| Summary: | 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.
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