Browsing by Author "Uzal, Burak"

Now showing 1 - 20 of 20

Asfalt Karışımlarında Atık Plastiklerin Kullanımı
(Abdullah Gül Üniversitesi, Fen Bilimleri Enstitüsü, 2022) Şaka, Şükrü; Uzal, Burak; AGÜ, Fen Bilimleri Enstitüsü, Sürdürülebilir Kentsel Altyapı Mühendisliği Ana Bilim Dalı; 01. Abdullah Gül University; 02.03. İnşaat Mühendisliği; 02. Mühendislik Fakültesi
Within the scope of this study, the use of waste plastics in asphalt mixtures for surface layer of pavements was evaluated considering the specification limits in the Highways Technical Specifications of Turkiye General Directorate of Higways. Waste plastic data collected in Talas region has been used, a circular economy model has been created and its contributions have been evaluated. Polyethylene type of waste plastics as high and low density were used to replace bitumen in hot asphalt mixtures with 7.5 to 12.5% by weight of bitumen. The optimum binder content currently used by the Talas municipality was kept constant as (5%). In the context of Highways Technical Specifications, Marshall stability and flow values of the mixtures with and without waste plastics were determined and 10% replacement level were selected to use for further testing due its maximum stability and proper flow value (2-4 mm). Air voids, voids filled with bitumen, voids in mineral aggregates parameters on asphalt mixtures as well as softening point and flash point of bituminous binders were also determined. In addition, environmental impacts of asphalt mixtures with and without waste plastic replacement were examined via life cycle assessment methodology in the scope of cradle-to-gate.10% replacement of bitumen with waste plastics increased stability, air voids, voids in mineral aggregates and decreased flow and void filled with bitumen of asphalt mixtures as compared with the control. Softening point and flash point of bitumen increased with waste plastic replacement. Considering the environmental impact of with and without waste plastic replacement asphalt mixtures, abiotic depletion, ozone layer depletion, terrestrial ecotoxicity, and eutrophication values increased. Abiotic depletion (fossil fuels), global warming, freshwater aquatic, marine aquatic ecotoxicity, photochemical oxidation, acidification, and human toxicity values decreased. The cost of waste plastic replacement asphalt mixtures can reduce the costs of production, and laying costs. Keywords: asphalt, life cycle assessment, stability, waste plastic, circular economy
Citation - WoS: 4
Citation - Scopus: 4
Characterizing Boron-Enhanced One-Part Alkaline-Activated Mortars: Mechanical Properties, Microstructure and Environmental Impacts
(Elsevier Sci Ltd, 2024) Orklemez, Ezgi; Ilkentapar, Serhan; Durak, Ugur; Gulcimen, Sedat; Uzal, Nigmet; Uzal, Burak; Atis, Cengiz Duran; 01. Abdullah Gül University; 02.03. İnşaat Mühendisliği; 02. Mühendislik Fakültesi
Since alkali activators negatively effect the environmental impact assessment, it is necessary to develop the alternative activators from natural sources with low environmental impact. Therefore, in this study, the usage of boron refined products colemanite, ulexite and boron pentahydrate as activators in slag-based alkali-activated mortar systems was investigated in detail. Flexural and compressive strength tests, isothermal calorimetry measurement, thermogravimetric and differential thermal analysis, inductively coupled plasma mass spectrometry analysis, field emission scanning electron microscopy, and energy dispersive analysis and elemental mapping and X-ray diffraction analysis were carried out on the samples. In addition, sample production was subjected to life cycle analysis (LCA) with a cradle-to-gate approach using two different transportation scenarios. According to the results obtained, it was determined that colemanite, ulexite and boron penta hydrate, when used in optimum proportions, had a positive effect on strength (up to increase 40% compressive strength by 20% ulexite replacement) and could be used as an activator in slag-based alkali-activated systems. The positive results obtained in strength as a result of using boron-refined products are also supported by other test results conducted within the scope of the study. Furthermore, according to the LCA results, it was observed that there was a significant decrease in global warming potential with the substitution of 20% colemanite, ulexite or boron pentahydrate as activators, not only compared to the reference sample but also traditional cementitious systems.
