Study on the Erosion Mechanism of the Solidified Silt Under Sulphate–Chloride Erosion

Silt and mucky soil have high natural moisture content, poor water permeability, high compressibility, low strength, and a large void ratio. Silt and mucky soil solidify by adding cement in practical projects. In this work, the erosion characteristics of the silt and mucky soil have improved by adding steel slag powder to it. This paper compared the mechanical properties of the solidified soil with that of the pure cement-solidified sludgy soil under the same erosion environment. The physical properties and the erosion mechanism of the solidified soil were analyzed in macroscopic and microscopic aspects. Our findings show that the strength range of the solidified soil sample mixed with steel slag powder is 0.028, and the strength change range of the sample mixed with cement soil is 0.062. It can see that the steel slag powder and its hydration products have effectively improved resistance to ions erosion of the solidified soil. When chloride ions and sulfate ions coexist in the erosion solution, chloride ions can delay the erosion rate of sulfate ions on the solidified soil and improve the compressive strength of the solidified soil. The higher the chloride ions concentration, the more pronounced the effect. As the concentration of SO₄²⁻:Cl⁻ increased from 3:1 to 1:3 during the same erosion time, solidified soil mass change rate increased by 0.8%. Finally, SEM images were used to analyze the microstructure changes of the solidified soil with Sulfate–chloride mixed solution and discussed the erosion and damage mechanism of solidified soil.