Bacterial self-healing of concrete and durability assessment

Bacterial self-healing is an innovative technology allowing repairing open micro-cracks in concrete by CaCO3 precipitation. This bio-technology improves the durability of the structure. In this paper, peptone, yeast extract and Bacillus Subtilis were added as microbial adjuvant in concrete mix design. This led to a decrease in porosity resulting in an increase of strength, dynamic modulus as well as a reduction of water uptake, gas permeability and chloride permeation. Scanning electron microscopy, energy dispersive spectroscopy and raman spectroscopy showed that the microbial precipitations in the crack were CaCO3. Moreover, the morphology of calcite crystals was a needle-like, bouquet-like and rhombohedral-shaped. At 44 days, 400 μm crack surface width was completely filled. Hence, peptone, yeast extract and Bacillus Subtilis could be considered as a promising concrete admixture in enhancing durability and mechanical properties of concrete. Furthermore it is established that Eurocode 2 could be applied with confidence for predicting properties of bacterial concrete.