Quantitative analysis of alumina addition on microbial remediation of concrete cracks
【Abstract】The environment-friendly and economical microbial repair technology in the concrete industry has attracted much attention. However, the repair efficiency is greatly affected by the alkaline environment. Therefore, it is of great significance to improve the efficiency of the technology and the repair quality. In this paper, the acceleration of Al2O3 on microbial calcification in strong alkaline environment was investigated. Concrete specimens with different crack widths were repaired by Al2O3 addition, during which the pH and urea content of the leachate were monitored. The repairing effect was evaluated by acoustic time value, CaCO3 production rate, and unconfined compressive strength. The results showed that Al2O3 could reduce the inhibition of alkaline environment on bacteria and enhance the urease activity and calcification efficiency. The Al2O3 addition reduced the pH of the leachate from 12 to 9, while the urea utilization ratio increased significantly to 81%, thus significantly shortening the repair time. The acoustic time of specimens with Al2O3 addition was close to that of specimens without cracks, which is significantly better than that of specimens repaired without Al2O3. After Al2O3 addition, the production rate of CaCO3 in the 2 mm crack specimen was 77.32%, which is higher than that of 20.98% specimens without Al2O3 addition. The strength recovery of repaired specimens increased with the decrease of crack width, and the strength recovery of repaired specimens repaired with Al2O3 was much higher than those of the specimens without Al2O3. Therefore, the addition of Al2O3 can effectively improve the efficiency in concrete repairing process, reduce the repair time, and provide important reference for the rapid and efficient repair of cracks by microorganisms in future practical projects.
【Keywords】 crack repair; Al2O3; acoustic time value; calcium carbonate production rate; strength recovery;
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