Use of liquid limit state to generalize water retention properties of fine-grained soils

Abstract

This technical note examines the hypothesis that the liquid limit state may serve as a reference state, with respect to which the water-holding capacity of fine-grained soils at other states may be referred, or, equivalently, that the moisture characteristic curve at a given void ratio is uniquely related to that for the liquid limit state. The hypothesis is considered in relation to experimental observations on several soil mixtures, made by the authors and other investigators. The authors used mixtures of fine sand and pure clay minerals to generate soils with different liquid limits. Samples were prepared as slurries, whose water contents exceeded their liquid limits, placed in standard consolidation rings, and consolidated in consolidometers until liquid limit void ratios were achieved. A scanning electron microscope was used to view the microstructure of selected samples in an attempt to assess qualitatively the uniqueness of the structure at the liquid limit state. The results of the tests indicate that the liquid limit state is a useful state, with respect to which the water retention properties of fine-grained soils at other states may be referred. Air-entry suction and pore-size distribution index were found to vary linearly, as the void ratio decreased from the liquid limit state.