Sürdürülebilir Kalkınma Amaçları
Yazarlar
- Dogan, Akar(5)
- Kismet, Yilmaz(5)
- Cemalgil, Selim(4)
- Etli, Serkan(4)
- Wagner, Manfred H.(4)
- Guler, Omer(3)
- Yön, Merve Şahin(3)
- ALMisned, Ghada(2)
- Akgül, Melek(2)
- Akkurt, Nevzat(2)
- Aslan, Naim(2)
- Bahceci, Ersin(2)
- Chen, Xingli(2)
- Gul, Ali Oktay(2)
- Gönen, Tahir(2)
- Kısmet, Y.(2)
- Kısmet, Yılmaz(2)
- Onat, Onur(2)
- Qiang, Yujie(2)
- Taşgın, Yahya(2)
- Tekin, H.O.(2)
- Xiong, Yaxuan(2)
- Xu, Qian(2)
- Yang, Gang(2)
- Yilmaz, Mehmet(2)
- Zheng, Qiang(2)
- Zhong, Liqiong(2)
- Zou, Zhenwei(2)
- Acikgoz, Abuzer(1)
- Agar, Salih(1)
- Akpolat, Mustafa(1)
- Aksakal, B.(1)
- Aksakal, Bunyamin(1)
- Aktas, Bulent(1)
- Albayrak, M. Gokhan(1)
- Arman, Yusuf(1)
- Arslan, Furkan(1)
- Arıkan, Volkan(1)
- Askin, Ali(1)
- Aydoğmuş, Ercan(1)
Yayınlar
- MakaleAçık Erişim2026Scopus SJRQ2Sustainable epoxy based biocomposites reinforced with Melilotus officinalis: Structural, mechanical, thermal, and dielectric performance evaluation
Solmaz, Adnan; Açar, Mikail; Demirel, Maruf Hurşit; Deniz, Şermin; Aydoğmuş, Ercan
The aim of this study is to investigate the manufacturability of Melilotus officinalis (L.) reinforced epoxy biocomposites as a renewable biofiller and to characterize the mechanical, thermal, and dielectric properties of these materials. For this purpose, composites containing biomass at 0, 3, 6, and 9 wt.% were prepared; the samples were examined by tensile testing, FTIR, SEM, EDX, XRD, Shore D hardness, thermal conductivity, and dielectric analysis. The findings showed that with increasing M. officinalis content, tensile strength, hardness, and density decreased, while ductility and elongation at break improved. The significant decrease in thermal conductivity revealed an increase in heat insulation efficiency. Dielectric analyses showed that strong interfacial polarization occurred at low frequencies, and the dielectric constant and loss values decreased as the frequency increased. SEM examinations confirmed that the plant-derived filler was homogeneously distributed and formed acceptable interfacial adhesion with the matrix. In conclusion, although the use of synthetic epoxy matrix and the decrease in mechanical strength limit load-bearing structural applications, M. officinalis is a promising biofiller for lightweight and partially bio-based epoxy composites thanks to its increased ductility and improved thermal insulation properties. © The Author(s) 2026. This article is distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 License (https://creativecommons.org/licenses/by-nc/4.0/) which permits non-commercial use, reproduction and distribution of the work without further permission provided the original work is attributed as specified on the SAGE and Open Access pages (https://us.sagepub.com/en-us/nam/open-access-at-sage).
