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Öğe Basalt Fibers and Mechanical Properties of Basalt Fiber Reinforced Concrete(Yildiz Technical Univ, 2014) Kızılkanat, Ahmet B.; Kabay, Nihat; Akyüncü, Veysel; Erdoğan, GokhanConcrete is a brittle material with a low energy absorption capacity. There are several methods to increase the ductility of concrete where incorporation of different type of fibers is usually known as the most effective one. The most common type of fibers used for reinforcing concrete is steel, polymer, glass and carbon fibers. Although the addition of fibers might slightly increase the compressive strength of concrete, the main benefit occurs in terms of flexural and tensile strength of concrete. The principal role of the fibers is to modify the behavior of the material once the concrete matrix has cracked by bridging across the cracks as they begin to open and preventing the crack development. Basalt fibers are obtained by melting process of volcanic basalt rock. These fibers have many superior properties when compared to other fibers. Studies have shown that basalt fibers favorably affect the mechanical properties of concrete such as tensile strength and fracture energy.Öğe Basalt powder dependent properties of mortars subjected to high temperatures(Croatian Soc Civil Engineers-Hsgi, 2019) Akyüncü, VeyselThe effects of high temperatures of up to 800 degrees C on residual physical and mechanical properties of mortars are presented in this paper. Due to its resistance to high temperatures, basalt powder is used as a substitute to standard sand at the ratios of 20% and 40%. Polypropylene or basalt fibres have been added to mortar mixtures to avoid spalling. Results show that the ratio of basalt powder does not change the strength reduction rate, and that the flexural strength performance of mortar mainly depends on fibre type and temperature rather than on basalt powder substitution.Öğe Bazalt tozu katkılı harçların mekanik ve geçirimlilik özeliklerinin araştırılması(2019) Akyüncü, Veysel; Cihan, Mehmet TimurBazalt beton üretiminde agrega olarak tercih edilen ancak üretimi esnasında yan ürünolarak yüksek miktarda atık bazalt tozu malzemesi ortaya çıkaran bir kayaçtır. Bu atıkmalzemenin geri dönüşümüyle çevreye ve insan sağlığına verdiği zararın azaltılmasınınyanında çimentoyla ikame edilmesi harç (beton) hammadde maliyetinde bir miktardüşme sağlayacaktır. Çalışma kapsamında kontrol serisi ve %5, %10, %15, %20oranlarında bazalt tozu çimento ile ikame edilerek toplamda 5 seri harç numuneüretilerek taze ve sertleşmiş harç deneyleri gerçekleştirildi. Taze harç deneyi olarakkıvam tayini, sertleşmiş harç deneyi olarak basınç, eğilme, yarmada çekme vegeçirimlilik deneyi olarak basınç altında su işleme derinliği deneyleri yapıldı. %10ikameli seride basınç dayanımında yaklaşık olarak %8 oranında artış elde edilirken,eğilme dayanımında ise %15 ikameli seride önemli bir artış elde edildi. %10 bazalt tozuikame oranına sahip seride basınç altında su işleme derinliği düşüş göstererek olumlubir katkı sağlamaktadır.Öğe Investigation of Mechanical and Permeability Properties of Fiber Mortars(2021) Akyüncü, VeyselConcrete is a brittle material which has a higher compressive strength compared to its tensile strength. Steel, glass or polymer fibers are usually added to concrete in order to improve the ductility under mechanical loads. One of the most important factors taken into consideration in producing a durable concrete is by imperviousness concrete. In this study, the mechanical and permeability properties of fiber reinforced mortars were investigated. For this purpose, in addition to the reference, 0.1%, 0.2% by volume, glass fiber reinforced and 1.15% and 2% impermeability admix incorporated series were prepared. The effective water/cement ratio of all produced mortar samples was determined to be 0.5. The workability, ultrasonic pulse velocity (UPV), flexural strength, compressive strength, splitting tensile strength, determination of water penetration depth under pressure were determined in all series. According to the test results, as the glass fiber ratio increased, the water penetration depth decreased by 15% compared to the reference. In the series where 0.2% glass fiber was used, there was a 20% increase compared to the reference in terms of splitting tensile strength. In addition, there is an increase in splitting tensile strength in series produced using glass fiber and impermeability additive.