- Əhsən Bəyləri
احسن اله بگلری قلعهedit
Research Interests:
Storing healing agents in capsules is one of the most promising self-healing methods in cementitious materials. Because of the considerable advantage of microencapsulation, it has become more interested as compared to the other... more
Storing healing agents in capsules is one of the most promising self-healing methods in cementitious materials. Because of the considerable advantage of microencapsulation, it has become more interested as compared to the other encapsulation methods. The sodium silicate, which has many advantages as a healing agent in cementitious materials, can be encapsulated through the interfacial polymerization of shell-forming monomer on the aqueous sodium silicate droplets. This study, which is a part of comprehensive project, aimed to produce these microcapsules by optimization of the monomer. The microcap-sules were characterized by the yield, SEM, EDS, FTIR, TGA, and XRD analyses. In addition, the fracture behavior of the optimized microcapsule was examined in a cement paste matrix. It was observed that most of the microcapsules seem to be spherical shaped and free-flowing powder. Fracture behavior of optimized microcapsules revealed a sufficient shell-matrix interfacial bond strength which is essential for releasing healing agent into cracks.
Research Interests:
Bu çalışmada, iki farklı başlangıç ortamında bekletilmiş lif içeren ve içermeyen ultra yüksek performanslı beton (UYPB) karışımlarının erken yaş (ilk 24 saat) büzülme özellikleri incelenmiştir. Erken yaşta oldukça yüksek mertebelerde... more
Bu çalışmada, iki farklı başlangıç ortamında bekletilmiş lif içeren ve içermeyen ultra yüksek performanslı beton (UYPB) karışımlarının erken yaş (ilk 24 saat) büzülme özellikleri incelenmiştir. Erken yaşta oldukça yüksek mertebelerde büzülme gösteren karışımların kısıtlanmış halde bekletilmesi halinde oluşan çatlakların çelik donatının korozyon gelişimine etkisi deneysel olarak belirlenmiştir. Kısıtlanmış büzülme çatlaklarının çelik donatı korozyonu üzerinde bazı olumsuz etkiler yarattığı tespit edilmiştir. Ancak düşük su/bağlayıcı oranlı UYPB örneklerinin yüzeyinde çatlak oluşmasına rağmen, donatıyı korumada oldukça iyi performans gösterdiği görülmüştür. UYPB'nin en önemli özelliği, geçirimsiz yapısı nedeniyle sağladığı üstün durabilite (kalıcılık) özelliğidir. UYPB'nin kalıcılık özelliklerinin korunması için erken yaş çatlaklarının önlenmesi amacıyla gerekli önlemler alınmalıdır. Çalışma kapsamında yapılan analizler, uçucu kül ikamesinin ve mikro çelik lif takviyesinin çatlak oluşumunu azaltarak donatı korozyonuna karşı korumayı geliştirdiğini göstermiştir.
Research Interests:
Düşük çekme dayanımına sahip olan çimento esaslı kompozitlerin performansını etkileyen en önemli sorun, farklı sebeplerden dolayı oluşan mikro ve makro çatlaklardır. Çatlakların varlığı agresif sıvı ve gazların girişini kolaylaştırarak,... more
Düşük çekme dayanımına sahip olan çimento esaslı
kompozitlerin performansını etkileyen en önemli sorun,
farklı sebeplerden dolayı oluşan mikro ve makro
çatlaklardır. Çatlakların varlığı agresif sıvı ve gazların
girişini kolaylaştırarak, donatı korozyonu gibi bir çok
durabilite ve yapısal sorunlara yol açmaktadır. Çimento
esaslı yapı malzemelerinde oluşan çatlakların
onarımı yüksek maliyet ve işgücü gerektiren karmaşık
bir işlemdir. Trafiğin yoğun olduğu önemli betonarme
köprülerin, tünellerin, yeraltı yapılarının veya tehlikeli
maddelerin depolandığı yapıların ve diğer önemli
ve hassas yapıların onarımı oldukça zor ve bazen tehlikelidir.
Bir diğer önemli husus ise, çoğu durumda
çatlakların görünür veya erişilebilir olmamasıdır. Bu
bağlamda, son yıllarda kendi kendine iyileşme (KKİ)
yöntemleri üzerinde araştırmalar artmıştır. Farklı
pasif KKİ teknikleri sayesinde, insan müdahalesi olmadan,
daha düşük maliyet ile yapıların servis ömrü
uzatılabilmektedir. Erken yaşlarda reaksiyona girmeyen
çimento taneciklerinin hidratasyonu, C-S-H jelinin
genleşmesi veya Ca(OH)2 kristallerinin karbonatlaşması
gibi mekanizmalar, klasik betonlarda uzun
yıllardan beri otojen KKİ mekanizması olarak bilinmektedir.
Otojen KKİ mekanizmasının sadece çok
ince çatlakların iyileştirmesinde başarılı olduğu, uzun
yıllar devam eden bir mekanizma olmadığı, dış faktörlere
çok bağlı olduğu ve mekanik özelliklerin geri
kazanılmasında belirsizlikler olduğu araştırmacılar
tarafından ifade edilmektedir. Çimentolu malzemelerin
üretim esnasında KKİ amacıyla bilinçli bir şekilde
kullanılabilecek birçok yöntem ise araştırma-geliştirme
aşamasındadır. Çatlak genişliğini kısıtlamak,
mineral katkıların farklı kombinasyonlarda kullanımı,
genleşen katkıların ikamesi, farklı içsel kürleme
tekniklerini uygulamak, CaCO3 üreten bakterilerden
yararlanmak ve KKİ katkıların kapsüllenmesi gibi
yöntemler araştırılmaktadır.
kompozitlerin performansını etkileyen en önemli sorun,
farklı sebeplerden dolayı oluşan mikro ve makro
çatlaklardır. Çatlakların varlığı agresif sıvı ve gazların
girişini kolaylaştırarak, donatı korozyonu gibi bir çok
durabilite ve yapısal sorunlara yol açmaktadır. Çimento
esaslı yapı malzemelerinde oluşan çatlakların
onarımı yüksek maliyet ve işgücü gerektiren karmaşık
bir işlemdir. Trafiğin yoğun olduğu önemli betonarme
köprülerin, tünellerin, yeraltı yapılarının veya tehlikeli
maddelerin depolandığı yapıların ve diğer önemli
ve hassas yapıların onarımı oldukça zor ve bazen tehlikelidir.
Bir diğer önemli husus ise, çoğu durumda
çatlakların görünür veya erişilebilir olmamasıdır. Bu
bağlamda, son yıllarda kendi kendine iyileşme (KKİ)
yöntemleri üzerinde araştırmalar artmıştır. Farklı
pasif KKİ teknikleri sayesinde, insan müdahalesi olmadan,
daha düşük maliyet ile yapıların servis ömrü
uzatılabilmektedir. Erken yaşlarda reaksiyona girmeyen
çimento taneciklerinin hidratasyonu, C-S-H jelinin
genleşmesi veya Ca(OH)2 kristallerinin karbonatlaşması
gibi mekanizmalar, klasik betonlarda uzun
yıllardan beri otojen KKİ mekanizması olarak bilinmektedir.
