Experimental investigation and analysis of the impact of salinity erosion on the strength of graphene oxide cement soil

In saline-alkali and coastal areas, cement soil faces various threats from salt erosion, and these environmental conditions can significantly impact the mechanical properties of cement soil. To counter external erosion, the addition of graphene oxide (GO) nanomaterials to cement soil is considered an effective solution. This study systematically investigates the strength variations of GO cement soil after erosion in different concentrations of NaCl solution (0 g/L, 4.5 g/L, 18 g/L, 30 g/L), Na₂SO₄ (0 g/L, 4.5 g/L, 18 g/L, 30 g/L), and a composite salt solution of both (0 g/L, 4.5 g/L, 18 g/L, 30 g/L) at different times (7d, 14d, 30d, 60d) through salt immersion tests, unconfined compressive strength tests, and SEM scanning electron microscope tests. Simultaneously, the study analyzes the mass change rate, stress-strain curves, peak stress of unconfined compressive strength, and modulus of elasticity changes in cement soil samples after erosion. The internal erosion mechanism of cement soil samples is explored at the microscopic level. When the GO cement soil was eroded in different concentrations of NaCl solution for 14 days, a consistent trend of mass decrease was observed. However, after 7, 30, and 60 days of erosion in various concentrations of NaCl solution, the mass showed an increasing trend. When immersed in pure water for 7d, 14d, 30d, and 60d, as well as in a 4.5 g/L NaCl solution for 7d and 14d erosion, the peak stress of GO cement soil samples shows an increasing trend, while it decreases under other conditions, especially significantly in Na₂SO₄ solution. Simultaneously, Na₂SO₄ has the greatest impact on the modulus of elasticity of cement soil. SEM test results reveal that due to nucleation effects, GO promotes the generation of hydration product C-S-H, enhancing the resistance of cement soil samples to external erosion. Furthermore, it is observed that under the influence of SO₄^2-, C-S-H undergoes decalcification to generate AFt, while the impact of Cl^- on C-S-H is relatively small.