Yazarlar
- Duran, Celal(26)
- Ozdes, Duygu(21)
- Baltaci, Cemalettin(10)
- Gundogdu, Ali(10)
- Gül, Abdulkadir(9)
- Çullu, Mustafa(8)
- Aksüt, Yavuz Selim(7)
- Baltacı, Cemalettin(7)
- Barut, Abdulkadir(7)
- Bozbeyoglu, Pinar(7)
- Erol, Ismail(7)
- Ozeken, Sengul Tugba(7)
- Peker, Iskender(7)
- Eker, Hasan(6)
- Külekçi, Gökhan(6)
- Altuner, Elif Esra(5)
- Ar, Ilker Murat(5)
- Güzel, Melih(5)
- Karahan, Selim(5)
- Karpuz, Ömer(5)
- Kıranşan, Murat(5)
- Odabaş, Halil İbrahim(5)
- Seferoğlu, Mehmet Tevfik(5)
- Uysal, Turan(5)
- Demir Şahin, Demet(4)
- Imamoglu, Mustafa(4)
- Karpuz, Omer(4)
- Top, Yener(4)
- Akar, Bülent(3)
- Akpinar, Muhammet Vefa(3)
- Akpınar, Özlem(3)
- Avci, Ibrahim(3)
- Aydoğmuş, Ercan(3)
- Bozbeyoğlu, Pınar(3)
- Cakir, Mehmet Ali(3)
- Camoglu, Aslihan Yilmaz(3)
- Cavusoglu, Ibrahim(3)
- Daulay, Amru(3)
- Ercikdi, Bayram(3)
- Komut, Osman(3)
Yayınlar
- MakaleAçık Erişim2024Performance of different fibre types in alkaline-activated concrete produced with industrial wastes: volcanic rock powder and blast furnace slag
Aksüt, Yavuz Selim; Külekçi, Gökhan; Çullu, Mustafa; Yetgin, Şükrü
The objective of the study is to determine the effects of different fibre types and ratios on the mechanical and physical properties of alkali-activated concrete (AAC) and to optimise important properties such as workability, unit weight, water absorption, compressive strength, modulus of elasticity and abrasion resistance of these concretes. Concrete samples were produced using steel and polyester fibres at ratios of 0.25%, 0.50%, 0.75% and 1%. The fibre ratios were varied, and various tests were conducted to determine the mechanical and physical properties of the concrete samples. The experiments clearly revealed the effects of fibre types and ratios on the performance of concrete. These results clearly demonstrate the effects of different fibre types and ratios on the mechanical and physical properties of AACs. Particularly noteworthy is the water-retaining property of polyester fibres, their effect on workability and their enhancing effect on abrasion resistance. The effects of steel fibres on compressive strength and modulus of elasticity are more pronounced, but they may present disadvantages in terms of workability and abrasion resistance. It is observed that mixed fibre usage provides a good balance in some properties. This study provides a roadmap for evaluating sustainable material options in the concrete industry and guiding future research.
- MakaleAçık Erişim2024Economic Evaluation of Thermal and Mechanical Activation Energies in Plaster Production
Şener, Muhammed; Uysal, Turan; Erdemoğlu, Murat
Plaster is among the most needed raw materials in the world. In this study, thermal activation provided by calcination and mechanical activation methods provided by intensive milling in the plaster production process were evaluated in terms of activation energy. In this context, the energies of laboratory-scale thermal and mechanical activation processes were calculated and these activation methods were evaluated economically and the ideal activation methods were determined. Although the mechanical activation method creates additional investment and operating costs, it reduces the calcination temperature by 13 °C, thus provides lower energy costs. Addition of a mechanical activator mill before thermal activation in plaster production as a more economical and more environmentally friendly method was proposed.
