INFLUENCE OF CLODS ON HYDRAULIC CONDUCTIVITY OF COMPACTED CLAY

The hydraulic conductivity of a highly plastic, compacted clay soil is significantly influenced by the size of clods used in preparing the soil for compaction. For soil compacted dry of optimum, hydraulic conductivity is 1,000,000 times smaller when the soil is prepared from small (4.6-mm) rather than large (19-mm) clods. For soil compacted wet of optimum, clod size is unimportant. Large differences are seen in the hydraulic conductivity of soils compacted with standard versus modified Proctor procedures. The conclusion reached is that the fate of clods and interclod pores during soil processing and compaction controlled the hydraulic conductivity of the compacted soil. To achieve low hydraulic conductivity, it is necessary to destroy the clods and to eliminate large interclod pores either by wetting the soil to a high water content or using a large compactive effort. © ASCE.