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BUNDUR, Zeynep Başaran

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Zeynep Başaran

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    Book ChapterPublicationMetadata only
    Design of energy-efficient white portland cement mortars for digital fabrication
    (Springer, 2020) Kurt, S.; Atalay, Yiğit Alper; Aydın, Ozan Eray; Avcıoğlu, B.; Yıldırım, T.; Göktepe, G. B.; Emir, S.; Bundur, Zeynep Başaran; Paksoy, H. Ö.; Civil Engineering; Bos, F. P.; Lucas, S. S.; Wolfs, R. J. M.; Salet, T. A. M.; BUNDUR, Zeynep Başaran; Atalay, Yiğit Alper; Aydın, Ozan Eray
    Additive manufacturing, i.e. three-dimensional (3D) printing technology has many advantages over traditional processes and the related technology is continuously improving. This study aims to develop an energy- efficient White Portland cement (WPC) mortar mix suitable for 3D printing applications. The mortar mix contained a blended binder content using Çimsa Recipro50 calcium aluminate cement (CAC) along with Çimsa Super WPC (sWPC). Microencapsulated Phase Change Materials (mPCMs) added to the mix enhance thermal performance through latent heat storage capability. The CAC used in the study has an alumina content of at least 50% Mineralogical analysis of the CAC and sWPC binder were characterized by the XRD-Rietveld method. In terms of material design for 3D printing, printable mortars must be workable enough to be extruded (extrudability) and retain its shape with little or no deformation after extrusion (buildability). In this study, the printability of mortar was evaluated through workability loss, open time, green strength, and early-age compressive strength. Results showed that use of sWCP and CAC composite enables a thixotropic behavior, which is required for 3D printing. The designed mortar mixes can enable high flowability necessary for successful extrusion and have high green strength at fresh state to maintain stable printing. The results also showed that the use of mPCMs can influence printability while improving buildability.
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    ArticlePublicationMetadata only
    Use of natural minerals to immobilize bacterial cells for remediating cracks in cement-based materials
    (ASCE, 2022-03-01) Tezer, M. M.; Bundur, Zeynep Başaran; Civil Engineering; BUNDUR, Zeynep Başaran
    Cracks in cement-based materials are one of the main factors affecting the durability of structure. Recent research in the field of concrete materials showed that self-healing in cement-based systems can be achieved by triggering biogenic calcium carbonate (CaCO3) precipitation. The goal of this study is to establish a comparative evaluation of the use of sepiolite, bentonite, and diatomaceous earth (DE) as an immobilization barrier of Sporosarcina pasteurii (S. pasteurii) cells to trigger self-healing in cement-based systems. For the first time in the literature, this study will provide insight into the use of natural minerals, such as bentonite and sepiolite, as protective carriers for vegetative S. pasteurii cells in cement-based materials and present a comparative evaluation of factors influencing crack healing, such as the microstructure and composition of immobilization barriers. A two-phase self-healing bioadditive was obtained by immobilizing vegetative S. pasteurii cell samples on natural porous minerals with or without the use of required nutrients. Then the samples were cracked by a three-point bending test, and the healing process was screened via stereomicroscope imaging and ultrasonic pulse velocity (UPV) testing after subjecting the cracked samples to 28 days of moist curing. Flexural cracks induced in mortar samples were filled with biogenic precipitate. Relatedly, the water absorption capacity of the samples was decreased in mortar samples containing bacterial cells, the nutrients were added in the curing solution. Fourier transform infrared spectroscopy and scanning electron microscopy analyses showed that calcite was the predominant polymorph of CaCO3 sealant in cracks.
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    Biomineralized cement-based materials: impact of inoculating vegetative bacterial cells on hydration and strength
    (Elsevier, 2015-01) Bundur, Zeynep Başaran; Kirisits, M. J.; Ferron, R. D.; Civil Engineering; BUNDUR, Zeynep Başaran
    Biomineralization in cement-based materials has become a point of interest in recent years due to the possibility that such an approach could be used to develop a self-healing cement-based system. The objective of this study was to investigate the impact of vegetative cells of Sporosarcina pasteurii on the hydration kinetics and compressive strength of cement-based materials. The hydration kinetics were greatly influenced when a bacterial solution consisting of urea-yeast extract nutrient medium and vegetative cells was used to prepare bacterial cement pastes; specifically, severe retardation was observed. In addition, an increase in calcium carbonate precipitation, particularly calcite, occurred within the bacterial pastes. Furthermore, after the first day of hydration, the bacterial mortar displayed compressive strength that was similar to or greater than the compressive strength of the neat mortar.
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    ReviewPublicationRestricted
    End-of-life materials used as supplementary cementitious materials in the concrete industry
    (MDPI, 2020-04) Nicoara, A. I.; Stoica, A. E.; Vrabec, M.; Rogan, N. S.; Sturm, S.; Ow-Yang, C.; Gulgun, M. A.; Bundur, Zeynep Başaran; Ciuca, I.; Vasile, B. S.; Civil Engineering; BUNDUR, Zeynep Başaran
    A sustainable solution for the global construction industry can be partial substitution of Ordinary Portland Cement (OPC) by use of supplementary cementitious materials (SCMs) sourced from industrial end-of-life (EOL) products that contain calcareous, siliceous and aluminous materials. Candidate EOL materials include fly ash (FA), silica fume (SF), natural pozzolanic materials like sugarcane bagasse ash (SBA), palm oil fuel ash (POFA), rice husk ash (RHA), mine tailings, marble dust, construction and demolition debris (CDD). Studies have revealed these materials to be cementitious and/or pozzolanic in nature. Their use as SCMs would decrease the amount of cement used in the production of concrete, decreasing carbon emissions associated with cement production. In addition to cement substitution, EOL products as SCMs have also served as coarse and also fine aggregates in the production of eco-friendly concretes.