Citation - WoS: 30
Citation - Scopus: 30
Compatibility of Superplasticizers With Limestone-Metakaolin Blended Cementitious System
(Springer, 2015) Zaribaf, Behnaz H.; Uzal, Burak; Kurtis, Kimberley; 01. Abdullah Gül University; 02.03. İnşaat Mühendisliği; 02. Mühendislik Fakültesi
This study investigates the performance of polycarboxylate ether (PCE), polymelamine sulfonate (PMS), sodium lignosulfonate and naphthalene formaldehyde condensate (PNS) superplasticizers (SPs) with ASTM C595 Type IL cement (with up to 15% calcium carbonate) combined with 10 and 30 % metakaolin (MK) substitutions by mass. The required dosage of each SP for 10 % and 30 % MK substitutions were determined based on mini slump test to establish equivalent paste flow. At these dosage rates, the effects of SPs on setting time, hydration kinetics, and strength development were measured. Life cycle assessment (LCA) was carried out on different cement compositions used in this study to evaluate the greenhouse gas emissions and embodied energy of limestone-metakaolin blended cement with SP addition. While MK substitution decreases the workability of samples and shortens the setting time, this study shows that adequate dosages of a compatible type of SP can be used to compensate for these effects. Of the SPs examined, PCE and PMS are found to be more compatible, compared to PNS and sodium lignosulfonate, with limestone-metakaolin blended cements.
Compatibility of Superplasticizers With Natural Pozzolan Blended Cement: Multi-Criteria Compatibility Index Through Rheology and Hydration Kinetics
(Taylor & Francis Ltd, 2025) Argin, Gizem; Uzal, Burak; 01. Abdullah Gül University; 02.03. İnşaat Mühendisliği; 02. Mühendislik Fakültesi
An effective technique to decrease carbon dioxide emissions in the cement industry is the partial replacement of clinker with supplemental cementitious materials (SCMs). Given the restricted supply of by-product SCMs such fly ash, blast furnace slag, and silica fume, natural pozzolans provide viable options in the manufacturing of blended cement. In cementitious systems with natural pozzolans, the use of superplasticizers is essential to compensate for the reduced workability caused by their higher water demand. This study investigates the compatibility of different superplasticizer types, administered at similar dosages, with Portland cement containing 40% natural pozzolan, focusing on paste rheology and hydration kinetics. A Multi-Criteria Compatibility Index (MCCI) was created to provide a comprehensive and quantitative evaluation of compatibility between natural pozzolans and different types of superplasticizers, utilizing rheological and hydration kinetics within a weighted scoring framework. The assessment findings indicated that PMS displayed the best overall compatibility, principally owing to its improved hydration properties, but PNS revealed enhanced performance in rheological characteristics. PCA demonstrated restricted compatibility in both categories. The MCCI framework delivered a balanced and thorough comparison unattainable by single-parameter studies, providing a solid methodological foundation for future study on SCM-admixture compatibility.
Citation - WoS: 15
Citation - Scopus: 16
Effect of Characteristics of Natural Zeolites on Their Geopolymerization
(Elsevier, 2021) Ozen, Sevgi; Uzal, Burak; 01. Abdullah Gül University; 02.03. İnşaat Mühendisliği; 02. Mühendislik Fakültesi
The properties of clinoptilolite-based geopolymers are investigated with a focus on the parameters affecting the reactivity of clinoptilolite in a geopolymer binder. A complete characterization of raw materials was carried out as well as a determination of the mineralogical composition, microstructure and mechanical properties of geopolymers. The results of the investigation show that of the investigated materials, geopolymer made with clinoptilolite-bearing tuff from Bayburt has the highest compressive strength. The chemical and mineralogical characteristics of a raw material are important parameters that potentially control the geopolymeric reaction, whereas physical properties (particle size and BET specific surface area) are mainly influential at early stages of geopolymerization. Geopolymeric gel was found to be the main reaction product through characterization by XRD and SEM analysis. The geopolymer produced with the raw material from Bayburt had a narrow range of Si/Al ratios and possessed a geopolymer binder structure with an advanced nature. Lastly, in addition to clinoptilolite, feldspar has an additional effect on the geopolymeric reaction and enhances the process, especially at later ages.
Citation - WoS: 10
Citation - Scopus: 11
Effect of Duration and Type of Grinding on the Particle Size Distribution and Microstructure of Natural Pumice With Low Pozzolanic Reactivity
(Elsevier, 2023) Taj, Khalilullah; Ilcan, Huseyin; Teksin, Eray; Argin, Gizem; Ardog, Mehmet Kemal; Uzal, Burak; Sahmaran, Mustafa; 01. Abdullah Gül University; 02.03. İnşaat Mühendisliği; 02. Mühendislik Fakültesi
Pumice, with low pozzolanic reactivity, was ground for 1, 3, and 6 h with a laboratory ball mill in dry conditions and it was ground for 1 h in wet conditions via an industrial-scale ball mill. Based on derivative particle dis-tribution, grinding for longer periods led to the disappearance of bimodal distribution and the development of unimodal distribution. Furthermore, the phase characterization, assessed through XRD, demonstrated appre-ciable changes in intensities of the peaks of quartz and dachiardite. The extension of grinding time resulted in a significant uptake at the early-age lime consumption and evolution of hydration heat. According to SEM images, the number of particles between 10 and 20 & mu;m was less in the powder ground for 3 and 6 h. Moreover, it was found that the prismatic shapes of raw pumice tended to transform to spheroid shapes after prolonged grinding, and the smooth surfaces of pumice particles became more rugged.
