This paper investigates the effect of the soaking process on gypseous sand soils. The recent research investigates the time-based soaking method on high gypsum contents (29%) of soil samples. The softening of gypsum materials upon the wetting process leads to break the bonds of the soil particles and the settlement of structures will occur. The settlement value and rate are the basic problems for the geotechnical engineers. The samples of this investigation have been collected from the selected site in Al-Najaf city in Iraq, then these samples are remoulded to the density of 85% of the maximum dry density from Proctor test and moisture content of 4% in the cell of the computerized Oedometer device and under different stress levels (1.11, 2.23 and 4.47 kg/cm 2). The soil specimen is soaked under three stress levels (1.11, 2.23, and 4.47 kg/cm 2) separately. The results revealed that with increasing the soaking periods and stress levels, there is increasing in the collapse potential of such soils. The collapse potential was increased from <1% after half-hour soaking to about 8% after two-week of soaking.

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