The effects of four organic fluids on hydraulic conductivity of compacted kaolinite are presented. Permeation fluids were 0.1 and 100% solutions of nitrobenzene, acetone, phenol, and benzene, which represent a wide range of dielectric constants. Full saturation hydraulic conductivities were obtained in flexible wall permeameters under continuous back pressure, at hydraulic gradients of less than 100 and effective stresses of 69 kPa (10 psi). Reference hydraulic conductivity values were determined with 0.01 N calcium sulfate (CaSO4) solution.
The effect of the testing scheme was evaluated by measuring the hydraulic conductivity of acetone in both a flexible wall permeameter at variable effective stresses and in a rigid wall permeameter. Dramatic hydraulic conductivity increases were observed in rigid wall permeameters. The results indicate that increases in the hydraulic conductivity measured in rigid wall permeameters can only be explained by side leakages due to shrinkage of the specimen.
All tests with chemicals at low concentrations resulted in slight decreases of hydraulic conductivity. Hydraulic conductivity with pure solutions slightly increased with acetone and phenol and significantly decreased with benzene and nitrobenzene. Diffusion through the cell membrane was found to be a considerable source of error in assessing the full strength of organic fluids. The direction of variations in the liquid limit and the free swell of kaolinite with organic fluids was observed to be inversely related to changes in absolute values of hydraulic conductivity at low effective stresses. These results together with fabric studies indicated that changes in hydraulic conductivity with organic fluids can be explained by the variations in the surface forces of interaction on clay particles affecting the flow characteristics.