Effect of Mineralogical Composition of Clinoptilolite-Bearing Tuffs on Their Performance as a Natural Pozzolan in Cementitious Systems
(Techno-press, 2021) Ozen, Sevgi; Uzal, Burak; 01. Abdullah Gül University; 02.03. İnşaat Mühendisliği; 02. Mühendislik Fakültesi
In this study, pozzolanic reactivity and strength activity of zeolitic tuffs containing similar amount of zeolitic phase (clinoptilolite) and different types and amounts of impurities were examined in order to understand the role of mineralogical composition in the efficiency of zeolitic natural pozzolans. Mineralogical and chemical compositions as well as the physical properties of the zeolitic tuffs were determined. Their pozzolanic reactivity were measured as depletion of calcium hydroxide in the pastes containing lime and zeolitic tuff, which is determined by thermogravimetric analysis. Furthermore, compressive strength of blended cement mortars prepared with 20% replacement of Portland cement by finely ground tuffs were determined at 7, 28 and 56 days of age. It was demonstrated that the type and amount of impurities in mineralogical composition of zeolitic tuffs are significantly effective on their early pozzolanic reactivity. Zeolite mineral content, however, is more determinative on long term reactivity. For a strength activity, mineralogical composition was clearly effective on the preparation of mortar samples, which depends on water requirement of zeolitic tuffs.
Citation - WoS: 5
Citation - Scopus: 6
Effect of Nano-SiO2 on Strength and Hydration Characteristics of Ternary Cementitious Systems
(Springer Heidelberg, 2023) Yorulmaz, Hediye; Uzal, Burak; Karahan, Okan; Durak, Ugur; Ilkentapar, Serhan; Atis, Cengiz Duran; 01. Abdullah Gül University; 02.03. İnşaat Mühendisliği; 02. Mühendislik Fakültesi
This paper shows results of laboratory study on the effects of nano-SiO2 on Portland cement-fly ash systems. It is aimed to improve performance of fly ash-cement systems, particularly at early age, with the inclusion of nano-SiO2. In order to observe the effects of nano-SiO2 particles on the strength and hydration kinetics of fly ash blended cementitious systems, binary and ternary systems were prepared by adding 0.25-1.5% nano-SiO2 by weight of blended cements. Workability, setting time, water absorption capacity, fire resistance, compressive strength and isothermal calorimeter tests were conducted on the cementitious systems. The results indicate that increasing quantity of fly ash increased workability, setting time, water absorption capacity of cementitious systems, whereas the increasing quantity of nano-SiO2 reduced these values. Significant increment in compressive strength were observed, especially at early ages of fly ash-cement systems with nano-SiO2 addition, compared to fly ash added systems, which may compensate for the decrease in compressive strength caused by fly ash. Nano-SiO2 addition accelerated hydration reactions at early age. By partially eliminating the negative effects of fly ash with nano-SiO2, high rates of fly ash can be used in cementitious systems, thus forming more sustainable systems.
Effects of Dry Particle Coating With Nano-and Microparticles on Early Compressive Strength of Portland Cement Pastes
(Tulpar Academic Publishing, 2021) Yorulmaz, Hediye; Özuzun, Sümeyye; Uzal, Burak; İLkentapar, Serhan; Durak, Uğur; Karahan, Okan; Atis, C. D.; 01. Abdullah Gül University; 02.03. İnşaat Mühendisliği; 02. Mühendislik Fakültesi
It is known that nano-and microparticles have been very popular in recent years since their advantages. However, due to the very small size of such materials, they have very high tendency to agglomeration particularly for nanoparticles. Therefore, it is critical that they are properly distributed in the system to which they are added. This paper investigated the effects of dry particle coating with nano-and microparticles to solve the agglomeration problem. For a clear evaluation, paste samples were preferred to detemine the compressive strength. Nano-SiO2 and nano-CaCO3, microCaCO3 and micro-SiO2, also known as silica fume, were selected as particulate additives. It was studied by the addition of various percentages (0.3, 0.7, 1, 2, 3 and 5%) of nano-and microparticles in cementitious systems, replacing cement by weight with and without dry particle coating. Dry particle coating was made by using a highspeed paddle mixer. Portland cement and additive particles were mixed at 1500 rpm for 30 seconds in high-speed powder mixer designed for this purpose. The 3-day compressive strength of the cement-based samples to which particles were added at the specified rates was determined and the effect of the dry particle coating on the early strength was investigated. According to the results, it was observed that the production of paste with the dry particle coating technique gave higher compressive strength compared to the production of paste directly in early period. Especially with dry particle coating, compressive strength increased more than 100% in paste samples containing 0.3% nano-SiO2 compared to direct addition without coating. © 2024 Elsevier B.V., All rights reserved.
