Enhancing wind-induced erosion resistance of Indian Thar Desert sand using enzyme-induced carbonate precipitation

Soil reinforcement is a potential solution to mitigate wind-induced sand erosion. Previously, microbiologically induced calcite precipitation (MICP) has been used to control sand erosion and enhance the strength of soil particles. However, it has limitations. The present study explores the effectiveness of an alternative biologically inspired method, enzyme-induced carbonate precipitation (EICP), in enhancing the stability and strength of aeolian sand. The novelty of this study lies in the identification of an optimal dosage through a multiscale evaluation of EICP performance, specifically targeting high-velocity erosion resistance (up to 30 m/s), surface strength uniformity, penetration depth, mechanical reinforcement and the explicit characterization of calcite thermal stability. Plant-based Jack bean urease was used at varying concentrations with a 1-M cementation solution. To mitigate wind-induced sand erosion, surface treatment was performed using the spray method. The treated specimens were subjected to a wind tunnel test, a surface strength test, a calcite test, scanning electron microscopy (SEM) analysis and energy-dispersive X-ray spectroscopy (EDX) analysis. To evaluate the strength of soil particles, unconfined compressive strength (UCS) and split tensile strength (STS) samples were treated using the stopped and gravity flow methods and were tested for UCS, STS, ultrasonic pulse velocity (UPV) and calcite formation. Additionally, to assess the thermal behaviour of the formed calcite, thermogravimetric analysis (TGA) was performed. The study demonstrated that the EICP method effectively mitigates erosion up to a wind speed of 30 m/s and achieves optimal soil strength, with a maximum UCS value of 756 kPa and 5% calcite formation. However, practical implementation considerations, including extended treatment duration and long-term durability under field conditions, require further investigation before large-scale application.