Study on dynamic elastic modulus and microstructure of cemented soil modified by Nano-Al2O3 in seawater corrosive environments

Abstract Foundations of coastal engineering are susceptible to seawater corrosion and dynamic loads such as waves and earthquakes. These adverse factors can degrade cemented soil foundations, potentially compromising structural stability and safety. To address these problems, this study explored the use of Nano-Al 2 O 3 as an additive for the modification of coastal cemented soil to enhance its performance. The GDS dynamic triaxial tests were employed to evaluate the effects of cyclic dynamic loading and seawater corrosion conditions on the dynamic elastic modulus ( E d ) of the cemented soil modified with Nano-Al 2 O 3 at different contents. Additionally, the microstructural characteristics of the Nano-Al 2 O 3 cemented soil were investigated by nuclear magnetic resonance (NMR) and scanning electron microscopy (SEM) tests to elucidate the correlation with the macroscopic E d changes. The experimental results indicate that the E d of the modified cemented soil initially increases with the addition of Nano-Al 2 O 3 , peaking at a content of 0.25%, beyond which it declines. Under seawater corrosion conditions, the E d decreases progressively with increasing seawater salinity. At constant salinity, the E d exhibits an increasing trend over time, although the magnitude of the increase gradually diminishes. The E d of Nano-Al 2 O 3 cemented soil consistently outperforms that of unmodified cemented soil. Microscopic analysis reveals that Nano-Al 2 O 3 effectively fills and binds the pores within the cemented soil, reducing pore volume and forming a cohesive network structure, even under corrosive conditions. Overall, Nano-Al 2 O 3 enhances the stiffness and corrosion resistance of cemented soil in seawater environments. This study provides theoretical guidance for the application of nanomaterials to improve the durability of infrastructure in marine engineering projects such as cross-sea bridges, seawalls, and harbors.