ABSTRACT
Hygroscopic Water Content is a behavioral characteristic of soils that essentially describes (in quantitative terms) how much water can be adsorbed on the internal and external surface area of clay minerals present in the soil. The Hygroscopic Water Content of a soil is the same as the air dried Water Content (i.e., Water Content when exposed to the atmosphere for a long period of time at constant relative humidity). However, since atmospheric Water Content changes with changes in the weather, the Hygroscopic Water Content of soils is not constant but varies with humidity. Measurement of the Hygroscopic Water Content was in practice at least as early as the 1930s according to Pichler (1953).
A number of studies have shown that the Hygroscopic Water Content depends primarily on the amount and type of clay minerals present in the soil. This is fundamentally related to the Specific Surface Area (SSA) (i.e., total surface area) and Cation Exchange Capacity (CEC). The test is simple, is easy to perform and requires only basic laboratory equipment.
