Sustainable improvement of granite sludge dust properties using microbially induced carbonate precipitation (MICP): strength enhancement, erosion prevention, and dust mitigation

Granite sludge dust (GSD), a significant byproduct of granite processing globally, poses severe environmental and public health challenges, with India alone generating 200 million tons annually. The conventional use of GSD in soil stabilization and construction materials is limited to 20–30%, underscoring the urgent need for sustainable repurposing solutions within the circular economy catering to broader bulk utilization. Unlike traditional techniques, repurposing granite dust using microbially induced calcite precipitation (MICP) offers a sustainable low-impact and eco-friendly ground improvement solution. It also reduces waste and associated environmental pollution. MICP leverages bacterial enzymes to catalyze urea hydrolysis, leading to calcite (CaCO₃) precipitation stabilizing the solids matrix. This study evaluates the efficacy of MICP in strength enhancement of GSD enabling its repurposing in low-volume roads. To assess this, unconfined compressive strength (UCS), wetting and drying (WD) durability, and X-ray diffraction (XRD) tests were conducted. Additionally, to assess the efficacy of MICP in mitigation of both wind and rainfall-induced erosion of GSD from waste containments, percentage weight loss in wind tunnel tests along with air quality parameters PM_2.5, PM₁₀, and drip erosion tests were conducted respectively. MICP treatment with Bacillus megaterium resulted in significant strength gain of up to 1355 kPa UCS, suitable for low-volume pavement subbases, enhanced durability up to two wetting and drying cycles, substantial reductions in PM_2.5 and PM₁₀ levels due to wind erosion, and improved resistance to rainfall-induced erosion sustaining the 10-min test. This low-carbon-intensive technique endorses circular economy goals by transforming GSD into a sustainable construction material addressing waste management, infrastructure resilience, and environmental sustainability. Further, the surficial application of MICP contributes to eco-friendly infrastructure and pollution control of GSD storage facilities.