Otojen KKİ mekanizmasının sadece çok
ince çatlakların iyileştirmesinde başarılı olduğu, uzun
yıllar devam eden bir mekanizma olmadığı, dış faktörlere
çok bağlı olduğu ve mekanik özelliklerin geri
kazanılmasında belirsizlikler olduğu araştırmacılar
tarafından ifade edilmektedir. Çimentolu malzemelerin
üretim esnasında KKİ amacıyla bilinçli bir şekilde
kullanılabilecek birçok yöntem ise araştırma-geliştirme
aşamasındadır. Çatlak genişliğini kısıtlamak,
mineral katkıların farklı kombinasyonlarda kullanımı,
genleşen katkıların ikamesi, farklı içsel kürleme
tekniklerini uygulamak, CaCO3 üreten bakterilerden
yararlanmak ve KKİ katkıların kapsüllenmesi gibi
yöntemler araştırılmaktadır.
Research Interests:
Fiber-matrix bond properties of alkali-activated slag cements (AASC)–based composites have not been studied comprehensively in literature. Within the scope of this study, the effects of AASC matrix phase composition and the silicate... more
Fiber-matrix bond properties of alkali-activated slag cements (AASC)–based composites have not been studied comprehensively in literature. Within the scope of this study, the effects of AASC matrix phase composition and the silicate modulus of activator solution on the pullout behavior of steel fiber were investigated under water-and steam-curing conditions. Test results showed that AASC have a superior bond strength compared to portland cement (PC). Bond strength of AASC mortars with a compressive strength greater than 18 MPa were found higher than that of PC mortar with a compressive strength of 55 MPa. When the compressive strength of AASCs is higher than 40 MPa, the bond strength of AASC exceeds the bond strength of PC mortars that have compressive strength of 120 MPa. Microstructural analysis revealed that the map cracking in the fiber-matrix transition zone, which was induced by high drying shrinkage of AASC, can be eliminated by incorporating pozzolans. Consequently, it is possible to produce much higher-performance fiber-reinforced composites by using AASC owing to its superior adherence to steel fiber.
Research Interests:
Deniz ortamında bulunan betonarme elemanlar değişik fiziksel ve kimyasal etkilere maruzdur. Bunlar arasında, sülfat etkisi, karbonik asit etkisi, beton içindeki kirecin yıkanarak uzaklaşması, klorür korozyonu, donma-çözülme, tuz... more
Deniz ortamında bulunan betonarme elemanlar değişik fiziksel ve kimyasal etkilere maruzdur. Bunlar arasında, sülfat etkisi, karbonik asit etkisi, beton içindeki kirecin yıkanarak uzaklaşması, klorür korozyonu, donma-çözülme, tuz kristalizasyonu, dalgaların ve yüzen parçacıkların aşındırıcı etkileri sayılabilir. Genel olarak en çok hasarın, ıslanma-kuruma bölgesinde bulunan elemanlarda oluştuğu söylenebilir. Tasarımda çimento tipi, bağlayıcı dozajı, su/bağlayıcı oranı, mineral katkı kullanımı gibi faktörlerin yanında pas payı kalınlığı gibi uygulama detayları dayanıklılık anlamında büyük önem arz eder. Deniz suyunda klorür ve
sülfat iyonlarından kaynaklanan karma bir etki söz konusu olduğu için, beton bir taraftan sülfat etkisinden dolayı tahrip olma riski taşırken diğer taraftan da klorür iyonlarının (betonarme sistemler için) donatıyı tahrip etme riski söz konusudur. Deniz ortamında hangi tip çimento kullanılmasının uygun olacağı konusunda tartışmalar mevcuttur. Klorür iyonlarını bağlama, dolayısıyla korozyon riskini azaltma kabiliyetinden dolayı C3A miktarının göreceli olarak daha yüksek olduğu çimento kullanılması uygun görünmesine rağmen, sülfat etkisine dirençli bir betonda C3A miktarının mümkün olduğunca az olması gerektiği bilinen bir gerçektir. Bu noktada baskın etkinin ne olduğuna karar vermek önem taşımaktadır. Bu çalışmada çimento tipi (CEM I 42.5R, CEM II 42.5R, CEM I-SR 5) başta olmak üzere, su/bağlayıcı oranı ve uçucu kül kullanımının betonun klorür işleme derinliği üzerindeki etkisi gerçek deniz ortamında bekletilen numuneler üzerinde incelenmiştir. Deney sonuçları söz konusu parametrelerin betonun geçirimliliği üzerinde önemli etkisi olduğunu göstermiştir.
sülfat iyonlarından kaynaklanan karma bir etki söz konusu olduğu için, beton bir taraftan sülfat etkisinden dolayı tahrip olma riski taşırken diğer taraftan da klorür iyonlarının (betonarme sistemler için) donatıyı tahrip etme riski söz konusudur. Deniz ortamında hangi tip çimento kullanılmasının uygun olacağı konusunda tartışmalar mevcuttur. Klorür iyonlarını bağlama, dolayısıyla korozyon riskini azaltma kabiliyetinden dolayı C3A miktarının göreceli olarak daha yüksek olduğu çimento kullanılması uygun görünmesine rağmen, sülfat etkisine dirençli bir betonda C3A miktarının mümkün olduğunca az olması gerektiği bilinen bir gerçektir. Bu noktada baskın etkinin ne olduğuna karar vermek önem taşımaktadır. Bu çalışmada çimento tipi (CEM I 42.5R, CEM II 42.5R, CEM I-SR 5) başta olmak üzere, su/bağlayıcı oranı ve uçucu kül kullanımının betonun klorür işleme derinliği üzerindeki etkisi gerçek deniz ortamında bekletilen numuneler üzerinde incelenmiştir. Deney sonuçları söz konusu parametrelerin betonun geçirimliliği üzerinde önemli etkisi olduğunu göstermiştir.
Research Interests:
In this study, the effects of recycled glass (RG) and recycled concrete (RC) fine aggregates on acid and sulfate resistance as well as alkali-silica reaction (ASR) expansion of mortar mixture were investigated comparatively. In addition,... more
In this study, the effects of recycled glass (RG) and recycled concrete (RC) fine aggregates on acid and sulfate resistance as well as alkali-silica reaction (ASR) expansion of mortar mixture were investigated comparatively. In addition, durability performance of mortar mixtures was supported by microstructural analysis. For this purpose, nine different mortar mixtures were prepared by replacing 25, 50, 75, and 100 wt% of crushed-limestone fine aggregate with recycled aggregates. Except for ASR and acid resistance, the sulfate resistance of mortar mixture improved by using RG aggregate. The performance of mortar in terms of ASR and acid sulfuric resistance increased by increasing RC aggregate replacement level. The ASR expansions in RG mixtures increased by increasing the RG aggregate content up to 100%. The RC mixtures containing more than 50% recycled aggregate, showed better performance than the control mixture in terms of sulfate resistance.