- MakaleAçık Erişim2024Enhancing the performance of parabolic trough solar collectors: Cost-effective innovative designs for sustainable energy harvesting
Karaağaç, Mehmet Onur; Akıncı, Burak; Ergün, Alper
This study aims to improve the performance and stability of parabolic trough solar collectors (PTSC), especially those with heat storage capacity. Three different receiver tube designs have been meticulously developed to achieve this goal. As a result of the research, the Black surface (BS) -PTSC and PTSC- Paraffin wax (PW) systems achieved 26.5% and 56.8% more thermal energy flow, respectively, compared to the conventional PTSC. In addition, while the average thermal efficiencies of the PTSC, BS-PTSC, and PTSC-PW systems were found to be 11.2%, 14.1%, and 16.9%, respectively, the average exergy efficiencies of the PTSC, BS-PTSC, and PTSC-PW were 1.4%, 1.9%, and 2.3%. Painting the black copper pipe and filling the receiver tube with paraffin wax PCM increased thermal and exergy efficiency. Besides, comparing the temperature differences based on the PTSC system, it was found that BS-PTSC and PTSC-PW systems have 12.3% and 16.4% higher tank temperatures, respectively. The findings of this research have demonstrated the potential of parabolic trough solar collectors equipped with heat storage. It has also increased the sustainability index in terms of sustainability and reduced CO2 emissions into the atmosphere. Furthermore, it has been shown that these simple and inexpensive designs, without significant modifications to the system, can achieve high thermal performance without unnecessary expensive components.
- MakaleAçık Erişim2024Effects of Ultrafine Fly Ash against Sulphate Reaction in Concrete Structures
Demir Şahin, Demet; Eker, Hasan
In this study, Afşin Elbistan C-type fly ash (FA) was used, which protects against the sulphate reaction that damages concrete. The detrimental effects of post-reaction decrease with increasing fly ash fineness. The study used 10%, 30%, and 50% weight substitutes of cement. The fly ash was ground in a ball mill for 0, 10, 20, 30, 45, and 60 min, and Blaine fineness values of 1555, 1632, 2347, 2589, 2766, and 3433 cm2/g were obtained, respectively. The effect of the samples on the sulphate resistance was investigated by exposing the samples to 5% or 10% added sulphate solutions, and the compressive strength and ultrasonic pulse velocity of the concrete were tested. The compressive strength values obtained decreased with the increase in sulphate content, and the increase in the grinding time and the amount of substituted FA increased the compressive strength values. It was observed that weight loss increased with increasing sulphate content and decreased with the addition of FA with a high Blaine fineness. It was determined that as the Blaine fineness value increased, the sulphate content, FA substitution amount, and ultrasonic pulse speed decreased. This study was carried out to determine the effects of fly ash used at different fineness and replacement ratios on the performance and strength of concrete after exposure to external influences such as sulphate. The use of fly ash instead of cement will reduce the use of waste materials and natural resources and prevent environmental pollution. The cost of cement and concrete will be reduced.
- MakaleAçık Erişim2023Geri dönüşüm işletmelerinin inşaat ve yıkım atıkları açısından performanslarının bütünleştirilmiş SWARA-EDAS yöntemiyle değerlendirilmesi: Türkiye örneği
Gergin, Ramazan Eyüp
Günümüzde, inşaat ve yıkım atıklarının artan miktarı nedeniyle ülke ekonomileri birçok zorlukla karşı karşıya gelmektedir. Döngüsel ekonomilerde inşaat ve yıkım atıklarının geri dönüşüm faaliyetlerinin daha önemli rol oynaması beklenmektedir. Buna paralel olarak inşaat ve yıkım atıklarının geri dönüşümü ülkelerin rekabet gücünü doğrudan etkilemektedir. Bu çalışma inşaat ve yıkım atıklarının geri dönüşüm faaliyetlerini gerçekleştiren işletmelerin performanslarını değerlendirmeyi amaçlamaktadır. İşletmelerin performanslarını değerlendirmek için kullanılan kriterler detaylı bir literatür taraması yapılarak belirlenmiştir. Çalışmanın alternatiflerini ise inşaat ve yıkım atıklarının geri dönüşüm faaliyetlerini gerçekleştiren işletmeler oluşturmaktadır. Belirlenen kriterlerin ağırlıklandırılmasında Step-Wise Weight Assesment Ratio Analysis (SWARA) kullanılmıştır. Kriter ağırlıklarının belirlenmesinin ardından inşaat ve yıkım atıklarının geri dönüşüm faaliyetlerini gerçekleştiren işletmelerin performansı Evaluation Based on Distance from Average Solution (EDAS) ile değerlendirilmiştir. Çalışmanın sonuçlarına dayalı olarak, inşaat ve yıkım atıklarının geri dönüşümünde en önemli kriter Sürdürülebilirlik olarak belirlenmiştir. Ayrıca çalışma çevresel etkiler ile inşaat ve yıkım atıklarının taşınması kriterlerinin sırasıyla diğer önemli kriterler olduğunu göstermektedir. EDAS yönteminin sonucu ise Alternatif 5 işletmesinin inşaat ve yıkım atıklarının geri dönüştürülmesi açısından en iyi performansa sahip olduğunu göstermektedir.
