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Öğe Activated carbon nanotube/polyacrylic acid/stearyl alcohol nanocomposites as thermal energy storage effective shape-stabilized phase change materials(Elsevier, 2022) Göksu, Haydar; Aydınlı, Elif; Hekimoğlu, Gökhan; Sarı, Ahmet; Gencel, Osman; Subaşı, Serkan; Tozluoğlu, AyhanStearyl alcohol (SA) as one of organic phase change materials (PCMs) has promising thermal energy storage prospective. However, the leakage issue during solid-liquid phase change period and low heat harvesting and releasing rate significantly attenuates its TES potential. Towards to overcome these drawbacks, the SA was shape stabilized using the cross-linked poly acrylic acid (PAA) and activated single walled carbon nanotubes (aSWCNTs) at three different weigh ratio of 1:1:2, 1:3:4 and 1:5:6 (a-SWCNTs:PAA:SA). The chemical/crystalline and morphologic structures of the produced shape stabilized-nano composite PCMs (SS-NCPCMs) were investigated by FT-IR, XRD and SEM analyses. The latent heat storage (LHS) features and thermal stability of the SSNCPCMs were measured by DSC and TGA techniques. The thermal cycling effect on the LHS properties and chemical structures of the SS-NCPCMs was also estimated. The DSC findings indicated that the SS-NCPCMs had melting temperature of around 55-56 C and latent heat capacity of about 135 J/g. TGA measurements disclosed that the thermal degradation temperatures of the nano composite PCMs were prolonged somewhat compared to the SA. A 500 heating-cooling cycling test revealed that the SS-NCPCMs had great chemical and LHS stability. The heat harvesting and releasing performance of the NCPCMs were considerably shortened compared to those of pure SA. The obtained results exposed that the synthesized SWCNTs/PAA/SA composites can be evaluated as promising LHS materials for thermal management of electronic systems, automobile modules, food carriers, solar PV panels etc.Öğe Artificial intelligence methods and their applications in civil engineering(IGI Global, 2017) Barrera, G. Martínez; Gencel, Osman; Beycioğlu, Ahmet; Subaşı, Serkan; N. Rivas, GonzálezSimulation of material properties generally involves the development of a mathematical model derived from experimental data. In structural mechanics and construction materials contexts, recent experiments have reported that fuzzy logic (FL), artificial neural networks (ANNs), genetic algorithm (GA), and fuzzy genetic (FG) may offer a promising alternative. They are known as artificial intelligence (AI). In civil engineering, AI methods have been extensively used in the fields of civil engineering applications such as construction management, building materials, hydraulic, optimization, geotechnical and transportation engineering. Many studies have examined the applicability of AI methods to estimate concrete properties. This chapter described the principles of FL methods that can be taught to engineering students through MATLAB graphical user interface carried out in a postgraduate course on Applications of Artificial Intelligence in Engineering, discussed the application of Mamdani type in concrete technology and highlighted key studies related to the usability of FL in concrete technology. © 2017 by IGI Global. All rights reserved.Öğe Artificial intelligence methods and their applications in civil engineering [2](IGI Global, 2015) Barrera, G. Martínez; Beycioğlu, Ahmet; Gencel, Osman; Subaşı, Serkan; Rivas, N. GonzálezSimulation of material properties generally involves the development of a mathematical model derived from experimental data. In structural mechanics and construction materials contexts, recent experiments have reported that fuzzy logic (FL), artificial neural networks (ANNs), genetic algorithm (GA), and fuzzy genetic (FG) may offer a promising alternative. They are known as artificial intelligence (AI). In civil engineering, AI methods have been extensively used in the fields of civil engineering applications such as construction management, building materials, hydraulic, optimization, geotechnical and transportation engineering. Many studies have examined the applicability of AI methods to estimate concrete properties. This chapter described the principles of FL methods that can be taught to engineering students through MATLAB graphical user interface carried out in a postgraduate course on Applications of Artificial Intelligence in Engineering, discussed the application of Mamdani type in concrete technology and highlighted key studies related to the usability of FL in concrete technology. © 2015, IGI Global. All rights reserved.