WoS İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/394
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Article Citation - WoS: 12Citation - Scopus: 14Production and Compatibility Assessment of Denitrifying Biogranules Tailored for Self-Healing Concrete Applications(Elsevier Sci Ltd, 2022-02) Sonmez, Merve; Ersan, Yusuf CagatayMicrobial granules have been mostly used for wastewater treatment. Recently, biogranules consisting nitrate-reducing microorganisms have appeared as a unique healing agent providing simultaneous self-healing of cracks and corrosion inhibition of rebar in concrete. Yet, information about the production process and microbial activity of these biogranules as well as their compatibility with cementitious materials remains unknown. This study presents the biogranule production procedure in detail and evaluates the compatibility of the produced biogranules with the cementitious composites. In the form of biogranules, bacteria doses varying between 0.25% and 3.00% w/w cement were incorporated into mortar and the variations in fresh and hardened properties of mortars were evaluated with respect to abiotic mortars. Biogranules were also tested for their compatibility with concrete at minimum and the defined maximum tolerable doses. Biogranules with a NOx-N reduction activity of 0.10 g NOx-N.g(-1) bacteria.d(-1) and organic carbon oxidation activity of 1.50 g HCOO-.g(- 1) bacteria.d(-1) were produced successfully by using minimal medium. It was found out that biogranules enable bacteria incorporation into mortar up to a dose of 2.50% w/w cement without compromising fresh and hardened properties of cementitious composites. It was revealed that the compatibility of the biogranules was due to the mineral layer surrounding the biogranules which prevented interaction between the cement matrix and the microbial content. The thickness of the protective mineral layer around the granules was varying between 50 and 300 mu m depending on the granule size. Net yield for concrete compatible biogranule production was determined as 0.05 g bio-granule.g(-1)HCOO-.Conference Object Citation - WoS: 5Citation - Scopus: 6Optimizing Nutrient Content of Microbial Self-Healing Concrete(CRC Press-Taylor & Francis Group, 2019) Ersan, Y. C.; Akin, Y.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.