Impact of Severe Climate Conditions on Loss of Mass, Strength, and Stiffness of Compacted Fine-Grained Soils–Portland Cement Blends

The influence of wet-dry cycles on the enduring performance (loss of mass, strength, and stiffness) of compacted fine-grained soils–portland cement blends might be important information for designing earthworks that could be subjected to severe climate conditions. This study assesses possible variations of cement-treated fine-grained soils’ accumulated loss of mass (ALM), unconfined compressive strength ($q_u$) and maximum shear stiffness ($G_0$) when subjected to wetting-drying cycles (mimicking severe climate conditions). Brushing of specimens (to check loss of mass), ultrasonic pulse velocity tests, and unconfined compression tests are performed after wetting-drying cycles for this study. Results show that, for each specimen tested, ALM changes at a constant rate with the number of cycles (NC). In addition, $q_u$ increases from zero to three wetting-drying cycles and fluctuates around an average for further cycles, whereas $G_0$ decreases from zero to three wetting-drying cycles and then fluctuates around an average (distinct for each dry unit weight and amount of cement used) for further cycles. The possible cause of such contradictory results is the effect of oven drying for 42 h at $71\pm 2°\mathrm{C}$ (during the drying part of the wet-dry cycles), which might provoke the catalysis of the chemical reactions of the portland cement, as well as the retraction (and consequent fissuring) of the specimens of silt–portland cement blends in the initial cycles. Finally, the porosity/cement index is found to be a predictor of the ALM, ALM/NC, $q_u$, and $G_0$ fine-grained soil–cement blends studied after a series of wetting-drying cycles.