Hygroscopic moisture content: determination and correlations

Abstract

Hygroscopic moisture content of fine-grained soil represents the water adsorbed by the negatively charged clay platelets when the oven-dried soil is exposed to an atmosphere with different levels of humidity, which is a variable. Hygroscopic moisture content has been linked with many clay mineralogical parameters in predictive geotechnical engineering. However, there appears to be no standard codal provisions to quantify this property. This paper uses the modified rectangular hyperbolic representation of the adsorbed water content against time of exposure to an environment with 100% relative humidity relationship to quantify the hygroscopic moisture content. The proposed method is very simple and fairly accurate. The hygroscopic moisture contents so predicted corresponding to 100% relative humidity have been shown to have one-to-one correspondence with the values obtained through actual time-consuming measurements. By virtue of common dependency factors, it is shown that the hygroscopic moisture content at 100% relative humidity of fine-grained soils can be uniquely related with their liquid limits and equilibrium sediment volumes. Furthermore, instead of a time-consuming method of determining the hygroscopic moisture content, a simple method of predicting the same knowing their liquid limits has been proposed.