- MakaleAçık Erişim2026Scopus SJRQ1Freeze–Thaw Performance and Microstructural Stability of Alkali-Activated Slag Mortars Incorporating Mussel Shell Waste
Şahin Yön, Merve
This study investigates the use of mussel shells (MSs), a biogenic by-product of the food industry, as a partial replacement for ground granulated blast furnace slag (GBFS) in alkali-activated mortars. Given their high CaCO3 content, MSs represent a sustainable secondary raw material that reduces both waste disposal burden and reliance on natural resources, while offering a low-carbon alternative to conventional cement-based binders. Alkali-activated mussel shell/slag mortars (AAMSs) were produced with MS replacement ratios of 0%, 5%, 10%, 15%, and 20% by mass of GBFS. Sodium hydroxide (NaOH) and sodium silicate (Na2SiO3) were used as alkaline activators. Fresh specimens were cured at 60 °C for 48 h. The experimental program included workability, compressive and flexural strength, water absorption, porosity, density, capillarity, ultrasonic pulse velocity (UPV), and freeze–thaw (F-T) resistance tests. Increasing MS content slightly reduced flowability and mechanical strength, while increasing water absorption, porosity, and capillarity. The M0 series achieved the highest 28-day compressive strength (54.06 MPa), while M15 exhibited the highest flexural strength (5.23 MPa). Following F-T cycling, the 5% and 10% MS series demonstrated the best compressive strength (30 MPa). The 10% MS exhibits a relatively balanced overall performance, providing the best balance between mechanical performance, F-T resistance, and microstructural stability, as confirmed by scanning electron microscopy (SEM)/energy-dispersive X-ray spectroscopy (EDS) analyses showing elevated Ca/Si ratios and the formation of Ca-rich crystalline phases.
- MakaleAçık Erişim2026Scopus SJRQ4Impact of Basalt Powder on the Physical, Fresh, Hardened and Microstructural Characteristics of Granulated Blast Furnace Slag-Based Alkali-Activated Mortars
Yön, Merve Şahin; Cemalgil, Selim
In this study, the workability, mechanical and physical aspects of alkali-activated mortar (AAM) containing basalt powder (BP) and granulated blast furnace slag (GBFS) were investigated. For the experimental study, alkali-activated mortars (AAM) containing BP at 8%, 16%, 24%, 32% and 40% substitution rates for GBFS were developed. Mortars were synthesized with a sodium silicate/sodium hydroxide ratio of 3.0 for the binder materials and a 0.45 alkali activator-to-binder ratio. The flow diameters of the fresh mortars prepared using 40x40x160 mm molds were determined according to the European Federation of Experts in Construction Chemicals and Concrete Systems (EFNARC) standard. The fresh AAMs were wrapped in stretch film to prevent evaporation and then kept in an oven at 60°C for 48 hours. The cured samples were evaluated for their mechanical strengths at 3 and 28 days, freeze-thaw effects after 33 and 100 cycles, and microstructures after 100 cycles. According to the results, using 40% BP instead of GBFS caused a decrease of approximately 15.08% in 28-day compressive strength compared to the reference sample (100% GBFS). G100 showed a minimum porosity of 15.81% and a water absorption rate of approximately 7.3%. The G60B40 mixture had the highest sorptivity capacity with 5.29x10-3 cm/s0.5, while the G100 mixture showed the lowest capacity with 3.88x10-3 cm/s0.5. After 100 freeze-thaw cycles, the G60B40 sample had the largest strength loss of 61.61%, while the G100 sample showed the lowest strength loss of 9.89%.
AtıfScopus1
İncele - MakaleYalnız künye2026Scopus SJRQ2Influence of Boron Addition on the Microstructure, Mechanical, and Corrosion Behavior of NiCrBSi Alloys Prepared by Spark Plasma Sintering
Çelik, Ertuğrul
This study investigates the effect of boron addition on the microstructural, mechanical, and corrosion properties of NiCrBSi alloy fabricated by the spark plasma sintering (SPS) method. Boron was added at levels of 1.5, 3, and 4.5 wt.%, and sintering was conducted at 950 °C for 5 min. Microstructural characterization was carried out using SEM–EDS and XRD analyses, hardness was measured by the Vickers method, and densities were determined according to Archimedes’ principle. The transverse rupture strength (TRS) was obtained by three-point bending tests, while wear performance was evaluated in a reciprocating wear mode. Corrosion behavior was examined through potentiodynamic polarization in a 0.1 M HCl solution. Increasing boron content promoted the formation of nickel and chromium boride phases, enhancing hardness (up to 675 HV0.5) and wear resistance but reducing TRS values due to brittle intermetallic formation. Furthermore, corrosion protection efficiency improved, reaching about 65.9% at 4.5 wt.% B addition.
- BildiriAçık Erişim2025Investigation of Mechanical Properties of Hot Mix Asphalt Modified with Elvaloy and Polyphosphoric Acid
Yilmaz, Mehmet; Yalcin, Beyza Furtana; El Naggar, H.; Barros, J.; Cachim, P.
