Hydraulic Conductivity Tests on Compacted Clay

Permeability tests were performed in the laboratory on compacted clay to study the effects of type of permeameter, hydraulic anisotropy, diameter of test specimens, storage time, and desiccation cracking. Essentially identical hydraulic conductivities were measured with compaction‐mold, consolidation‐cell, and flexible‐wall permeameters. With good bonding between lifts, hydraulic conductivity was isotropic. Test specimens having a diameter of 15 cm were twice as permeable as specimens having a diameter of 4 cm, but this difference is too small to be of any consequence. There was no tendency for hydraulic conductivity to increase with increasing storage time. Desiccation cracks in compacted clay close only partially when the clay is moistened and permeated, unless substantial effective stresses are applied to aid in closing the cracks.