Öğe Investigation of physical and mechanical properties of mortars produced by polymer coated perlite aggregate(Elsevier Ltd, 2021) Akyüncü, Veysel; Şanlıtürk, FıratWith its low unit weight, expanded perlite (EP) offers significant advantages in heat and sound insulation in the construction sector. However, due to its high-water absorption capacity, EP affects the physical and mechanical properties of concrete negatively. Therefore, it is aimed to reduce water absorption by coating the EP with polymer and thus to improve its mechanical and physical properties. In this study, mortar production was carried out by replacing coated and uncoated EP with CEN reference sand at 0%, 20%, 40%, 60%, and 80% respectively. The effective water/cement ratio of all produced mortar samples was determined to be 0.6. For coated and uncoated EP aggregate mortar series, unit weight, compressive strength, bending tensile strength, water absorption, ultrasonic pulse velocity (UPV), and thermal conductivity coefficient were determined. The results showed that the unit weight of the mortar samples decreased as the amount of EP increased, but their physical and mechanical properties also changed. Mortar samples with better thermal insulation properties were obtained with decreasing thermal conductivity values. The polymer coating of EP improved physical and mechanical properties. Especially in the 80% substituted EP series, the thermal conductivity decreased from 1.20 to a coefficient of 0.91 W/mK. © 2021Öğe Mechanical properties and fracture behavior of basalt and glass fiber reinforced concrete: An experimental study(Elsevier Sci Ltd, 2015) Kızılkanat, Ahmet B.; Kabay, Nihat; Akyüncü, Veysel; Chowdhury, Swaptik; Akca, Abdullah R.Basalt fiber (BF) is a novel kind of inorganic fiber which is manufactured from the extrusion of melted basalt rock and is commercially available. This study comparatively analyze the application of basalt and glass fibers as fiber reinforcement in high strength concrete. It was observed from the test results that there was no significant effect of fiber inclusion on the compressive strength and modulus of elasticity of concrete. The splitting tensile strength of basalt fiber reinforced concrete (BFRC) increased with increasing fiber dosage whereas there was no increase in strength for glass fiber reinforced concrete (GFRC) was observed beyond 0.50% fiber dosage. In a trend similar to splitting tensile strength, the flexural strength of BFRC increased with increasing fiber content in a gradual fashion but no such change was observed for GFRC after 0.50% fiber content. Fracture energy increased significantly after 0.25% dosage for both basalt and glass reinforced concrete. The K-IC and CTODC results of the BFRC showed that BF inclusion improves the performance of concrete more when compared to GF with respect to crack resistance and ductility. (C) 2015 Elsevier Ltd. All rights reserved.Öğe Modeling the weight and length changes of the concrete exposed to sulfate using artificial neural network(Pontificia Univ Catolica Chile, Escuela Construccion Civil, 2018) Akyüncü, Veysel; Uysal, Mücteba; Tanyıldızı, Harun; Sümer, MansurThis paper presents the modeling of an experimental investigation carried out to evaluate some mechanical and durability properties of concrete mixtures in which cement was partially replaced with Class C and Class F fly ash. A total of 39 mixtures with different mix designs were prepared. After compressive strength testing, the mixtures containing Class F and Class C fly ashes which had similar compressive strength values to control mixtures at 28 d for each series were used for sulfate resistance tests. The degree of sulfate attack was evaluated using expansion and weight loss. The test results indicated that Class C fly ash showed higher compressive strength than Class F fly ash. Moreover, the addition of fly ash significantly increased the resistance to sulfate attack when each amount of fly ash addition regardless of fly ash types was employed. In this paper, the Artificial Neural Network (ANNs) techniques were used to model the relative change in the weight and length of the concrete exposed to sulfate. The best algorithm for length changes of concrete exposed to sulfate is BFGS quasi-Newton backpropagation algorithm while the best algorithm for weight changes of concrete exposed to sulfate is the Levenberg-Marquardt backpropagation algorithm.