Dynamic properties and micro-mechanisms of nano-Al2O3 modified cement-stabilized soil under seawater erosion

Cement-stabilized soil in coastal soft soil regions is essential for infrastructure construction. However, under the combined effects of seawater erosion and cyclic loading, cement-stabilized soil often faces issues such as strength degradation, reduced durability, and stiffness softening. To enhance the engineering properties of cement soil, this study utilized nano-Al2O3 as a modifier. The effects of nano-Al2O3 on the dynamic properties of cement soil under various erosion environments were assessed using the GDS dynamic triaxial system. Furthermore, scanning electron microscopy (SEM) and X-ray diffraction (XRD) tests were performed to study the microstructural changes in cement-stabilized soil modified with nano-Al2O3 subjected to seawater erosion. The results indicate that nano-Al2O3 significantly improves the resistance of soil to deformation. As the content of nano-Al2O3 increases, the dynamic strain of cement-stabilized soil initially decreases and then increases, while the dynamic shear modulus first increases and then decreases, showing optimal performance at a 0.25% content. Seawater erosion severely weakens the strength and stiffness of cement-stabilized soil; as erosion concentration increases, dynamic strain increases, and dynamic shear modulus decreases. Nano-Al2O3 improves the strength of cement-stabilized soil and mitigates the negative impacts of seawater erosion through pozzolanic reactions and filler effects.