In order for the bituminous hot mix layers to resist the increased traffic load and volume as well as the adverse environmental conditions for a long time without being deformed, the bituminous binder used in the mixture has been commonly modified with the Styrene-Butadiene-Styrene (SBS) polymer. The high demand for SBS makes it difficult to supply and therefore brings on the use of alternative additives. In this study, the combined use of Elvaloy and phosphoric acid (PPA) was investigated. Additionally, the effects on the mechanical properties of bituminous mixtures were examined. Modified binders were prepared using Elvaloy/PPA additives mixed under specified conditions. Hot mix asphalt (HMA) samples prepared with these binders were subjected to Marshall stability and flow, indirect tensile stiffness modulus, and indirect tensile fatigue tests to comprehensively evaluate the effects of modified bi nders on the mechanical properties of bituminous hot mixtures. As a result, the bituminous hot mix tests revealed that asphalt mixtures improved their mechanical properties at the specified ratios.
- MakaleYalnız künye2025Scopus SJRQ2Investigation of Mechanical Properties of Jute and Tea Waste-Reinforced Epoxy Composite Material Produced by Vacuum Assisted Resin Infusion Molding
Dogan, Akar; Mahmat, Aybars; Agar, Salih
Recently, the production of materials obtained from plant sources has been increasing due to their environmentally friendly and sustainable sources. Natural fibers and waste materials offer a remarkable alternative in composite production due to their biodegradability, low cost and renewability. In this study, composite materials were produced using hybrid Jute and industrial tea waste-reinforced epoxy materials by vacuum assisted resin infusion molding. In this context, the reason for using natural and industrial resources such as jute fiber and tea waste is to contribute to both the improvement of mechanical properties and the reduction of environmental impacts. It was observed that tensile and flexural strength decreased as the amount of tea waste increased. Conversely, the energy absorbed during the quasi-static punch shear and Charpy impact tests increased, unlike the tensile and flexural strength. Approximately 50% decrease was observed in the tensile strength of the 60% tea waste reinforced material compared to the pure jute composite material. In Charpy impact and quasi-static punch shear tests, a 5% increase in the energy absorbed in the 60% tea waste reinforced composite materials was obtained.
AtıfScopus2WoS1OpenAlex1
İncele - MakaleYalnız künye2025Scopus SJRQ1Multivariable assessment of ınfill strategies for enhanced mechanical properties in 3D-printed curved beams
Arıkan, Volkan; Dogan, Akar
Purpose – This study specifically focuses on low-to-medium infill densities where the influence of internal geometry on structural performance becomes most dominant. This study aims to explore how different infill patterns and densities affect the mechanical response of curved-axis beams produced by fused filament fabrication-based additive manufacturing (AM), providing insights for optimizing lightweight and material-efficient components subjected to bending loads. Design/methodology/approach – Twenty-seven PLA-based specimens with varying curvature radii (500, 750 and 1000 mm), infill patterns (grid, triangular and trihexagonal) and densities (20%, 30% and 40%) were manufactured. Each was subjected to three-point bending tests following ASTM standards. The experimental approach focused on analyzing force-displacement behavior to evaluate stiffness, load capacity and deformation characteristics under static loading conditions. Findings – Increasing infill density enhanced the maximum force capacity of curved beams but reduced their displacement tolerance, reflecting greater rigidity. The trihexagonal (TH) pattern exhibited the highest displacement values, confirming its energy absorption capability, while the triangular (TA) pattern provided the greatest rigidity with lower deformation. The grid (GR) pattern showed intermediate behavior, with displacement capacity strongly influenced by curvature radius. Straighter beams generally displayed reduced displacement and higher stability, while more curved beams exhibited greater deformation. These results highlight the critical role of infill geometry and curvature in balancing strength, stiffness and energy absorption in three-dimensional (3D)-printed curved beams. Originality/value – Unlike prior studies that focus on high or near-solid infill levels, this work uniquely highlights the mechanical response of additively manufactured curved beams within the low-to-medium infill density range, where infill geometry plays a critical role. The study presents the first detailed comparison of how infill strategies interact with curvature in 3D-printed beams. It delivers practical design guidance for engineers working with curved structures in mechanical, aerospace and civil applications. Its novelty lies in demonstrating how trihexagonal patterns can optimize performance across various geometries, supporting enhanced structural resilience in AM.
