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Öğe LASTİK AGREGALI BETONLARDA ELASTİSİTE MODÜLÜNÜN DENEYSEL VE TEORİK OLARAK İNCELENMESİ(Gazi Univ, Fac Engineering Architecture, 2009) Emiroğlu, Mehmet; Yıldız, Servet; Özgan, ErcanIn this study, fine and coarse rubber aggregates were produced for using in concrete. Rubber filled concretes have been produced by replacing the normal aggregates with rubber aggregates (5%, 10%, 15% and 20%) by volume respectively. Physical and mechanical properties of the produced rubber filled concretes have been determined. Beam specimens with 100 x 100 x 500 mm were prepared for the three point bending tests. The three point bending tests have conducted on these beam specimens and deflection amount of the beams during the test have been measured. By using the deflection values elasticity modulus of the produced specimens have been determined. Also, the elasticity modulus of the specimens has been calculated by using empirical equations which were proposed from some countries' standards. It was tried to determine that the relationship between the experimental results and empirical equation results for elasticity modulus. As a result, it is determined that while increasing rubber content in the concrete the relationship between experimental results and empirical equation results for elasticity modulus were decreased. However, it is observed that there was a high correlation between experimental results and empirical equation proposed by American Concrete Institute (ACI) for elasticity modulus.Öğe Genetic Algorithm Application for Hydrometer Tests(Asian Journal Of Chemistry, 2009) Özgan, Ercan; Öztürk, AliIn this study, the results of the hydrometer tests were analyzed with statistical method and optimized by using genetic algorithms. For hydrometer tests; 0, 10, 20, 30, 40, 50 and 60 g sodium-hexametaphosphate was respectively added into the prepared suspension. The specific gravity, pH and the conductivity were measured for each solution. As pointed out in the Turkish Standard (TS 1900), the soil' grain diameter in the suspension prepared with 40 g sodium hexametaphosphate was taken into consideration as reference. As a result. it was determined that the soil' average grain diameter in suspension added 0 g sodium hexametaphosphate was bigger 4.515 times than the reference grain diameter. When respectively added 10 g sodium hexametaphosphate in the suspension, the soil average grain diameter bigger was 3.907 times than the reference grain diameter, when 20 g was added. It was 3.463 times bigger and in adding it was 30 g 2.119 times bigger. Besides, the hydrometer reading could only be done at 260 min when 50 g sodium hexametaphosphate was added in to the suspension. Moreover, the hydrometer couldn't be read in the suspension prepared with 60 g sodium hexametaphosphate. The obtained data were analyzed statistically by using SPSS programme and the experimental results were optimized by using genetic algorithms.Öğe Fuzzy logic and statistical-based modelling of the Marshall Stability of asphalt concrete under varying temperatures and exposure times(Elsevier Sci Ltd, 2009) Özgan, ErcanIn this study, the Marshall Stability(MS) of asphalt concrete under varying temperature and exposure times was modelled by using fuzzy logic and statistical method. This is an experimental study conducted using statistics and fuzzy logic methods. In order to investigate the Marshall Stability of asphalt concrete based on exposure time and environment temperature, exposure times of 1.5, 3.4.5 and 6 h and temperatures of 30,40 and 50 degrees C were selected. The MS of the asphalt concrete at 17 degrees C(in laboratory environment temperature) was used as reference. The results showed that the MS of the asphalt core samples decreased 40.16% at 30 degrees C after 1.5 h and 62.39% after 6 h. At 40 degrees C the decrease was 74.31% after 1.5 h, and 78.10% after 6 h. At 50 degrees C the stability of the asphalt decreased 83.22% after 1.5 h, 88.66% after 6 h. The relationships between experimental results, fuzzy logic model and statistical results exhibited good correlation. The correlation coefficient was R = 0.99 for fuzzy logic model and R(2) = 0.9 for statistical method. Based on the results Of the study, it could be said that both the fuzzy logic method and statistical methods could be used for modelling of the stability of asphalt concrete under varying temperature and exposure time. (C) 2008 Elsevier Ltd. All rights reserved.Öğe Effects of Freezing and Thawing on the Consolidation Settlement of Soils(Springer, 2015) Özgan, Ercan; Serin, Sercan; Ertürk, S.; Vural, İsaThe effects of freezing and thawing on consolidation parameters and other properties of soil were investigated experimentally. Samples of soils were collected in-situ and characterized in the laboratory. Index properties of soil samples were determined by conducting sieve analyses, hydrometer tests, specific gravity tests, and liquid limit, plastic limit, and shrinkage limit tests before and after 30 freezing-thawing cycles. Microstructure and elemental composition of the soil samples were determined by scanning electron microscope (SEM) and energy dispersive X-ray (EDX) analysis, respectively. To determine the effects of freezing thawing onto the consolidation parameters of soil, consolidation tests were conducted on the samples before and after the freezing-thawing cycles. After 30 freezing-thawing cycles, consolidation settlements increased by about 23%.