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Öğe Cam Lifi Uzunluğu ve Oranının Çimento Harçlarının Mekanik Özelliklerine Etkisi(Kırıkkale Üniversitesi, 2022) Toklu, Kenan; Avşar, Yunus Emre; Cihan, Mehmet Timur; Bıçakcı, EnginBetonun mühendislik özelliklerinde iyileştirmeler yapabilmek için farklı lif türleri beton üretiminde kullanılmaktadır. Fakat lif türü, narinlik gibi değişkenler üretilecek olan betonun özellikleri üzerinde farklı etkilere sahiptir. Bu çalışma kapsamında, farklı uzunluklardaki (3 mm, 6 mm ve 12 mm) cam lifleri, karışıma hacimce % 0.3, % 0.4 ve % 0.5 oranlarında ilave edilerek üretilen harçların yayılma değeri, basınç dayanımı, eğilmede çekme dayanımı ve ultrasonik atımlı dalga hızı incelendi. Elde edilen sonuçlara göre, karışım içerisindeki cam lif miktarının artmasıyla genel olarak karışımın yayılma değerinde, basınç dayanımı ve ultrasonik atımlı dalga hızında azalmalar meydana gelirken, eğilmede çekme dayanımında ise iyileşmeler meydana geldiği görülmüştür.Öğe Çelik liflerin geometrik şeklinin ve oranının beton özelliklerine etkisinin araştırılması(2021) Şimşek, Osman; Toklu, Kenan; Ünal, Muhammed TalhaBirçok araştırmada betonun teknik özelliklerini artırmak için farklı cins ve tiplerdeki liflerle çalışmalar yapılmıştır. Genellikle sonyıllarda betonun mekanik özeliklerinin öncelikli olan yerlerde çelik lif tercih edilmektedir. Bu çalışmada, tarafımızca şekil verilerekoluşturulan 2 farklı çelik lif tipi (Z, C şeklinde) ve 80/60 çelik lifi, çimento ağılığının 0.0, 0.10, 0.15 ve 0.20 oranlarındakullanılmıştır. Bu farklı şekillere sahip çelik liflerin, taze betonda oluşturdukları hava %’si miktarı ve işlenebilme özelliğigözlenirken; sertleşmiş betonda ise basınç, eğilme ve aşınma dayanımlarına olan etkileri incelenmiştir. Lifin şekli ve oranının, tazeve sertleşmiş beton özellikleri üzerinde etkili olduğu görülmüştür. Taze ve sertleşmiş betonda en optimum özellik, 80/60 lifinin%10 kullanılmasıyla elde edilmiştir.Öğe Effect of quaternary binder slag-based geopolymer slurries on mechanical durability and microstructural properties of green prepacked composites(Elsevier Ltd, 2024) Alcan, Haluk Görkem; Dheyaaldin, Mahmood Hunar; Toklu, Kenan; Bayrak, Barış; Kaplan, Gökhan; Aydın, Abdulkadir CüneytThis study conducts a detailed investigation into the effects of slag-based quaternary binder geopolymer slurries on the physico-mechanical properties, high temperature resistance, and microstructural characteristics of prepacked composites. This research employs a strategic combination of aluminosilicate precursors, including metakaolin (MK), pumice powder (Pum), and perlite powder (Per), which are blended with slag in varying mix proportion to identify and optimizing the composite's performance. In the key finding reveal that samples containing 20 % of MK achieved superior performance, displaying the lowest porosity and water absorption rates. The oven-dry density of the mixtures demonstrated a marked improvement with the inclusion of MK, increasing from a range of 2150–2230 kg/m3 in 0 % MK mixture to 2250–2350 kg/m3 in those with 20 % MK. Post heat curing, the compressive strength peaked at 31.12 MPa in the mixture comprising 20 % MK, 20 % pumice, and 10 % perlite; however, this strength reduced to 11.92 MPa when subjected to a temperature of 600?. In high temperature resistance tests, the combination of 20 % MK and 10 % perlite resulted in a minimal mass loss of 4 % at 600?, indicating a robust resistance to thermal degradation. Furthermore, the 24-h water capillary absorption displaying lowest water absorption rates. This study provides a critical advancement in the use of natural pozzolans for developing high-performance, slag based geopolymer slurries. The enhanced high-temperature strength and reduced water absorption underscore the potential of these materials to deliver durable and sustainable solution for the construction industry, particularly in application requiring superior thermal resistance and longevity. © 2024 Elsevier LtdÖğe Effect of Supplementary Cementitious Materials with Similar Specific Surface Area on Cementitious Composite Systems(Amer Soc Testing Materials, 2023) Sevim, Özer; Şengül, Çağrı