Method Improvement and Micromechanism Analysis of Plant Urease–Induced Calcium Carbonate Precipitation for Curing Pisha Sandstone

To promote resource utilization and environmental protection of Pisha sandstone and effectively control soil erosion in the Yellow River Basin, this research employs enzyme-induced calcium carbonate precipitation (EICP) to cure Pisha sandstone. A new curing method is proposed: mixing jack bean powder with Pisha sandstone, followed by spraying with a cementing solution. The curing effects of various jack bean dosages and curing methods were evaluated based on cured-layer volume, calcium carbonate mass, penetration strength, and water stability. The influence of different curing methods on EICP curing effects was examined through X-ray diffraction, field-emission scanning electron microscopy, Fourier-transform infrared spectroscopy, and heat loss analysis. Results indicated that the mixing method yields the best curing effect and water stability when the jack bean powder–Pisha sandstone mass ratio is 1:30. Compared with the measures for step-by-step grouting, the calcium carbonate mass, cured-layer volume, and penetration strength for the proposed method were 9.26%, 100%, and 140% higher, respectively, while the final disintegration coefficient for the proposed method was 8% lower. The mixing method effectively reduced the precipitation rate of calcium carbonate, mitigating the blockage of pore channels that limits a cementing solution’s infiltration into deeper layers. Micromechanism analysis showed that the mixing method forms calcium carbonate cluster crystals, improving the bonding between loose Pisha sandstone particles. Overall, this study provides a theoretical basis for using EICP in controlling soil erosion in Pisha sandstone.