Optimizing nutrient content of microbial self-healing concrete
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Cracks in microbial self-healing concrete are autonomously sealed through microbial induced calcium carbonate precipitation (MICP). The biogenic production of dissolved inorganic carbon (i.e. CO2) is the main drive for MICP and it is limited by the bioavailability of the nutrients. When added as admixtures bioavailability of the nutrients becomes even more significant for crack sealing as they disperse in mortar and a considerable portion stays far from an individual crack. Therefore, determination of the nutrient bioavailability and optimization of the nutrient content is necessary to enhance self-healing performance of bioconcrete. This study defines an optimum nutrient content range for nitrate reduction based microbial self-healing concrete. Ca-formate and Ca-nitrate were used as nutrient admixtures and their wt/wt ratio was kept constant at 2.50: 1.00 while testing various nutrient doses. Variation in mortar properties and nutrient bioavailability was observed and the optimum nutrient content range was defined as 3.5% to 7% depending on the expectations.