Predicting the hydraulic conductivity of saturated clays using plasticity-value correlations

Hydraulic conductivity is one of the important, basic engineering properties of soils. However, as a soil parameter it is difficult to measure and can be highly variable, necessitating the investigation of a large number of samples. For these reasons several researchers have proposed various indirect methods for predicting the hydraulic conductivity of soils from easily measured and routinely obtainable data. As plasticity is the most distinctive and the easiest property of clays to measure, it would be a very convenient basis for predicting the hydraulic conductivity. This paper focuses on an investigation of the relationship between the hydraulic conductivity of clays and their Atterberg limits. For this purpose five samples of expanding and non-expanding clays were used. The results of laboratory tests showed that the hydraulic conductivity of a clay at a selected void ratio could be adequately determined when the external surface area of the clay grains was considered. The finding that there exists an exactly defined relationship between the Atterberg limits of clays and their external specific surfaces helped us to express the hydraulic conductivity in terms of the void ratio and the plasticity value.