Characteristics of Soybean Urease Mineralized Calcium Carbonate and Repair of Concrete Surface Damage

Abstract

The C60 concrete blocks with surface crack damage under high temperature environment were soaked by adding appropriate amount of soybean urease into the CO(NH₂)₂-CaCl₂ solution, the soybean urease mineralized calcium carbonate were characterized, and the effect of repairing concrete surface crack damage were evaluated by the surface sedimentation of C60 concrete blocks in the study. The experimental results showed that the activity of soybean powder was statistically significant, and its productivity of urease was comparable with that of urease-producing bacteria. After immersion in a soybean solution, a layer of complete and continuous white sediment covered the concrete surface. The cracks on the concrete surface were completely shielded, and the rising temperature on infrared thermal image of the concrete after repair was lower than before. Besides, through analysis by SEM, EDS, and XRD, the products formed after repair were found to be calcite-type CaCO₃ with high purity, and the crystals exhibited different morphological features. The above results indicate that soybean urease can regulate and induce the formation of calcium carbonate, and the precipitate is innocuous and harmless, suitable for a new type of concrete crack repair material.

Keywords

soybean urease / concrete / calcium carbonate / remediation / damage