A relatively large number of drying and wetting tests have been performed on clayey soils compacted at the standard or modified Proctor optimum water content and maximum density and compared with tests on normally consolidated or overconsolidated soils. The results show that drying and wetting paths on compacted soils are fairly linear and reversible in the void ratio or water content versus negative pore-water pressure planes. On the wet side of the optimum, the wetting paths are independent of the compaction water content and can be approached by compaction tests with measurement of the negative pore-water pressure. Correlations have been established between the liquid limit of the soils and such properties as the optimum water content and negative pore-water pressure, the maximum dry density, and the swelling or drying index. Although based on a limited number of tests, these correlations provide a fairly good basis to model the drying–wetting paths when all the necessary data are not available.Key words: compaction, unsaturated soils, clays, drying, wetting, Proctor conditions.

Experimental research was carried out on 11 different clayey materials to determine the main characteristics of the drying and wetting paths and the influence of initial state and other factors. Normally consolidated paths are shown to have a large saturated domain, in which a negative pressure is equivalent to an isotropic stress increase; such paths can be derived from correlations with the liquid limit. On the other hand, the behavior of overconsolidated or dried samples is largely dependent on the range of stresses and negative pressures. Key words : suction, unsaturated soils, drying, wetting, correlations, models.

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