Portland cement, a conventional binder for soft soil stabilization, faces limitations in treating specialized soils due to its high carbon footprint and environmental impact during production. This study proposed an eco-friendly alternative using reactive magnesia (MgO) and magnesium chloride (MgCl2) for carbonation treatment of saline soft soils. The mechanical properties, hydrochemical behavior, water stability, and microstructural evolution of carbonation-stabilized soils were systematically investigated under varying salinity levels (MgCl2 content) and initial moisture conditions. Key findings revealed that unconfined compressive strength and modulus decreased with increasing initial water content but exhibited a unique trend under MgCl2 variation—initial gradual reduction (3–6% MgCl2) followed by significant enhancement (6–12% MgCl2). Carbonation efficiency declined from 40% to 10% with rising initial water content, while showing a V-shaped relationship with MgCl2 dosage (minimum at 6%). Post-carbonation pH decreased with higher MgCl2 content and lower initial moisture, whereas electrical conductivity increased proportionally to both parameters. Microstructural analyses identified distinct phase formations: low-MgCl2 (6%) systems produced flower-like hydromagnesite, spheroidal dypingite, and prismatic nesquehonite, while high- MgCl2 (12%) systems generated short-rod chloro-carbonates and acicular magnesium oxychloride crystals (5Mg(OH)2 MgCl2 8H2O). These crystalline phases collectively enhanced soil stabilization. Optimized performance was achieved at a magnesium-chloride molar ratio
Guanghua Cai, Yibo Wang and Han Zhang — College of Civil and Engineering, Nanjing Forestry University, Nanjing 210037, China
Zhaoyuan Guo — School of Transportation, Southeast University, Nanjing 211189, China; Jiangsu Provincial Transportation Engineering Construction Bureau, Nanjing 210004, China
Tianyun Liu — Tianjin Port Engineering Institute Ltd. of CCCC First Harbor Engineering Company Ltd., Tianjin 300222, China
Hongsen Liu — Yellow River Engineering Consulting Co., LTD, Zhengzhou 450003, China
Chi-Sun Poon — Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Kowloon, Hong Kong
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