Determining the thickness of adsorbed water layers on the external surfaces of clay minerals based on the engineering properties of soils

• The thicknesses of the adsorbed water layers on clay minerals were determined.
• These thicknesses depend on the total water content of the soils.
• This relationship is exactly defined and can be expressed by a non-linear function.

This article discusses the basic findings that enable a determination of the thicknesses of the adsorbed water layers on the external surfaces of clay minerals and their dependence on the total water content in soils. The thicknesses of the water films were first determined indirectly from tests of the undrained shear strength of clay mineral samples. A comparison between these thicknesses and the total quantity of water in the samples showed that this ratio is exactly defined and can be expressed by a non-linear function in which the type of soil is determined by two parameters, which depend on the size and the quantity of the clay minerals. A test of the correctness and usefulness of the established expression was made on two samples of clays. The thicknesses of the water films, calculated using the proposed equation for different moisture contents, were compared with the thicknesses determined from the adsorptive potential of the soils. These results showed a good agreement. The possible application of the proposed expression is shown for the case of an estimation of the soil–water characteristic curve in the range between the water content at the air-entry value and the residual water content.

Figure optionsDownload as PowerPoint slide