Citation - Scopus: 1
Energy Simulation Optimization for Building Insulation Materials
(Springer International Publishing, 2023) Himmetoğlu, Salih; Delice, Yılmaz; Kızılkaya Aydoğan, Emel Kizilkaya; Uzal, Burak; 01. Abdullah Gül University; 02.03. İnşaat Mühendisliği; 02. Mühendislik Fakültesi
Recently increased energy consumption and carbon emissions caused by energy consumption have mobilized governments. Energy-efficient building designs have become one of the most fundamental strategies preferred by governments. The heating and cooling demands have an important share in energy consumption in buildings. Therefore, thermal insulation systems have become the basic building elements to design energy-efficient buildings. Determining suitable thermal insulation strategies for energy-efficient structures built in different climates is an important decision problem for designers. This study aims to select insulation material and insulation thickness for energy-efficient building design. The stone wool, extruded polystyrene (XPS) insulation materials, and their alternative thicknesses are considered for Turkey’s two different climate zones. The Energy Plus and Design Builder energy simulation programs are used to analyze all alternatives. A decision support system is generated by considering both the material cost and the heating and cooling energies to be consumed during the building life cycle. The most suitable insulation material for the first zone is stone wool, and its thickness is 10 cm. The most suitable insulation material for the second zone is stone wool, and its thickness is 10 cm. The total saving is 11% for the building in the first zone. The total saving is 9% for the building in the second zone. The generated designs have been quite stimulating for decision-makers. © 2024 Elsevier B.V., All rights reserved.
Citation - WoS: 28
Citation - Scopus: 31
Green Building Envelope Designs in Different Climate and Seismic Zones: Multi-Objective ANN-Based Genetic Algorithm
(Elsevier, 2022) Himmetoglu, Salih; Delice, Yilmaz; Aydogan, Emel Kizilkaya; Uzal, Burak; 01. Abdullah Gül University; 02.03. İnşaat Mühendisliği; 02. Mühendislik Fakültesi
In recent years, the major component of green building designs adopted by governments in order to reduce CO2 emissions as well as energy consumption is the green building envelope. The green envelope has the most important share in terms of thermal energy consumption, environment, and indoor comfort criteria. Determining the most suitable building envelope combination in the building life cycle is an important problem for designers. This study presents a new multi-objective approach that determines the most suitable green envelope designs for the buildings in different climate and earthquake zones, taking into account CO2 emissions, heating/cooling energy consumption, and material cost in terms of life cycle cost analysis. To this end, EnergyPlus building performance simulation program, artificial neural network (ANN), and genetic algorithm are used together. After the heating and cooling energy consumption, CO2 emissions, and material cost values are obtained for a certain number of the envelope alternatives with the EnergyPlus, ANN models that learn the working mechanism of EnergyPlus are trained according to these values. An ANN-based genetic algorithm procedure is developed to search the whole envelope alternative space by using the trained ANN models with EnergyPlus. The proposed approach allows searching in a very short time the whole alternative space, which is almost impossible to scan with EnergyPlus by reducing the time spent and the number of alternatives required for the design and simulation processes of the green building envelope. The proposed approach is performed for a design-stage city hospital structure in Turkey. Window type, the internal/external plaster, wall, and insulation materials along with the thicknesses of these materials, which consist of 46 different variables, are determined as envelope attributes for four different climate and seismic zones. The green building envelope designs obtained with the proposed approach are entered into EnergyPlus and the consistency of the results is compared. ANN models with an average accuracy of over 97% are developed. Without the CO2 emission cost in the life cycle cost, the mean absolute percent error (MAPE) values for each region are 0.67%, 0.6%, 0.58%, and 1.78%, respectively. With the CO2 emission cost in life cycle cost, the MAPE values for each region are 0.96%, 0.88%, 0.86%, and 0.43%, respectively. According to the obtained results, there is a consistency of over 99% between EnergyPlus and the proposed approach.
