High pH in cracks depresses activities of bacteria even after they are protected well in cement-based materials, thereby restricting bacteria-based autonomous healing. To resolve this problem, graphene oxide was added to hydrogels encapsulating endospores for self-healing cementitious composites. Due to the graphene oxide incorporation, breakage ratios of hydrogels upon cracking were increased thus graphene oxide could be released to cracks. Thereafter, pH was declined to around 9 at crack mouths, where metabolic activities of bacteria were improved. Owing to the improved activities, bacteria-mediated calcium carbonate in cracks was expedited, thereby accelerating crack closure and water permeability reduction. Furthermore, flexural strength was completely restored in the presence of graphene oxide, which could be associated with needle-like morphology of generated calcium carbonate in cracks. With the outstanding self-healing performance, carbon emissions of the cementitious composites experiencing 150–400 μm wide cracks were reduced at a cradle-to-grave boundary, due to their extended service life.

中文翻译：

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揭示氧化石墨烯对基于细菌的水泥基复合材料裂纹自主愈合的影响


即使细菌在水泥基材料中得到很好的保护，裂缝中的高 pH 值也会抑制细菌的活动，从而限制细菌的自主愈合。为了解决这个问题，将氧化石墨烯添加到封装内生孢子的水凝胶中，以实现自修复水泥基复合材料。由于氧化石墨烯的掺入，破裂时水凝胶的破损率增加，因此氧化石墨烯可以释放到裂纹中。此后，裂缝口处的 pH 值降至 9 左右，细菌的代谢活动得到改善。由于活性的提高，细菌介导的碳酸钙在裂缝中的速度加快，从而加速了裂缝的闭合和透水性的降低。此外，在氧化石墨烯存在下，弯曲强度完全恢复，这可能与裂纹中生成的碳酸钙的针状形态有关。凭借出色的自修复性能，由于使用寿命延长，水泥基复合材料在经历 150-400 μm 宽裂缝时的碳排放量在从摇篮到坟墓的边界处都减少了。