- MakaleAçık Erişim2025Scopus SJRQ2Effect of Tungsten Content on the Microstructure, Mechanical and Tribological Properties of AlCoCrFeNi High-Entropy Alloys
Bahceci, Ersin; Gul, Ali Oktay; Basgoz Orhan, Oykum; Kumruoglu, Levent Cenk; Guler, Omer
High-entropy alloys (HEAs) have recently attracted considerable attention due to their unique combination of high strength, hardness, and corrosion and wear resistance, making them promising candidates for advanced structural and functional applications. Among these, AlCoCrFeNi-based HEAs are well known for their high hardness and good wear resistance; however, their limited tribological stability under operational conditions restricts their broader application. To address this limitation, tungsten (W) was incorporated into the AlCoCrFeNi system to enhance its mechanical and tribological performance. In this study, the microstructural, mechanical, and tribological properties of AlCoCrFeNiWx (x = 0, 0.1, 0.25, 0.5 and 1 mol) HEAs were systematically investigated. The alloys were fabricated using the vacuum arc melting method and characterized by XRD, SEM-EDS, elemental mapping, microhardness, and wear tests. The addition of W caused a shift in the 2θ ≈ 44° (110) peak toward lower angles. While the W-free alloy exhibited Body-Centered Cubic (BCC) + B2 phases, W addition led to the formation of a new W-rich phase, and at higher W contents, a pure W phase appeared. The hardness increased from 507.11 HV1 to 651.81 HV1 with increasing W content. Furthermore, wear resistance improved and the coefficient of friction decreased with higher W addition. When comparing the W-free alloy to the alloy with the highest W content, the wear rate decreased by approximately 1.85 times under a 2 N load and 1.89 times under a 5 N load. These results demonstrate that W addition significantly enhances the wear resistance of AlCoCrFeNi-based HEAs by nearly twofold.
AtıfScopus1WoS1OpenAlex1İncele - MakaleYalnız künye2025Scopus SJRQ3Development of alternative carbon fibre powder and rare earth element-based filler for high density polyethylene; [Entwicklung von alternativen Kohlenstofffaserpulvern und Seltene Erden-basierten Füllstoffen für Polyethylen hoher Dichte]
Ayikurt, P.; Kısmet, Y.; Dogan, A.; Höchstötter, K.H.; Fiedler, B.
This study developed alternative fillers to enhance the flowability of high-density polyethylene (HDPE). Lanthanum and cerium oxide with over 90 % purity were used as binder interfacial elements in fillers developed using both carbon fiber powder wastes and powder coating wastes. Polyethylene gel was used to make the fillers thermoplastic and homogenous. A total of six different fillers were developed and melt flow index analyses were performed. As a result of these analyses, it was found that the fluidity of high-density polyethylene improved significantly, especially with fillers containing carbon fiber powder. As a result, high-density polyethylene mixtures containing 10 %, 20 %, 30 %, 40 %, and 50% by weight of carbon fiber powder-based fillers were pressed into molds by a plastic injection molding machine, and samples were produced. According to the mechanical analysis results of these specimens, tensile and flexural strengths decreased slightly depending on the filling ratio, while the impact strengths remained constant. Differential scanning calorimetry analysis was performed to determine the glass transition temperature and melting/crystallization temperatures of the obtained mixtures, while thermogravimetric analysis was performed to determine the mass losses. At the same time, electron microscope analysis of the cross sections of the samples were performed.
- Derleme MakaleYalnız künye2025Scopus SJRQ1A short review of structural, mechanical and magnetic properties of high and medium entropy alloys added rare earth elements
Yayla, Nihal; Güler, Ömer
This study presents a comprehensive review of the structural, mechanical and magnetic properties of high and medium entropy alloys (HEA and MEA) with rare earth elements (REE) additions. The addition of REE has been shown to have significant effects on phase transformations, microstructural arrangements and thermodynamic stability. Studies in the literature show that REE addition improves properties such as hardness, strength, deformation resistance and magnetic performance. In particular, changes such as transitions from FCC to HCP, formation of intermetallic phases and grain refinement have been observed in phase types with the addition of elements such as Gd, Y and Nd. REE added HEAs offer great potential for modern engineering and advanced technology applications with their superior magnetic moments, magnetocaloric effects and thermal stability. However, there is limited information in the literature on REE added HEAs. This review aims to provide a comprehensive framework for the development of REE added HEAs and to serve as an important reference point for future research.
