Chen Xin, Yuan Jie, Alazhari Mohamed
State Key Laboratory of Safety and Health for In-Service Long Span Bridges, JSTI Group, Nanjing 210019, China.
School of Transportation Science and Technology, Harbin Institute of Technology, Harbin 150090, China.
Materials (Basel). 2019 Apr 20;12(8):1303. doi: 10.3390/ma12081303.
Previous studies of bacteria-based self-healing concrete have shown that it is necessary to encapsulate and separate the self-healing ingredients (bacteria, nutrients, and precursors) in the concrete so that when a crack forms, capsules rupture, which allows the self-healing ingredients to come together and precipitate calcite into the crack. Because of the shearing action in the concrete mixer, there is a chance that these capsules, or other carriers, may rupture and release the self-healing ingredients. This would affect the efficiency of self-healing, but may detrimentally affect the concrete's properties. This work investigated the effects of multi-component growth media, containing germination and sporulation aids for the bacterial aerobic oxidation pathway, on the basic properties of fresh and hardened concrete instead of the potential self-healing efficiency in a structural service. Tests were carried out to measure the effects of growth media on air content, fluidity, capillary absorption, strength development of cement mortar following corresponding standards, hydration kinetics, setting properties, and the microstructure of cement paste, according to certain specifications or using specific machines. The research has demonstrated that a multi-constituent growth media will not have a significant effect on the properties of concrete in the proportions likely to be released during mixing. This important conclusion will allow further development of these novel materials by removing one of the key technical barriers to increased adoption.
以往对基于细菌的自修复混凝土的研究表明，有必要将自修复成分（细菌、养分和前体）封装并隔离在混凝土中，以便在裂缝形成时，胶囊破裂，使自修复成分聚集在一起并在裂缝中沉淀方解石。由于混凝土搅拌机中的剪切作用，这些胶囊或其他载体有可能破裂并释放出自修复成分。这会影响自修复效率，但可能对混凝土性能产生不利影响。这项工作研究了含有细菌需氧氧化途径发芽和孢子形成助剂的多组分生长培养基对新拌混凝土和硬化混凝土基本性能的影响，而非结构服役中的潜在自修复效率。按照相应标准、根据特定规格或使用特定机器进行了试验，以测量生长培养基对含气量、流动性、毛细吸水、水泥砂浆强度发展、水化动力学、凝结性能以及水泥浆微观结构的影响。研究表明，在搅拌过程中可能释放的比例下，多组分生长培养基对混凝土性能不会产生显著影响。这一重要结论将消除增加采用率的关键技术障碍之一，从而推动这些新型材料的进一步发展。
