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A binary concrete crack self-healing system containing oxygen-releasing tablet and bacteria and its Ca2+-precipitation performance
- Zhang, J. L., Wang, C. G., Wang, Q. L., Feng, J. L., Pan, W., Zheng, X. C., Liu, B., Han, N. X., Xing, F., Deng, X.
- Applied microbiology and biotechnology 2016 v.100 no.24 pp. 10295-10306
- bacteria, bacterial spores, biochemical pathways, calcium, calcium peroxide, concrete, dissolved oxygen, lactic acid, nutrients, oxygen, pH, vegetative cells
- A strategy to supply molecular oxygen for microbial calcium precipitation was developed for the first time. Firstly, a controlled oxygen-releasing tablet (ORT) containing CaO₂ and lactic acid with a suitable ratio of 9:1 was developed. It can provide a stable oxygen supply and maintain pH in the range of 9.5–11.0 for 45 days while contacting with water. In the presence of oxygen, a self-healing bacterium H4 spores germinated more effectively and maintained high metabolic activity. Furthermore, H4 vegetative cells induced 50 % more calcium precipitation than that obtained without oxygen supply. Finally, a binary self-healing system containing bacterial spores and ORT was established. The calcium precipitation experiments showed that H4 in the binary self-healing system precipitated 27.5 mM calcium with oxygen supply after 32 days and dissolved oxygen (DO) concentration of the solution decreased from 15 to 4 mg l⁻¹, while only 6.9 mM calcium precipitation was obtained without oxygen supply. This work can disclose the effect of oxygen on microbial calcium precipitation and further lay a foundation for the establishment of ternary self-healing system containing bacteria, ORT, and nutrients, which will be promising for the self-healing of cracks deep inside the concrete structure.