AtıfScopus7WoS7OpenAlex6İncele - MakaleAçık Erişim2025Scopus SJRQ1Improvement of mechanical, dynamic mechanical, and thermal properties of almond shell powder reinforced acrylonitrile butadiene styrene composites by addition of cerium oxide
Doğan, Akar; Güneş, Çağdaş
Currently, natural materials are gradually replacing synthetic materials in polymer composites due to factors including cost-effectiveness, sustainability, and the availability of raw materials. This study examined the variations in thermal, mechanical, and dynamic mechanical properties of acrylonitrile butadiene styrene (ABS) thermoplastic composite materials incorporating varying ratios of almond shell powder (ASP) and Cerium Oxide (CeO2). Tensile tests, three-point bending tests, dynamic mechanical analyses, and thermogravimetric analyses were conducted. Scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) analyses were employed to assess pure ABS and nine distinct composite materials. The tensile strength, elastic modulus, and three-point bending strength of the composite material exhibited increases of 6%, 7%, and 7.5%, respectively, compared to pure ABS, with various ratios of almond shell powder and CeO2 reinforcement. Moreover, composite materials exhibit elevated glass-transition temperatures and storage moduli compared to pure ABS. Microstructure images obtained through SEM and EDS element mapping illustrate the distribution of ASP and CeO2 in ABS, influencing its mechanical and thermal properties. Highlights: Almond shell powder and cerium oxide were used as filler materials in ABS. Mechanical, morphological, and dynamic mechanical properties were investigated. Almond shell powder enhanced the mechanical properties of the ABS composite. Low cerium oxide supplementation improved the mechanical properties.
AtıfScopus4WoS4OpenAlex5İncele - MakaleAçık Erişim2024Scopus SJRQ2Titanium alloys: A closer-look at mechanical, gamma-ray, neutron, and transmission properties of different grade alloys through MCNPcode application
ALMisned, Ghada; Guler, Omer; Sen Baykal, Duygu; Kilic, G.; Tekin, H.O.
Titanium alloys play a vital role in optimizing the effectiveness and security of nuclear reactors, strengthening structural durability, and facilitating the effective handling of nuclear waste. The aim of this study is to investigate the gamma-ray, neutron, and transmission properties of four common titanium alloys through the examination of the deposited energy amount in the liquid sodium coolant material, in relation to the mechanical properties of these alloys. MCNP (version 6.3) is utilized for designing the titanium pipes. Next, the pipes were re-designed considering the elemental mass fractions and densities of the investigated titanium alloys. Grade 26 sample is reported with the highest values of mass attenuation coefficients and the lowest HVL values among those investigated alloys. Grade 26 is reported to have the lowest TF value, whereas Grade 12 demonstrated the highest TF value. The highest Effective Removal Cross Section (ΣR, 1/cm) value against fast neutrons is reported for Grade 26. The utilization of Grade 26 sample as pipe material resulted in the lowest deposited energy amount (MeV/g) and subsequent lowest contamination in the coolant material. Out of the alloys that were chosen for analysis, it has been determined that Grade 26 exhibits the highest level of strength. It can be concluded that the Grade 26 alloy exhibits desirable characteristics for applications in nuclear technologies that require superior gamma-ray and neutron absorption properties, as well as exceptional mechanical properties. Nevertheless, it is essential to emphasize the importance for ongoing studies to enhance the existing material properties of Grade 26, with the aim of achieving improved safety and efficacy in nuclear applications.
AtıfScopus11OpenAlex11İncele - MakaleYalnız künye2024Scopus SJRQ3Powder coating waste filler in high-density polyethylene – Variations in morphology, mechanical and thermal performance; [Variationen in Morphologie, mechanischer und thermischer Leistung von Pulverlackrecyclaten als Füllstoff in Polyethylen mit hoher Dichte]
Kısmet, Y.
