Theoretically, there are two limiting conditions during wetting of expansive soils. These are: The completely unconfined condition in which the soil is allowed to swell freely along all directions; and the completely confined condition in which no overall volume change is allowed. In the present work, to simulate field conditions, partial loading was considered using two modes of wetting the upward and downward water supply. Partial loading has been achieved experimentally using the oedometer by loading one plate of a fixed area on different specimen areas or by loading plates of different areas on a fixed specimen area. The upward water supply has been achieved by providing one filter paper and one porous plate under the specimen only. In case of downward water supply a steel plate was placed under the specimen and the free unloaded surface area surrounding the loading plate was provided with aluminum porous plate and filter paper. Test results indicated that, the mode of wetting has a significant effect on swelling characteristics, particularly swelling pressures and surface heave.