- MakaleAçık Erişim2023Natural and H2SO4 modified plane sawdust as a low-cost adsorbent: Removal of anionic and cationic dyes from aqueous solutions
Duran, Celal; Kalkışım, Özgün; Ozdes, Duygu; Ozeken, Sengul Tugba; Top, Yener
Natural and H2SO4-modified plane (Platanus orientalis L.) sawdust were used for the adsorptive removal of cationic methylene blue (MB) and anionic indigo carmine (IC) dyes from aqueous media to suggest a new and cost-effective method for wastewater treatment applications. The influences of initial pH values, concentrations of MB and IC, period of contact, dosages of the natural and modified plane sawdust, and the presence of foreign ions on the adsorption of dyes were investigated in the experimental studies to describe the best conditions of the most efficient adsorption processes. Initial pH values were optimized to be between 6.0-8.0 for MB and 2.0 for IC. Experimentations of Boehm titration, FTIR analysis, pHpzc value, and moisture content determinations were utilized to characterize the natural and modified sawdust materials. Langmuir, Freundlich, and Dubinin-Radushkevich isotherm models were used to evaluate the sorption mechanism. Maximum adsorption capacities of natural plane sawdust (NPS) and H2SO4-modified plane sawdust (MPS) calculated from the Langmuir isotherm model were 55.56 and 38.46 mg g-1 in MB adsorption, and 55.82 and 55.55 mg g-1 in IC adsorption, respectively. Results showed that the natural and H2SO4-modified plane sawdust serve as low-cost and efficient materials in the adsorptive removal of MB and IC dyes for industrial wastewater treatment applications.
- MakaleAçık Erişim2023AB’de Döngüsel Ekonomi Üretim ve Tüketim Göstergelerinin Değerlendirilmesi: MEREC Temelli MARCOS Uygulaması
Seyhan, Nazlı
Bu çalışmada, MEREC (Method based on the removel effects of criteria) temelli MARCOS (Measurement of alternatives and ranking according to compromise solution) yöntemi kullanılarak 2020 yılı için AB üyesi 27 ülkenin döngüsel ekonomideki üretim ve tüketim performansları değerlendirilmiştir. Çalışmada; malzeme ayak izi, kaynak üretkenliği, tüketim ayak izi, malzeme ithalat bağımlılığı, geri dönüştürülebilir hammadde ticareti, üretim faaliyetlerinden kaynaklanan sera gazı emisyonu gibi birçok üretim ve tüketim göstergeleri ele alınmıştır. MEREC yöntemiyle elde edilen bulgularda en önemli kriterin geri dönüştürülebilir hammadde ticareti olduğu ve bu kriteri sırasıyla döngüsel ekonomi sektörleriyle ilgili özel yatırım ve brüt katma değer ve döngüsel malzeme kullanım oranı kriterlerinin takip ettiği görülmektedir. MEREC yöntemiyle belirlenen kriter ağırlıklarının kullanıldığı MARCOS yöntemi uygulaması sonuçlarına göre, döngüsel ekonomide üretim ve tüketim göstergelerine göre performansı yüksek olan ülkelerin sırası ile Hollanda, Almanya, Fransa ve İspanya; performansı düşük olan ülkelerin ise, Lüksemburg, Finlandiya, Malta, Kıbrıs ve Estonya olduğu görülmüştür. Elde edilen bulgularda döngüsel ekonomiye geçişte bazı ülkelerin çok hızlı dönüşüm gerçekleştirirken bazı ülkelerde bu geçişin daha yavaş olduğu tespit edilmiştir. Ülkelerin alabileceği bazı tedbirler (geri kazanımı olmayan atıklarda yüksek vergilendirme vb., değişim sürecinde olan işletmelere net süre belirtilmesi) ve desteklerle (özellikle sera gazı emisyonu için yenilikçi iş modelleri, geri kazanım projeleri vb.) geçiş sürecinin daha kontrollü yapılabilmesi mümkün olabilir.
