To enhance the engineering properties of granite residual soil for subgrade filling, cement is incorporated to improve the soil. Through compaction tests, direct shear tests, and scanning electron microscope (SEM) tests, the influence of adding different doses of cement on the shear strength, residual strength, and microstructure of granite residual soil is investigated. The experimental results show that the maximum dry density increases and the optimal moisture content decreases with increasing cement content up to 7%. The shear strength is significantly enhanced with the increase in cement ...