Effects of cement content and soil texture on strength, hydraulic, and microstructural characteristics of cement-stabilized composite soils

The cemented soils by trench cutting re-mixing deep (TRD) wall or trench cutting assembled diaphragm (TAD) wall are a mixture of various soils. The physical and mechanical properties of these cement-stabilized soils are thus not only affected by construction technologies but also significantly controlled by cement content and soil texture. Three typical soils, including clay soil, silty soil, and fine sand, were used to prepare samples of cement-stabilized soils with different combinations of cement content and soil texture. Then, the workability (including fluidity, cohesion, and water retention), strength, hydraulic, and microstructure characteristics of different cement-stabilized soils were investigated by depth compression, permeability, and microstructural tests. Results indicate that there should be a higher water-cement ratio for clay soil while a low value for fine sand to achieve the required compactness. The unconfined compressive strength of cement-stabilized soils increased linearly with cement content, while their permeability had an approximate power relationship with cement content. The permeability magnitude of cement-stabilized composite soils was greatly affected by the proportion of the soil with high permeability. The clay soil could partly improve the pore structure of cement-stabilized composite soils and reduce permeability due to fine particles’ high activity, which was further confirmed by the microstructural analysis. The relationship between unconfined compressive strength and permeability coefficient was approximately consistent with a power function. The unconfined compressive strength of cement-stabilized soils decreased linearly with porosity, and the logarithm to base 10 of permeability coefficients of cement-stabilized soils increased with porosity.