- MakaleAçık Erişim2023Adsorption of hexavalent chromium from aqueous solution onto corn cobs – activated carbon
Gundogdu, Ali; Bozbeyoglu, Pinar
This study evaluated the performance of a new activated carbon (CCs-AC) produced from corn cobs by boric acid activation for the effective removal of hexavalent chromium, a heavy metal with high potential to pollute the environment, from wastewater. For this purpose, with the help of parameters such as solution pH, contact time, initial Cr(VI) concentration, CCs-AC dose, desorption and temperature, the removal of Cr(VI) ions from aqueous solution by adsorption on CCs-AC was investigated from equilibrium, kinetic and thermodynamic point of view. As a result of the experiments, it was determined that the optimum solution pH was 2.0, the contact time was 4 hours, and the desorption solution was 3.0 M NaOH. From the kinetic data, it was determined that the adsorption was compatible with the pseudo-second order kinetic model and the maximum Cr(VI) adsorption capacity (123.7 mg/g) obtained from the Langmuir isotherm model showed that CCs-AC was of competitive quality with the literature. From the thermodynamic data, the positive ΔH value indicates that the adsorption is endothermic and the value of 12.00 kj/mol indicates that the adsorption is rather chemically driven. The negative ΔG value indicates that the process proceeds spontaneously with an increase in temperature, while the ΔS value indicates an increase in the amount of unused energy.
- MakaleAçık Erişim2023Some Quality and Microbiological Traits of Tokat Tarhana Obtained from Different Wheat Cultivars Under Various Drying Conditions
Bahar, Bilge; Baltaci, Cemalettin; Gençer, Sevil
This study was carried out to evaluate the variations in some quality traits of Tokat red pepper tarhana samples according to the cultivars and drying techniques. For this aim, five white grained bread wheat cultivars such as Altınöz, Candaş, Gökkan, Şahika, and Yakamoz were used as material. And, tarhana samples were dried under open air, airflow oven and vacuum. The study was conducted with three replications according to the split plot design in random plots. All quality traits showed statistically significant variations for the bread wheat cultivars (C), drying techniques (DT), and DT×C interactions. Thus, airflow oven showed the highest values among the drying techniques for the contents of ash (8.5892%), total titration acidity (27.433%) and salt (6.842%). On the other hand, open air drying technique presented the highest values for moisture (14.556%), pH (4.349) and the density of lactic acid bacteria (LAB) (1.4×104 CFU g-1 for M17 agar, 2.4×104 CFU g-1 for MRS agar. Also, Gökkan cv had the highest percents for all quality traits except LAB density. These findings showed that the most suitable bread wheat cultivar for Tokat red pepper tarhana was Gökkan cv, and the most favorable drying technique was open air drying. In addition, it is understood from the results that wheat cultivar and drying technique which used in tarhana production were essential factors. So, tarhana sector should choose the best wheat cultivar and drying technique to be used in tarhana production for consumer taste and healthy diet. From this study, it is understood that the open air drying is the most sustainable technique in terms of both production and consumption.