Öğe EFFECTS OF FREEZING AND THAWING CYCLES ON THE ENGINEERING PROPERTIES OF SOILS(Springer, 2015) Özgan, Ercan; Serin, Sercan; Ertürk, S.; Vural, İsaIn this study, particular engineering characteristics of soil exposed to freezing and thawing cycles were investigated. Low plasticity clay (CL) soil samples (classified according to the USCS soil classification system) were sampled in situ, and some basic properties of these soil samples were investigated by performing sieve analyses, hydrometer tests, specific gravity tests, and liquid, plastic, and shrinkage limits tests. The same tests were also conducted after freezing and thawing cycles. Additionally, scanning electron microscope (SEM) tests to determine the microstructures of the soil samples and energy dispersive X-ray-EDX tests to determine the chemical compositions of the samples were performed. Finally, triaxial compression tests were conducted before and after the freezing and thawing cycles to determine the strength parameters of the soil samples. The experimental results show that the physical and mechanical properties of the soil changed significantly after the freezing and thawing cycles.Öğe Effect of the PC, diatomite and zeolite on the performance of concrete composites(Techno-Press, 2016) Koçak, Yılmaz; Savaş, MuhsinThis study has been carried out to investigate the effect of the surface properties of Portland cement, diatomite and zeolite on the performance of concrete composites. In this context, to describe the materials used in this study and determine the properties of them, chemical, physical, mineralogical, molecular, thermal, and zeta potential analysis have been applied. In the study, reference (Portland cement), 10%-20% diatomite, 10%-20% zeolite, 5+5%-10+10% diatomite and zeolite were substituted for Portland cement, a total of 7 different cements were obtained. Ultrasonic pulse velocity, capillary water absorption and compressive strength tests were performed on the hardened concrete specimens. Hardened concrete tests have been done on seven different types of concrete, for 28, 56 and 90 days. As a result of experiments it has been identified that both the zeolite and diatomite substitution has a positive effect on the performance of concrete.Öğe Very ductile polymer concrete using carbon nanotubes(Elsevier Sci Ltd, 2019) Douba, AlaEddin; Emiroğlu, Mehmet; Kandil, Usama F.; Taha, Mahmoud M. RedaPolymer concrete (PC) is a type of concrete where a polymer is used to replace cement as the binder. PC is an impermeable and chemical resistant concrete with appreciable mechanical properties. However, for most structural engineers, PC advantages do not outweigh its higher cost when compared with normal cement concrete. We report on the production of very ductile PC (measured by tensile strain at failure) with appreciable tensile strength utilizing a hybrid mixture of pristine and carboxyl (COOH) functionalized multi-walled carbon nanotubes (MWCNTs) at 2.0 wt% of epoxy resin. Experimental investigations reveal that COOH functionalization maximizes PC ductility reaching unprecedented 5.5% failure strains and increasing toughness by 184%. Fourier transformation infrared spectroscopy and dynamic modulus analysis indicate an increase in crosslinking density of the epoxy matrix up to 84% due to the carbonyl band formation induced by the COOH functionalization of MWCNTs. The significant improvement in ductility and energy absorption provides a promising platform for creating very ductile PC with attractive properties. (C) 2018 Elsevier Ltd. All rights reserved.Öğe THE INVESTIGATION OF THE EFFECT OF MINEROLOGICAL MOLECULAR ELECTROKINETICAL AND THERMAL COMPLIANCE OF PUMICE, ZEOLITE AND CEM I CEMENT ON HIGH STRENGTH CONCRETE(Gazi Univ, Fac Engineering Architecture, 2010) Yıldız, Kürşat; Dorum, Atilla; Koçak, YılmazIn this study, usage of minerals with high silica content such as pumice and zeolite in high strength concrete (HSC) as pozzolans was investigated within the context of mineralogical, molecular, electrokinetic (zeta potential) and simultaneous thermal compliance. For this purpose, physical, chemical, mineralogical, molecular, electrokinetic and thermal analyses were performed on bindings. Subsequently, four types of HSC were produced (0P15Z "0% Pumice+ 15% Zeolite", 5P10Z, 10P5Z and 15P0Z) by replacing in cement when designing high strength concrete. Some fresh concrete tests and compressive strength tests were performed on produced HSCs. It was tried to determine the compliance of the data taken from the analyses performed on the bindings and the data from the HSCs. In conclusion, it was determined that the chemical, mineralogical, molecular, electrokinetic and thermal compliance of pumice, zeolite and CEM I 42.5 R cement has also appeared in HSC types.