基于微胶囊的滨海混凝土结构微生物自修复特性研究

The cracks of concrete structures in marine environments frequently lead to concrete deterioration that cause heavy financial losses. A novel, environmentally friendly self-healing technique based on microbially mediated calcium carbonate precipitation has generated extensive attention by researchers because of its advantages over traditional crack-healing techniques such as grouting or electrochemical rehabilitation. However, the study of concrete repairing techniques in the past has mainly focused on surface repairing of historic and urban architectures all over the world by means of immersion and smearing. The study of microbial techniques in self-healing of concrete cracks in marine environment has rarely been reported. In marine environment, to identify the most suitable microorganisms we propose to develop a high throughput screening system in order to identify appropriate alkaliphilic marine microorganism systematically, based on their capacity to raise mineralization and produce spores induced by UV radiation. Next we will design a microbial microcapsules system and optimize the coating systems to protect the microorganisms. In the last phase we will systematically research the healing efficiency and the mechanism with the ultimate goal of developing a theoretical and experimental foundation that could make possible the widespread use of microbial techniques in self-healing of concrete cracks in marine environments.

混凝土结构在滨海严酷环境下因开裂而导致的性能劣化屡屡发生，给社会造成了巨大经济损失。区别于传统的灌浆修复、电化学修复等混凝土裂缝修复方法，一种利用微生物诱导形成碳酸钙沉淀来修复混凝土裂缝的新型环保技术正受到科研工作者的广泛关注。然而，目前国内外针对这一技术的研究主要集中在古建筑和内陆城市建筑的表面修复，且大多采用浸泡、涂抹等工艺，而对于滨海腐蚀环境中混凝土裂缝的微生物修复鲜见报道。本研究针对滨海腐蚀环境，构建高通量筛选体系，系统筛选适宜的海洋嗜碱矿化微生物。通过紫外诱导、优化工艺条件等手段提高微生物的矿化和产芽孢能力。设计微生物微胶囊体系，选择适宜的包埋材料对体系中微生物提供有效保护。对微生物自修复过程的修复效果和作用机制等方面进行全面系统的研究，探明提高混凝土裂缝修复效果的优化措施和调控手段，为最终实现滨海环境混凝土裂缝的微生物自修复奠定理论和实验基础。

在滨海严酷环境下混凝土结构因开裂而导致的性能劣化屡屡发生。相对于传统的裂缝修复方式，一种利用细菌来修复混凝土裂缝的新型绿色环保技术正受到科研工作者的广泛关注。该技术主要基于自然界较为常见的微生物诱导形成碳酸钙沉淀现象来修补混凝土裂缝，因此微生物矿化能力的高低显然是影响裂缝修复效果的重要因素。项目组针对滨海高盐高氯离子的腐蚀环境，构建高通量选育体系，快速有效地实现对大批量待测菌株矿化活性的检测；以耐碱性能和矿化活性为指标筛选海洋嗜碱菌株，从滨海环境中系统分离筛选环境友好型海洋嗜碱高矿化能力微生物；改进芽孢发酵培养基配方，监测了不同碳源、不同氮源、金属离子及其浓度对芽孢产量的影响，选择最优芽孢发酵体系提高微生物产芽孢能力。对于微生物而言，混凝土内部高碱环境以及水化过程内部微孔的收缩均使微生物生存空间受限，项目组针对性地设计微生物微胶囊体系，选择乙基纤维素作为适宜的包埋材料对体系中微生物提供有效保护，对微胶囊制备过程中微生物活性、有机溶剂等影响因素进行了分析。通过光学显微镜、XCT、SEM等多种微观测试手段对微生物自修复过程中微胶囊的促发机制、修复产物、裂缝修复效果等进行了研究，为最终实现滨海环境混凝土裂缝的微生物自修复奠定理论和实验基础。