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NBPT controlled microbially induced calcite precipitation for sustainable soil stabilization in transportation infrastructure

Year: 2026
Type: article
Abstract: Microbially induced calcium carbonate precipitation (MICP) faces persistent obstacles in transportation subgrade stabilization because rapid ureolysis can trigger premature clogging and pronounced spatial heterogeneity. This study develops a construction-oriented biocementation strategy that uses the urease inhibitor N-(n-butyl)-thiophosphoric triamide (NBPT) to regulate reaction kinetics and improve treatment uniformity under groundwater-relevant conditions. A multivariate optimization framework was established by jointly evaluating inhibitor dosage, cementation solution concentration, biological-to-chemical ratio, ambient temperature, and pH buffering. The optimal formulation was achieved at 0.1% NBPT, which delivered an unconfined compressive strength of 2.53 MPa compared with 2.72 MPa for the inhibitor-free control, indicating that strength was largely preserved while reaction kinetics were moderated. Calcium carbonate deposition proceeded steadily over 72 h and reached a carbonate content of 11.2 kg/m³ under the optimized protocol. This mineral accumulation reduced hydraulic conductivity from 1.7 × 10⁻³ m/s to 6.4 × 10⁻⁵ m/s, corresponding to a 96.3% decrease, while avoiding localized pore occlusion. Under simulated AASHTO T307 cyclic loading, the optimized treatment achieved a resilient modulus of 152 MPa and limited residual deformation to 0.32 mm per 1000 load cycles at an 80 kN axle load. The proposed NBPT-controlled MICP framework provides an operational window that balances strength gain, hydraulic functionality, and field implementability for subgrade applications.
DOI: 10.1038/s41598-026-43817-w
Language: English
Open Access status: gold
Estimated APC paid: $2,690
OpenAlex ID: W7162115084
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