The standard absorption moisture

as one of the three discrimination indexes recommended by specifications for design of highway subgrades (JTG D30-2004)

its applicability in Hefei expansive soil classification is discussed; and the correlated character with liquid limit

plasticity index

free swelling ratio and the content of colloidal particle less than 0.002 mm are presented. It has been approved by a lot of laboratory tests that the standard absorption water content can reflect the swelling potential level of Hefei expansive soil

but the criterion suggested by the above specifications is unsuitable. A certain dependence relation exists between standard absorption water content and other discrimination parameters; square values of correlation coefficients is from 0.468 to 0.663. In brief

standard absorption moisture can be the discrimination index because it can explain the nature of the expansive soil.