- MakaleAçık Erişim2023Yerel yönetimlerde katı atık yönetimi ve gelişimi: genel çerçeve ile türkiye’ye bakış
Sarıhan, Nazlı Özcan; Çakır, Erkan
Son yıllarda kentleşme, hızlı nüfus artışı ve sanayileşmeyle birlikte doğal kaynaklar üzerindeki baskının hızla artmasıyla ekolojik dengenin bozulduğu görülmektedir. İnsanoğlunun doğal kaynakları hoyratça ve savurganca kullanması, toplumsal refahın yalnızca tüketimle sağlanacağı görüşü, kentleşme ve gelir seviyesindeki artışlar, tüketim alışkanlıklarında meydana gelen değişiklikler kentsel atıkların ortaya çıkmasına neden olmuştur. Tüketim alışkanlığındaki artışların temelde iki önemli problemi ortaya çıkardığı görülmektedir. Bunlardan ilki tüketimde meydana gelen artışın doğal kaynaklar üzerinde yapmış olduğu baskı, bir diğeri ise tüketim sonrasında ortaya çıkan atığın bertarafına ilişkin sorundur. Kentsel katı atıkların ortaya çıkmasını önlemek ve ortaya çıkan bu atıkların atılıp kurtulunması gereken madde olmaktan çıkarıp ekonomik bir değere dönüştürecek ve en önemlisi de sağlıklı bir şekilde bertaraf edilecek Entegre Katı Atık Yönetimine ihtiyaç duyulmaktadır. Bu çalışmada, katı atık yönetimi ve bu kapsamda atık yönetimi hiyerarşisi açıklanarak, Türkiye’de katı atık yönetiminin veriler ışığında ne düzeyde olduğu ve bu süreçte yerel yönetimlerin görev ve sorumluluklarının yasalar çerçevesinde neler olduğuna ilişkin bilgi verilmeye çalışılmıştır. Türkiye’de bu sürecin gün geçtikçe daha sağlıklı bir şekilde yönetilmesine rağmen bazı atık yönetim stratejilerinin verimli bir şekilde kullanılmadığı sonucuna ulaşılmıştır.
- MakaleYalnız künye2023An Overview of Applications of the Electro-Fenton (e–/H2O2/Fe2+) Oxidation Processes: Degradation of Acid and Basic Dyes in the Industrial Wastewaters
Kıranşan, Murat
Abstract: As a result of the rapid development of industry and technology, a great increase has been observed in the use of chemicals and toxic substances harmful to the environment, especially in the last 20 yr. The harmful effects of industrial wastewater, which are formed as a result of the use of chemical and toxic substances as raw substances and by products in many technology branches, adversely affect the environment. Traditional treatment methods are quite inadequate in the treatment of industrial wastewater. Water pollution is one of the most important environmental problems of today. Since water is the most basic need of living things and the source of great economic activities, it is an indispensable resource for the continuation of living and non-living life. Acid dyes, one or more in the molecule contain a sulfonic acid group or a carboxylic acid group. Acid dyes are chemically classified as anionic dyes. Direct metal-complex and reactive dyestuffs containing sulfonic acid groups are also anionic. Basic dyes are in the form of hydrochlorides of organic bases and are found in the colored part of the cationic group dye. Basic dyes, contain N or S atoms as positive charge carriers. Different chemical, physical and biological processes such as chlorination, ozonation, adsorption and microfiltration are widely used in cleaning the environments where industrial wastes are present. However, in all of these methods organic substance can be removal by transferring it from one phase to another. However, due to increasing environmental pollution, the treatment process has changed to develop new methods that can decompose organic substances into CO2 and H2O instead of transferring them from one phase to another. Hybrid systems in which different oxidation processes are applied simultaneously in the same electrochemical cell, are widely used today in order to increase the efficiency of the electrochemical methods.
