Bacterial Mortaras a Sustainable Self-Healing RepairMaterial for Concrete Structures: A Rational Approach

Over the past decade, bacterial calcite (BC) has been gaining popularity among scientists and engineers as a sustainable building material. In this article, we wanted to explore the performance of bacterial mortar (BM) as a function of BC precipitation. A step-by-step rational approach was adopted that helped in correlating calcite precipitation in bacterial cultures with the strength of the BM produced by the same. The optimized BM samples thus produced were stronger (up to 70% increase in compressive strength), more resistant to water absorption than normal mortar (up to 24% reduction in water absorption), and exhibited remarkable self-healing effects. The mechanical properties of the mortar samples were assessed through compressive and flexural strength tests, while self-healing effects were confirmed through the capacity to autoheal an entirely split BM cube. Microstructural analyses of the BM samples were done using FESEM–EDS and XRD data which helped in providing mechanistic insights into the observed characteristics of BM. The optimized BM formulations when used for coating concrete beams imparted higher strengths to the same compared to the uncoated beams as derived through their higher flexural strengths (26% approx.). Our developed BM, possessing improved mechanical properties coupled with its water-resistant features and excellent self-healing properties, makes it an economically and environmentally sustainable repairing material for existing and upcoming concrete structures.