A novel selection strategy of microbial consortia for improving crack self-healing in mass concrete via thermal pretreatment: Preliminary tests
Microbially induced carbonate precipitation (MICP) is a promising technology for self-healing concrete. However, most previous studies have relied on pure cultures, whose low robustness in complex environments markedly limits their application potential. Moreover, high temperature environments in mass concrete generated by cement hydration may markedly inhibit microbial mineralization processes. Therefore, in this study, a strategy for selecting aerobic alkali-tolerant consortia derived from thermally pretreated waste activated sludge (WAS) was developed. The optimal microbial consortia were identified by comparing their mineralization capacity and enhancement effectiveness on recycled concrete aggregates (RCAs). Additionally, their application potential was confirmed by preliminarily evaluating the crack healing of concrete. The selected microbial consortia subjected to 80 C pretreatment were optimal and exhibited the highest inorganic carbon conversion rate (IC-CR). Moreover, RCAs enhanced by the optimal microbial consortia showed the greatest decrease in water absorption. MiSeq sequencing revealed that the microbial consortia primarily promoted MICP through mutualistic interactions among functionally diverse microorganisms, and several thermotolerant genera were identified. In addition, compared with nonmicrobial specimens, the optimal microbial consortia exhibited promising crack healing capacity. The findings of this study are expected to provide a promising microbial selection strategy for practical applications.