Microbial calcite,a bio-based smart nanomaterial in concrete remediation

The concept of developing a biosealant in concrete remediation is based on unique microbial metabolic processes.A common soil microorganism,Sporosarcina pasteurii,can induce CaCO_(3) precipitation in the surroundings in response to environmental cues such as high pH and available nutrients and minerals.A new biomolecule,microbial calcite is introduced as a smart nanomaterial for self-healing concrete-its effects on concrete performance were evaluated with regard to surface crack remediation and durability enhancement.For crack remediation,S.pasteurii cells immobilized on porous glass beads,Siran^(TM),were applied to cracks and tested for stiffness and compressive strengths.For durability tests,cement mortar beams prepared with bacteria were subjected to freeze-thaw cycles and examined for mean expansions and weight changes.Overall performance of the concrete was significantly enhanced by treatment with microbial calcite in simulated concrete cracks and cement mortar beams.