Research Interests:
Agregada bulunan amorf silis ve boşluk çözeltisindeki alkaliler arasında gerçekleşen alkalisilis reaksiyonu (ASR), hasarla sonuçlanan önemli durabilite sorunlarındandır. Bu çalışmada, çeşitli karışımların alkali-silis reaktiviteleri,... more
Agregada bulunan amorf silis ve boşluk çözeltisindeki alkaliler arasında gerçekleşen alkalisilis reaksiyonu (ASR), hasarla sonuçlanan önemli durabilite sorunlarındandır. Bu çalışmada, çeşitli karışımların alkali-silis reaktiviteleri, RILEM komitesi tarafından geliştirilen AAR-3 ve AAR-4 deneyleriyle araştırılmıştır. Bu hızlandırılmış deneylerde numunelerde yer alan alkalilerin ne kadarının dışarıya sızdığını belirlemek için kapların alt
kısmında yer alan sudan örnekler alınmış ve atomik absorpsiyon spektrometrisi ile sodyum ve potasyum iyonlarının konsantrasyonu belirlenmiştir. Sonuçlara göre alkalilerin önemli bir miktarının betonlardan dışarıya sızabildiği ve buna rağmen, özellikle atık cam agregası içeren karışımlarda halen çok yüksek miktarda genleşme ile karşılaşıldığı görülmüştür.
kısmında yer alan sudan örnekler alınmış ve atomik absorpsiyon spektrometrisi ile sodyum ve potasyum iyonlarının konsantrasyonu belirlenmiştir. Sonuçlara göre alkalilerin önemli bir miktarının betonlardan dışarıya sızabildiği ve buna rağmen, özellikle atık cam agregası içeren karışımlarda halen çok yüksek miktarda genleşme ile karşılaşıldığı görülmüştür.
Research Interests:
Steel fibers are commonly used in cement based materials for many applications such as floors, structural elements, repairing works, etc. The chloride-induced corrosion via ingress of seawater may become a risk for performance of the... more
Steel fibers are commonly used in cement based materials for many applications such as floors, structural elements, repairing works, etc. The chloride-induced corrosion via ingress of seawater may become a risk for performance of the steel fiber reinforced cement based composites. Despite of few studies that have dealt with the corrosion behavior of steel fibers embedded in cement based composites, there are lack of information about the chloride-induced corrosion of steel fibers embedded with sufficient cover in non-cracked matrixes, reactive powder concrete, and especially polymer-modified cement based mortars. The open-circuit potential and corrosion current density of single steel fibers embedded in various cement based matrices were monitored after 200, 400, 600, 1200 wetting-drying cycles in 3.5% NaCl solution. The corrosion and microstructure analyses revealed that the steel fibers can be protected by a well-designed mixture, non-cracked matrix and sufficient cover. However, it could be corroded in long terms depending on the type and the dosage of the polymer latex used. In addition, the residual stresses in the deformed regions of the hooked-end steel fibers is critical in terms of the protection against to chloride-induced corrosion.
Research Interests:
High temperature resistance is one of the most important parameters which affects the durability and service life of materials. Due to synergistic interaction of different mechanisms, mechanical performance can be lowered especially for... more
High temperature resistance is one of the most important parameters which affects the durability and
service life of materials. Due to synergistic interaction of different mechanisms, mechanical performance
can be lowered especially for the multi-component composite materials exposed to high temperature.
Standard or steam cured slurry infiltrated fiber concrete (SIFCON) and slurry specimens were subjected
to 300, 600, 750 and 900 C in the scope of present study. Exposing the specimens to 300 C enhanced the
mechanical performance, while higher temperatures have detrimental effects on the SIFCON composites
such as the loss in the cross section of steel fibers and the destruction of C–S–H structure. Mechanical test
results were in accordance with micro-structural and thermal analyses.
service life of materials. Due to synergistic interaction of different mechanisms, mechanical performance
can be lowered especially for the multi-component composite materials exposed to high temperature.
Standard or steam cured slurry infiltrated fiber concrete (SIFCON) and slurry specimens were subjected
to 300, 600, 750 and 900 C in the scope of present study. Exposing the specimens to 300 C enhanced the
mechanical performance, while higher temperatures have detrimental effects on the SIFCON composites
such as the loss in the cross section of steel fibers and the destruction of C–S–H structure. Mechanical test
results were in accordance with micro-structural and thermal analyses.
Research Interests:
In this study, the utilization of bottom ash as an aggregate in the production of lightweight building blocks was investigated. Pumice aggregate which was used in lightweight control mixture replaced by the bottom ash aggregate and on the... more
In this study, the utilization of bottom ash as an aggregate in the production of lightweight building blocks was investigated. Pumice aggregate which was used in lightweight control mixture replaced by the bottom ash aggregate and on the other hand, cement replaced by high volume fly ash. Physical and mechanical properties of mixtures were determined after different curing regimes (standard water, in air, in oven, steam and autoclave curing) and in addition, water resistance of the mixtures was also determined. After that, microstructure of the specimens was investigated by using the scanning electron microscopy. Then, the thermal conductivity of the mixtures containing pumice and bottom ash was compared. Finally, in order to produce construction elements, prototypes of lightweight building blocks were manufactured. After these very procedures, it concludes that bottom ash is a good alternative for pumice aggregate in producing lightweight building blocks.
Research Interests:
The type and amount of filler are amongst the most important parameters influencing rheological, mechanical and durability characteristics of self consolidating concrete (SCC). Influence of using a limestone powder, the filler portion of... more
The type and amount of filler are amongst the most important parameters influencing rheological, mechanical and durability characteristics of self consolidating concrete (SCC). Influence of using a limestone powder, the filler portion of reactive basalt filler and a type of class C fly ash on the fresh properties, alkali–silica reactivity and transport properties were investigated in this study. For this purpose, six SCC mixtures having three filler types and two water/powder ratios were prepared. Alkali–silica reactivity was evaluated by conducting RILEM AAR-3 (38 °C) and AAR-4 (60 °C) concrete prism tests. Besides, the mixtures were exposed to permeable void content, sorptivity and chloride ion permeability tests in order to evaluate the transport properties. According to the results, using a high amount of powder from a reactive basalt in SCC mixture led to the highest expansion level and poor transport properties.
Research Interests:
The effect of ASR on fiber–matrix bond behavior has been investigated in this research. The potentially reactive basaltic aggregate was chosen as a reactive material. Two series of specimens containing different amounts of supplementary... more
The effect of ASR on fiber–matrix bond behavior has been investigated in this research. The potentially
reactive basaltic aggregate was chosen as a reactive material. Two series of specimens containing different
amounts of supplementary cementing materials (SCMs) were prepared. One of them was cured in 1 M
NaOH solution at 80 C, other series were cured in 80 C water up to 150 days to obtain similar maturity.