Öğe Characterisation and energy storage performance of 3D printed-photocurable resin/microencapsulated phase change material composite(Elsevier, 2024) Er, Yusuf; Guler, Onur; Ustaoglu, Abid; Hekimoglu, Gokhan; Sari, Ahmet; Subasi, Serkan; Gencel, OsmanThe 3D fabrication of microencapsulated phase change material (MEPCM) doped resin polymer composites enables the creation of complex shapes and customized designs, opening doors for many applications in fields. This investigation fabricated a range of resin/MEPCM (20 %, 30 %, and 40 % by volume) composites using a mechanical mixing technique. This study investigates how the addition of MEPCM impacts resin matrix composite's mechanical strength, latent heat storage characteristics, and ability to regulate temperature effectively. With a 40 % MEPCM additive ratio, a pure resin porosity value of approximately 0.4 % increased to around 17 %. Thanks to the production of homogeneously dispersed MEPCM added resins with production with stereolithography (SLA), 40 % MEPCM additive enabled characteristic FTIR peaks of both MEPCM and resin to appear and, melting and solidification enthalpy values reached 87.15 j/g and 86.25 j/g, respectively. MEPCM addition enhanced the thermoregulatory properties of resin by absorbing or releasing heat during temperature fluctuations. On hotter days, 8 mm-thick composites create temperature differences exceeding 11 C, while this difference exceeds 6 C in the room center case. The produced 3D printed MEPCM/resin composite can be a potential material to effectively regulate the temperature of electronic devices, food packets, building materials, and electronic devices and automotive components.Öğe Developing Wallpaper/Dodecyl alcohol composite phase change materials as new kind of wall covering elements for building interior thermoregulation(Elsevier, 2023) Gencel, Osman; Ustaoglu, Abid; Sari, Ahmet; Hekimoglu, Gokhan; Sutcu, Mucahit; Tozluoglu, Ayhan; Tutus, AhmetThis study introduces a novel wall-covering element consisting of wallpapers (WP) impregnated with Phase Change Material (PCM), with the aim of enhancing thermal properties and providing effective thermal regulation performance in interior spaces. The study conducts practical investigations into the thermal attributes of wall-papers (WPs) impregnated with Dodecyl alcohol (DDA) as the chosen PCM, culminating in a leakage-free WP/ DDA wall covering element. The process of impregnating involved applying liquid DDA to the back side of the WP using a manual coating apparatus. Four distinct DDA ratios, ranging from 0% to 20% by mass of WP, were applied. The chemical compatibility of the developed WP/DDA composite was explored using Fourier Infrared Spectroscopy (FTIR). The thermal energy storage (TES) properties were assessed through Differential Scanning Calorimeter (DSC) analysis, and the thermo-regulative performance of the WP/DDA composite was evaluated in laboratory-scale test rooms under real weather conditions. The DSCoutcomesexposed that melting temperature and latent heat capacity of WP/DDA were 21.78 degrees C and 26.9 J/g, respectively.The thermoregulation tests showed that the prepared WP/DDAsignificantly reduce interior room temperature fluctuation and can maintain indoor temperature longer in comfortable temperature ranges. The largest difference between the reference room and test room was observed to be about 2celcius. The room temperature was cooler for about 9 h 53 min during day times for the DDA case.The results designated that the developed WP/DDA composite could be evaluated as a promising new kind of building wall covering element for reducing the cooling load of room.Öğe Development, characterization and thermo-regulative performance of microencapsulated phase change material included-glass fiber reinforced foam concrete as novel thermal energy effective-building material(Pergamon-Elsevier Science Ltd, 2022) Gencel, Osman; Subaşı, Serkan; Ustaoğlu, Abid; Sarı, Ahmet; Maraşlı, Muhammed; Hekimoğlu, Gökhan; Kam, ErolThermal energy storage (TES) materials present very crucial role for heating and cooling load of building envelopes. This investigation focused on manufacturing of novel TES materials as a lightweight concrete by integration of microencapsulated PCM (MPCM) with foam concrete (FC) to improve thermal mass of buildings. Novel hybrid building material design is presented by combining static insulation property of FC and dynamic thermoregulation property of MPCM. In production of MPCM-included innovative FC, MPCM was used at 5%, 10% and 15% by weight. MPCM increased bulk density up to 592.1 kg/m(3), compressive strength up to 2.52 MPa and thermal conductivity up to 0.153 W/mK. Fourier transform infrared spectroscopy (FTIR) analysis confirmed that any chemical interaction did not occur between MPCM and ingredients of FC. Onset melting temperature and energy storage capacity were measured as 11.88 degrees C and 204 J/g for MPCM and 12.27 degrees C and 30.8 J/g for FC-MPCM, respectively. Center temperature of room with MPCM impregnated foamed concrete became about 1.9 degrees C lesser according to reference room through daytime. Moreover, it achieved about 1.72 degrees C higher room center temperature after sunset hour. Advantageous physico-mechanic and thermal properties make FC-MPCM as promising energy effective material for manufacturing thermo-regulative building components. (c) 2022 Elsevier Ltd. All rights reserved.