Abstract
Improving the strength and deformation behavior of soils is an important challenge in civil engineering and requires reliable and sustainable ground improvement methods. Microbially induced calcite precipitation (MICP) is a bio-mediated soil improvement technique; however, the effect of drying conditions on the mechanical behavior of biocemented soils has not been fully investigated. This study experimentally evaluates the influence of different drying regimes on the strength and deformation response of MICP-treated soil. Soil specimens were biocemented and cured for 0, 7, 14, 28, and 35 days under two drying regimes: mechanical drying and natural drying. Direct shear tests were performed to determine cohesion and internal friction angle at all curing stages, while deformation behavior was evaluated using shear stress–displacement responses. Microstructural characteristics were qualitatively analyzed using scanning electron microscopy (SEM) for untreated soil and treated specimens cured for 7, 14, and 28 days. SEM results showed the formation of carbonate bridges and partial pore filling, and complementary energy-dispersive spectroscopy (EDS) analysis indicated that the calcium content in MICP-treated specimens was approximately twice that of untreated soil, confirming successful calcite precipitation. The results demonstrate that drying conditions have a stage-dependent effect on the mechanical behavior of MICP-treated soils and mainly influence the rate of strength and deformation development rather than the final stabilized mechanical properties. These findings provide experimental insight into the relationship between curing conditions and biocementation efficiency and support the practical application of MICP in geotechnical ground improvement.