Strength, Durability, Corrosion Resistance, and Microstructure of Cemented Soil Incorporating Nano-MgO under Static and Cyclic Loading: A Laboratory Study

Abstract

Coastal regions often face challenges with the degradation of cementitious foundations that have endured prolonged exposure to corrosive ions and cyclic loading induced by environmental factors, such as typhoons, vehicular traffic vibrations, and the impact of waves. To address these issues, this study focused on incorporating Nano-magnesium oxide (Nano-MgO) into cemented soils to investigate its potential impact on the strength, durability, corrosion resistance, and corresponding microstructural evolution of cemented soils. Initially, unconfined compressive strength tests (UCS) were conducted on Nano-MgO-modified cemented soils subjected to different curing periods in freshwater and seawater environments. The findings revealed that the addition of 3% Nano-MgO effectively increased the compressive strength and corrosion resistance of the cemented soils. Subsequent dynamic cyclic loading tests demonstrated that Nano-modified cemented soils exhibited reduced energy loss (smaller hysteresis loop curve area) under cyclic loading, along with a significant improvement in the damping ratio and dynamic elastic modulus. Furthermore, employing an array of microscopic analyses, including nuclear magnetic resonance (NMR), X-ray diffraction (XRD), and scanning electron microscopy (SEM), revealed that the hydration byproducts of Nano-MgO, specifically Mg(OH)2 and magnesium silicate hydrates, demonstrated effective pore space occupation and enhanced interparticle bonding. This augmentation markedly heightened the corrosion resistance and durability of the cemented soil. Soft soils in coastal environments typically require deep cement mixing (DCM) to meet infrastructure demands. However, excessive cement usage leads to increased costs, environmental pollution, and maintenance difficulties. Given prolonged cyclic loading and seawater corrosion, the durability and strength of cemented-soil can be significantly compromised. This study investigates the effectiveness of combining Nano-magnesium oxide (Nano-MgO) with cement for soil improvement in freshwater and seawater. The results indicate that Nano-MgO effectively promotes early hydration of cement and reduces the porosity of cemented-soil, thereby enhancing its resistance to seawater corrosion and compressive strength. Furthermore, Nano-MgO significantly improves the dynamic properties of cemented-soil, reducing energy loss under cyclic loading. This enhancement extends the service life and lowers the maintenance costs of infrastructure. The technique shows promising applications in coastal road construction, foundation treatment, and antiseepage engineering, offering an efficient and environmentally friendly solution for geotechnical engineering.