Bioremediation of Desiccation Cracking in Clayey Soils Using Enzyme Induced Calcite Precipitation

Abstract

Desiccation cracking in expansive soils is critical to their hydraulic and mechanical properties and affects the long-term performance of various geotechnical infrastructure. In recent years, bio-mediated methods such as bio-cementation have been explored as a possible approach for ground improvement. This study explores the potential of using Enzyme Induced Calcite Precipitation (EICP) for desiccation cracking remediation in clayey soils. EICP uses biologically derived material (plant-based urease enzyme) without requiring bacteria incubation. In this study, crude extract from soybean (Glycine max) is used for urea hydrolysis. Three different enzyme concentrations (10, 30, and 50 g/L) are used to evaluate the effect of calcite precipitation on desiccation crack. According to the analysis of soil cracking images, this technique significantly induces calcite precipitations and effectively reduces the extent of desiccation cracking in clayey soils. The EICP-treated sample demonstrated that the crack area, crack width, and crack length decrease for the higher concentration of urease enzyme with the increasing W–D cycle. The lower concentrations (10 g/L) have minor effects on crack remediation but effectively limit the growth of new cracks. Moreover, when the enzyme concentration increases, calcium carbonate precipitations tend to form a crust on the soil surface, gradually increasing soil surface roughness. This study is expected to improve the fundamental understanding of the EICP technique and provide new insights into its potential application for soil improvement.