Göktuğ; Kartal, Saruhan; Toklu, Kenan; Çağlar, YasinThis study investigated the effect of the mechanical and durability properties of cementitious composite systems with supplementary cementitious materials (SCMs), including fly ash (FA), ground granulated blast furnace slag (GGBS), and bottom ash (BA), with similar specific surface areas (similar to 3,300 cm2/g). FA, GGBS, and BA were ground to a specific surface area of similar to 3,300 cm2/g (about the cement-specific surface area) and then replaced with cement at 5 %, 10 %, 15 %, and 20 % replacement ratios. The compressive strength, flexural strength, length change, and rapid chloride ion permeability of the cementitious composites incorporating FA, GGBS, and BA with similar specific surface areas were recorded after 7-, 28-, and 90-day curing periods. As a result, cementitious composites containing GGBS improved the mechanical and durability properties at the maximum rate. It was shown that the properties of cementitious composites containing 20 % GGBS yielded better results than the control specimens without any SCMs.Öğe Investigation of Cement, Mineral and Chemical Additive Interactions in Micro Scales(2021) Şimşek, Osman; Gökçe, Murat; Toklu, KenanSelf-compacting concretes (SCC), a new type of concrete, were realized with the development of polycarboxylate-based chemical additives. The interaction of these additives with the powder materials in the nano and micro scales affects the fresh and hardened properties of concrete in meso and macro scales. To change and improve the macro-dimensional properties of concrete, it is necessary to better analyze the nano-microdimensional interaction. The aim of this study is to examine the interactions of cement, mineral and chemical additives in micro scale. For this purpose, the zeta potential values of the mixtures consisting of cement, water, calcite and blast furnace slag prepared by using a polycarboxylate based plasticizer additive were analyzed. In addition, SEM analyzes of hardened samples were made on the 28th days.Öğe Investigation of the effect of silica fume and synthetic foam additive on cell structure in ultra-low density foam concrete(Elsevier, 2022) Şeker, Burçin Şenol; Gökçe, Murat; Toklu, KenanIn this study, the properties of ultra-low density foam concrete with silica fume substitute and synthetic foam additive were investigated. Two different references and silica fume substituted foam concretes with densities of 220 and 200 kg/m(3) were produced. Silica fume was used as the replacement material and its ratio in the mixtures was kept constant at 5% by weight. According to the results of the study, the compressive strengths and the thermal conductivity coefficients of the references and silica fume substituted foam concretes with densities of 220 and 200 kg/m(3) were found to be 0.26, 0.21 and 0.32, 0.26 Mpa at 28 days and 0.073, 0.069 and 0.068, 0.060 W/mK, respectively. In addition, the behavior of foam concrete at high temperatures was investigated using a flame source, which can reach up to 1200 degrees C, since temperatures usually exceed 1000 degrees C during a fire. At the end of ten minutes, the heat permeability of silica fume substituted foam concrete exposed to a 1200 degrees C temperature was 6.5% and 5.3%, which was better than reference foam concretes, respectively. As a result, silica fume has positively affected the compressive strength at later ages and thermal conductivity properties of foam concrete.Öğe Investigation of the Effect of Vacuum Application in Fresh Concrete on Concrete Depth(Gazi Univ, 2022) Simsek, Osman; Toklu, Kenan; Demirel, CanIn this study, the process of withdrawing the concrete mixture water by vacuum was applied to a field concrete at different times while it was fresh. By applying vacuum to fresh concrete, some of the mixing water in the concrete and also the trapped air was removed in a controlled manner. In the concrete blocks produced to be 15 cm thick, the names A or reference, B and C were respectively given to concrete block without vacuum, 17 minutes vacuum applied concrete block, 35 minutes vacuum applied concrete block. Core samples of 75mm diameter and 