碳酸酐酶微生物沉积碳酸钙修复水泥基材料表面裂缝

Restoration of Cracks on Surface of Cement-Based Materials by Carbonic Anhydrase Microbiologically Precipitation Calcium Carbonate

采用琼脂作为载体将细菌菌株和营养物质涂刷在水泥石表面,为碳酸酐酶微生物酶化反应过程创造适宜环境以加速矿化,7d后在水泥石表面形成连续密实的沉淀膜层,X射线衍射分析表明该膜层中碳酸钙为方解石晶型。通过扫描电子显微镜观察到碳酸钙颗粒呈花生状,碳酸钙膜与水泥石表面黏结紧密。此外,改变水泥石表面裂缝宽度,对水泥石表面吸水性能进行测试,结果表明:当裂缝宽度小于100μm时,微生物覆膜修复后水泥石表面初始吸水速率和毛细吸水系数大大降低,修复效果明显;当裂缝宽度为100~200μm时,微生物覆膜修复能力有限;当裂缝宽度大于200μm时,微生物覆膜修复无效果。碳酸酐酶微生物诱导矿化修复过程既吸收大气中的温室气体CO2,也不产生任何有害物质,具有优异的环境友好特性。

A CaCO3 film was prepared by brushing immobilized bacteria and nutriments onto the cement paste surface after 7d.According to the X-ray diffraction analysis,the film is a calcite crystal.A carrier was used to immobilize the bacteria with agar,which could create a suitable environment for microbial enzyme reaction to accelerate the process of mineralization.The CaCO3 particles are peanut-shaped,the CaCO3 film is bound with the surface tightly.The crack width on cement paste surface was examined by water absorption test.The results show that the initial water absorption rate and capillary water absorption coefficient both are reduced after the microbial coating repair when the crack width is<100μm,and the microbial coating repair ability is restricted when the crack width is between 100--200μm and is invalid when the crack width is>200μm.The process of carbonic anhydrase microbial mineralization absorbs CO2 in the atmosphere without any harmful substances,thus having the superior environment-friendly features.