permeant, the precision of the model h as been found to decrease.