ASR expansion, single fiber pull-out load, debonding toughness, flexural and compressive strength was
determined. Test results indicate that the ASR gel congestion in fiber–matrix interface increased the bond
strength significantly during alkali exposure. Furthermore, SCMs are effective to reduce ASR expansion
and to prevent the mechanical properties loss due to ASR. Micro-structural investigations revealed the
reaction products having different morphology (fibrous, rosette type, network appearance, etc.) in alkali
exposed specimens.
reactive basaltic aggregate was chosen as a reactive material. Two series of specimens containing different
amounts of supplementary cementing materials (SCMs) were prepared. One of them was cured in 1 M
NaOH solution at 80 C, other series were cured in 80 C water up to 150 days to obtain similar maturity.
ASR expansion, single fiber pull-out load, debonding toughness, flexural and compressive strength was
determined. Test results indicate that the ASR gel congestion in fiber–matrix interface increased the bond
strength significantly during alkali exposure. Furthermore, SCMs are effective to reduce ASR expansion
and to prevent the mechanical properties loss due to ASR. Micro-structural investigations revealed the
reaction products having different morphology (fibrous, rosette type, network appearance, etc.) in alkali
exposed specimens.
Research Interests:
The effect of combining brass-coated steel microfiber and ground-granulated blast-furnace slag (GGBS) on the mitigation of deleterious expansion due to alkali-silica reaction (ASR) was investigated in this research. A potentially reactive... more
The effect of combining brass-coated steel microfiber and ground-granulated blast-furnace slag (GGBS) on the mitigation of deleterious expansion due to alkali-silica reaction (ASR) was investigated in this research. A potentially reactive basaltic aggregate was
chosen as a reactive material. Two series of specimens containing different amounts of microfiber were prepared. One of them was cured in 1 M NaOH solution at 80°C to obtain a similar maturity; the other series was cured in 80°C water up to 120 days. ASR expansion, strength
development, and toughness properties were observed for 120 days in NaOH solution and the results were compared with specimens kept in water. Test results indicate that the combination of GGBS and steel fibers reduced ASR expansion significantly. Furthermore, the combination
was very effective at preventing the mechanical property loss due to ASR, such as flexural strength, compressive strength, and toughness. Microstructural investigations revealed that the reaction products had a different morphology (e.g., fibrous, network appearance) when the specimens were kept in NaOH solution
chosen as a reactive material. Two series of specimens containing different amounts of microfiber were prepared. One of them was cured in 1 M NaOH solution at 80°C to obtain a similar maturity; the other series was cured in 80°C water up to 120 days. ASR expansion, strength
development, and toughness properties were observed for 120 days in NaOH solution and the results were compared with specimens kept in water. Test results indicate that the combination of GGBS and steel fibers reduced ASR expansion significantly. Furthermore, the combination
was very effective at preventing the mechanical property loss due to ASR, such as flexural strength, compressive strength, and toughness. Microstructural investigations revealed that the reaction products had a different morphology (e.g., fibrous, network appearance) when the specimens were kept in NaOH solution
Research Interests: Materials Science, Microstructure, Composite Materials, Concrete Technology, Cement, and 5 moreSEM microscopy, Fiber Steel Reinforced Concrete, Cement and Concrete Materials, Utilization of Cementitious Industrial Waste Products (Slag, and Utilization of cementitious industrial waste products (slag, fly ash, silica fume) and natural pozzolans
The aim of this research is to investigate some of the factors which affect the steel fiber–matrix bond characteristics by means of pull-out test. Ordinary mortar (OM) and reactive powder concrete (RPC) were used as main matrices. The... more
The aim of this research is to investigate some of the factors which affect the steel fiber–matrix bond
characteristics by means of pull-out test. Ordinary mortar (OM) and reactive powder concrete (RPC) were
used as main matrices. The effect of parameters such as end condition of fiber (smooth or hooked-end),
embedment length, water/binder ratio, paste phase of RPC, steel-micro fiber, and curing conditions on
fiber–matrix pull-out behavior were determined. The fiber–matrix bond characteristics improved as
the embedment length of fiber increased, especially for smooth fiber. Low W/C ratio, which enhances
the bond strength, reduces the importance of embedment length of the hooked-end fiber. Furthermore,
the pull-out peak load and debonding toughness increased as the W/C ratio decreased in the all curing
conditions. Microstructural investigation revealed that the congestion of hydration products in
fiber–matrix interface improves pull-out behavior remarkably.
characteristics by means of pull-out test. Ordinary mortar (OM) and reactive powder concrete (RPC) were
used as main matrices. The effect of parameters such as end condition of fiber (smooth or hooked-end),
embedment length, water/binder ratio, paste phase of RPC, steel-micro fiber, and curing conditions on
fiber–matrix pull-out behavior were determined. The fiber–matrix bond characteristics improved as
the embedment length of fiber increased, especially for smooth fiber. Low W/C ratio, which enhances
the bond strength, reduces the importance of embedment length of the hooked-end fiber. Furthermore,
the pull-out peak load and debonding toughness increased as the W/C ratio decreased in the all curing
conditions. Microstructural investigation revealed that the congestion of hydration products in
fiber–matrix interface improves pull-out behavior remarkably.
Research Interests:
Reactive Powder Concrete (RPC) is a type of ultra-high performance cement based composite with high strength and ductility. RPC was developed in the 1990s by Bouygues' laboratory in France. It is a special type of concrete which has... more
Reactive Powder Concrete (RPC) is a type of ultra-high performance cement based composite with high strength and ductility. RPC was developed in the 1990s by Bouygues' laboratory in France. It is a special type of concrete which has properly optimized micro grain, binder phase and steel micro-fibers. RPC can achieve compressive strength values between 150–800 MPa, while traditional concrete which is used in current structures usually has 20–50 MPa compressive strength. In addition, its high performance under flexural loads is the most important advantage of RPC in the field of civil engineering. RPC has the potential to compete with steel from the point of aesthetics and structural capability. One of the curing methods to enhance the strength of this composite material is autoclaving. Autoclave curing needs additional SiO2 source to fill micro pores and strengthen hydration products. In the scope of this study, the effect of volume fraction of steel micro-fibers and silica fume dosage as SiO2 source on mechanical properties of RPC under autoclave curing was investigated. High performance cementitious composites were produced with 0%, 1%, and 2% volume fractions of steel micro-fibers. Nine mixtures with three different silica fume dosages were produced. Workability of fresh state and flexural-compressive strengths of hardened specimens were determined. In addition, fracture energies of the mixtures under bending loads were evaluated.
Research Interests:
SIFCON (Slurry Infiltrated Fiber Concrete) can be described as a special type of cement based composite produced with fiber volume fraction values between 5 to 30%. As a result of superior mechanical properties such as compressive,... more
SIFCON (Slurry Infiltrated Fiber Concrete) can be described as a special type of cement based composite produced with fiber volume fraction values between 5 to 30%. As a result of superior mechanical properties such as compressive, tensile, shear and flexural strengths with extraordinary toughness values, SIFCON can be used in in industrial floors, repair and reinforcement works and military applications such as anti-missile hangers. Mechanical properties of fiber reinforced cement based composites are dramatically influenced by steel fiber–matrix bond characteristics. Many parameters such as fiber type and geometry, matrix strength, curing conditions and properties of fiber-matrix interface affect the fiber-matrix bond characteristics. The density of this zone can be increased with supplementary cementitious materials such as metakaolin. In this study the effect of metakaolin and end type of steel fiber on bond characteristics has been investigated. The fiber-matrix bond characteristics were determined by applying single-fiber pull-out test. Utilization of metakaolin has improved the compressive strength and fiber-matrix bond characteristics. In addition, hooked-end fiber has a better performance compared to the smooth fiber.
