期刊
ACS APPLIED MATERIALS & INTERFACES
卷 12, 期 9, 页码 10938-10948出版社
AMER CHEMICAL SOC
DOI: 10.1021/acsami.9b21465
关键词
sporulation rate; germination; crack-healing; MICP; concrete
资金
- National Science Foundation of China [51678384, 51911530238, 51708385, 51808375]
- Natural Science Foundation of Shanxi Province, China [201801D121095, 201801D221350]
- China Postdoctoral Science Foundation [2018M631776]
- Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi [2019L0324]
While microbial spore production and germination of bacteria have been widely studied for their applications in animal husbandry, aquatic products, medicine, and food, few studies have investigated their use for the crack-healing of concrete. To effectively heal the cracks in concrete, studies suggest that the rate of sporulation and the germination of bacteria should be sufficiently high. This study investigates the effects of different carbon sources, nitrogen sources, Mn2+ concentrations, and external culture conditions on the sporulation rate and analyzes the effects of the pH value, heat activation, germinants, various cations, and nutrients on the germination of spores. Bacillus cohnii (B. cohnii) is chosen as the bacterium to be mixed in concrete because of its alkalophilic nature. The mineralization activity of spores after germination and the crack-healing capacity of concrete are studied. The optimal culture medium and the optimum external conditions for spore production are obtained. The total cell count and sporulation rate of bacteria obtained on this medium are 3.14 x 10(9) CFU/mL and 92.6%, respectively, under the optimum external conditions. The optimal pH value for the spore germination of B. cohnii is 9.7. While the cation Na+ strongly stimulates the germination of B. cohnii spores, other cations (such as K+, NH4+, and Ca2+) do not stimulate spore germination. The optimal concentration of Na+ is 200 mM. The germination rate of spores in the control group concrete specimen (room temperature 24 degrees C) was more than 50%, thus suggesting that B. cohnii bacteria can be used in the self-healing of concrete cracks. The mineralization activity test proves that the spores of B. cohnii have a mineralizing function after germination, and the crystals produced by microbial-induced carbonate precipitation (MICP) are of pure calcite. When the crack width of the concrete specimen with spores of B. cohnii is less than 1.2 mm, it can be completely repaired after 28 days of healing.
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