Nano-Assisted Enzyme-Induced Calcium Precipitation (EICP) for Acidic Soil Improvement

Enzyme-induced calcium precipitation (EICP) is a promising technique for soil improvement. EICP utilizes enzymes to induce the precipitation of calcium carbonate (CaCO3) within soil pores, enhancing their mechanical properties. This study investigates the potential of using iron oxide (Fe2O3), aluminum oxide (Al2O3), and zinc oxide (ZnO) nanoparticles to enhance the performance of EICP-treated sands in acidic and alkaline environments. The pH, unconfined compressive strength (UCS), and calcium carbonate content of treated specimens were evaluated. Results showed that ZnO nanoparticles diminished the EICP effect, while Al2O3 nanoparticles improved UCS by 6.4% at a concentration of 0.20%. Fe2O3 nanoparticles retained 28.5% and 13.7% of UCS at concentrations of 0.10% and 0.40%, respectively. The addition of nanoparticles reduced the calcium carbonate content, with ZnO-EICP showing the highest reduction (~90%). This research highlights the need for further enhancement of the EICP technique in acidic and alkaline environments.