Surface crack treatment of concrete via nano-modified microbial carbonate precipitation.

As a new concrete crack patching technology, microbial self-healing slurries offer favourable characteristics including non-pollution, ecological sustainability and good compatibility with concrete. In this paper, a nano-sio₂-modified microbial bacteria liquid, combined with sodium alginate and polyvinyl alcohol, was used to prepare a nano-modified microbial self-healing slurry. This slurry was used to coat concrete under negative pressure in order to verify its restoration effect, and the micromorphology of the resulting microbial mineralization products was observed. The results revealed that patching the concrete using the nano-modified microbial slurry significantly improved its permeability, and increased its carbonization resistance by three times in comparison with the control group. Through a combination of Scanning electron microscopy (SEM) and X-ray diffraction (XRD) observation, it was determined that the microbial mineralization reaction products were mainly calcite crystals, which, integrated with the nano-sio₂, sodium alginate and polyvinyl alcohol at the microscopic level, filled the internal pores of concrete, thus improving its durability. Highlights: • Surface crack treatment of concrete using a nano-modified microbial slurry was investigated. • Patching concrete using nano-microbial slurry clearly improved its chloride penetration. • The carbonization of the concrete was three times in comparision with the control group. • The main product of the microbial mineralization reaction was calcite crystal. [ABSTRACT FROM AUTHOR]