150mm length were taken from the vacuum concrete blocks, which were exposed to outdoor conditions for 66 months in Ankara. In addition, three samples, 75 mm in diameter and 50 mm in length, were prepared from each of the cores taken, as lower, middle and upper. Thus, the compressive strength, abrasion resistance and capillary water absorption effect of vacuuming time at different depths of concrete were investigated. As a result of the study, it was observed that the compressive strength and abrasion resistance of the reference concrete increased, the amount of capillary water absorption decreased and the capillary coefficient decreased as it moved away from the upper surface of the reference concrete. It was also observed that as the vacuum moved away from the vacuum applied surface, the compressive strength and abrasion resistance of the concrete decrease, the amount of capillary water absorption increases and the capillary coefficient increases.Öğe Investigation of the Properties of Foam Concrete Produced Using Liquid Latex(2024) Gökçe, Murat; Toklu, KenanFoam concrete, a type of lightweight concrete, is highly preferred due to its lightness and ease of application. In addition, substitute materials are used in the foam concrete mixture in order to further improve the properties of foam concrete. In this study, the engineering properties of foam concrete produced using liquid latex were analyzed. For this purpose, liquid latex was added to the mixing water in this study. The amount of latex is fixed at 25% of the cement weight. Additionally, the amount of liquid latex added to the mixture was reduced to equal the amount of mixing water. According to the results, it was seen that liquid latex made positive contributions to the engineering properties of the produced foam concrete. It was observed that the water absorption value of latex-added samples decreased by 59% compared to the reference sample. In addition, the thermal conductivity coefficient of the samples with latex added was lower than the reference sample. In the microstructural analysis, it was seen that the pores were more homogeneous than the reference sample and no cracks occurred. Finally, the long chain bonds formed by liquid latex in concrete were first determined by SEM image analysis.Öğe Manyetize Edilmiş Su Kullanılarak Beton Üretimi(2020) Üngör, Murat Gökçe; Toklu, KenanDünyada ve özellikle gelişmiş ülkelerde beton, ekonomik olması, üretiminin kolaylığı, istenilenşeklin verilebilmesi ve özellikle dayanım ve durabilite gibi mühendislik üstünlükleri nedeniyleen çok tercih edilen yapı malzemesidir. Sürekli artan beton üretimi neticesinde bu alanda yapılanbilimsel araştırmalarda hızlı bir ivme kazanmıştır. Bu çalışmada, manyetize edilmiş su ile üretilenbeton ile normal karışım suyu ile üretilen geleneksel beton kıvam ve basınç dayanımı açısındankarşılaştırılmıştır. Manyetize edilmiş su kullanılarak üretilen betonların su ihtiyacı azalmış vesu/çimento oranı azalması neticesinde basınç dayanımı artış göstermiştir. Beton üretimindekullanılan karışım suyunun manyetize edilerek kullanılması ile prefabrik ve hazır betonüreticilerine yeni bir bakış açısı kazandırılarak daha ekonomik ve kaliteli beton üretim olanağısunulmuştur.Öğe Manyetize Edilmiş Su Kullanılarak Manyetik Ortamda Beton Üretimi(Gazi Üniversitesi, 2020) Gökçe, Murat; Toklu, KenanDünyada ve özellikle gelişmiş ülkelerde beton, ekonomik olması, üretiminin kolaylığı, istenilen şeklin verilebilmesi ve özellikle dayanım ve durabilite gibi mühendislik üstünlükleri nedeniyle en çok tercih edilen yapı malzemesidir. Sürekli artan beton üretimi neticesinde bu alanda yapılan bilimsel araştırmalarda hızlı bir ivme kazanmıştır. Bu çalışmada, manyetize edilmiş su ile üretilen beton ile normal karışım suyu ile üretilen geleneksel beton kıvam ve basınç dayanımı açısından karşılaştırılmıştır. Ayrıca bu çalışmada, karışım suyunun manyetize edilmesi ve manyetik ortamda bulamaç şeklindeki karıştırma tekniği ile ülkemizde çimento esaslı beton üretecek bütün üreticilere yeni bir bakış açısı kazandırılarak daha ekonomik ve kaliteli beton üretim olanağı sunulmuştur.