Citation - WoS: 71
Citation - Scopus: 76
Influence of NaNo SiO2 and NaNo CaCo3 Particles on Strength, Workability, and Microstructural Properties of Fly Ash-Based Geopolymer
(Ernst & Sohn, 2020) Durak, Ugur; Karahan, Okan; Uzal, Burak; Ilkentapar, Serhan; Atis, Cengiz Duran; 01. Abdullah Gül University; 02.03. İnşaat Mühendisliği; 02. Mühendislik Fakültesi
The influence of nano SiO2(NS) and CaCO3(NC) particles on the properties of class F fly ash based geopolymer mortar activated with different sodium ion concentrations have been investigated. Mortar mixture proportions were 1:3:0.3 for binder, sand, and water, respectively. Nano SiO2 and CaCO3 particles were replaced with a binder by weight basis at the ratios of 1, 2, and 3% in the mixtures. Sodium concentrations amount used were 8, 10, and 12% Na+ of binder content. Geopolymer mortar samples were cured at 60, 75, and 90 degrees C in a furnace for 24, 48, and 72 hr. After the heat curing process, flexural, and compressive strength tests were performed. The changes in the microstructure of geopolymer due to influence of nanoparticles were examined by utilizing isothermal calorimetric studies on geopolymer paste, and field-emission scanning electron microscopy (FESEM). Based on laboratory work results, it was concluded that for all sodium ion concentrations, the addition of nano SiO2 and CaCO3 particles improved the flexural and compressive strengths after 24 hr heat curing. However, the favorable effects of nanoparticles on strength properties tend to disappear after 48 and 72 hr heat curing. The results of isothermal calorimetric studies showed that nano SiO2 and CaCO3 particles accelerated the geopolymeric reactions at an early age. FESEM results showed that additions of nanoparticles made the microstructure of geopolymer products more intense and compact.
Nanotanecikler İçeren Yüksek Miktarda Doğal Puzolan Katkılı Çimentolar: Özellikler, Hidratasyon ve Hamur İç Yapısı
(TUBİTAK, 2015) Uzal, Burak; Korkanç, Mustafa; Karahan, Okan; 0000-0002-3810-7263; AGÜ, Mühendislik Fakültesi, İnşaat Mühendisliği Bölümü; Uzal, Burak; 01. Abdullah Gül University; 02.03. İnşaat Mühendisliği; 02. Mühendislik Fakültesi
Çimento sektörü dünya genelinde atmosfere salınan CO2 gazının %7’sinden tek başına_x000D_ sorumludur. Çimento sektörü odaklı CO2 emisyonlarının azaltılabilmesinde en etkin yol,_x000D_ çimentolardaki mineral katkı kullanım oranının yükseltilebilmesidir. Bunun önündeki en büyük_x000D_ engel göreceli olarak yüksek miktarda mineral katkılı çimentoların geç priz süreleri, düşük_x000D_ dayanımları ve yüksek büzülme eğilimleridir. Son yıllarda nanoteknolojiye olan ilgi artışıyla_x000D_ beraber, nanotaneciklerin çimento sistemlerinde kullanımına yönelik çalışmalar dikkat_x000D_ çekmektedir._x000D_ Bu projede yüksek miktarda doğal puzolan içeren çimentolara nanotanecik ilavesinin, farklı_x000D_ doğal puzolan tiplerine de bağlı olarak, bu çimentoların hidratasyonu, hamur iç yapısı ve_x000D_ özellikleri üzerindeki etkisi irdelenmiştir. Yirmi üç farklı doğal puzolanik malzemeden türlerini_x000D_ en iyi şekilde yansıtacak şekilde seçilen bir zeolit, bir pomza ve bir volkanik tüfün her birisi,_x000D_ ağırlıkça %50 oranında Portland çimentosuna ikame edilerek katkılı çimentolar hazırlanmıştır_x000D_ (toplam 20 farklı çimento kompozisyonu). Bu çimentolara %1 ve %2 oranlarında nanoCaCO3 ve nano-SiO2 tanecikleri ilave edilerek, çimentoların hidratasyonu, hamurların iç_x000D_ yapısı ve harç özellikleri incelenmiştir. Bu kapsamda izotermal kalorimetreyle hidratasyon_x000D_ kinetiği, taze hamurların vizkositesi, termal analizle sertleşmiş hamurların kalsiyum hidroksit_x000D_ ve bağlanmış su içerikleri, elektron mikroskobuyla iç yapı gözlemleri, harçların dayanımları_x000D_ ve büzülme (rötre) ölçümleri gerçekleştirilmiştir._x000D_ Yapılan deneysel çalışmaların sonucunda nanotanecik ilavesinin, yüksek miktarda doğal_x000D_ puzolan içeren çimentoların başta hidratasyon kinetiği (reaksiyon hızı ve açığa çıkan_x000D_ hidratasyon ısısı) olmak üzere, iç yapısını mikro ve nano düzeyde modifiye ettiği tespit_x000D_ edilmiştir. Çimento harçlarında %19’a varan oranlarda basınç dayanımı artışları ile_x000D_ büzülmelerde belirgin düşüşler gözlenmiş ve bu durumun nanotanecik ilavesiyle hamur iç_x000D_ yapısının gözenek boyut dağılımında meydana gelen yoğunlaşmayla ilgili olduğu_x000D_ değerlendirilmiştir.
