Experimental Study on Curing Strength and Freeze-thaw Characteristics of Supersulphate Saline Soil

Insufficient strength and salt–frost heave failure are the primary causes of channel lining structure failure in saline soil areas. This study conducts strength and microscopic analysis of the supersulphate saline soil treated with a combined curing agent to address the problem of inadequate strength of saline soil and reduce its sensitivity to environmental temperature. The relationship between the curing agent’s dosage and the strength is established to assess the curing effect, and the microscopic pore structure is examined using a mercury injection test. The variation law of frost heave force and quantity is revealed through freeze-thaw cycle testing. The results demonstrated that the strength of solidified saline soil significantly increases, and the hydration products enhance the cementation between particles. As the curing agent’s dosage increases from 0 to 30%, the porosity decreases gradually, the pore size transitions from super-large pore to micro-small pore, and the fractal dimension of the calculation model increases incrementally. The Menger and Neimark model shows multiscale fractal characteristics. In the range of 0.1～1.0 μm, the fractal characteristics are not obvious. The fractal dimension (DT) of the thermodynamic model varies within a reasonable range of 2.824 to 2.849, accurately representing the fractal characteristics of the pore surface. After 10 freeze-thaw cycles, the salt–frost heave capacity of solidified saline soil decreased by 117% compared to uncured saline soil. The fluctuation range of salt–frost heave force in solidified saline soil gradually increased with the number of freeze-thaw cycles. The salt–frost heave force of solidified saline soil exhibited periodic attenuation. According to engineering practice, it is recommended that the proportions of cement, fly ash, silica fume, and desulfurized gypsum should be 1.00∶1.67∶ 0.83∶1.00 and that the dosage of the curing agent should be 30%. © 2024 Sichuan University. All rights reserved.