In the present study, electrostatic powder coating waste was recycled and employed to reinforce high-density polyethylene. The hydrolysis method was preferred to modify the powder coating waste of various systems, and they were mixed with high-density polyethylene at various weight ratios. The mixtures were prepared in a mechanical mixer and then in an extruder to obtain a homogeneous mixture. This homogeneous structure was pressed into molds with a plastic injection device to obtain standard tensile samples. Mechanical and thermal tests were conducted on the samples. It was determined that the tensile stress of the sample decreased with the increase in filler content. The changes in sample tensile strength were investigated after the samples were aged. Three-point bending strength of the samples was also investigated and it was observed that they became more resistant to vertical loads as the filler content increased. The Izod impact strength of the samples differed based on the filler type and weight ratio. Furthermore, mass loss in the produced mixtures was determined with thermogravimetric analysis. The matrix and filler bonding mechanisms were observed under an electron microscope.
AtıfScopus1WoS1OpenAlex1İncele - MakaleYalnız künye2024Scopus SJRQ1Influence of praseodymium oxide on the structural, mechanical and photon, charged particles, and neutron shielding properties of alumina borate glass
Acikgoz, Abuzer; Izguden, Ilyas; Tasgin, Yahya; Yilmaz, Demet; Demircan, Gokhan; Kalecik, Sedanur; Aktas, Bulent
The structural, mechanical and radiation shielding properties of (69-x)B2O3-20TeO2-10Al2O3-1HfO2-xPr6O11 (where x = 0, 0.25, 0.5, 0.75, 1 mol %) glass system were investigated. This study introduces a novel approach by incorporating Pr6O11 into glass composition, highlighting its unique contributions to enhancing elastic properties, fracture toughness, hardness, and radiation shielding abilities. Experimental measurements were conducted within the energy range of 59.54–661.62 keV and theoretical calculations are made for MAC values. The presence of Pr6O11 was noted to positively influence the gamma shielding capabilities. At 59.54 keV, the addition of 0.25 mol% Pr6O11 increased the mass attenuation coefficient of the glass by 2.9 %, and the addition of 1 mol% Pr6O11 increased it by 29.8 %. The addition of 0.25 mol% Pr6O11 increased the fast neutron removal cross section of the glass by 4.4 %. Also, it is observed that the glass with 1 mol% Pr6O11 is the best shielding material against alpha and proton particles. A significant enhancement of 24.36 % in the fracture toughness value was observed, increasing from 1.059 to 1.317 MPa m1/2 at 1 mol% Pr6O11. Experimental hardness values increased from 3.374 to 3.985 GPa, resulting in an improvement of 18.11 % at 1 mol% Pr6O11. The thermal stability (ΔT, °C) value demonstrated a notable increase from 85 to 106, indicating a significant 24.7 % improvement at 0.25 mol% Pr6O11.
AtıfScopus58WoS57OpenAlex60İncele - MakaleAçık Erişim2024Scopus SJRQ2Development of rare earth element and carbon fiber-based filler for polyethylene—Mechanical and thermal performance
Kısmet, Yılmaz; Ayikurt, Pamuk
In the present study, three fillers produced with carbon fiber powder (CFP) and rare earth elements were developed for low-density polyethylene production. These fillers included CFP with a grain size of less than 400 microns and over 90% pure lanthanum and cerium oxides. Polyethylene was employed to ensure the thermoplasticity and homogeneity of the fillers. The fillers were mixed with the matrix material separately, first mechanically and then homogenously in the extruder, then the test bars were produced with an injection machine. In the mechanical tests, it was determined that the tensile strength of the test bars improved by ~20% and the elastic region increased due to the increasing amount of filler. Similarly, an improvement of about 40% in bending stress was realized. In addition, as the fluidity of the mixtures has improved, it has been possible to produce at lower temperatures and save energy in the production. Thermogravimetric analysis was conducted to determine the melting/crystallization temperatures and material losses in the compounds. The scanning electron microscope analysis showed that the fillers were irregularly distributed on the surface in parallel and perpendicular directions. In addition, x-ray diffraction and energy dispersive spectroscopy analyses were performed on the surfaces.
