Effect of freeze–thaw cycles on durability and strength of very soft clay soil stabilised with recycled Bassanite

This paper investigates the influence of freeze–thaw cycles on the unconfined compressive strength and durability of very soft clay soil stabilised with recycled Bassanite, which is produced from gypsum wastes. The results of this study show that an increase in the number of freeze–thaw cycles decreases the unconfined compressive strength and durability index. The presence and increase in the Bassanite content in the soil mixture has a significant effect on the improvement of strength, volume change and durability of samples subjected to freeze–thaw cycles. The role of Bassanite in increasing the soil strength and durability is more significant in the case of samples exposed to freeze–thaw cycles compared to those not exposed to freeze–thaw cycles. The dry unit weight increased, and moisture content decreased with the increase of Bassanite content in the soil mixture. The effect of freeze–thaw cycles on the dry unit weight and moisture content is insignificant compared to unexposed samples. The maximum volumetric changes occurred in the first freeze–thaw cycle, and afterward, the volume changes decreased with an increase in freeze–thaw cycles. The use of recycled Bassanite obtained from gypsum wastes as a stabiliser material for very soft clay soil achieves the acceptable durability and strength against the effects of freeze–thaw cycles.