Microbial induced calcium carbonate precipitation (MICP) technology has been successfully used to enhance the properties of recycled concrete aggregates. However, the complex source and varied physical and chemical properties of recycled aggregates may have influence on the modification efficiency since microbes are often sensitive to the surroundings. In this study, two representative types of recycled aggregates, recycled concrete aggregates (RCA) and recycled brick aggregates (RBA), were subjected to two kinds of MICP treatments, basic MICP treatment and sodium alginate (SA) aided MICP treatment. The absorption and desorption of bacteria in/on aggregates during MICP treatments were quantified. The physical and chemical properties of aggregates after the bio-treatments were tested, and the influence of alkalinity and pore structure of aggregates under various MICP treatment methods on treatment efficiency were detailed investigated. Results indicated that, when the aggregates were subjected to the basic MICP treatment, the treatment efficiency was more remarkable in RBA, because of its high porosity and moderate pH (around 8–9), which facilitated the absorption of bacteria in/on aggregates and urease activity respectively. While under SA-aided MICP treatment, the influence of pore structure and alkalinity of aggregates on the treatment efficiency was not significant compared with that under the basic MICP treatment, especially the mass of CaCO on the aggregates. The biogenic CaCO generated by SA-aided MICP treatment not only plugged micropores, but also distributed all over the entire surface of the aggregates, resulting in a sufficient repair of microcracks. Meanwhile, the surface repair may reduce the influence of pore structure and pH of aggregates on the precipitation process, thereby reducing the impact of varied physical and chemical properties of aggregates on the treatment efficiency, which was conducive to the widely unified application of SA-aided MICP treatment in the modification of recycled aggregate based on construction solid waste.

中文翻译：

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孔隙性质和碱度对再生骨料生物沉积处理效率的影响

微生物诱导碳酸钙沉淀（MICP）技术已成功用于增强再生混凝土骨料的性能。然而，再生骨料来源复杂，物理化学性质多样，微生物对周围环境敏感，可能会影响改性效率。在这项研究中，两种代表性的再生骨料，再生混凝土骨料（RCA）和再生砖骨料（RBA），进行了两种MICP处理，即基本MICP处理和海藻酸钠（SA）辅助MICP处理。对 MICP 处理期间聚集体中/聚集体上的细菌的吸收和解吸进行了定量。对生物处理后骨料的理化性质进行了测试，详细考察了不同MICP处理方法下骨料的碱度和孔隙结构对处理效率的影响。结果表明，当骨料经过碱性 MICP 处理时，RBA 的处理效率更为显着，因为 RBA 具有较高的孔隙率和适中的 pH 值（8-9 左右），有利于骨料内部/表面细菌的吸附，并且 RBA 的处理效果更显着。分别为脲酶活性。而在SA辅助MICP处理下，骨料的孔隙结构和碱度对处理效率的影响与碱性MICP处理相比并不显着，特别是骨料上CaCO的质量。 SA辅助MICP处理产生的生物CaCO不仅堵塞了微孔，而且分布在骨料的整个表面，从而对微裂纹进行了充分的修复。同时，表面修复可以减少骨料孔隙结构和pH值对沉淀过程的影响，从而减少骨料物理化学性质变化对处理效率的影响，有利于SA辅助的广泛统一应用MICP处理在建筑固废再生骨料改性中的应用