Optimization of growth medium for Sporosarcina pasteurii in bio-based cement pastes to mitigate delay in hydration kinetics.

Microbial-induced calcium carbonate precipitation has been identified as a novel method to improve durability and remediate cracks in concrete. One way to introduce microorganisms to concrete is by replacing the mixing water with a bacterial culture in nutrient medium. In the literature, yeast extract often has been used as a carbon source for this application; however, severe retardation of hydration kinetics has been observed when yeast extract is added to cement. This study investigates the suitability of alternative carbon sources to replace yeast extract for microbial-induced calcium carbonate precipitation in cement-based materials. A combination of meat extract and sodium acetate was identified as a suitable replacement in growth medium for Sporosarcina pasteurii; this alternative growth medium reduced retardation by 75 % (as compared to yeast extract) without compromising bacterial growth, urea hydrolysis, cell zeta potential, and ability to promote calcium carbonate formation.