【摘要】微生物修复裂缝技术由于环保经济的特点被广泛关注，但修复效率因混凝土内碱性环境受到很大影响；开展提高该技术的修复效率与效果的研究具有重要意义。探究高碱性环境下Al2O3对微生物钙化的促进作用，然后添加Al2O3对不同裂缝宽度的混凝土试件进行修复，修复中检测浸出液pH值与尿素含量，修复后通过声时值、碳酸钙生成效率、无侧限抗压强度等指标评价修复效果。结果表明：Al2O3能够降低碱性环境对细菌活性的抑制，提升其脲酶活性与碳酸钙转化效率。添加Al2O3使试件浸出液p H值从12降为9,pH值为9时更适合菌种的繁殖，尿素利用率显著提升到81%，提高了碳酸钙的产出率，明显缩短修复时间。添加Al2O3修复试件的声时值接近无裂缝试件，明显优于无添加试件。添加Al2O3后2 mm裂缝试件的碳酸钙生成率为77.32%，远高过无添加试件的20.98%。添加Al2O3修复试件强度恢复远高于无添加Al2O3修复试件，且强度恢复随裂缝宽度减小而增加。因此，混凝土修复过程中添加Al2O3能有效提高修复效率，减少修复时间，为后续实际工程中微生物快速高效修复裂缝提供重要参考。
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;
【Funds】 National Natural Science Foundation Project (51578147);
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