Pilot-Scale Soybean Crude Urease–Based EICP for Soil Improvement in Sand: Distribution and Performance Using Commercial-Grade Reagents

Abstract Pilot-scale injection-based soybean crude urease–based enzyme-induced carbonate precipitation (EICP) (SCU-CP) was evaluated in poorly graded sand using commercially available reagents in a 1 m 3 test box. Solution A (soybean crude urease amended with nonfat milk powder) and Solution B (urea– CaCl 2 ) were pumped separately and combined immediately before injection. The treatment achieved measurable cementation, with unconfined compressive strength reaching up to 497 kPa near injection-influenced zones and up to 355 kPa at the surface layer, while the maximum measured CaCO 3 content reached 2.9%. Postcuring sampling at 64 locations ( 4 × 4 × 4 grid) and three-dimensional mapping showed heterogeneous carbonate precipitation governed by flow pathways and proximity to injection ports. SEM‍–‍EDS further confirmed CaCO 3 precipitates on sand grain surfaces and at interparticle contacts, supporting carbonate bonding within the treated matrix. Overall, these results support the feasibility of pilot-scale SCU-CP using industry-relevant materials and highlight that treatment uniformity depends primarily on injection layout, sequencing, and preferential flow control.