脲解型微生物的矿化过程及其在水泥基材料早期裂缝修复中的应用

Mineralization Process of Urealytic Microorganism and Its Application in Early Age Crack Repair of Cement-based Materials

裂缝的产生会对水泥基材料的耐久性产生不利影响,并降低其使用寿命。针对水泥基材料裂缝的修复问题,利用微生物诱导碳酸钙沉淀(MICP)来修复裂缝是一种绿色环保的技术。本研究选用一种脲解型微生物,首先研究了温度、初始pH值和Ca^(2+)浓度对其细菌生长的影响;随后,通过Ca^(2+)浓度变化和钙化速率揭示了CaCO_(3)沉淀的矿化过程;同时,详细探讨了脲解型微生物MICP的矿化机理;然后,制得微生物自修复砂浆试件,并通过折断法制作宽度在0.30~0.45 mm的裂缝,以面积修复率和抗水渗透修复率表征裂缝的自修复效果。实验结果表明,该微生物的最佳温度,初始pH值和Ca^(2+)浓度分别为25℃,7.0~10.0和0~90 mM。加入微生物自修复剂后,经过28 d修复,砂浆试件裂缝的面积修复率和抗水渗透修复率分别为99.2%和95%。与其他裂缝修复方法相比,微生物矿化修复方法具有及时、高效和环保的优点。

The generation of cracks will have an adverse impact on the durability of cement-based materials and reduce the service life.Using the microbial induced calcium carbonate precipitation(MICP)to repair cracks of cement-based materials is a green and environmentally friendly technology.Aiming at the problem of repairing cracks in cement-based materials,a kind of urealytic microorganism was selected to study the effects of temperature,initial pH and Ca^(2+)concentration on the growth of bacteria.The Ca^(2+)concentration and the calcification rate were used to reveal the mineralization process of CaCO_(3)precipitation.The mineralization mechanism of MICP was discussed in detail.Then,the microbial self-healing mortar specimens were prepared,and the crack with a width of 0.30-0.45 mm were made by the breaking method.The self-healing efficiency of the crack was characterized by the area repair ratio and anti-penetration repair ratio.The experimental results showed that the optimal temperature,initial pH and Ca^(2+)concentration of the microorganism were 25℃,7.0-10.0 and 0-90 mM,respectively.After adding the microbial self-healing agent,the area repair ratio and anti-penetration repair ratio of the mortar specimens were 99.2%and 95%after 28 d healing time,respectively.Compared with other methods,the microbial mineralization self-healing method has the advantages of timeliness,high efficiency and environmental protection.