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    ArticlePublicationMetadata only
    Impact of air entraining admixtures on biogenic calcium carbonate precipitation and bacterial viability
    (Elsevier, 2017) Bundur, Zeynep Başaran; Amiri, Ali; Ersan, Y. C.; Boon, N.; Belie, N. de; Civil Engineering; BUNDUR, Zeynep Başaran; Amiri, Ali
    The applications of self-healing in cement-based materials via biomineralization processes are developing quickly. The main challenge is to find a microorganism that can tolerate the restricted environment of cement paste matrix (i.e. very high pH, lack of oxygen and nutrients, small pore size etc.). The focus of this work was to determine the possible use of an ammonium salt-based air-entraining admixture (AEA) as a protection method to improve the survival of incorporated Sporosarcina pasteurii cells in cement-based mortar. Bacterial cells were directly added to the mortar mix with and without nutrients. Nutrients should be provided to keep the microorganisms viable even at early ages (i.e. 7 days). Surface charge of the bacterial cells and in vitro biogenic calcium carbonate (CaCO3) precipitation were not affected by the incorporation of AEA. However, introducing AEA did not influence the viability in mortar samples, which might be attributed to the type and chemistry of AEA used.
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    Conference paperPublicationOpen 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.
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    Influence of Sporasarcina pasteurii cells on rheological properties of cement paste
    (Elsevier, 2019-11-20) Azima, Mahzad; Bundur, Zeynep Başaran; Civil Engineering; BUNDUR, Zeynep Başaran; Azima, Mahzad
    Nowadays with the developments in the concrete materials technology, researches started to focus on highly flowable mixes with improved rheological properties. These highly flowable mixes generally require use of viscosity modifying agents (VMAs) to reduce bleeding and segregation. VMAs are water-soluble polymers that can be produced from acrylic polymers and polysaccharide-based biopolymers obtained from cellulose, starch or bacterial fermentation. Through the literature, nopal mucilage, brown algae and bacterial cell walls were proposed as alternatives to these bio-based admixtures. However, these alternatives also require extra processing which results again with a higher unit cost. This paper summarizes the rheological properties of a cement paste including bacterial cells. The main goal of this study was to investigate the influence of Sporasarcina pasteurii (S. pasteurii) cells on viscosity and yield stress of cement-based materials. The bacterial cells were directly incorporated to the mix water and influence of cells on viscosity and yield strength was evaluated by rheological tests. In addition, the influence of bacteria dosage, water to cement ratio (w/c), use of superplasticizers and fly ash on performance of biological VMA were investigated. Our results showed that the apparent viscosity and yield stress of the cement-paste mix were increased with the addition of the microorganisms. Moreover, the provided biological VMA was found to be compatible with the use of fly ash and superplasticizers depending on the w/c of cement paste.
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    ArticlePublicationMetadata only
    Calcium sulfoaluminate cement and supplementary cementitious materials-containing binders in self-healing systems
    (Elsevier, 2023-08) Acarturk, B. C.; Sandalcı, Ilgın; Hull, N. M.; Bundur, Zeynep Başaran; Burris, L. E.; Civil Engineering; BUNDUR, Zeynep Başaran; Sandalcı, Ilgın
    Creation of more durable concrete is one pathway to achieving improved sustainability and carbon footprint over a concrete structure's life. Microbially induced calcite precipitation has been shown to densify concrete microstructure and fill cracks, reducing moisture transport. One challenge associated with the longevity of bacterial-concrete systems is the high pH environment of the cement paste. Herein, two approaches to address this challenge were investigated: (i) sustainable binder systems, such as calcium sulfoaluminate (CSA) cement and fly ash substitutions of ordinary portland cement (OPC), which lead to lower pH systems, and (ii) non-axenic bacterial cultures, which may facilitate growth of more alkaline-resistant bacteria. Mechanical properties, water absorption, self-healing ability, and survivability of the bacterial systems were tracked, finding that incorporation of non-axenic bacteria did not result in increased bacteria survivability compared to axenic bacteria. However, both bacteria healed cracks [removed]
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    ArticlePublicationOpen 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.
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    Evaluation of self-healing of internal cracks in biomimetic mortar using coda wave interferometry
    (Elsevier, 2016-05) Liu, S.; Bundur, Zeynep Başaran; Zhu, J.; Ferron, R. D.; Civil Engineering; BUNDUR, Zeynep Başaran
    Calcium carbonate biomineralization is a bio-chemical process in which calcium carbonate precipitation is obtained by leveraging the metabolic activity of microorganisms. Studies have shown that biomineralization can be used to repair surface cracks in cement-based materials. One of the challenges in determining whether biomineralization is a feasible option for internal crack repair pertains to how to monitor and quantify self-healing of internal microcracks. In this study, mortar samples with and without microcracks and microorganisms were cured in different environments until 50 days. Coda wave interferometry measurements, a nondestructive method that is very sensitive to small changes in material, were conducted on these samples to evaluate the extent of self-healing during the entire curing period. Compressive strength tests were performed after 7 and 28 days of curing. The results indicated that the cracked mortar samples with microorganisms showed significantly higher strength development and higher relative velocity change than samples without microorganisms.