Citation - WoS: 27
Citation - Scopus: 30
A New Parameter Influencing the Reaction Kinetics and Properties of Fly Ash Based Geopolymers: A Pre-Rest Period Before Heat Curing
(Elsevier, 2021) Durak, Ugur; Ilkentapar, Serhan; Karahan, Okan; Uzal, Burak; Atis, Cengiz Duran; 01. Abdullah Gül University; 02.03. İnşaat Mühendisliği; 02. Mühendislik Fakültesi
In this study, the influence of a pre-rest period before heat curing (as a new parameter), on the physical properties, flexural and compressive strength, and microstructure of geopolymer mortars and pastes produced with alkali activation of fly ash were investigated. In this context, geopolymer mortar and paste samples were prepared and pre-rested under laboratory conditions for 0, 1, 2, 3, 7, 14, and 28 days before heat curing. After the pre-rest period, the samples were subjected to heat curing at 75 degrees C in an oven, for 2 days. Mortar and paste samples exposed to a pre-rest period while in the fresh state before heat curing were compared with control samples without pre-resting. Water absorption, porosity, specific gravity, capillarity, flexural strength, compressive strength, and abrasion resistance tests were conducted on the geopolymer mortar samples. A reaction kinetics study using an isothermal calorimeter, XRD, and SEM analyses were performed on the geopolymer paste samples for microstructural investigations. Based on the results obtained, it was observed that the mechanical strength of the samples subjected to the pre-rest period before heat curing increased considerably compared to the reference (without pre-resting) samples. In addition, because of pre-resting, the capillarity coefficient, water permeability, and porosity of the samples decreased compared to the reference samples, and it was concluded that pre-resting improves durability-related properties. Moreover, the reaction kinetics and SEM analysis results, supporting the above findings, showed that a pre-resting period increases the geopolymeric reaction products and causes a denser microstructure.
Citation - WoS: 17
Citation - Scopus: 18
Practical Charts to Identify the Predominant Clay Mineral Based on Oxide Composition of Clayey Soils
(Elsevier, 2017) Sivrikaya, Osman; Uzal, Burak; Ozturk, Yunus Emre; 01. Abdullah Gül University; 02.03. İnşaat Mühendisliği; 02. Mühendislik Fakültesi
This study proposes some useful practical charts representing the relationships between oxide composition and the type of predominant clay mineral present in clay soils. In order to produce the charts, the data set are collected from published literature. Some useful classification schemes for predominant clay mineral type were obtained by using binary and ternary graphs of oxide composition data. The most successful relations indicating the type of clay mineral have been found on SiO2 versus Al2O3 + Fe2O3 + FeO, SiO2 versus MgO + CaO + Na2O + K2O binary plots, SiO2 Al2O3 Others and SiO2 - Al2O3 - K2O ternary plots. (C) 2016 Elsevier B.V. All rights reserved.
Citation - WoS: 4
Citation - Scopus: 4
Reaction Kinetics and Properties of Pumice-Based Geopolymer Systems Cured at Room Temperature
(Elsevier Sci Ltd, 2023) Kucukyildirim, Enver; Yorulmaz, Hediye; Durak, Ugur; Ilkentapar, Serhan; Uzal, Burak; Karahan, Okan; Atis, Cengiz Duran; 01. Abdullah Gül University; 02.03. İnşaat Mühendisliği; 02. Mühendislik Fakültesi
This research investigated the kinetics of pumice-based geopolymer systems and their physical and mechanical properties. The effect of the Na2SiO3/NaOH ratio of geopolymer systems on the rate of heat evolution and total heat of reaction were examined via isothermal calorimetry of geopolymer pastes prepared with Na2SiO3/NaOH ratios of 2.5, 3, and 3.5. Hardened pastes were also studied with thermo-gravimetric analysis to determine weight loss. In addition, the unit weights and compressive strengths of the pastes prepared using pumice were measured. Although the hydration process starts the earliest in pumice-based geopolymer pastes with a Na2SiO3/ NaOH ratio of 2, they have the lowest total hydration temperature. Na2SiO3/NaOH ratio of 2.5 by mass, shows higher weight loss obtained from TGA results. The compressive strength of the paste sample, prepared with a Na2SiO3/NaOH ratio of 3.5 by mass, was the highest, with 36.30 MPa at 28d. Depending on the Na2SiO3/NaOH ratio, it is thought that as the amount of Na2SiO3 increases in the samples, silica gel formation increases in later ages.