Öğe The Investigation into the Effect of Hydrostatic Pressure on the Engineering Properties of Hardened Concrete(Taylor & Francis Ltd, 2018) Uzunoğlu, Metin M.; Özgan, Ercan; Kap, TuncayThe aim of this study is to investigate the effect of hydrostatic pressure on the engineering properties of hardened concrete. To this end, a concrete column with dimensions of 100 cm width, 25 cm depth and 250 cm height was produced using C20 class concrete. While pouring the concrete, 15 cm reference cube samples were taken from the fresh concrete. After 28 days, 8 from the cube samples and 128 from different hydrostatic heights, in total 136 pieces of core samples with & Oslash;100 mm diameter were taken and their compressive strength was determined. The average compressive strength of the reference core samples was 36.95 N/mm(2) and the compressive strength of other samples changed between 37.3 N/mm(2) and 43.0 N/mm(2) according to the hydrostatic pressure. It was concluded that compressive strength changed between 0.95% and 16.37% according to the reference sample. Statistical analysis was conducted based on the experimental results. The compressive strength of the core samples related to its hydrostatic height and physical properties were predicted with a high reliability. A model equation was formed to convert the compressive strength of the core samples into reference compressive strength according to hydrostatic height and the convertibility coefficients were ascertained.Öğe The effects of various formwork surfaces on the corrosion performance of reinforcing steel in concrete(Wiley-V C H Verlag Gmbh, 2010) Subaşı, Serkan; Arslan, Metin; Durmuş, Gökhanin this study, the effects of various formwork surfaces on the corrosion performance of reinforcing steel in concrete were examined. For this purpose, seven formwork surfaces from populus nigra, pinus silvestris, steel sheet, and four of plywoods were prepared. Three of the plywood formworks were covered with different geotextile liners and drainage channel and holes were drilled on their surfaces. one of the plywood formworks having no processes on its surface was for control. Reinforcing steels were first embedded in formworks and then the concrete was poured. The samples were exposed to corrosion in a way of settling them in 5% NaCl solution. We tested the corrosion potential and bonding strength of the samples. Later, the mass loss and tensile strength were measured on reinforcing bars that were pulled out from the concrete. The chloride content and pH values were also tested on concrete powders. The results indicated that drained-lined formwork (F5 with TB50 + F613 geotextile liner) compared to steel sheet (F4 undrained and unlined) gave 16% lower corrosion and 68% higher bonding strength on reinforcing bars embedded samples, 73% lower mass loss and 4% higher tensile strength on reinforcing bars, and 70% lower chloride content and 4% higher pH on concrete powders. in addition, it was found that the corrosion strength of reinforcing steels in concrete could be increased if drained-lined formworks were utilized.Öğe The effects of using fly ash on high strength lightweight concrete produced with expanded clay aggregate(Academic Journals, 2009) Subaşı, SerkanIn this study, the effect of using fly ash in high strength lightweight aggregate concrete produced with expanded clay aggregate on physical and mechanical properties of the concrete was investigated. For this purpose, lightweight concrete mixtures with 350, 400 and 450 kg/m(3) cement content were prepared using expanded clay aggregate. Besides, concretes with 0, 10, 20 and 30% fly ash replacement were produced out of the mixtures with different cement contents. Concrete density, porosity, ultrasonic pulse velocity, compressive and split tensile strength experiments were performed on the prepared samples. As a result, it was seen that it is possible to produce high strength lightweight concrete using expanded clay aggregate; the cement content with 450 kg/m(3) among concrete mixtures had the highest strength values; mechanical properties of concrete could be enhanced by using 10% fly ash; thus a saving in cement amount could be achieved.Öğe THE EFFECTS OF USING PERMEABLE FORMWORK ON CONCRETE MATURITY(Gazi Univ, Fac Engineering Architecture, 2009) Subaşı, SerkanThe aim of this study is to investigate the effects of using permeable formwork on concrete maturity. For this purpose, four curtain wall formworks having 120 cm height, 70 cm with and 20 cm thickness; were prepared. As a surface material one Black pine and three plywoods formworks were used. Drainage channels and holes were cut on the surfaces of two of plywoods formworks and the surfaces of these formworks were covered with different geotextile liners. The other polywood formwork selected as reference sample any processing has done. Maturity measuring apparatuses were placed on the geometric centre of the curtain wall formworks. C30 concrete were cast into the prepared formworks and compressed with a vibrator. In addition, 16 number of concrete samples having 15x15x15 cm dimensions were prepared. The maturity measuring device was placed into the one of these samples. And the other samples were waited into the curing pool and the compressive strength of the samples was determined at the 1(st), 3(rd), 7(th), 14(th), and 28(th) days respectively. As a result, it is seen that, maturity index of the concrete cast into the permeable formworks is high as 11% than the black pine and plywood formworks and the concrete cast into the permeable formworks were gained earlier strength. Besides, it is seen that, concrete maturity may be accelerated with using permeable formworks.