Research Interests:
Reactive Powder Concrete (RPC) is characterized by high cementitious material content, very low water to cement ratio and steel micro-fiber reinforcement. This type of cementitious composite has greater ductility, durability and... more
Reactive Powder Concrete (RPC) is characterized by high cementitious material content, very low water to cement ratio and steel micro-fiber reinforcement. This type of cementitious composite has greater ductility, durability and mechanical properties compared to traditional concrete. Abrasion resistance of the composite material is still not well understood, although it has a variety of applications, including bridge deck construction and floor covering. In the scope of this study, three water-to-cement ratios and various micro-fiber volume fractions were investigated. Mechanical properties under steam curing were determined. Cubic specimens with a 71 mm side were prepared for the surface abrasion test by means of Böhme apparatus. In addition, the flexural toughness and Charpy impact tests were performed on unnotched prismatic specimens. A relationship between loss of mass by the Böhme abrasion test and mechanical properties was investigated. Test results indicated that abrasion resistance and mechanical properties can be improved by incorporating steel micro-fiber. The positive effect of fibers can be enhanced by reducing W/C ratio. It seems that RPC has a great potential to use in civil engineering structures subjected to abrasion.
Research Interests:
In this study, it was aimed to produce a four-person lightweight concrete canoe to participate in the National Intercollegiate Concrete Canoe Competition organized by Istanbul Technical University. Concrete canoe competition is a... more
In this study, it was aimed to produce a four-person lightweight concrete canoe to participate in the National Intercollegiate Concrete Canoe Competition organized by Istanbul Technical University. Concrete canoe competition is a prestigious activity held regularly in the USA since 1988 by ASCE, mainly aimed at sharing knowledge among civil engineering students. For this purpose, two lightweight concrete mixtures with a hardened unit weight lower than 1000 kg/m 3 were designed. Despite of such a low hardened unit weight, they have 13 MPa and 18 MPa compressive strength with excellent bond properties with basalt mesh reinforcement. A nonlinear finite element model for concrete canoe was generated to determine the moment capacity in such a way that four rowers could row at the same time, taking into account the competition rules.
Research Interests:
Self-healing approaches in cementitious materials are enhancing day by day. Microencapsulation of a healing agent is one of the most promising self-healing methods. In the event of any crack occurrence, the microcapsule breaks and the... more
Self-healing approaches in cementitious materials are enhancing day by day. Microencapsulation of a healing agent is one of the most promising self-healing methods. In the event of any crack occurrence, the microcapsule breaks and the healing agent release into the crack. The sodium silicate, which has many advantages as a self-healing agent in cementitious materials, can be encapsulated via the interfacial polymerization of shell-forming monomer on the aqueous sodium silicate droplets. In previous study, aqueous sodium silicate (SS) micro droplets dispersed in toluene and coated with different amount of shell-forming monomer by using interfacial polymerization method. In this study, the healing agent was optimized by changing the SS and water portions. SEM and microencapsulation efficiency (yield) analyses showed that 50% is the optimum SS and water ratio.
Research Interests:
Reinforced concrete elements in marine environment are exposed to various physical and chemical influences. In general, it can be stated that the elements in the wetting-drying regions are exposed to highest rate of damage. Since there is... more
Reinforced concrete elements in marine environment are exposed to various physical and chemical influences. In general, it can be stated that the elements in the wetting-drying regions are exposed to highest rate of damage. Since there is a combined effect generated by chloride and sulphate ions in sea water, the concrete while on one hand bears the risk of destruction due to sulphate effect, on the other hand there is a risk for the reinforcement to be corroded by chloride (for reinforced concrete systems) ions as well. There are discussions on which type of cement would be the best for use in marine environment. Although it seems that use of cement type with relatively high amount of C3A would be more suitable due to its capability of binding chloride ions and therefore to reduce the risk of corrosion, it is a known fact that a concrete with resistance to sulphate effect should have as low C3A content as possible. In this study, the effects of cement type (CEM I 42.5R, CEM II 42.5R, CEM I-SR 5), water/binder ratio and use of fly ash on the chloride penetration depth of concrete were investigated on samples kept in actual marine environment. The results of the experiments revealed that the given parameters have remarkable effects on permeability of the concrete.
Research Interests:
The mechanical performance and durability of steel fiber reinforced concrete have been investigated by many researchers. However, the durability problems which affect the fiber-matrix bond characteristics have not been investigated... more
The mechanical performance and durability of steel fiber reinforced concrete have been investigated by many researchers. However, the durability problems which affect the fiber-matrix bond characteristics have not been investigated extensively. The corrosion via ingress of sea water which includes chloride ions may become a risk in terms of the steel fiber-matrix bond. If the fiber-matrix bond was affected negatively by the corrosion of steel fiber, the ductility of composite would be affected negatively either. Due to the fact that corrosion is the biggest weakness of steel, special precautions must be taken. In this study, an ultra-high performance concrete which had a compressive strength higher than 100 MPa and a traditional mortar were used as the cementitious mixtures. The steel fiber-matrix bond characteristics were investigated before and after wetting-drying cycles. After specific wetting-drying cycles, the corrosion development of embedded fibers was monitored by polarization technique. After corrosion tests the specimens were subjected to pull-out test.
Research Interests:
Deniz suyu etkisine maruz betonarme yapılar önemli durabilite problemleri ile karşı karşıya kalmaktadır. Betonun bozulma sürecinin ve betonarme donatısının korozyon sürecinin doğru değerlendirilmesi deniz yapılarının servis ömrü açısından... more
Deniz suyu etkisine maruz betonarme yapılar önemli durabilite problemleri ile karşı karşıya kalmaktadır. Betonun bozulma sürecinin ve betonarme donatısının korozyon sürecinin doğru değerlendirilmesi deniz yapılarının servis ömrü açısından büyük önem arz etmektedir. Bu çalışma kapsamında, CEM I çimentosu ile üretilmiş ve çimento miktarının %20 oranında uçucu kül ikamesi ile hazırlanmış iki farklı C25/30 sınıfı beton karışımının özel bir platforma yerleştirerek deniz ortamındaki performansı incelenmiştir. Test sonuçları, uçucu kül kullanımının betonun elektriksel direnç değerlerini belirgin bir şekilde arttırdığını ve klor geçirimlilik değerlerini belirgin şekilde azalttığını göstermiştir. Islanma-kuruma çevrimleri sonunda eğilme ve basınç dayanımlarının hala ıslanma-kuruma çevrimleri öncesi dayanım değerlerinden büyük olduğu tespit edilmiştir. Paspayı küçük olan örneklerde donatı korozyonu hasarlarının oluştuğu, uçucu kül içeren betonlardaki donatıların korozyon akım yoğunluğu değerlerinin düşük mertebelerde kaldığı tespit edilmiştir.
