Yazar "Emiroglu, Mehmet" seçeneğine göre listele

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    Comparison of the effect of basalt and glass fibers on the fracture energy of asphalt mixes using semi-circular bending test
    (Elsevier Sci Ltd, 2023) Serin, Sercan; Onal, Yakup; Emiroglu, Mehmet; Demir, Eren
    This paper has focused on the effect of basalt and glass fibers in HMA in terms of crack formation and damage mechanisms. The experimental study was carried out under two stages; i) defining optimum fiber lengths and rates based on Marshall Stability performances using three different fiber lengths (4 mm, 12.5 mm, 22.5 mm) and three different fiber rates (0.75%, 1.00% and 1.5% by weight), ii) examining of fracture tests by using the op-timum fiber values (4 mm fiber length and 0.50%, 0.75%, 1.00% fiber content by weight) obtained from the first stage. Fracture energy characteristics of HMA mixtures were examined via Semi-Circular Bending (SCB) test. A total of 24 SCB test specimens from 6 different series, B-0.50, B-0.75, B-1.00, G-0.50, G-0.75, and G-1.00, were used in the experiments. Experimental results were discussed based on some basic physical properties, fracture energy (Gf), dissipated energy (DE), flexibility index (FI), and crack resistance index (CRI) values of HMA mixtures. When 0.50% basalt fiber is utilized in asphalt mixtures, the maximum peak load and Gf value are achieved. Moreover, using 1.00% basalt and 0.75% glass fiber in asphalt mixtures yielded the highest values of FI and CRI, respectively. Nevertheless, when 1.00% glass and 0.75% basalt fiber were added to asphalt mixtures, the minimum values of FI and CRI were obtained, respectively.
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    Examination of cryogenic durability in self-consolidating concretes through mechanical and fracture mechanics approaches
    (Elsevier, 2024) Yurt, Umit; Emiroglu, Mehmet
    Thermal shocks under extreme conditions, such as leakage in concrete-enclosed tanks, which are a popular choice for cryogenic liquid storage, may lead to undesirable effects on the structures. In this study, the effects of cyclic cryogenic exposures have been investigated using both mechanical and fracture mechanics approaches. To ensure durable concrete, self-consolidating concretes have been chosen in the mix design. While previous studies have primarily investigated the effects of a single cryogenic exposure on conventional concrete, this study focuses on repetitive exposure to cryogenic effects on self-consolidating concretes. Furthermore, the selfconsolidating concretes were subjected to two different curing conditions: air curing and water curing, before cryogenic processing, in order to consider real application conditions and laboratory circumstances. After the first and fifth cryogenic exposures, fundamental engineering properties and fracture mechanics parameters were evaluated. To determine the fracture mechanics parameters, beams of three different dimensions were produced, with three different notch lengths for each dimension. The dynamic modulus of elasticity, ultrasonic pulse velocity, compressive strength, and bending strength of self-consolidating concretes were examined after 0, 1, and 5 cycles of cryogenic exposure. As a result, the air-cured samples exhibited greater resistance to cryogenic cycles than the water-cured samples. The KIC and CTODC values increased after one cycle of cryogenic exposure, as noted in the literature. However, the results obtained in this study demonstrate a decrease in KIC and CTODC values after five cycles compared to one cycle of cryogenic exposure.
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    Investigation of the fracture energy of hot mixtures asphalt incorporating metallic wastes via semi-circular bending test
    (Elsevier Sci Ltd, 2021) Serin, Sercan; Emiroglu, Mehmet; Gonul, Veysel Ekrem
    In the study, metallic wastes were evaluated in order to reduce environmental impacts and to contribute fracture energy of HMA mixtures. In this context, aluminum chips and iron powders were included in the mixtures at 0.50%, 1.00%, and 1.50% (by weight of mixtures), and the effect of HMA mixtures on fracture energy was investigated by Semi-Circular Bending (SCB) test. Experiments were performed on a total of 28 SCB test specimens from 7 different series including reference, Al-0.50, Al-1.00, Al-1.50, Fe-0.50, Fe-1.00, Fe-1.50. Basic physical properties, dissipated energy (DE), fracture energy (G(f)), flexibility index (FI), and crack resistance index (CRI) values of HMA specimens were measured and compared. Based on test results, carrying load capacity and G(f) values of the mixtures were increased in the use of waste iron powders. A decrease in G(f) and peak load values were obtained while increasing the aluminum chips ratios. However, with the use of 0.5% waste aluminum chips were contributed G(f), peak load, CRI, and FI values compared by the reference sample. It is concluded that both aluminum chips and iron powders contributed to fracture energy of HMA mixtures. (C) 2021 Elsevier Ltd. All rights reserved.
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    Physico-mechanical properties and thermal monitoring performance of thermal enhanced cement slurry-coated LWAs containing microencapsulated phase change material
    (Elsevier, 2024) Emiroglu, Mehmet; Ozguler, Alper Tunga; Nas, Memduh; Subasi, Serkan; Sari, Ahmet; Hekimoglu, Gokhan; Ustaoglu, Abid
    Over the past decade, phase change materials (PCMs) have emerged as promising solutions for thermal energy storage (TES) systems, aimed at minimizing heating and cooling energy requirements in buildings. Nevertheless, despite their potential, there are some significant challenges in effectively integrating PCMs into building components. As part of this study, lightweight aggregates (LWA) were coated with a cement slurry containing microencapsulated phase change material (MPCM) to produce lightweight concrete (LWC) with the aim of investigating its mechanical and thermal properties. The LWAs were coated with MPCM at proportions of 2.5%, 5%, and 7.5% of their weight, and an LWC-MPCM was produced using these coated aggregates. The LWC-MPCM exhibited a decrease in dry unit weight up to 1248 kg/m 3 and a reduction in thermal conductivity up to 0.60 W/ mK with negligible loss of strength. SEM examinations revealed that the cement slurry coating provided strong adhesion to the aggregates, resulting in a robust concrete-aggregate interface. The room with the LWC-MPCM experienced a decrease of approximately 0.23 degrees C in center temperature compared to the reference room during the daytime. Additionally, after sunset, the LWC-MPCM showed an increase of approximately 1 degrees C in room center temperature. These advantageous physico-mechanical and thermal properties establish LWC-MPCMs as promising and energy-efficient components for producing thermo-regulative building materials.
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    Polarization and relaxation mechanisms in glass fiber-reinforced LED-cured polyester composites incorporating graphene nanotubes
    (Elsevier, 2023) Subasi, Azime; Emiroglu, Mehmet; Demir, Ahmet
    The current research aimed to understand how the polarization and relaxation mechanisms in light-emitting diode (LED) cured glass fiber reinforced polyester (GFRP) composites change with graphene nanotubes (GNTs). In this context, the complex permittivity (?*), loss tangent (tan & delta;), AC electrical conductivity (& sigma;), and complex modulus (M*) features of the samples were measured via impedance spectroscopy. According to the virtual electrical modulus values, electrical polarization occurred after the first peak at 127 kHz. With increasing GNT ratio, a polarization mechanism was obtained at approximately 350 kHz as a result of a shift towards higher frequencies. Although a significant change was observed in the electrical conductivity value as the frequency increased depending on the GNT ratio, there was no change in the conductivity values up to 10 kHz. At high frequencies, dipole formation and orientation occurred, resulting in an increase in conductivity up to 150 kHz.