Control of Placement Moisture and Density in Compacted Expansive Clays

This paper presents the basic properties of an expansive clay soil which is of frequent occurence in Southcentral China. The soil is characterized by medium-high swell, it commonly contains significant quantities of clay minerals predominately composed of illite. The results of laboratory tests for determination of swell under loads and swelling pressure or loads required to restrain expansion are given, with several series of soil specimens compacted at a variety of moistures and densities in the consolidometer. For controlling the swell potential in compacted expansive clay, it is suggested that a combination of placement densities lower than those obtained by standard compaction and placement moistures higher than standard optimum are required to insure low expansion. The paper also has a discussion on the influence of the soil fabric of compacted clay on swelling characteristics.