Investigating MICP sand stabilization with Bacillus thuringiensis: nutrient concentration and availability

This study investigates Bacillus thuringiensis TISTR 126 in Microbially Induced Calcium Carbonate Precipitation (MICP) for sand stabilization in neutral pH environments. It addresses a gap in research on non-alkali-tolerant bacteria. Most MICP studies focus on ureolytic bacteria, which thrive in alkaline conditions. B. thuringiensis is cost-effective, widely available, non-pathogenic, and suitable for neutral pH, making it a promising alternative. The study investigates the effects of nutrient availability and calcium chloride (CaCl2) on calcium carbonate formation and the mechanical properties of sand, including water permeability, unconfined compressive strength (UCS), and internal friction angle. Results show that optimizing the cementation solution enhances sand properties, leading to a 12.1% increase in density, a ten-fold reduction in water permeability, and a UCS of approximately 339.6 kPa. The highest cementation ratio produced an internal friction angle of 48°, indicating a dense structure. This research addresses the critical gap in nutrient optimization for MICP processes. It introduces B. thuringiensis as a viable, sustainable, and non-pathogenic alternative to traditional ureolytic bacteria for sand stabilization, broadening the scope of MICP applications.