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Study on calcareous sand treated by MICP in different NaCl concentrations
Calcareous sand foundations may be damaged by waves or earthquakes. Therefore, such foundations should be reinforced. In this study, a series of bacterial solution tests and cyclic triaxial tests were performed to investigate the reinforcing effect of microbially induced carbonate precipitation (MICP) treatment of calcareous sand in different NaCl concentrations. In bacterial solution tests, the microbial activity and microbial mineralization products were examined. At 32 hr, the OD600 and urease of MAT35 were lower than MAT0 by 21.94% and 43.53%. In 0–48 hr, the OD600 and activity of MAT80 and MAT100 were below 0.15 and 1 mM urea/min. The productivity of calcium carbonate after MICP decreased with an increase in NaCl concentration. The cyclic triaxial tests showed that with an increase in NaCl concentration, the accumulation rate of pore pressure increased, and the number of strain-accumulation cycles decreased. Although the stiffness and cyclic resistance of the samples decreased with an increase in NaCl concentration, both were higher than those of untreated sands. Scanning electron microscopy images showed that as the NaCl concentration increased, the calcium carbonate was precipitated gradually changed from a cluster to individual crystals; this change in form is the main reason for the decrease in liquefaction resistance.
Study on calcareous sand treated by MICP in different NaCl concentrations
Calcareous sand foundations may be damaged by waves or earthquakes. Therefore, such foundations should be reinforced. In this study, a series of bacterial solution tests and cyclic triaxial tests were performed to investigate the reinforcing effect of microbially induced carbonate precipitation (MICP) treatment of calcareous sand in different NaCl concentrations. In bacterial solution tests, the microbial activity and microbial mineralization products were examined. At 32 hr, the OD600 and urease of MAT35 were lower than MAT0 by 21.94% and 43.53%. In 0–48 hr, the OD600 and activity of MAT80 and MAT100 were below 0.15 and 1 mM urea/min. The productivity of calcium carbonate after MICP decreased with an increase in NaCl concentration. The cyclic triaxial tests showed that with an increase in NaCl concentration, the accumulation rate of pore pressure increased, and the number of strain-accumulation cycles decreased. Although the stiffness and cyclic resistance of the samples decreased with an increase in NaCl concentration, both were higher than those of untreated sands. Scanning electron microscopy images showed that as the NaCl concentration increased, the calcium carbonate was precipitated gradually changed from a cluster to individual crystals; this change in form is the main reason for the decrease in liquefaction resistance.
Study on calcareous sand treated by MICP in different NaCl concentrations
Zhao, Jitong (author) / Shan, Yi (author) / Tong, Huawei (author) / Yuan, Jie (author) / Liu, Jiaming (author)
European Journal of Environmental and Civil Engineering ; 27 ; 3137-3156
2023-07-27
20 pages
Article (Journal)
Electronic Resource
Unknown
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