Öğe Optimization of durability properties of concrete containing fly ash using Taguchi's approach and Anova analysis(Pontificia Univ Catolica Chile, Escuela Construccion Civil, 2018) Uysal, Mücteba; Akyüncü, Veysel; Tanyıldızı, Harun; Sümer, Mansur; Yıldırım, HasanIn this study, optimization of durability properties of the concretes was performed by using Taguchi method and Anova analysis. The durability performance of the concretes was evaluated using measurements of rapid chloride ion permeability, freezing-thawing resistance and sorptivity tests. The degree of freezing-thawing resistance was assessed the change of weight, ultrasonic pulse velocity (UPV) and flexural strength after 300 cycles. The use of fly ash improved the rapid chloride ion permeability and sorptivity of concrete. The best resistance to chloride ion permeability was obtained from a combination of type of class C fly ash content of 102 kg/m(3) with PC content of 332 kg/m(3). There was a remarkable reduction in the UPV after the specimens are subjected to freezing-thawing cycles. The amounts of flexural strength loss have been measured in the range of 6.70 - 29.83%. The use of type of class C fly ash positively affected freezing-thawing resistance of concrete. The Anova analysis indicated that the cement dosage has an utmost importance on the sorptivity level, chloride ion permeability and ultrasonic pulse velocity loss. Furthermore, the fly ash percentage has an utmost importance on the weight loss and flexural strength loss.Öğe Physical and Mechanical Properties of Alkali Activated Mortars Produced Using Different Types of Fly Ash(Tekirdağ Namık Kemal Üniversitesi, 2022) Akyüncü, Veysel; Avşar, Yunus EmreCarbon dioxide (CO2) released into the atmosphere during cement production is one of the important factors causing global warming. Therefore, the use of different materials has gained importance to reduce cement consumption. For this purpose, the use of alkali-activated materials (AAM) is becoming widespread. The physical and mechanical properties of alkali-activated mortars produced with blast furnace slag (BFS) and 2 different types of fly ash (FA) were investigated in this study. Mortars were produced by using F class FA from Tunçbilek Thermal Power Plant and C class FA from Çayırhan Thermal Power Plant, CEN reference sand, BFS, sodium hydroxide (NaOH), distilled water, and chemical additives. The water/binder and sand/binder ratios were taken as 0.5 and 3, respectively. FA was used by replacing 0%, 10%, 20%, 30%, and 40% by weight of BFS. For 1st series of alkali-activated mortar samples sealing cure was applied at 21±1℃ for 28 days. For 2nd series of alkali-activated mortar samples the thermal cure was applied at 105±5℃ for 2 days, and the sealing cure was applied at 21±1℃ for 26 days. The workability, water absorption ratio by weight, void ratio, flexural strength, and compressive strength of the alkali-activated mortar samples were determined. As a result of the study, the closest compressive strength to YFC100 was obtained for UKF10 in the 1st and 2nd series.