Existing studies on microbial self-healing concrete often employed an arbitrary approach to the initial amount of healing agents, leading to significant performance variations. The amount of bacteria becomes a crucial parameter affecting the overall cost of the material. Therefore, assessing the effect of initial bacteria content on microbial self-healing performances is essential. This study presents the variation of self-healing performances of biomortars with initial bacteria content ranging from 0.05 % to 2.50 % (0.07 %–3.20 % biogranule) w/w cement. All biomortars outperformed the crack healing performance of abiotic control specimens. The net contribution of microbial healing () was determined by analysing autogenous healing and microbial healing periods separately. The variations in initial bacteria content did not significantly affect which could reach up to 125 μm in 2-weeks of water immersion. The minimum effective bacteria dosage in the form of biogranules for developing microbial self-healing concrete was determined as 0.05 % bacteria w/w cement with an overall crack healing limit of 300 μm. Microbial healing of cracks up to 300 μm crack width led to 50–80 % higher water tightness regain compared to the autogenously healed specimens. The purity of CaCO minerals sealing the cracks decreased with the increasing initial bacteria content of the biomortars. Overall, the initial bacteria content did not significantly affect the microbial self-healing performance in the tested dosage range. At the minimum effective bacteria dosage, consistent self-healing of cracks up to 300 μm became possible at the expense of approximately 20 % increase in the overall cost of the material.

中文翻译：

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水泥基复合材料微生物自修复性能随生物颗粒含量的变化


现有的微生物自修复混凝土研究通常对修复剂的初始用量采用任意方法，导致显着的性能变化。细菌的数量成为影响材料总体成本的关键参数。因此，评估初始细菌含量对微生物自愈性能的影响至关重要。本研究展示了初始细菌含量范围为 0.05% 至 2.50%（0.07%–3.20% 生物颗粒）w/w 水泥的生物砂浆自修复性能的变化。所有生物砂浆的裂缝愈合性能均优于非生物对照样本。微生物愈合的净贡献（）是通过分别分析自体愈合和微生物愈合周期来确定的。初始细菌含量的变化并没有显着影响，在水中浸泡 2 周后，细菌含量可达到 125 μm。用于开发微生物自修复混凝土的生物颗粒形式的最小有效细菌剂量被确定为 0.05% 细菌 w/w 水泥，总体裂缝愈合极限为 300 μm。与自体愈合的样本相比，微生物愈合裂缝宽度达 300 μm 的裂缝可使水密性恢复率提高 50-80%。随着生物砂浆初始细菌含量的增加，密封裂缝的碳酸钙矿物质的纯度降低。总体而言，在测试的剂量范围内，初始细菌含量并没有显着影响微生物的自愈性能。在最小有效细菌剂量下，可以实现长达 300 μm 的裂纹的一致自修复，但代价是材料的总成本增加了约 20%。