Stabilizing Compacted Clay against Chemical Attack

Concentrated organic chemicals have been shown to cause large increases in the hydraulic conductivity of compacted clay. Mechanical and chemical methods of stabilizing four different types of compacted clay against chemical attack are investigated. Mechanical stabilization using a large compactive effort (modified Proctor compaction) or application of a compressive stress ≥ 10 psi (70 kPa) is found to render a compacted clay invulnerable to attack by concentrated organic chemicals under laboratory‐test conditions. Attapulgite, a clay mineral having little electrical charge, was found to be relatively unaffected (compared to more common clay minerals such as kaolinite, illite, and smectite) by concentrated organic chemicals. Addition of approximately 7% (by weight) of lime, portland cement, or lime plus sodium silicate greatly improved the ability of compacted clay to resist attack by concentrated organic chemicals; in some cases the amended soils were less permeable to concentrated organic chemicals than the unamended soils were to water.