Classification of expansive soils used as embankment fills

The research group of proiect "Research on design, stabilization and construction technology of expansive soil subgrade" sponsored by Chinese Ministry of Communications has successfully built several trial embankments in some areas by directly using expansive soils with different swelling potentials and achieved valuable experience. In order to promote the application of the new technology and ensure the strength and the stability of the subgrade, it is necessary to establish the classification of expansive soils used as fills. Based on numerous laboratory results of engineering properties of expansive soils, summarization of the experience in building trial embankments with expansive soils and criticism of some old classification indices, a new classification of expansive soils used as embankment fills is put forward by use of three indices-CBR strength, swelling rate of CBR samples in modified CBR tests and consistency. The corresponding indices are verified through tests on three kinds of typical expansive soils. It is shown that the new classification can reflect the basic characteristics of the expansive soils and the engineering properties of embankment fills. Furthermore, it is very easy and convenient to obtain these indices, so that the application of expansive soils used as embankment fills can be enlarged, theses indices may be and provide engineers with references in the design and construction of expensive soil embankments.