Control of mechanical properties and permeability of silty soils by modified sodium alginate

Certain geologic conditions in silty soils exhibit poor engineering properties, including low strength and instability, which threaten the stability of geotechnical systems. This study introduces a novel soil stabilization approach using a ternary interpenetrating polymer network (IPN) formed through the synergistic reaction of sodium alginate (SA), acrylamide (AM), and hexadecyl methacrylate (HMA). This strategy is innovative because it leverages both hydrophobic association and ionic cross-linking to create a robust gel matrix that effectively binds soil particles. A three-factor, three-level orthogonal design was used to optimize the component ratios (SA:AM:HMA). Using SA as a control, conduct a dry-wet cycle test to compare changes in unconfined compressive strength between SA and SA-modified polymer-treated soils. Results indicate that after 28 days of curing, soil samples treated with the optimal mixture (1.5:1.5:2.5) attained a maximum unconfined compressive strength (UCS) of 2405.69 kPa. Compared to untreated soil, the cohesion significantly increased to 119.66 kPa, while the internal friction angle showed no significant change. The hydraulic conductivity was reduced to 3.45 × 10 −6  cm/s. The durability of SA-modified polymer-stabilized soil is significantly superior to that of SA. Microstructural analyses confirmed that the polymer gel enhances soil-polymer interaction through pore-filling and chemisorption, drastically improving the pore structure and mechanical properties. This study provides a theoretical basis for the application of this novel biopolymer-based stabilizer in silty soil improvement.