低温微生物诱导碳酸钙沉积及其在混凝土裂缝修复中的应用研究

Low Temperature Microbial Induced Calcium Carbonate Precipitation and Its Application in Concrete Crack Repair

近些年来,对于混凝土裂缝的修复,微生物诱导碳酸钙沉积(MICP)已成一种高效和环境友好的技术。本文选用一种可在低温环境下生长的矿化微生物,然后在碱性溶液中研究Ca^(2+)浓度、pH值和钙化速率的变化,来揭示微生物诱导矿化的动态过程。随后,将此微生物应用到混凝土裂缝自修复中,同时采用裂缝愈合率和渗水系数来表征混凝土裂缝的自修复效果。试验结果表明,微生物能够快速降低溶液中的Ca^(2+)浓度,并提高钙化速率,矿化产物主要是球状方解石CaCO_(3)。对于宽度小于0.50 mm的早期混凝土裂缝,在10℃的养护温度下,28 d修复后裂缝表面基本能被白色物质填充,渗水系数下降2个数量级,并且裂缝区修复产物主要是大小不一的球状方解石CaCO_(3)。

In recent years,microbial induced calcium carbonate precipitation(MICP) has become an efficient and environmentally friendly technology for repairing concrete cracks.In this paper,a mineralization microorganism that grows in a low temperature environment was selected,and then the changes of Ca^(2+) concentration,pH value and calcification rate were studied in alkaline solution to reveal the dynamic process of microbial induced mineralization.Subsequently,the microorganism was applied to the self-healing of concrete cracks,and the crack healing ratio and permeability coefficient were used to characterize the self-healing effect of concrete cracks.The results show that the microorganism quickly reduces the Ca^(2+) concentration in the solution and increases the calcification rate.Meanwhile,the mineralization products are mainly spherical calcite CaCO_(3).For the early concrete cracks with the width of less than 0.50 mm,the surface of the crack basically fills with white precipitations after 28 d healing time at the curing temperature of 10 ℃,and the permeability coefficient drops by two orders of magnitude.In addition,the healing products at the crack mouth are mainly spherical calcite CaCO_(3)with different sizes.