Biochemical process of ureolysis-based microbial CaCO3 precipitation and its application in self-healing concrete
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Urea hydrolysis has already been considered as the most effective pathway for microbially induced CaCO3 precipitation (MICP). The present work first studied the combination of several key factors including initial pH, temperature, and dosage of urea, which contribute to the biochemical process of MICP. Under an amiable condition of pH and temperature, the dosage of urea has a significant impact on the rate of urea degradation and CaCO3 precipitation. A bacteria-based self-healing system was developed by loading healing agents on ceramsite carriers. The self-healing efficiency was evaluated by visual inspection on crack closure, compressive strength regain, and capillary water absorption. A preferable healing effectiveness was obtained when the bacteria and organic nutrients were co-immobilized in carriers. Image analysis showed that cracks up to 273 μm could be healed with a crack closure ratio of 86% in 28 days. The compressive strength regain increased 24% and the water absorption coefficient decreased 27% compared to the reference. The findings indicated a promising application of ureolysis-based MICP in restoring the mechanical properties and enhancing the durability of concrete.
KeywordsBacteria Concrete Biochemistry Crack Self-healing
The authors would like to acknowledge the financial support for this study from the National Natural Science Foundation of China (51378011), the Shanghai Municipal Natural Science Foundation (17ZR1441900), and the National Key Research and Development Program of China (2016YFC0700802).
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Conflict of interest
The authors declare that they have no conflict of interests.
This article does not contain any studies with human participants or animals performed by any of the authors. The article is original and has not been formally published in any other peer-reviewed journal and does not infringe any existing copyright and any other third party rights.
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