AtıfScopus1WoS1OpenAlex1İncele - MakaleYalnız künye2024Scopus SJRQ1Investigation of the variation of mechanical and durability properties of elements manufactured with rubber substituted SCMs with element height
Akgül, Melek; Etli, Serkan
Controlling the homogeneous distribution of granulated rubber materials added to self-compacting concrete/mortars along the height is of great importance in terms of preserving and defining the holistic behavior of structural elements. In this study, the effect of EPDMGR (ethylene propylene diene monomer granulated rubber) ratio (0 %, 5 %, 10 %, 15 %, 20 % and 25 %), test age, L/D (slenderness ratio) and element test zone (bottom, middle and top) on the mechanical properties (flexural and compressive), durability properties (porosity and sorptivity) of the elements produced with SCM were evaluated. The results obtained were statistically evaluated by GLM-ANOVA. It was observed that flexural tensile strength was strengthened up to 5 % substitution rate due to the hydrophobic properties and elasticity properties of EPDMGR used, while porosity values increased with height in the upper regions compared to the lower regions due to the placement properties of SCM. Differences in compressive strength appeared in the upper and lower sections after 5 % EPDMGR substitution. This indicates that for the mixture properties used, the properties examined in terms of mechanical and durability test results may have different properties with limited variability in terms of L/D ratio depending on the EPDMGR ratio used and the region where the element was taken.
AtıfScopus7WoS7OpenAlex10İncele - MakaleAçık Erişim2024Scopus SJRQ1Effect of curing conditions on cement based self-compacting mortar produced with mortar waste aggregate
Akgül, Melek
Concrete and mortar wastes, which have a large volume and economic value among construction demolition wastes, are the most targeted demolition waste group to be recycled. An important area where construction demolition waste can be utilized is self-compacting mortar (SCM) systems. SCMs are innovative and economical systems designed to minimize the labor requirements that are difficult to meet in the production process. In this study, mortar waste aggregate (MWA) obtained by mechanical crushing and grinding was used in SCM elements by substituting different ratios (5-10-20-30-40 %) by mass to aggregate. In this way, it was aimed to evaluate both the sustainability of MWAs and the usability of MWAs in SCMs, which are considered as a new production technology. The fresh and hardened mortar tests performed in the study are presented comparatively. The physical (dry unit volume weight, porosity), durability (capillary water absorption) and mechanical properties (flexural tensile, compressive strength) of the hardened SCM elements are based on the determinations made at 3, 7 and 28 test days and according to different curing conditions (water curing, air curing and heat curing). In addition, X-ray Diffractometer (XRD) analysis was performed on specimens obtained from 0 %, 10 %, 20 % and 40 % MWA substituted specimens after heat curing (after 7 days water curing) and 28 days water curing. In the light of the data obtained, it is reported that SCM production with 10 % MWA substitution is feasible in terms of sustainability and engineering properties evaluated in this study.
AtıfScopus2WoS1OpenAlex2
İncele - MakaleYalnız künye2024Scopus SJRQ1Effects of Er2O3 contribution on microstructure and mechanical properties of high entropy and dual phase alloys
Taşgın, Yahya; Malkoç, Aziz; Kanca, M. Sait
The study aimed to look at the differences between a high entropy alloy and a dual phase high entropy alloy with high iron and Mn content. It also wanted to find out what happened when a small amount of the rare earth element erbium oxide (Er2O3) was added to these alloys, especially on the mechanical and microstructure of the alloy. The first step in this study was to get 99 % pure metal powders, which were then made by dividing the powders into 30 g of equal weight. The powders were mixed evenly and then pressed into 10-g blocks under 6 tons of pressure. They were then set up to be melted in an arc. Four of the eight samples that were melted in an arc under vacuum were treated with heat. The four different compositions were then turned into small metallographic samples for SEM, EDX, Mapping, XRD, and microhardness tests. The study's imaging and analysis processes were also carried out. After that, SEM images were taken at various magnifications (100X, 500X, 1000X, 2500X, and 5000X), and EDS and XRD analyses were done on different structures found in these images. These analyses were based on literature research about the clarity of the metallographic images in the alloy, which showed the study's metallographic differences. The samples were put through microhardness and wear tests to see which one was stronger and less worn. The dual phase high entropy alloy (A2) was stronger and less worn than the high entropy alloy (A1). Er2O3 had little effect on the alloys' mechanical properties or microstructure. The heat treatment that was done to the samples helped the metallographic structure. In terms of physics, it didn't change the hardness much, but it did make the material wear less quickly.
