Factors affecting the MICP stabilization of washed recycled sands derived from demolition wastes

Abstract

Microbially induced calcium carbonate precipitation (MICP) is recognized as an eco-friendly approach in biological chemistry, offering significant potential for enhancing soil engineering properties. This study investigates the viability of MICP for stabilizing washed recycled sands (RS) sourced from construction and demolition wastes, offering significant potential for enhancing soil engineering properties and aligning this research study with sustainable waste management practices. Through meticulously designed laboratory experiments, this research examined the micro and macro biomineralization processes to assess the feasibility and factors influencing RS stabilization. The experimental setup evaluates the impact of cementation media concentration, ambient temperature, treatment cycles, and curing time on MICP-treated RS efficiency. The findings indicate that the optimal MICP conditions can be found at a cementation media concentration of 0.5 mol/L, an ambient temperature of 30 °C, and furthermore, up to 12 treatment cycles can significantly enhance the unconfined compressive strength (UCS) of RS to 724 kPa. In addition, extending the curing time results in a 28% increase in UCS compared to the initial strength of MICP-stabilized RS. Analyses via scanning electron microscopy and X-ray diffraction provide insights into the microstructural and mineralogical transformations that aid the biostabilization of RS. This research underscores the effectiveness of MICP-treated RS for usage as a geomaterial, emphasizing its environmental and practical benefits and furthermore advocates the sustainable usage of MICP for the biostabilization of RS for construction activities.