Microorganisms can enhance functions present in cementitious composites. For instance, biomineralization is a popular phenomenon used to enhance the healing capacity of concrete. Various axenic cultures are tested accordingly and proposed as healing agents to enhance the self-healing capacity of cementitious composites. Meanwhile the advantageous traits of non-axenic cultures such as economic feasibility and high specific activity have been overlooked and thus their performance as a healing agent remains unclear. It is necessary to investigate cementitious composites that contain a non-axenic culture as well for a justified evaluation of available healing agents. Here we present the self-healing performance of a mortar containing NO_3~- reducing non-axenic culture as a healing agent. Specimens with a defined crack width of 400 μm were used in the experiments and treated with tap water. Self-healing was quantified via crack closure, water permeability and sealing thickness along the crack depth. Complete crack sealing was achieved in microbe-based specimens in 28 days. The thickness of the sealed layer was recorded as ～5 mm and the water permeability under 0.1 bar pressure decreased by 80% upon microbial self-healing. Overall, non-axenic cultures have great potential for development of self-healing bioconcrete and due to their economic feasibility they may supersede axenic cultures in situ.
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