Öğe Pomza Agregalı Hafif Beton Blokların Mekanik Özeliklerinin ve Yangın Etkisi Altındaki Davranışının İncelenmesi(2019) Akyüncü, VeyselGünümüz beton teknolojisinde hafif doğal agregaların hafif beton üretiminde kullanımı giderek artmaktadır.Bu çalışmada hafif agrega olarak Kayseri – Talas yöresine ait pomza kullanılmış olup, normal agregalı betonblok ile değişik oranlarda pomza içeren beton bloklar, karşılaştırmalı olarak incelenmiştir. Toplamda 6 seri betonblok üretimi yapılmış olup, normal beton blok dışında beş seride belirli oranlarda kum ile pomza yerdeğiştirilerek hafif beton blok üretimi yapılmıştır. Hafif beton ve normal beton blokların yangın direncinikarşılaştırmak amacıyla 1 m3 hacime sahip kapalı alan oluşturulmuş ve yangın başlatılmıştır. Beton bloktuğlalarda yüzey sıcaklığı değerleri ölçülmüş olup hafif beton blok tuğlalarda ulaşılan maksimum yüzey sıcaklığı%50 oranında daha düşük çıkmıştır. Yangın etkisine maruz kalmış normal beton ve hafif beton bloklar basınçetkisi altında kırılmış olup hafif beton bloklarda % 6 oranında düşüş meydana gelirken normal beton bloklardabasınç dayanım kaybının % 18 oranında meydana geldiği görülmüştür. Sonuç olarak pomza ile üretilmiş hafifbeton blokların yangın etkisinde normal blok betonlara göre daha iyi sonuç verdiği görülmüştür.Öğe Statistical analysis of mechanical properties of waste glass powder substituted glass fiber mortars by ANOVA(Nigde Omer Halisdemir University, 2025) Cihan, Mehmet Timur; Akyüncü, VeyselUsing waste in the cement and concrete industry helps reduce costs and the need for large storage spaces for waste disposal. In particular, disposing of waste glass powder (WGP) from the glass industry requires significant storage capacity. Therefore, utilizing WGP as a raw material in construction is both an environmentally and economically viable solution. This study examined the workability, flexural strength, compressive strength, and splitting tensile strength of glass fiber-reinforced mortars containing WGP. A face-centered composite design was used to determine 13 test points. The fiber ratio was selected at 0%, 0.3%, and 0.6% by weight of the mixture, while WGP substitution levels were 0%, 7.5%, and 15% by weight of cement. The results indicate that adding glass fiber and WGP reduces flow value, flexural strength, compressive strength, and splitting tensile strength. However, at higher glass fiber ratios, the negative effect of WGP on flow value and compressive strength is less pronounced. The R2 values for flow value, flexural strength, compressive strength, and splitting tensile strength were 0.9983, 0.9586, 0.9069, and 0.8526, respectively, indicating a strong correlation between the tested parameters and the predictive model.Öğe Sulphate Performance of Different Types of Fly Ash Concrete(Yildiz Technical Univ, 2014) Akyüncü, Veysel; Yıldırım, HasanFly ash is the waste product of the thermal power plants, where coal is burned for generating electricity. Using fly ash in concrete production is one of the important ways of reducing its negative effects. When fly ash is used alone, it doesn't show binder property. However, if it is added to concrete mixture with cement, it improves the mechanical and durability properties of concrete. In this study, F and C type fly ashes efficiencies and their effects on the mechanical properties and durability of concrete are compared. For this study, 39 different mixtures were produced. Catalagzi Thermal Plant fly ash (F type), Cayirhan Thermal Plant fly ash (C Type) and CEM I 42,5 R type cement were used as binder. When exposed to magnesium sulphate, control specimens showed higher deteriorations when compared with concretes with fly ash. This also confirmed that fly ash improved the durability properties.Öğe SULPHATE PERFORMANCE OF DİFFERENT TYPES OF FLY ASH CONCRETE(Yildiz Technical University, 2014) Akyüncü, Veysel; Yıldırım, HasanFly ash is the waste product of the thermal power plants, where coal is burned for generating electricity. Using fly ash in concrete production is one of the important ways of reducing its negative effects. When fly ash is used alone, it doesn’t show binder property. However, if it is added to concrete mixture with cement, it improves the mechanical and durability properties of concrete.In this study, F and C type fly ashes efficiencies and their effects on the mechanical properties and durability of concrete are compared. For this study, 39 different mixtures were produced. Çatalağzı Thermal Plant fly ash (F type), Çayırhan Thermal Plant fly ash (C Type) and CEM I 42,5 R type cement were used as binder. When exposed to magnesium sulphate, control specimens showed higher deteriorations when compared with concretes with fly ash. This also confirmed that fly ash improved the durability properties.
