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Microbially induced calcite precipitation (MICP) has emerged as a promising and environmentally friendly technique to ameliorate unfavorable soil conditions. However, the durability of biotreated clay under freeze–thaw cycles, crucial for road pavement applications, remains inadequately investigated. This research aims to evaluate the effectiveness and long-term performance of biostimulated MICP in improving the engineering properties of expansive clayey soils. The study encompasses both macroscopic and microscopic analyses of untreated and biostimulated soils. Plasticity, strength, mineralogical composition, and chemical characteristics are thoroughly examined. Mechanical tests, including unconfined compressive and split tensile strength assessments, are conducted to evaluate the strength of the biocemented specimens. Additionally, chemical analyses such as pH, electrical conductivity, and calcite content are performed to study the changes in chemical properties. Microstructural examination allows for an in-depth understanding of the structural modifications. Biocemented specimens are subjected to repeated freeze–thaw cycles (2, 4, 6, 8, and 10 cycles) to assess the durability of the treated soils. The study investigates the evolution of properties after each cycle, addressing concerns related to long-term sustainability and performance. The results demonstrate that the biostimulated MICP treatment significantly enhances the calcite content of the treated specimens, exhibiting up to 205% increase, which directly correlates with improved unconfined compressive and split tensile strength. Furthermore, the distribution of calcite content in the biotreated samples is analyzed to provide insights into the uniformity of the biocementation process. In conclusion, the findings underscore the efficacy of the MICP technique for enhancing the strength and stability of expansive clayey soils under freeze–thaw conditions. The study reveals its potential as an eco-friendly alternative for road pavement applications without adverse effects on the natural soil ecosystem. This investigation contributes essential knowledge toward the practical implementation of biostimulated MICP in civil engineering projects, offering sustainable solutions for soil improvement in the field of geotechnical engineering.
Tiwari et al. (Sat,) studied this question.