Citation - WoS: 11
Citation - Scopus: 13
Role of Inclusion Size Distribution of Titanium Dioxide on the Nitrogen Oxides Reduction Capability and Microstructural Characteristics of Cementitious Systems
(Elsevier Sci Ltd, 2022) Bahsi, Emrah; Sahin, Oguzhan; Ilcan, Huseyin; Uzal, Burak; Gunal, Muhammed Faruk; Yildirim, Gurkan; Sahmaran, Mustafa; 01. Abdullah Gül University; 02.03. İnşaat Mühendisliği; 02. Mühendislik Fakültesi
This paper explores the effect of the inclusion size of titanium dioxide (TiO2) particles on a variety of performance properties of cementitious systems via experimental studies. In addition to comprehensive microstructural analysis including pore size distribution and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX) analyses, particular consideration was given to the effect of particle size distribution (PSD) of TiO2 particles on mechanical and photocatalytic properties and hydration kinetics of cementitious systems. Nano-sized, submicron-sized and micron-sized anatase-phase TiO2 powders were utilized as photocatalysts at a dosage of 5% by total weight of powder material. In addition to the single use of TiO2 particles with three different size ranges (nano, submicron and micron), they were also used in combination by adjusting their PSDs with three different PSD moduli (q): 0.1, 0.5, and 0.9. Test results show that techniques for achieving optimal microstructural characteristics of cementitious systems also help design and improve their performance in favor of multifunctionality. As a result of PSD optimization of TiO2 particles with three different size ranges, which was significantly influential on the microstructure of the cementitious systems, superior photocatalytic degradation results were obtained from mixtures containing lower amounts of nano-sized TiO2 particles. Cementitious composites with denser microstructure showed lower performance in terms of being able to maintain photocatalytic degradation capability for a prolonged period, whereas the opposite was the case for compressive strength.
Sürdürülebilir Beton için Hümik Asit-Esaslı Süperakışkanlaştırıcı
(Abdullah Gül Üniversitesi, 2019) ÖZUZUN, SÜMEYYE; Özuzun, Sümeyye; Uzal, Burak; AGÜ, Fen Bilimleri Enstitüsü, Sürdürülebilir Kentsel Altyapı Mühendisliği Ana Bilim Dalı; ÖZUZUN, SÜMEYYE; 01. Abdullah Gül University; 02.03. İnşaat Mühendisliği; 02. Mühendislik Fakültesi
Süper akışkanlaştırıcılar, taze betonun işlenebilirliğini artıran ve karışımlarda gerekli su miktarını azaltarak sertleşmiş betonun mekanik özelliklerini geliştiren polimerik ajanlardır. Yaygın olarak kullanılan süper akışkanlaştırıcılar, yüksek enerji tüketimi ve üretimde kullanılan yüksek hammadde maliyeti nedeniyle eko-verimli ürünler olarak kabul edilmez. Literatürde hümik asidin dispersant olarak kullanımı, bir süper akışkanlaştırıcı olarak işlev gören elektrostatik ve sterik itme ile moleküller arası bir ayırma kuvveti oluşturduğu konusunda çalışmalar vardır. Fakat yayınlanmış literatürde, hümik asidin süper akışkanlaştırıcı olarak çimentolu sistemlerde kullanımı üzerine mevcut bir çalışma bulunmamaktadır. Bu çalışmanın amacı, aslında tarımsal kullanım için ticari olarak temin edilmişleonarditten elde edilen hümik asit (HA) esaslı çözeltinin çeşitli dozajlarında, çimento esaslı sistemler içinde akışkanlaştırma verimliliğini ve bunun yanı sıra hidratasyon ve mekanik özellikler üzerindeki etkilerini araştırmaktır. HA esaslı çözelti, lignin esaslı ve naftalin esaslı süper akışkanlaştırıcılar açısından karşılaştırmalı olarak değerlendirildi. HA esaslı çözelti, lignin ve naftalin esaslı ürünlerine benzer bir akışkanlaştırma etkinliği göstermiştir. Sonuçlar hümik asit esaslı ajanlar, naftalin esaslı süper akışkanlaştırıcıyla kıyaslandığında çimento esaslı sistemlerin işlenebilirlik, hidratasyon kinetiği ve mekanik özellikler üzerindeki benzer performansı nedeniyle eko-verimli süper akışkanlaştırıcılar olarak dikkate alınması gerektiğini göstermektedir.
