水工混凝土矿化微生物固载及自修复试验研究

Experimental study on mineralized microbial immobilization and self-healing of hydraulic concrete

直接内掺方式制备微生物自修复混凝土会因拌合的机械挤压摩擦、生存环境受限等因素影响矿化微生物的长期活性。本文选择巴氏芽孢杆菌为矿化微生物,以膨胀珍珠岩和陶粒为微生物载体,以水泥浆和偏高岭土浆液为载体包覆材料,通过试验优选有助于微生物释放和保护的载体及其合理粒径、包覆材料,并研究微生物固载对裂缝自修复效果的影响。结果表明:掺入定量的膨胀珍珠岩的水工混凝土试样劈裂裂缝处拉裂面积比更大,作为水工混凝土微生物固载材料时较陶粒更能有效释放矿化微生物;偏高岭土浆液较水泥浆更适合作为载体的包覆材料,其包覆的微生物14 d存活率为86.63%,有效保证了固载微生物的长期活性;对微生物进行膨胀珍珠岩固载和偏高岭土浆液包覆,修复养护90d裂缝最大修复宽度为0.616mm,高于直接内掺的0.453mm,有效改善了混凝土试件的裂缝自修复效果。

Preparation of microbial self-healing concrete by direct internal mixing will affect the long-term activity of mineralized microorganisms due to factors such as squeezing friction and limited living environment.In this work,we select Bacillus pasteurii as a mineralized microorganism,and use expanded perlite and ceramsite as microbial carriers,and cement slurry and metakaolin slurry as carrier coating materials.An experiment is conducted to optimize the carrier and its reasonable particle size and coating materials that contribute to the release and protection of the microorganism;the effect of microbial immobilization on the self-healing effect of cracks is studied.The results show that quantitative expanded perlite,added to a hydraulic concrete specimen,increases the tensile crack ratio at its splitting crack;as a microbial immobilization material,it is more effective to release mineralized microorganisms than ceramsite.Metakaolin slurry is more suitable as a carrier coating material than cement slurry,and its encapsulation of the microorganism achieves a 14-day survival rate of 86.6%,effectively ensuring the long-term activity of the immobilized microorganism.The microorganism that are immobilized with expanded perlite and coated with metakaolin slurry can achieve a 90-day repair and maintenance effect of the cracks up to a width of 0.616 mm,wider than 0.453 mm of the direct addition method.Thus,our method effectively improves the crack self-healing effect of concrete specimens.