Rheological and micromechanical analysis of fluidized EICP-cured soils

The enzyme-induced calcium carbonate precipitation (EICP) method has been utilized for curing low-permeability clay by directly mixing the reaction solution with soil. The added reaction solution quantity is limited by the optimal water content, producing insufficient calcium carbonate. Herein, the high-activity urease and high-concentration cementation solution efficacy in treating dispersive soils was evaluated. Phase transitions and structural modifications in EICP-cured soils were investigated through oscillatory amplitude scanning. The soil gradation influence on the EICP treatment effectiveness was assessed. The fluidized EICP-cured soil cementation and rupture mechanisms were investigated by viscosity measurements, electron microscopy, and zeta potential evaluations. A 3 M cementation solution, coupled with 500g/L of soybean urease, significantly enhanced the soil shear resistance, increasing it by 339% to 1807%. The EICP-cured soil gradually transitioned from a fluid to a paste and eventually to a solid within 168 h. High-clay-particle-content soils exhibited pronounced increases in shear resistance after EICP treatment. Under dynamic loading, three shear crack types emerged in EICP-cured soils, emphasizing the importance of soybean protein viscosity and calcium carbonate crystal filling–bonding capability in enhancing soil structural stability. The fluid solidification effectiveness in treating fine-grained soils utilizing EICP was validated through erosion trenches in fluid-solidified check dams, validating its potential.