Simultaneous Reinforcement of Sand and Mortar Cracks Using Enzyme-Induced Carbonate Precipitation

Enzyme-induced calcium carbonate precipitation (EICP) technology shows great potential for reinforcing granular materials and sealing cracks. This study investigates the coreinforcement of sand and mortar cracks using the EICP method, focusing on the effects of soybean powder concentration in a urease solution and the width of mortar cracks. Permeability was assessed by the constant-head permeability test, and the mechanical properties of the reinforced specimens were evaluated through shear tests, unconfined compressive strength (UCS) tests, and splitting tensile tests. Additionally, the distribution and microstructure of calcium carbonate precipitation in mortar cracks were examined. The results demonstrated that the EICP method effectively synchronized the cementation of sand particles and the sealing of mortar cracks, achieving coreinforcement of the particle–crack medium. The permeability of the specimens was reduced by two to three orders of magnitude. The shear strength between the sand column and the mortar ranged from approximately 25 to 65 kPa. The recovery of the splitting tensile strength of the cracked mortar (0.1–0.5 mm) reached 33.4%. This study provides valuable insights and data supporting the application of the EICP method for sealing cracks in tunnel linings within sandy soil environments.