AtıfScopus1WoS1OpenAlex1İncele - Yüksek Lisans TeziAçık Erişim2023Karbon elyaf takviyeli polietilenin mekanik, termal vefiziksel özelliklerine nadir toprak elementlerinin etkileri
Pamuk Ayikurt
Bu çalıĢmada termoplastiklerin önemli bir üyesi olan polietilenin mekanik, termal ve morfolojik özellikleri üzerine karbon elyaf tozu ve nadir toprak elementlerinin etkileri incelenmiĢtir. Polietilen olarak alçak yoğunluklu (AYPE) ve yüksek yoğunluklu (YYPE) polietilenler ayrı ayrı çalıĢılmıĢtır. Nadir toprak elementi olarak ise %90 ve üzeri saflıkta lantan ve seryum oksitler kullanılmıĢtır. Öncelikle bu elementler saf suda ayrı ayrı çözüldükten sonra karbon elyaf tozu bu çözeltilere karıĢtırıldı. Lantan ve seryumun karbon elyafa emilimi sağlandıktan sonra bu karıĢımlar hazırlanan alçak yoğunluklu polietilen çözeltisi içerisine dökülerek termoplastik karakterde takviye elemanı geliĢtirildi. Lantan ve seryum esaslı olarak ayrı ayrı elde edilen bu takviye elemanları kurutulup granül hale getirildikten sonra çalıĢmada kullanılacak olan matris malzemeler (AYPE ve YYPE) ile ayrı ayrı ağırlıkça %5, %10, %20 ve %30 oranlarında önce mekanik olarak daha sonrada uygun sıcaklıklarda ekstrüzyonda homojen olarak karıĢtırıldı. Ekstrüzyonda homojen hale getirilen bu karıĢımlar ekstrüzyon çıkıĢında soğutuldu ve akabinde kırıcıdan geçirilerek granül hale getirildi. Elde edilen bu granüller plastik enjeksiyon makinası ile kalıplara basılarak standart çekme çubukları üretildi. Üretilen bu çekme çubuklarının mekanik olarak çekme, eğilme, izod darbe ve sertlik analizleri gerçekleĢtirildi. Elde edilen karıĢımların camsı geçiĢ sıcaklıkları, erime sıcaklıkları ve kütle kayıplarının belirlenmesi için ise TGA/DTA analizi yapıldı. Aynı zamanda matris ve dolgu arasında ki bağlanma mekanizmasının belirlenmesi için ise numunelerin kesit görüntüleri elektron mikroskobu ile incelendi. Hem AYPE hem de YYPE içerisinde artan takviye elemanı miktarına bağlı olarak değiĢimler grafiklerle gösterilerek tartıĢıldı.
- MakaleAçık Erişim2023Scopus SJRQ4Using the Taguchi Method to Optimize the Compressive Strength of Concrete in Different Aggregates Typology; [Farklı Tipolojideki Doğal Agregalı Betonların Basınç Dayanımını Optimize Etmede Taguchi Metodunun Kullanımı]
Gönen, Tahir; Cemalgil, Selim
Concrete quality is affected by many factors such as mixing ratios, material quality, transporting, placing and curing. One of the crucial factors that changes the compressive strength of concrete is aggregate which makes up 75% of concrete during concrete production. Properties of aggregate are more unstable than other materials depending on various reasons. Granulometry, moisture or organic substance amount of the aggregates which have same origin may differ within time. This study investigates physical and mechanical properties of crushed limestone and crushed river aggregates. It is on optimum design of concrete with crushed limestone and crushed river aggregates. At first, physical and mechanical properties of the aggregates are measured, then Taguchi method is applied. Test variables are water-to-binder ratio, cement dosage, river sand ratio to limestone and air entrained agent. L16 orthogonal array as an experimental design method is applied to determine the optimum concrete design in terms of compressive strength and flexural strength. Furthermore, contribution of variables on compressive and flexure strength is determined statically by using ANOVA method. Among the 4 different aggregate ratios evaluated in the study, the best performance is from the combination of 70% stream and 30% limestone. The weakest performance is from the series that do not contain any stream material.
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