Research Interests:
Reinforced concrete elements in marine environment are exposed to various physical and chemical influences. In general, it can be stated that the elements in the wetting-drying regions are exposed to highest rate of damage. Since there is... more
Reinforced concrete elements in marine environment are exposed to various physical and chemical influences. In general, it can be stated that the elements in the wetting-drying regions are exposed to highest rate of damage. Since there is a combined effect generated by chloride and sulphate ions in sea water, the concrete while on one hand bears the risk of destruction due to sulphate effect, on the other hand there is a risk for the reinforcement to be corroded by chloride (for reinforced concrete systems) ions as well.
There are discussions on which type of cement would be the best for use in marine environment. Although it seems that use of cement type with relatively high amount of C3A would be more suitable due to its capability of binding chloride ions and therefore to reduce the risk of corrosion, it is a known fact that a concrete with resistance to sulphate effect should have as low C3A content as possible.
In this study, the effects of cement type (CEM I 42.5R, CEM II 42.5R, CEM I-SR 5), water/binder ratio and use of fly ash on the chloride penetration depth of concrete were investigated on samples kept in actual marine environment. The results of the experiments revealed that the given parameters have remarkable effects on permeability of the concrete.
There are discussions on which type of cement would be the best for use in marine environment. Although it seems that use of cement type with relatively high amount of C3A would be more suitable due to its capability of binding chloride ions and therefore to reduce the risk of corrosion, it is a known fact that a concrete with resistance to sulphate effect should have as low C3A content as possible.
In this study, the effects of cement type (CEM I 42.5R, CEM II 42.5R, CEM I-SR 5), water/binder ratio and use of fly ash on the chloride penetration depth of concrete were investigated on samples kept in actual marine environment. The results of the experiments revealed that the given parameters have remarkable effects on permeability of the concrete.
Research Interests:
In this study the effects of recycled glass and recycled concrete fine aggregates on the compressive strength, water absorption, chloride-ion penetration, freeze-thaw and sulfate resistance as well as ASR expansion of mortar mixtures were... more
In this study the effects of recycled glass and recycled concrete fine aggregates on the compressive
strength, water absorption, chloride-ion penetration, freeze-thaw and sulfate resistance as well as ASR
expansion of mortar mixtures were investigated comparatively. For this purpose, 9 different mortar
mixtures were prepared by replacing 25, 50, 75 and 100 wt% of crushed-limestone fine aggregate with
recycled aggregates. Test results demonstrated that, compared to the control mixture, compressive
strength of the mortar mixture decreased with increasing the recycled aggregate replacement level. The
transport properties of recycled concrete aggregate-containing mixture were lower than those of the other
two series. Frost resistance of mortar mixture improved by using both of the recycled aggregates. ASR
expansion increased with increasing recycled glass aggregate replacement level. Mortar mixtures
containing more than 50% recycled concrete aggregate showed higher sulfate resistance than the control
mixture. This was attributed to the accumulation of ettringite in pores of the RC aggregate resulting in
lower expansion.
strength, water absorption, chloride-ion penetration, freeze-thaw and sulfate resistance as well as ASR
expansion of mortar mixtures were investigated comparatively. For this purpose, 9 different mortar
mixtures were prepared by replacing 25, 50, 75 and 100 wt% of crushed-limestone fine aggregate with
recycled aggregates. Test results demonstrated that, compared to the control mixture, compressive
strength of the mortar mixture decreased with increasing the recycled aggregate replacement level. The
transport properties of recycled concrete aggregate-containing mixture were lower than those of the other
two series. Frost resistance of mortar mixture improved by using both of the recycled aggregates. ASR
expansion increased with increasing recycled glass aggregate replacement level. Mortar mixtures
containing more than 50% recycled concrete aggregate showed higher sulfate resistance than the control
mixture. This was attributed to the accumulation of ettringite in pores of the RC aggregate resulting in
lower expansion.
Research Interests:
Lif-matris aderansı çimento esaslı lifli kompozitlerin performansını etkileyen en önemli faktörlerden biridir. Lif türü ve geometrisi, matris dayanımı, lif-matris arayüzey özellikleri ve kür koşulları gibi birçok parametre lif-matris... more
Lif-matris aderansı çimento esaslı lifli kompozitlerin performansını etkileyen en önemli faktörlerden biridir. Lif türü ve geometrisi, matris dayanımı, lif-matris arayüzey özellikleri ve kür koşulları gibi birçok parametre lif-matris aderansını etkilemektedir. Çalışma kapsamında çeşitli su/bağlayıcı oranına sahip karışımlar tasarlanmış ve farklı kür yöntemleri uygulanarak, lif-matris aderansları çekip-çıkarma deneyi ile incelenmiştir. Otoklav kürü sonrası çarpıcı aderans artışları içyapı analizleri ile açıklanabilmiştir. Ayrıca su/bağlaycı oranının önemi kapsamlı olarak irdelenmiştir.
Research Interests:
Alkali-silica reaction (ASR) which takes place between amorphous silica in the aggregate and alkali pore fluids in the concrete is one of the durability problems causing expansion and deterioration. In this study, alkali-silica reactivity... more
Alkali-silica reaction (ASR) which takes place between amorphous silica in the aggregate and alkali pore fluids in the concrete is one of the durability problems causing expansion and deterioration. In this study, alkali-silica reactivity of different mixtures was evaluated according to AAR-3 and AAR-4 tests developed by RILEM. In both tests, specimens were kept over water in sealed containers. Throughout AAR-3 tests containers were stored in a walk-in chamber maintained at 38°C and in AAR-4 test, containers were stored within a reactor generating 60°C. The total exposure durations in AAR-3 and AAR-4 were 1 year and 20 weeks, respectively. One of the challenges in determining the exact expansion level in these accelerated tests is the alkali leaching from the concrete specimen. For determining the reduction in the alkali content of the mixtures, samples were taken from the water existing at the bottom of the containers. At the same time with periodic expansion measurements, sodium and potassium concentrations in water samples were determined using atomic absorption spectrometry. According to the results, although a significant proportion of alkalis can leach out from concrete during the tests, particularly waste glass aggregate still shows a very high reactivity leading to a significant expansion.
Research Interests:
Durability aspects are significant concern for cement based materials. The pore structure of concrete is one of the most important factors which affect the interaction of concrete and aggressive environment. There are well-known and... more
Durability aspects are significant concern for cement based materials. The pore structure of concrete is one of the most important factors which affect the interaction of concrete and aggressive environment. There are well-known and accepted permeability tests to characterize the pore structure of concrete. The correlations between non-destructive Torrent air permeability test, capillary suction, rapid chloride ion permeability, electrical resistivity and ultrasonic pulse velocity test methods were examined in the scope of this research. For this propose two different concrete class (C25/30 and C40/50) were prepared. In addition fly ash replacement (15% and 30% by cement weight) also investigated. The results allow establishing meaningful correlations of above-mentioned test.