- MakaleYalnız künye2023Effect of Reduced Fineness of Fly Ash Used on the Alkali–Silica Reaction (ASR) of Concrete
Eker, Hasan; Demir Şahin, Demet; Çullu, Mustafa
This study aimed to determine the effect of fly ash added to concrete with high calcium content (C class) and different fineness on durability properties such as the alkali–silica reaction (ASR). By substituting ultra-fine fly ash for cement at specific proportions in concrete mixes and increasing the fly ash fineness, fly ash filled the spaces between cement grains or aggregates in concrete and accelerated the hydration process. Thus, the mechanism of ASR development was reduced. Class C Afşin Elbistan ash was used and was ground in a ball mill for 0, 10, 20, 30, and 45 min, and Blaine fineness values of 1555, 1632, 2347, 2589, and 2766 cm2/g were obtained, respectively. For each fly ash fineness, the effect of mixtures with 10%, 30%, and 50% replacement of cement on the ASR mechanism was observed during curing periods of 3, 7, 14, and 28 days compared to concrete without fly ash admixture. Furthermore, the effect of the increased fineness and substitution rate of fly ash with high calcium content in cement on the microstructure was revealed by microscopic mineralogical images. The prepared fine fly ash added to concrete mixes at different replacement ratios showed ASR reducing properties compared to the concrete mix without additions. The fly ash fineness and the substitution rate in the concrete had a reducing effect on the ASR, and this effect resulted in values lower than the reference concrete value.
- MakaleAçık Erişim2023Sustainable water consumption and water-saving behaviours: A review of consumers' environmental and economic concerns in Turkey
Avci, İbrahim
Water, which plays an important role in human life, has been depleted as a result of changing consumption patterns, climate change and increasing population, and water scarcity has emerged as one of the most pressing issues facing the world in the coming years. One solution to this problem is to make more efficient and sustainable use of existing water resources. In this context, the study aims to investigate the effects of consumers' environmental and economic concerns on sustainable water consumption behaviour, as well as the mediating role of water-saving behaviour in these effects. For this purpose, it was discovered that environmental and economic concerns have positive effects on sustainable water consumption behaviour as a result of an analysis of data collected from 591 consumers in Turkey via the online survey method; it was determined that environmental concerns have no effect on water-saving behaviour, whereas economic concerns have a positive effect on water-saving behaviour. According to the findings of the mediation analysis, water-saving behaviour only serves to mediate the effect of economic concerns on sustainable water consumption behaviour.
- MakaleAçık Erişim2023Multi-criteria evaluation of medical waste management process under intuitionistic fuzzy environment: A case study on hospitals in Turkey
Çelik, Sefa; Peker, İskender; Gök-Kısa, A. Cansu; Büyüközkan, Gülçin
Waste management has come to the fore in the whole world with the increasing impact of the Covid-19 pandemic along with concerns about human health, environmental threats, and socio-economic factors, etc. Medical waste is one of the waste types that need special management processes including particularly collection, storage, separation, and disposal. Healthcare activities create a great amount of medical waste deriving from the hospitals. This study aims to determine the hospital that carries out medical waste management in the most effective way in Erzurum, Turkey. To handle intense uncertainty in the evaluation process, the case is analyzed by Intuitionistic Fuzzy Multi-Criteria Decision-Making (IFMCDM) methods. The present study contributes to the literature by focusing on a real case problem under IF environment in a Group Decision-Making (GDM) framework. Additionally, based on the literature review and expert judgments, the evaluation criteria relevant to the case are defined in this paper. To this end, a four-phased integrated methodology that involves Intuitionistic Fuzzy Weighted Averaging (IFWA), IF Analytical Hierarchy Process (IFAHP), IF Technique for Order Preference by Similarity to Ideal Solution (IFTOPSIS) and One-Dimensional Sensitivity Analysis, is conducted. Firstly, IFWA is aimed to express the significance levels of decision makers (DMs) based on their knowledge, qualifications and experiences. Secondly, IFAHP is used to calculate the importance weights of the decision criteria and IFTOPSIS is preferred to rank the available hospitals. Then, sensitivity analysis is employed to display robustness. According to the results, the most important criteria are Qualified personnel, Health institution infrastructure, and Control of waste, respectively and the most efficient hospital is determined.