Öğe THE EFFECTS OF FORMWORK SURFACE PROPERTIES ON CONCRETE CARBONATION(Gazi Univ, Fac Engineering Architecture, 2008) Subaşı, Serkan; Arslan, MetinThe aim of this study is to investigate the effects of formwork surface properties on concrete carbonation. Seven concrete wall formworks with different surface properties, Scotch pine, Black poplar, sheet iron and four plywoods, were constructed in this study. Tree out of four wall plywood formworks were prepared with drainage channels and holes. The formwork surfaces consisting of drainage channels and holes were covered with different geotextile liners. The concrete were casted into all prepared wall formworks, which were removed after 28 days that the sample blocks were prepared. The blocks were kept under atmospheric conditions for six years. After that, the depths of carbonation were determined using the taken core samples of all blocks. In addition, the pH values were investigated on the concrete powder samples that were obtained from different depth levels of the concrete blocks. The results indicated that formworks including both drainage and liners gave lower carbonation compared to the other formworks. The lowest carbonation was observed with the formwork that was covered with SB-20 geotextile. On the other hand, the highest carbonation was found with the sheet iron formwork.Öğe THE EFFECTS OF CONTROLLED-PERMEABLE FORMWORKS ON THE SURFACE HARDNESS OF THE CONCRETE(Gazi Univ, Fac Engineering Architecture, 2008) Arslan, Metin; Subaşı, SerkanThe purpose of this study was to investigate the effects of different formworks on the surface hardness of the concretes under long-term atmospheric conditions. Ten wall formworks (2 Scots pine, 2 Black poplar, 1 stell iron and 5 plywood) with different surface properties were constructed in this study. Three out of five plywoods were prepared with holes and canals and these prepared formworks were covered with different types of geotextile liners. The concrete was casted into all formworks under the same conditions. The prepared concrete walls were kept under atmospheric conditions for six years in horizontal position. Every year, the surface hardness of the concrete walls were determined with a Schmidt hammer. The findings were evaluated regarding the climate conditions. The findings of this study indicated that the concrete blocks containing geotextile liners were less affected from climate conditions. In addition, formworks with liner gave better surface hardness compared to the others.Öğe The effect of using natural zeolite on the properties and hydration characteristics of blended cements(Elsevier Sci Ltd, 2013) Koçak, Yılmaz; Taşçı, Eda; Kaya, ÜnalIn this study, various properties and the hydration mechanisms of cements containing natural zeolite were investigated. In the first stage a complete physical, chemical, mineralogical, molecular characterization of the zeolite and cement was performed. In the second stage, the mechanical and physical properties of blended cements, incorporating 0%, 5%, 10%, 15% and 20% zeolite by weight were determined. Finally, the hydration rate and products of cement pates were studied by means of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscope (SEM) at 28 days. As it is concluded, the examined zeolite consists mainly of cliniptilolite, which reacts with the Ca(OH)(2) generated during the hydration of Portland cement to form cement-like hydrated products. Finally, the addition of zeolite has affected the physical and mechanical properties of the blended cements depending on the amount of zeolite. (C) 2013 Elsevier Ltd. All rights reserved.Öğe THE EFFECT OF ELECTROKINETIC SPESIFICATION FEATURES TO HYDRATION DEVELOPMENT IN FLY ASH BLENDED CEMENT(Gazi Univ, Fac Engineering Architecture, 2010) Dorum, Atila; Koçak, Yılmaz; Yılmaz, Bülent; Uçar, AliIn this study, surface interaction mechanisms of the reference (OPC) and fly ash blended cements (FAC) were investigated. The physical, chemical, mineralogical and mechanical properties of OPC, fly ash (FA) and FAC, as well as the electrokinetic potentials (zeta potential) of FA-OPC particles were examined. After cement pastes were prepared with OPC and FA, they were water-cured for 2, 7 and 28 days. The pastes were made using X-ray diffraction (XRD), differential thermal analysis (DTA) and Fourier transform infrared spectroscopy (FT-IR) in order to determine their mineralogical composition and the determination of the phases developed during the hydration. Furthermore by scanning electron microscope (SEM) 28 days microstructures of pastes were determined and mortars were examined following strength tests. While the addition of FA has increased the setting time and the amount of water demand, amount of portlandit (Ca (OH)(2)) decreased during the hydration. Moreover FA has shown different electrokinetic behaviors and surface features compared to OPC. These variations effected on compressive strength of mortar samples.