Research Interests:
Slurry infiltrated fiber concrete (SIFCON) is a special type high performance composite material which includes 5-30% steel fiber volume. Its superior toughness property indicates the potential of using SIFCON in industrial floors,... more
Slurry infiltrated fiber concrete (SIFCON) is a special type high performance composite material which includes 5-30% steel fiber volume. Its superior toughness property indicates the potential of using SIFCON in industrial floors, strengthening works, explosion resistant military structures, and seismic resistant structures. Since fiber-reinforced composites (FRCs) resists the tensile forces as a composite material by its fiber and matrix phases, the fiber-matrix bond affects force transmission between them. Mechanical properties of FRCs are dramatically influenced by steel fiber–matrix bond characteristics. The aim of this research is to investigate the correlations between single fiber pull-out and direct tension tests in SIFCON composites. For this propose, the effect of ground granulated blast-furnace slag replacement ratio and water to binder ratio on steel fiber-SIFCON matrix bond characteristics and tensile performance of SIFCON were investigated. The results obtained from single fiber pull-out test and direct tension test were analyzed.
Research Interests:
Self-Compacting Mortar (SCM) is a relatively new repair material. This type of mortar may be preferred for narrow sections of reinforced concrete structures due to lack of coarse aggregate and its self-compacting behavior. However, it... more
Self-Compacting Mortar (SCM) is a relatively new repair material. This type of mortar may be preferred for narrow sections of reinforced concrete structures due to lack of coarse aggregate and its self-compacting behavior. However, it needs higher cementitious and fine materials to enhance segregation resistance. Marble powder (MP) as an industrial solid waste can be utilized in concrete products. The main goal of this study is to demonstrate the possibility of using waste marble powder as a substitute rather than crushed aggregates in SCM production. For this purpose, crushed limestone sand was replaced with MP up to 30%. Mini slump-flow and V-funnel experiments were performed at fresh state. Moreover, rheology of mixtures has been investigated. Compressive and flexural strengths were determined under standard and steam curing conditions. Results showed that MP can be used up to 20% volume of fine aggregate without remarkable workability loss. Moreover, mechanical properties were not significantly affected by MP substitution. In addition, water curing provided higher strengths compared to steam curing.
Research Interests:
Research Interests:
Ultra yüksek performanslı beton (UYPB), üstün mekanik özelliklere ve kalıcılık performansına sahip yeni nesil çimento esaslı bir kompozittir. Düşük su/çimento oranı ve yüksek sıkışma yoğunluğu ihtiyacı, uygun işlenebilirliğe erişmek için... more
Ultra yüksek performanslı beton (UYPB), üstün mekanik özelliklere ve kalıcılık performansına sahip yeni nesil çimento esaslı bir kompozittir. Düşük su/çimento oranı ve yüksek sıkışma yoğunluğu ihtiyacı, uygun işlenebilirliğe erişmek için yüksek oranda akışkanlaştırıcı katkı kullanımını gerektirmektedir. Bağlayıcıların karışım içerisinde yeni nesil süper akışkanlaştırıcılar sayesinde çok iyi dağılması ve hızlı hidratasyonu kompozit malzemede büzülme kaynaklı erken yaş çatlama riskini arttırabilmektedir. Çalışma kapsamında akışkanlaştırıcı katkı dozajının ve ortam sıcaklığının UYPB’nin erken yaşta basınç dayanımı gelişimine ve lineer otojen deformasyonuna etkisi araştırılmıştır. Erken yaşta daha sıcak ortamda bekletilen numunelerin uzun dönemli dayanımlarının düştüğü saptanmıştır. Düşüş, düşük katkı dozajında daha belirgindir. Katkı içeriğindeki artış ve sıcaklık artışı erken yaşta kaydedilen maksimum otojen deformasyon değerini önemli ölçüde arttırmamış, çatlak riski açısından kritik olan büzülme hızını ise arttırmıştır.
Research Interests:
Research Interests:
Reaktif pudra betonu, çok yüksek dayanım ve sünekliğe sahip yüksek performanslı çimentolu bir kompozittir. 1990’lı yıllarda Fransa’nın Bouygues Laboratuarı’nda geliştirilmiştir. Mikro tanelerin, bağlayıcı fazının ve kısa kesilmiş çelik... more
Reaktif pudra betonu, çok yüksek dayanım ve sünekliğe sahip yüksek performanslı
çimentolu bir kompozittir. 1990’lı yıllarda Fransa’nın Bouygues Laboratuarı’nda
geliştirilmiştir. Mikro tanelerin, bağlayıcı fazının ve kısa kesilmiş çelik liflerin iyi şekilde
optimize edildiği özel bir beton türüdür. Günümüz yapılarında kullanılan geleneksel
betonlar 20 – 50 MPa basınç dayanımına sahipken, RPB 150 – 800 MPa basınç
dayanımına erişebilmektedir. Bunun yanı sıra, inşaat mühendisliğine getirdiği en önemli
avantaj eğilme yükleri altında yüksek performansa sahip olmasıdır. Estetik ve yapısal
açıdan çelik malzemesine rakip olabilecek niteliklere sahiptir. Bu kompozit malzemenin
mukavemetini geliştirmede kullanılan kür yöntemlerinden birisi otoklav kürüdür. Otoklav
küründe, hidratasyon ürünlerini güçlendirmek ve mikro boşlukları doldurmak için SiO2
kaynağına gereksinim vardır. Çalışma kapsamında, mikro çelik lif hacminin ve SiO2
kaynağı olan silis dumanı dozajının RPB’nin otoklav kürü altındaki mekanik özelliklerine
etkisi araştırılmıştır. Yüksek performanslı çimentolu kompozitin üretiminde hacimce %0,
%1 ve %2 mikro çelik lif kullanılmıştır. İki farklı oranda silika dumanı içeren 6 karışım
üretilmiştir. Taze halde işlenebilirlik, sertleşmiş halde ise basınç ve eğilme dayanımları
belirlenmiştir. Ayrıca eğilme yüklemesi altında kırılma enerjileri araştırılmıştır.
