Abstract：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 were 73.3% 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.
 JONKERS H M, THIJSSEN A, MUYZER G, et al. Application of bacteria as self-healing agent for the development of sustainable concrete[J]. Ecological Engineering, 2010, 36(2):230-235.  WANG J Y, SOENS H, VERSTRAETE W, et al. Self-healing concrete by use of microencapsulated bacterial spores[J]. Cement and Concrete Research, 2014, 56:139-152.  WIKTOR V, JONKERS H M. Quantification of crack-healing in novel bacteria-based self-healing concrete[J]. Cement and Concrete Composites, 2011, 33(7):763-770.  WANG J Y, VAN TITTELBOOM K, DE BELIE N, et al. Use of silica gel or polyurethane immobilized bacteria for self-healing concrete[J]. Construction and Building Materials, 2012, 26(1):532-540.  XU J, YAO W. Multiscale mechanical quantification of self-healing concrete incorporating non-ureolytic bacteria-based healing agent[J]. Cement and Concrete Research, 2014, 64:1-10.  BANG S S, GALINAT J K, RAMAKRISHNAN V. Calcite precipitation induced by polyurethane-immobilized Bacillus pasteurii[J]. Enzyme and Microbial Technology, 2001, 28(4-5):404-409.  AIMI M A R M, KHALILAH K, HANA H N, et al. Autogenous healing mortar made of alginate-encapsulated Geobacillus stearothermophilus[M]//YUSOFF M, HAMID N, ARSHAD M, et al. InCIEC 2015. Singapore:Springer, 2016:601-619.  袁晓露, 胡为民, 刘冬梅. 微生物水泥净浆的自修复性能研究[J]. 混凝土, 2015(6):114-116, 120. YUAN X L, HU W M, LIU D M. Effect of magnesium on properties of microbial cement paste[J]. Concrete, 2015(6):114-116, 120. (in Chinese)  KHALIQ W, EHSAN M B. Crack healing in concrete using various bio influenced self-healing techniques[J]. Construction and Building Materials, 2016, 102:349-357.  Zhang J G, Zhou A J, Liu Y Z, et al. Microbial network of the carbonate precipitation process induced by microbial consortia and the potential application to crack healing in concrete[J]. Scientific reports, 2017, 7:14600.  BRENNER K, YOU L C, ARNOLD F H. Engineering microbialconsortia:A new frontier in synthetic biology[J]. Trends in Biotechnology, 2008, 26(9):483-489.  DA SILVA F B, DE BELIE N, BOON N, et al. Production of non-axenic ureolytic spores for self-healing concrete applications[J]. Construction and Building Materials, 2015, 93:1034-1041.  ERŞN Y C, GRUYAERT E, LOUIS G, et al. Self-protected nitrate reducing culture for intrinsic repair of concrete cracks[J]. Frontiers in Microbiology, 2015, 6:1228-1228.  ZHANG J G, LIU Y Z, FENG T, et al. Immobilizing bacteria in expanded perlite for the crack self-healing in concrete[J]. Construction and Building Materials, 2017, 148:610-617.  KRUMHOLZ L R, HARRIS S H, TAY S T, et al. Characterization of two subsurANCe H2-utilizing bacteria, Desulfomicrobium hypogeium sp. nov. and Acetobacterium psammolithicum sp. nov. and their ecological roles[J]. Applied and Environmental Microbiology, 1999, 65(6):2300-2306.  钱春香, 王瑞兴, 詹其伟. 微生物矿化的工程应用基础[M]. 北京:科学出版社, 2015. QIAN C X, WANG R X, ZHAN Q W. Basis of microbial mineralization applied in engineering[M]. Beijing:Science Press, 2015. (in Chinese)  冯涛. 基于膨胀珍珠岩固载微生物的混凝土裂缝抗渗水性能及自修复机理分析[D]. 太原:太原理工大学, 2018. FENG T. Analysis on anti-seepage performance and self-healing mechansim of concrete cracks based on immobilizing bacteria in expomded perlite[D]. Taiyuan:Taiyuan University of Technology, 2018. (in Chinese)