- MakaleAçık Erişim2023The effects of environmental value and ecological worldview on eco-recreative attitude: an application in Turkey; [O efeito do valor ambiental e visão de mundo ecológica na atitude eco-recreativa: um estudo na Turquia]
Kement, Üzeyir; Çavuşoğlu, Sinan; Çalık, Ismail; Durmaz, Yakup
This study aims to investigate the effects of environmental value and ecological worldview on eco-recreative attitudes. In recent years, human-related pollution has seriously increased. Therefore, it is critical to explain the eco-recreative attitudes of participants with an emphasis on how these attitudes support natural life. Another indicator of the significance of this study is that it explains the premises of the attitude. Environmental value in the proposed model was examined as three sub-factors: biospheric, altruistic, and egoistic. Also, an eco-recreative attitude has three sub-factors, which are affective, cognitive and behavioural. The study population consisted of individuals who participated in eco-recreation activities in Turkey. The data were collected through a questionnaire form using the convenience sampling method. The analyses were conducted using SmartPLS. The findings showed that biospheric (positive) and egoistic value (negative) had an effect on ecological worldview, while ecological worldview had a positive effect on affective, cognitive and behavioural attitude. Also, the altruistic value did not significantly affect the ecological worldview.
- MakaleAçık Erişim2023Engineering Properties of Cemented Paste Backfill with Full-Range Water-Reducing Admixture
Cavusoglu, Ibrahim; Fall, Mamadou
This paper presents the effects of a full-range water-reducing (FRWR) admixture on the key engineering properties of cemented paste backfill (CPB). CPB samples with a certain slump are prepared with 4.5% cement by mass of the tailings and different dosages of an FRWR admixture (superplasticizer contents of 1%, 3%, and 5%) to evaluate their water demand during hydration, rheological properties, self-desiccation ability, and microstructural and mechanical properties. Moreover, cement paste samples with a high water-to-cement ratio (w/c = 2) which are used to model the cement matrix of the CPB are prepared for x-ray diffraction (XRD) scanning and thermal analyses (TAns). The results show that the addition of an FRWR admixture to the studied CPB can reduce its water demand by up to 23% and significantly increase its strength from 1.0 MPa to 2.38 MPa (by approximately 2.4 times) at 28 days. The pore volume of the CPB samples is also significantly reduced from 27.17 to 18.27% due to the capability of the FRWR admixture to reduce water demand. Also, the addition of an FRWR admixture to the CPB results in a substantial decrease (up to 83%) of its yield stress, thereby improving its flowability. The CPB samples with an FRWR admixture are found to have a higher negative pore water pressure, i.e., higher self-desiccation, than the CPB sample without an FRWR admixture. The microstructural analysis also shows that the FRWR admixture has an increasing effect on the hydration products in the CPB mixture.
- MakaleYalnız künye2023Mechanical Properties of Shotcrete Produced with Recycled Aggregates from Construction Wastes
Külekçi, G.; Çullu, M.; Yilmaz, A.O.
Abstract: This study examines the usability of concrete wastes generated from buildings demolished for various reasons in shotcrete. The strength properties of shotcrete produced from recycled aggregates (RA), cylinder specimen and plate specimen were tested. it was observed that as the ratio of RA used instead of natural aggregate increases, the strength of the cylinder specimen decreases, ultrasonic pulse velocity increases. The toughness value has increased in the concrete samples prepared by replacing the natural aggregate with 50% or more RA. It was observed that the fiber amount and load carrying capacity were proportional in fiber reinforced plates prepared using RA. As a result, it has been observed that the interaction of RA with fiber is positive and it can be used in shotcrete. It has been revealed that RA can contribute to the reduction of environmental pollution caused by construction and wreckage wastes and can be presented as an alternative to natural aggregate.
