Enhancing coastal saline dispersive soil with ionic stabilizer-cement synergy: Mechanisms and performance

Coastal saline dispersive soils (CSDSs), characterized by high sodium content and severe erosion susceptibility, are widely distributed in eastern China's coastal zones, posing significant challenges to the long-term stability of marine infrastructures. This study systematically evaluates the ionic soil stabilizer (ISS)-cement synergistic solidification method through direct shear tests, nuclear magnetic resonance (NMR) pore structure analysis, and SEM-EDS microcharacterization. The results indicate that the independent application of ISS reduces the strength of CSDS, whereas the synergistic incorporation of cement can enhance its strength by 41%. Ca 2+ substitution dominates ion exchange with CSDSs as ISS content increases, while the effects of Mg 2+ and Al 3+ diminish beyond 5% ISS content. When ISS is used in conjunction with cement for solidification, the relative content of free water is predominantly influenced by ISS content, with a critical threshold observed at 5% ISS. Due to the high content of montmorillonite in CSDS, even a small increase in free water content caused by ISS can hinder the effectiveness of solidification process. However, the hydration reactions of cement effectively consume excess free water, transforming its negative impact into a beneficial one. Based on the findings, a combination of 5% ISS and 12% cement is recommended for optimal solidification of CSDSs in engineering applications. This study provides valuable insights into the mechanisms of ISS-cement synergistic solidification and offers a practical solution for improving the durability of dispersive soil in marine engineering. • A feasible solution for the solidification of coastal saline dispersed soil (CSDS) was provided. • ISS-cement synergistic solidification mechanism for CSDS was elucidated. • Increased ISS-induced free water harms CSDS, impact significant. • Ion exchange effect on dispersive soil is mainly the substitution of Ca 2+ for Na + . • The optimal ratio of ISS and cement for solidifying CSDS is S5%+C12%.