Öğe The Effect of Aggregate Size and Cure Conditions On The Engineering Properties of Concrete(Fırat University, 2020) Toklu, Kenan; Yazıcıoğlu, SalihIn this study, the effect of curing conditions and aggregate size on the engineering properties of concrete was investigated. Aggregates in the range of 0-8 mm and 0-16 mm were used in concrete production and then cubic samples of 100x100x100 mm were prepared. In the study, slump value of fresh concrete was determined as S3. Three samples were used for each experiment. Compressive strength, abrasion, porosity and carbonation tests were performed on 28-day concrete samples subjected to water and air curing. According to the results obtained, it is determined that concrete samples under the effect of water curing give better results. In addition, better results were obtained for compressive strength, abrasion, porosity and carbonation properties of concrete by increase in aggregate size. It has also been observed that there is an increase in compressive strength of concrete, a positively decrease for abrasion, porosity and carbonation properties.Öğe The impact of RCA and fly ash on the mechanical and durability properties of polypropylene fibre-reinforced concrete exposed to freeze-thaw cycles and MgSO4 with ANN modeling(Elsevier Ltd, 2021) Bayraktar, Oğuzhan Yavuz; Eshtewı, S. Salem Taher; Benli, Ahmet; Kaplan, Gökhan; Toklu, Kenan; Günek, FurkanAn experimental study has been conducted to investigate the impact of recycled coarse aggregate (RCA) and fly ash (FA) on the transport, mechanical and durability properties of polypropylene fiber reinforced concretes. In this context, nine concrete mixtures with 25% FA as cement replacement (by wt.) and nine mixtures without FA were produced. RCA was used to replace natural coarse aggregates (NCA) at 0, 25 and 50% by wt. in all concrete mixtures. In addition, polypropylene fiber (PPF) was added to concrete mixtures at 0, 3 and 6% by volume. Mechanical performance was evaluated by compressive, splitting tensile strength at 7, 28 and 90 days and Schmidt rebound hammer at 90 days. Dry bulk density, water absorption, apparent porosity and sorptivity of concrete were also evaluated. Durability performance of concretes was evaluated by exposing to 50,100 and 150 freeze-thaw cycles and MgSO4 attack. Abrasion test on the concretes was also performed. After performing durability tests, compressive, splitting tensile strength, ultrasonic pulse velocity, microstructural observations and mass loss of the concretes were assessed. An artificial neural network (ANN) was also modeled for predicting experimental data. The results indicated that combined use of RCA, FA and PPF improved the compressive strength considerably and approximately 60 MPa was obtained in concretes with 25 and 50% RCA. The use of RCA in concretes with 25% FA has improved the mechanical properties. The mixture with 25% RCA, 6%PPF and without FA and the mixture with 50% RCA, 3%PPF and FA showed the best abrasion resistance. Reference and the mixture with 0% RCA, 25% FA and 6% PPF exhibited the lowest strength loss after the MgSO4 attack. Reference and the mixture with 25% RCA, 25% FA and 3% PPF performed the best after 100F-T cycles in terms of compressive strength. With the Bayesian regularized algorithm, material quantities for the target concrete properties can be obtained. The main outcome of this study is that using RCA, FA and PPF in concrete can give better performance in terms of mechanical and durability performance than normal concrete. © 2021 Elsevier LtdÖğe Ultra-low density foam concrete production using electrolyzed water(ASTM International, 2022) Gökçe, M.; Toklu, KenanWith the development of foam concrete production technology, its usage area is increasing day by day. In this study, foam concrete was produced by using electrolyzed water to solve the problem of setting and low early-age strength, especially in low-density foam concrete production. According to obtained results, with the use of electrolyzed water technology in the production of foam concrete, the thermal conductivity coefficient decreased and the strength at early ages increased. Thus, foam concrete production will be made more rapidly. © 2021 by ASTM International
