Key Laboratory of Advanced Civil Engineering Materials (Tongji University), Ministry of Education, Shanghai, 201804, China.
Appl Microbiol Biotechnol. 2018 Apr;102(7):3121-3132. doi: 10.1007/s00253-018-8779-x. Epub 2018 Feb 17.
Urea hydrolysis has already been considered as the most effective pathway for microbially induced CaCO 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 CaCO 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.
尿素水解已被认为是微生物诱导碳酸钙沉淀（MICP）最有效的途径。本工作首先研究了包括初始 pH 值、温度和尿素用量在内的几个关键因素的组合，这些因素对 MICP 的生化过程有贡献。在 pH 值和温度适宜的条件下，尿素用量对尿素降解和碳酸钙沉淀的速率有显著影响。通过将愈合剂负载在陶粒载体上，开发了一种基于细菌的自愈合系统。通过对裂缝闭合、抗压强度恢复和毛细吸水率的目视检查来评估自愈合效率。当细菌和有机营养物共同固定在载体中时，获得了较好的愈合效果。图像分析表明，在 28 天内，裂缝最大可达 273μm，闭合率为 86%。与对照相比，抗压强度恢复提高了 24%，吸水率系数降低了 27%。研究结果表明，基于尿素水解的 MICP 在恢复混凝土力学性能和提高耐久性方面具有广阔的应用前景。
