In this study, we explored the potential of microbiologically induced calcite precipitation (MICP) for enhancing the microstructural integrity of waste concrete fines (WCF). Traditionally, ureolytic bacteria, such as Sporosarcina pasteurii, have been widely used in MICP due to their ability to produce calcium carbonate via urea hydrolysis, but this process generates ammonia, raising environmental concerns. As an alternative, we employed the carbonic anhydrase pathway using Bacillus pseudofirmus and Bacillus cohnii to induce biomineralization without ammonia byproducts. We examined three types of WCF materials and found that samples containing gypsum facilitated the formation of AFt phases (ettringite/thaumasite crystals) when treated with these bacteria, significantly increasing WCF cohesion and forming strong conglomerates. Comparative analysis revealed that facultative anaerobes exploiting the carbonic anhydrase pathway outperformed ureolytic bacteria in strengthening the material. Investigations into pre-compaction and feather fiber reinforcement did not yield improvements in strength and stiffness.

中文翻译：

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利用假硬芽孢杆菌和科氏芽孢杆菌促进 CaCO [公式省略] 和 AFt 相的形成，以稳定废混凝土细粉


在这项研究中，我们探讨了微生物诱导方解石沉淀 （MICP） 在增强废混凝土细粉 （WCF） 微观结构完整性方面的潜力。传统上，尿素分解细菌（如巴氏孢子丝菌）因其能够通过尿素水解产生碳酸钙而被广泛用于 MICP，但这个过程会产生氨，引发环境问题。作为替代方案，我们采用了使用假芽孢杆菌和科氏芽孢杆菌的碳酸酐酶途径来诱导生物矿化，而无需氨副产物。我们检查了三种类型的 WCF 材料，发现含有石膏的样品在用这些细菌处理时促进了 AFt 相（钙石/奇石晶体）的形成，显着增加了 WCF 内聚力并形成强大的砾岩。比较分析表明，利用碳酸酐酶途径的兼性厌氧菌在强化材料方面优于尿管溶解细菌。对预压实和羽毛纤维加固的研究并没有产生强度和刚度的改善。