不同矿化微生物对混凝土裂缝自修复效果影响

Effect of mineralized bacteria type on concrete crack self-healing capacity

微生物矿化沉积能够有效地实现混凝土的裂缝自修复,从而延长混凝土结构的服役时间,然而直接掺入混凝土的微生物成活率会显著降低。该文以高孔隙率的膨胀珍珠岩作为微生物载体,研制了具有裂缝自诊断和自修复能力的混凝土,考察了不同类型矿化微生物对混凝土裂缝自修复效果的影响,并对混凝土裂缝处沉淀物进行了微观结构分析。试验结果表明:科氏芽孢杆菌和筛选的好氧型、兼性厌氧型、厌氧型混菌均具有良好的矿化沉积能力,混凝土经修复养护28d后裂缝修复率分别达到73.3%、83.3%、63.3%和41.5%。微观结构分析结果表明:利用不同类型矿化微生物研制的裂缝自修复混凝土的裂缝处填充物为不同形态的碳酸钙晶体。研究结果可为基于微生物矿化的混凝土裂缝自修复性能研究提供参考。

Microbially induced carbonate precipitation(MICP)can provide self-healing of cracks in concrete to prolong the service life of concrete structures.However,the survival rate of the bacteria incorporated into the concrete directly affects the self-healing capability.This study used concrete with a high porosity expanded perlite as the bacteria carrier which possessed excellent crack self-diagnosis and self-healing properties.The study analyzed the effects of different types of mineralized bacteria on the concrete crack self-healing and the microstructures of the crystals inside the concrete cracks.The results show that a pure culture of Bacillus cohnii and a microbial consortia of aerobic,facultative anaerobic and anaerobic bacteria both exhibited excellent healing capacities.The crack healing rates of the concrete after curing for 28 days were73.3%for Bacillus cohnii,83.3%for the aerobic,63.3%for the facultative anaerobic and 41.5%for the anaerobic bacteria.The microstructure analyses show that the crystals in the concrete cracks formed by different types of mineralized bacteria were various forms of calcium carbonate crystals.The results of the present study will be useful for further studies of the crack-healing properties of concrete based on MICP.