Water Content‐Density Criteria for Compacted Soil Liners

Abstract

Soil liners have traditionally been compacted in the field to a minimum dry weight over a specified range in water content. This approach evolved from the practice for structural fills for which strength and compressibility are of primary concern. With soil liners, hydraulic conductivity is usually of paramount importance. Hence, the approach used to ensure adequate strength and permissible compressibility is not necessarily applicable to the construction of soil liners. Data are presented to show that the water content‐density criteria for compacted soil liners can be formulated in a manner that is different from the approach currently used by many engineers. The recommended approach is based on defining water content‐density requirements for a broad, but representative, range of compactive energy, and relating those requirements to hydraulic conductivity and other relevant factors. A case history illustrates the recommended procedure and its implementation. Hydraulic conductivity measurements were performed on three soils to develop an “acceptable zone” on the compaction curve that was used for quality control during construction. As a result of implementing the recommended procedure, construction operations were significantly accelerated.