Öğe PRODUCTION OF STRUCTURAL LIGHTWEIGHT CONCRETE WITH EXPANDED CLAY AGGREGATE(Gazi Univ, Fac Engineering Architecture, 2009) Subaşı, SerkanIn this study, the manufacturing possibility of the high strength lightweight concrete having different amount of the cement by using expanded clay aggregate and its physical and mechanical properties were investigated. For this purpose, concrete mixtures used expanded clay aggregate and natural sand was designed. 0-2, 2-4 and 4-8 mm expanded clay aggregate and 0-2 mm natural sand were used in the concrete mixtures. Three different lightweight concrete having 350, 400 and 450 kg/m(3) amount of the cement were produced. Slump and ve-be tests were performed on the fresh concrete samples and the unit weight, porosity,, compressive strength, split tensile strength and ultrasonic pulse velocity tests were performed on the hardened concrete specimens. As a result, it is seen that production of the structural lightweight concrete having 1,7 kg/m(3) unit weight and 41,27 MPa compressive strength could be possible. Besides the maximum compressive strength and split tensile strength values were obtained from the concrete mixture having 450 kg/m(3) cement dosage.Öğe PREDICTION THE EFFECT OF CHROME MAGNESIT BRICK DUST ON THE STARTING and FINISHING SETTING TIME OF PORTLAND CEMENT WITH FUZZY LOGIC(Gazi Univ, Fac Engineering Architecture, 2009) Özgan, Ercan; Yıldız, KürşatIn this study, Portland cement (PC 42,5) replaced with Chrome Magnesit brick dust as a ratio of its weight of %0, %5, %10, %15, %20, and %25. By this procedure, six different mixtures were prepared and effect of cement was investigated on the starting and finishing time of the setting. As a result, while the mixture with 5% Chrome Magnesit brick dust decreases the starting and finishing setting time in small amount with, the increasing amount of the Chrome Magnesit increases the starting and finishing setting time. Also, by using Fuzzy Logic method, prediction model was constituted based on the quantity of Chrome Magnesit brick dust to predict the starting and finishing time of the setting for cement which could not be determined with experimental. It was showed that the prediction model could be used to predict the starting and finishing time of the setting for cement based on the quantity of brick dust.Öğe Prediction of photon attenuation coefficients of heavy concrete by fuzzy logic(Pergamon-Elsevier Science Ltd, 2010) Akkurt, İskender; Başyiğit, Celalettin; Kılınçarslan, Şemsettin; Beycioğlu, AhmetThe fuzzy logic (FL) model to determine the radiation shielding properties of concretes containing barite in the ratio of 0%, 50%, 60%, 70%, 100%, and different water-to-cement ratio (w/c) have been developed. For training of the networks in the model, w/c and barite ratio were input, while the photon attenuation coefficient was output. The FL results were compared with experimental results and correlation between experiment and FL was compared with the correlation between experiment and calculation (XCOM). It was found that the correlation between FL and experiment was better than the correlation between XCOM and experiment. (C) 2010 The Franklin Institute. Published by Elsevier Ltd. All rights reserved.Öğe Prediction of mechanical properties of cement containing class C fly ash by using artificial neural network and regression technique(Academic Journals, 2009) Subaşı, SerkanThe aim of this study is to investigate the estimation ability of the effects of utilizing different amount of the class C fly ash on the mechanical properties of cement using artificial neural network and regression methods. For this reason, 0, 5, 10, 15 and 20% amount of the class C fly ash were substituted with cement and 40 x 40 x 160 mm dimension specimens were prepared. On the prepared specimens unit weight, flexural tensile strength and compressive strength tests were performed after the 2, 7 and the 28(th) days. 2 different estimation models regression techniques (RT) and the artificial neural network (ANN) methods were used for determining the flexural tensile strength and the compressive strength of the cement specimens. Experimental results were used in the estimation methods. Fly ash content (%), age of specimen (day) and unit weight (g/cm(3)) were used as input parameters and flexural tensile and compressive strengths (N/mm(2)) were used as output parameters. The developed models and the experimental results were compared in the testing data set. As a result, compressive and flexural tensile strength values of mortars containing various amounts class C fly ash can be predicted in a quite short period of time with tiny error rates by using the multilayer feed-forward neural network models than regression techniques.
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