Browsing by Author "Tezer, Mustafa Mert"

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Open Access
Çimento-esaslı harçlarda kendiliğinden iyileşmenin sağlanması için 2 bileşenli biyolojik katkı maddesinin geliştirilmesi
(Gazi Üniversitesi, 2021) Tezer, Mustafa Mert; Bundur, Zeynep Başaran; Civil Engineering; BUNDUR, Zeynep Başaran; Tezer, Mustafa Mert
Purpose: Throughout the literature, studies showed that among several alternatives such as diatomaceous earth (DE), metakaolin, zeolites and expanded clay could be suitable for protection of the bacteria based on their effects on compressive strength and setting, in particular DE was found to be effective in self-healing of cracks. A correct choice of the protection barrier and application methodology are of crucial for further development of self-healing concrete. This study presents a comparative study on the possible use of a mineral additive (DE) and a porous lightweight aggregate (pumice) as a protective barrier for bacterial cells. Theory and Methods: To obtain a two-phase bio additive, half of the minerals were saturated with a nutrient medium consisting of urea, corn-steep liqueur (CSL) and calcium acetate and the cells with immobilized to the other half without nutrients. Screening of the healing process was done with stereomicroscopy imaging, ultrasonic pulse velocity (UPV) analysis and water absorption testing. Results: Cracks with an average width of 0.4 mm in 28-day old mortar specimens were almost completely filled by bio-based precipitate depending on the curing regime. Cracks were sealed even in sample including relatively smaller dosage of nutrients and bacterial cells in presence of moisture. Moreover, the duration of crack healing was approximately 21 days, which was almost half of the duration to remediate the cracks when cells were directly incorporated to the mix. Conclusion: With this approach, the cracks on mortar surface were sealed and the water absorption capacity of the socalled self-healed mortar decreased compared to its counterpart cracked mortar samples.
Metadata only
Development of two-phase biological self-healing agents for cement-based mortar
(2020-01-13) Tezer, Mustafa Mert; Bundur, Zeynep Başaran; Bundur, Zeynep Başaran; Çinicioğlu, Safiye Feyza; Zihnioğlu, N. Ö.; Department of Civil Engineering; Tezer, Mustafa Mert
Factors affecting durability of concrete structures are generally associated with each other. Due to its brittle nature, concrete can crack under stress and these cracks can decrease the service life of concrete structures. Therefore, it is crucial to find alternative methods to detect and recover microcracks, then to repair them before they were developed into wider cracks. Recent research in the field of concrete materials suggested that it might be possible to develop a smart cement-based material that is capable of remediate cracks by triggering biogenic calcium carbonate (CaCO3). The mineral precipitation was obtained by leveraging the metabolic activity of microorganisms to provide microbial induced calcium carbonate precipitation (MICP). The research done on possible use of MICP in cement-based systems has showed promising results and the studies suggest this process could be a useful approach for remediation of cracks on the surface of concrete. The goal of this study was to design a 2-phase biological self-healing agent for cement-based materials. For this specific goal vegetative Sporosarcina pasteurii (S. pasteurii) cells were immobilized on the selected natural minerals or light weight aggregate (LWA). Herein, the bacterial cells were immobilized on diatomaceous earth, bentonite, sepiolite and pumice, to remediate flexural cracks on mortar in early ages (14 and 28 days after mixing). To obtain the 2-phase bio additive, half of the minerals were saturated with a nutrient medium consisting of urea, corn-steep liqueur (CSL) and calcium acetate and the cells with immobilized to the other half without nutrients. Screening of the healing process was done with ultrasonic pulse velocity (UPV) testing and stereomicroscopy. Additional evaluations were conducted with water absorption test and viability assessment. Precipitated formations were further examined with scanning electron microscopy (SEM) analysis. With this approach, the cracks on mortar surface were sealed with the biogenic precipitate and the water absorption capacity of the so-called self-healed mortar was decreased compared to its counterpart cracked mortar samples. Calcite was found to be the dominant precipitate in the remediated cracks. At last, the bacterial cells immobilized on various protection barriers were viable and functional for extended time periods.
Open Access
Two-part bio-based self-healing repair agent for cement-based mortar
(International Center for Numerical Methods in Engineering, 2020) Tezer, Mustafa Mert; Bundur, Zeynep Başaran; Civil Engineering; BUNDUR, Zeynep Başaran; Tezer, Mustafa Mert
Factors affecting durability of concrete structures are generally associated with each other. Due to its brittle nature, concrete can crack under stress and these cracks are one of the main reasons for a decrease in service life in concrete structures. Therefore, it is crucial to detect and recover microcracks, then to repair them as they were developed to wider cracks. Recent research in the field of concrete materials suggested that it might be possible to develop a smart cement-based material that is capable of remediate cracks by triggering biogenic calcium carbonate (CaCO3) precipitaton. This paper summarizes a study undertaken to investigate the self-healing efficiency of Sporosarcina pasteurii (S. pasteurii) cells immobilized on both diatomaceous earth and pumice, to remediate flexural cracks on mortar in early ages (28 days after mixing). To obtain a two-phase bio additive, half of the minerals were saturated with a nutrient medium consisting of urea, corn-steep liqueur(CSL) and calcium acetate and the cells with immobilized to the other half without nutrients. Screening of the healing process was done with ultrasonic pulse velocity (UPV) testing and stereomicroscopy. With this approach, the cracks on mortar surface were sealed and the water absorption capacity of the so-called self-healed mortar decreased compared to its counterpart cracked mortar samples.