During the past two decades, aerobic bacteria induced biomineralization has gained popularity for autonomous sealing of cracks in concrete structures due to its environmentally friendly characteristics of carbon retention. However, the mechanism of the biomineralization induced by aerobic bacteria for concrete crack sealing is still unclear due to the complex chemistry of cement matrix. Also, as the main nutrient for bacterial growth, the effect of yeast extract (YE) on biomineralization should be properly evaluated. For the first time, this study investigates the effects of YE and calcium content on the development of nanostructure and chemical composition of cement matrix during the biomineralization process induced by aerobic bacteria Bacillus cohnii. The effects of calcium content were realized by constructing a simulated cement mixture consisting of calcium hydroxide and synthesised C-S-H with different C/S ratios. The effects of YE content were evaluated by the addition of different amounts of YE into simulated cement mixture with different C/S ratios. Results suggest that 10g/l of YE can cause a high pH value of 10 and an unsuccessful growth of bacteria in simulated cement mixture with C/S ratios 0.6 and 0.8. Upon increasing the YE from 10 g/l to 20 g/l, the pH reduced from 10 to 9 and the bacteria was successfully grown. Higher amounts of bicarbonate ions can cause an enhanced decalcification of synthesised C-S-H rather than calcium hydroxide. The aerobic bacteria Bacillus cohnii showed superior performance on calcium absorption and calcite precipitation, being a promising way for practical concrete crack sealing.

中文翻译：

---

好氧菌诱导的生物矿化：养分和钙含量对模拟水泥混合物纳米结构和化学成分的影响


在过去的二十年里，由于其环保的碳保留特性，好氧菌诱导的生物矿化在自主密封混凝土结构裂缝方面越来越受欢迎。然而，由于水泥基体的复杂化学性质，好氧菌诱导的混凝土裂缝密封生物矿化机制尚不清楚。此外，酵母提取物 （YE） 作为细菌生长的主要营养物质，应适当评估酵母提取物 （YE） 对生物矿化的影响。本研究首次探讨了在需氧细菌 Bacillus cohnii 诱导的生物矿化过程中，YE 和钙含量对水泥基体纳米结构和化学成分发展的影响。钙含量的效果是通过构建由氢氧化钙和不同 C/S 比例合成的 C-S-H 组成的模拟水泥混合物来实现的。通过在具有不同 C/S 比率的模拟水泥混合物中加入不同量的 YE 来评估 YE 含量的影响。结果表明，10 克/升 YE 会导致 10 的高 pH 值和细菌在 C/S 比为 0.6 和 0.8 的模拟水泥混合物中无法成功生长。将 YE 从 10 g/l 增加到 20 g/l 后，pH 值从 10 降低到 9，细菌成功生长。较大量的碳酸氢根离子会导致合成的 C-S-H 而不是氢氧化钙的脱钙增强。好氧细菌 Bacillus cohnii 在钙吸收和方解石沉淀方面表现出优异的性能，是一种很有前途的混凝土裂缝密封方法。