çimentolu bir kompozittir. 1990’lı yıllarda Fransa’nın Bouygues Laboratuarı’nda
geliştirilmiştir. Mikro tanelerin, bağlayıcı fazının ve kısa kesilmiş çelik liflerin iyi şekilde
optimize edildiği özel bir beton türüdür. Günümüz yapılarında kullanılan geleneksel
betonlar 20 – 50 MPa basınç dayanımına sahipken, RPB 150 – 800 MPa basınç
dayanımına erişebilmektedir. Bunun yanı sıra, inşaat mühendisliğine getirdiği en önemli
avantaj eğilme yükleri altında yüksek performansa sahip olmasıdır. Estetik ve yapısal
açıdan çelik malzemesine rakip olabilecek niteliklere sahiptir. Bu kompozit malzemenin
mukavemetini geliştirmede kullanılan kür yöntemlerinden birisi otoklav kürüdür. Otoklav
küründe, hidratasyon ürünlerini güçlendirmek ve mikro boşlukları doldurmak için SiO2
kaynağına gereksinim vardır. Çalışma kapsamında, mikro çelik lif hacminin ve SiO2
kaynağı olan silis dumanı dozajının RPB’nin otoklav kürü altındaki mekanik özelliklerine
etkisi araştırılmıştır. Yüksek performanslı çimentolu kompozitin üretiminde hacimce %0,
%1 ve %2 mikro çelik lif kullanılmıştır. İki farklı oranda silika dumanı içeren 6 karışım
üretilmiştir. Taze halde işlenebilirlik, sertleşmiş halde ise basınç ve eğilme dayanımları
belirlenmiştir. Ayrıca eğilme yüklemesi altında kırılma enerjileri araştırılmıştır.
Research Interests:
SIFCON (Slurry Infiltrated Fiber Concrete) hacimce %5-30 oranında lif içeren çok yüksek sünekliğe, enerji yutma kapasitesine, eğilme ve çekme dayanımına sahip bir kompozittir. Yüksek performansı sayesinde endüstriyel zeminlerde,... more
SIFCON (Slurry Infiltrated Fiber Concrete) hacimce %5-30 oranında lif içeren çok yüksek
sünekliğe, enerji yutma kapasitesine, eğilme ve çekme dayanımına sahip bir kompozittir.
Yüksek performansı sayesinde endüstriyel zeminlerde, güçlendirme işlerinde, patlamaya
ve rokete dirençli askeri yapılarda kullanılabilmektedir. Çimento esaslı lifli kompozitlerde
lif-matris aderansı kompozitin performansı etkileyen en önemli faktörlerden biridir. Lifmatris
aderansı, lif türü ve geometrisi, matris dayanımı, kür köşulları ve lif-matris arayüzey
özellikleri gibi bir çok faktörden etkilenmektedir. Lif-matris arayüzeyini iyileştirmek
amacıyla metakaolin gibi mineral katkılar kullanılmaktadır. Bu çalışmada, metakaolin
ikame oranının, çelik lifin kancalı ve kancasız durumunun lif-matris aderansı özelliklerine
etkisi araştırılmıştır. Lif-matris aderansı özellikleri, tek lif çekip-çıkarma deneyi ile
belirlenmiştir. Metakaolin ikamesi ile basınç dayanımı ve aderans özelliklerinde iyileşme
sağlanmıştır. Ayrıca kanca uçlu lifin daha üstün bir performans sergilediği belirlenmiştir.
sünekliğe, enerji yutma kapasitesine, eğilme ve çekme dayanımına sahip bir kompozittir.
Yüksek performansı sayesinde endüstriyel zeminlerde, güçlendirme işlerinde, patlamaya
ve rokete dirençli askeri yapılarda kullanılabilmektedir. Çimento esaslı lifli kompozitlerde
lif-matris aderansı kompozitin performansı etkileyen en önemli faktörlerden biridir. Lifmatris
aderansı, lif türü ve geometrisi, matris dayanımı, kür köşulları ve lif-matris arayüzey
özellikleri gibi bir çok faktörden etkilenmektedir. Lif-matris arayüzeyini iyileştirmek
amacıyla metakaolin gibi mineral katkılar kullanılmaktadır. Bu çalışmada, metakaolin
ikame oranının, çelik lifin kancalı ve kancasız durumunun lif-matris aderansı özelliklerine
etkisi araştırılmıştır. Lif-matris aderansı özellikleri, tek lif çekip-çıkarma deneyi ile
belirlenmiştir. Metakaolin ikamesi ile basınç dayanımı ve aderans özelliklerinde iyileşme
sağlanmıştır. Ayrıca kanca uçlu lifin daha üstün bir performans sergilediği belirlenmiştir.
Research Interests:
Bu çalışmada yüksek sıcaklığın cüruf katkılı olarak üretilmiş SIFCON (slurry infiltrated fiber concrete) kompozitlerin eğilme performansına etkisi incelenmiştir. Bağlayıcı fazında %50 oranında yüksek fırın cürufu kullanılmış olup,... more
Bu çalışmada yüksek sıcaklığın cüruf katkılı olarak üretilmiş SIFCON (slurry infiltrated fiber concrete) kompozitlerin eğilme performansına etkisi incelenmiştir. Bağlayıcı fazında %50 oranında yüksek fırın cürufu kullanılmış olup, kompozitler hacimce %20 oranında yönlendirilmiş çelik lif içermektedir. Kür işlemi (buhar kürü veya standart kür) tamamlandıktan sonra örnekler doygun veya kuru halde yüksek sıcaklık etkisine (300, 600C) maruz bırakılmıştır. Sonuçlar, yüksek sıcaklık etkisine maruz kalmamış olan kontrol numuneleri ile kıyaslanmıştır. Çalışma sonuçlarına göre 300C sonrasında lifli numunelerde eğilme dayanımı ve tokluk artışı olduğu görülmüştür. 600C uygulanmış numunelerde ve çelik liflerde ise önemli oranda dayanım kaybı oluşmuştur. Numunenin nem durumu, yüksek sıcaklık dayanıklılığını önemli derecede etkilememiştir.
Research Interests:
—In this study, it was aimed to produce a lightweight concrete canoe with engineering features suitable for use by 4 people. It was aimed to participate in International Concrete Canoe Competition which will be organized in Istanbul... more
—In this study, it was aimed to produce a lightweight concrete canoe with engineering features suitable for use by 4 people. It was aimed to participate in International Concrete Canoe Competition which will be organized in Istanbul Technical University with concrete canoe to be made and to be successful. Concrete canoe races are a prestigious competition held regularly in the USA since 1988 by ASCE, aimed at sharing knowledge among civil engineering students. With the investigations made, light aggregates with high adherence and guaranteed strength with concrete were determined. Expanded glass aggregates are materials in a hollow structure that have a specific strength that has begun to be used as a lightweight aggregate in recent years. The expanded glass aggregate is aimed to gain new properties by testing with different pozzolans, fibers and equipments. Fiber reinforcement improves at concrete, will be bending and tensile strength, improves ductility and energy swallowing capacity. Waste additives such as silica fume, blast furnace slag and fly ash can be used as binders instead of cement to increase the mechanical properties of concrete. The mechanical properties of lightweight concrete obtained using lightweight aggregates can be enhanced by various mineral additives and fibers. By determining the appropriate utilization rates of the fibers and binders, multi-cracked ductile concrete with a unit volume weight of less than 1 gr / cm 3 was obtained. The displacement controlled bending tests were analyzed with finite element programs and prime stresses were determined. In order to construct tensile strength, it was decided to use lightweight concrete with adherence reinforcement and to use basalt reinforcement. The required meat thickness was determined with the aid of structural analysis. The casting technique has been decided depending on the consistency of the concrete and the results of the structural analysis.