- MakaleAçık Erişim2023Comparison of the removal efficiencies of Basic red 46 from aqueous solutiousing Aşkale lignite with and without ultrasound assisted processes
Karaca, Canan; Karaca, Melike; Kıranşan, Murat; Karaca, Semra; Açışlı, Özkan; Gürses, Ahmet
This study compared the removal efficiencies of Basic red 46 from aqueous solutions with and without ultrasound-assisted processes using lignite as a low-cost adsorbent. The effects of various experimental parameters such as contact time, adsorbent dosage, initial solution, pH, initial dye concentration and temperature on the dye removal efficiency were investigated. The experimental results were modelled by the kinetic and isotherm models. Both of processes fitted well to pseudo-second-order kinetics and the Langmuir model with highest correlation coefficients for all of three temperatures. The results showed that the influence parameters have a different effect on the removal efficiency in the presence and absence of ultrasonic irradiation. When the results obtained for both processes are compared, it is seen that the removal efficiency obtained with the ultrasound assisted process is much higher than that obtained with non-ultrasound assisted process at high dye concentrations. The removal efficiency of ultrasound-assisted and unassisted processes was found to be 81.5% and 54.6%, respectively, at 80 mg/L dye concentration and 60 min. Thermodynamic parameters showed that the adsorption process was spontaneous and exothermic. The enthalpy and entropy changes for the ultrasound-assisted process were –9.35 kJ/mol and –0.03 kJ/K·mol, respectively.
- MakaleYalnız künye2023Investigating the environmental Kuznets curve hypothesis with recovered paper consumption, human development index, urbanization, and forest footprint
Aydin, M.; Koc, P.; Tumay, M.
The aim of this study, which covers the period from 1991 to 2017, is to analyze the relationships between recovered paper consumption, human development index, urbanization rate, and forest footprint in the framework of the Environmental Kuznets Curve (EKC) hypothesis in the 10 countries that consume the most recovered paper. Considering that wood is the raw material of paper, the study investigates whether the increase in the consumption of recovered paper has a positive effect on the forest footprint. Therefore, unlike other studies, the dependent variable of the EKC model is the forest footprint. The study is original in that it is the first to analyze the effects of recovered paper consumption on environmental degradation in the context of the EKC hypothesis. To analyze the relationships between the variables, we use panel cointegration tests based on AMG and CCE estimators, which allow analysis on both a country and group basis. According to the results, the EKC hypothesis is valid only in the Netherlands. While there is a statistically significant and negative relationship between recovered paper consumption and forest footprint in the Netherlands, there is a statistically significant and negative relationship between urbanization and forest footprint in Italy. Economic and ecological benefits and costs must be considered to measure the net benefit of waste management programs. In addition, to analyze how environmental impacts change over time, ecological footprint and gas emissions during waste generation or disposal should be measured similarly to carbon emissions.
- MakaleYalnız künye2023Examining the role of urban-industrial symbiosis in the circular economy: an approach based on N-Force field theory of change and N-ISM-Micmac
Erol, Ismail; Peker, Iskender; Ar, Ilker Murat; Searcy, Cory
The circular economy (CE) refers to a new industrial paradigm that contrasts with the linear supply chain structure based on a "take, make, use, dispose" pathway. Due to its potential contributions to improving the CE, industrial symbiosis (IS) has been recognized as a feasible way to advance it. Urban symbiosis is an extension of IS that involves a series of symbiotic relationships among enterprises within the urban area. Combining urban and industrial symbiosis (Ur-IS) is a step toward better resource efficiency in urban areas and industrial zones and urban areas. However, while there are several driving forces for Ur-IS adoption, there are also many inhibiting factors. A comprehensive decision framework is needed to address the principal drivers and challenges for Ur-IS initiatives. Türkiye, designated as a candidate for full EU membership in 1999, also places importance on environmental sustainability goals and effective resource management in its own move towards a CE. Our literature review concluded that there is only one quantitative study investigating the driving and (or) restraining forces for Ur-IS adoption in emerging and industrialized countries. The main purpose of this study is to investigate the potential of Ur-IS implementation in Türkiye through the proposed Neutrosphopic-Simple Additive Weighting Method-based force field theory of change and the Neutrosphopic–Interpretive Structured Modeling-Cross-Impact Matrix Multiplication Method. The findings suggest that lack of policies, lack of incentives and regulations, and vulnerability and supply uncertainty are the most significant restraining forces for Ur-IS implementation in Türkiye. The research findings can assist decision-makers in Türkiye in effectively implementing Ur-IS.
