Strength and Durability Study on Enzyme Induced Carbonate Precipitation Stabilized Clayey Soil

Abstract

A bio-inspired technology called enzyme-induced carbonate precipitation (EICP) aims to improve the geo-mechanical characteristics of soils by causing calcium carbonate to precipitate. The creation of calcium carbonate, a cementitious agent that binds soil particles together at their contact sites and increases the strength and stiffness of treated soils, is catalyzed by enzymes in this process. EICP has various benefits over conventional binders and is used in erosion control, building materials, and ground improvement. While several studies have examined the efficacy of EICP on granular soils, there hasn't been much study on soils with a high fine content (more than 40%). Additionally, the enzyme source in the majority of investigations has been urease powder that is readily available commercially. In order to fill these gaps, this research focuses on testing the efficacy of EICP at different molar concentrations utilizing yellow soybean as the enzyme source in strengthening and maintaining clayey soil. Unconfined compression testing and immersion experiments are carried out to evaluate the effects of EICP. The strength of a cylindrical soil specimen is determined by measuring the highest axial compressive stress that it can sustain before failing in the unconfined compression test. On the other hand, the immersion test measures the mass loss over time while immersing the soil to test its resistance to erosion and determines how durable it is. According to the study's findings, in situations when there is too much water, enzyme-induced carbonate precipitation successfully increases soil strength and prevents erosion. The soil's mechanical qualities are enhanced, resulting in greater strength and stiffness, by stimulating the development of calcium carbonate.Additionally, EICP has been found to be effective in reducing the soil erosion, when soil is exposed to water as evidenced by immersion tests performed on cylindrical samples.