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 CaCO3 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.