Sürdürülebilir Beton için İlave Bağlayıcı Malzeme Olarak Kalsine Killer
(Abdullah Gül Üniversitesi, 2019) ARGIN, GİZEM; Argın, Gizem; Uzal, Burak; AGÜ, Fen Bilimleri Enstitüsü, Sürdürülebilir Kentsel Altyapı Mühendisliği Ana Bilim Dalı; ARGIN, GİZEM; 01. Abdullah Gül University; 02.03. İnşaat Mühendisliği; 02. Mühendislik Fakültesi
Betonda bağlayıcı olarak kullanılan Portland çimentosu dünya genelinde CO2 salınımında önemli bir paya sahiptir. Bunun için çimento ile belli miktarlarda ikame edilecek ilave bağlayıcı malzemeler kullanılmaktadır. Uçucu kül, silis dumanı ve cüruf gibi endüstriyel yan ürünlerin ilave bağlayıcı malzeme olarak kullanımı avantajlı gözükmektedir. Ancak, yerel ölçekte iyi kalitede yan ürünlerin bulunmaması, bu malzemelerin alternatifini bulmak konusunda arayışa sebep olmuştur. Bu çalışmanın amacı, Türkiye'de iki farklı rezervden temin edilen kil örneklerini kalsinasyon sonrası ilave bağlayıcı malzeme olarak kullanımları açısından değerlendirmektir. Kil örneklerinin kimyasal, mineralojik ve termal karakterizasyonları çeşitli sıcaklıklarda kalsinasyon öncesi ve sonrasında gerçekleştirilmiştir. Kil numunelerinin puzolanik aktivitesi ve reaksiyon kinetiği, kireçtaşı tozu ilavesi ve kireçtaşı ilavesi olmadan, sırasıyla termal analiz ve izotermal kalorimetre ile değerlendirilmiştir. Ayrıca puzolanik aktivitelerine bağlı olarak seçilen kalsine killerin su ihtiyacı ve dayanım aktivite indeksi de belirlenmiştir. Görece daha yüksek miktarda kaolinit minerali içeren kilin puzolanik aktivitesinin daha yüksek olduğu tespit edilmiştir. 700 ºC'de kalsine edilen killer en yüksek puzolanik ve dayanım aktivitesini gösterirken 1100 ºC gibi bir kalsinasyon sıcaklığı nispeten daha düşük bir aktivite ile sonuçlanmıştır. Kireçtaşı ilavesi, puzolanik aktiviteyi ve hidratasyon sırasında ısı çıkarımını iyileştirmiştir. BET yüzey alanı arttıkça kalsine killerin su ihtiyacı da artmıştır.
Citation - WoS: 7
Citation - Scopus: 7
Very High Early Strength Calcium Aluminate Based Binary and Ternary Cementitious Systems: Properties, Hydration and Microstructure
(Taylor & Francis Ltd, 2023) Saydan, Murat; Keskin, Ulku Sultan; Uzal, Burak; 01. Abdullah Gül University; 02.03. İnşaat Mühendisliği; 02. Mühendislik Fakültesi
Calcium aluminate cement (CAC) is a cement type that has superior properties such as rapid strength gain, high resistance to high temperatures and harmful chemicals. However, the result of the using of CACs in the production of structural elements occur strength decreases at later ages as a result of a series of chemical reactions called 'conversion reactions' seen in these cements. In this study, the hydration kinetics and the crystalline and amorphous structures formed as a result of hydration were investigated in CAC containing different amounts and types of main oxides-based binary and ternary systems. Considering the results obtained, the main hydration product seen in these specimens was ettringite. Unlike many studies in the literature, metastable structures which cause conversion reactions, such as CAH(10), C(2)AH(8), have not been observed. Instead of conversion of the phases, ettringite needles were became thin and elongate which causes the paste structure porous and thus causing expansion and strength reduction at the later stages of hydration in some mixtures produce high amounts of ettringite. On the other hand, it is understood that the formation of stratlingite was limited strength decreases in systems where high silica fume is used.