Öğe Effect of carbon nanotube and microencapsulated phase change material utilization on the thermal energy storage performance in UV cured (photoinitiated) unsaturated polyester composites(Elsevier, 2023) Subaşı, Azime; Subaşı, Serkan; Bayram, Muhammed; Sarı, Ahmet; Hekimoğlu, Gökhan; Ustaoğlu, Abid; Gencel, OsmanThe utilization of phase change materials in the synthesis of polyester is an economically viable approach for the production of polymer composites with remarkable thermal and mechanical characteristics, thereby facilitating thermal energy savings. This study manufactured a series of unsaturated polyester resin (UPR)/carbon nanotubes (CNT)/MPCM composites via mechanical mixing and ultrasonication processes and the produced composites were cured with ultraviolet (UV) curing technology. The unsaturated polyester resin was utilized as a support matrix, and to improve the thermal conductivity of MPCM-UPR composites, CNT were introduced into the matrix. This paper discusses the effect of CNT and MPCM on the mechanical, thermal, and thermal regulative performance of polyester composites. A 10 wt% incorporation of MPCM led to an almost 77 % and 15 % drop at Charpy impact strength and Shore D hardness values of reference UPR, respectively. Similarly, the introduction of substitution of 0.005 wt% of CNT reduced the impact strength of the specimen with 10 % MPCM by 31 %, while it increased the Shore D hardness by almost 5 %. Although the thermal conductivity of reference resin was reduced by 15 % with a 10 % addition of MPCM, CNT content increased the thermal conductivity values by almost 20 % regardless of MPCM concentration. The onset melting and freezing temperatures of MPCM were found to be 21.71 and 22.74 degrees C, respectively; while for the composites with and without CNT, this value ranged between 20.70 and 22.39 degrees C and 22.45-22.90 degrees C, respectively. Thermoregulation test results indicate that MPCM improved the thermal energy storage capacity of composites. The results of this research will be of great sig-nificance in order to gain a more comprehensive understanding of the thermal properties of polyesters with MPCM/CNT, thus allowing for the utilization of this material as a latent heat thermal energy storage system for energy conservation.Öğe Effect of Elevated Temperatures on Properties of Blended Cements with Clinoptilolite(Kaunas Univ Tech, 2016) Beycioğlu, Ahmet; Aruntaş, Hüseyin Yılmaz; Gencel, Osman; Lobland, Haley E. Hagg; Şamandar, Ayhan; Brostow, WitoldWe have investigated the effect of elevated temperature on properties of clinoptilolite blended cements. Clinoptilolite was used at 5 %, 10 %, 15 % and 20 % replacement by weight for Portland cement while sand and water quantities were kept constant in all mix designs. Dry weights, flexural strengths, and compressive strengths of specimens were determined as a function of time. The same properties were again evaluated after specimens, having reached the age of 90 days, were exposed to 300 degrees C, 400 degrees C and 500 degrees C temperatures for 3 h. Initial setting times for all cements prepared were >= 60 minutes, the limiting time according to TS EN 197-1. The mortars with 5 % or 10 % cliniptilolite substitution have compressive strength exceeding 42.5 MPa after being subjected to 400 degrees C and 500 degrees C.Öğe Engineering properties of hybrid polymer composites produced with different unsaturated polyesters and hybrid epoxy(Elsevier, 2024) Gokce, Neslihan; Eren, Sevki; Nodehi, Mehrab; Ramazanoglu, Dogu; Subasi, Serkan; Gencel, Osman; Ozbakkaloglu, TogayIn this study, the mechanical properties of hybrid polymer composites produced with different unsaturated polyesters and hybrid epoxy resins are investigated. The composites were produced by blending unsaturated polyester resins (i.e., orthophthalic, isophthalic, and terephthalic) and bisphenol-A-based epoxy-vinyl ester resin to produce single, binary and ternary blends. In doing this, a total of 14 different combinations were produced. The results show that the binary and ternary polymer blends tend to improve almost all the tested properties of the polymer composites. Further, the fourier-transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) results confirmed that the reason for enahcned properties is due to better crosslinking and longer chains of polymers produced in binary and ternary mixtures. The absence of peaks determining the styrene polymerization character for all mixtures also demonstrates that the polymerization reaction takes place in all mixtures. It is also believed that the binary and ternary resin mixtures have developed higher energy absorption compared to single resin composites. All of the mentioned has been achieved while the gelation temperatures of the hybrid resin mixtures were not changed significantly and they began gelation at the expected temperature values. In addition to the gelation, peak exotherm temperatures, and barcol hardness values demonstrated that all mixtures achieved sufficient curing. The result of this study is significant and point to the great potential of producing high performance polymer composites through the use of binary or ternary resin mixtures.Öğe Enhancing sustainability with waste hemp-shive and phase change material: Novel gypsum-based composites with advanced thermal energy storage properties(Elsevier Sci Ltd, 2024) Gencel, Osman; Guler, Onur; Ustaoglu, Abid; Erdogmus, Ertugrul; Sari, Ahmet; Hekimoglu, Gokhan; Boztoprak, YalcinThis study addresses the rising demand for sustainable construction by introducing composite materials from natural and renewable resources: gypsum, hemp, and phase change materials (PCMs). These materials cater to the growing preference for eco-friendly building solutions. Incorporating hemp enhances sustainability while integrating PCMs into the porous hemp structure ensures adequate thermal energy storage and release without leakage. Firstly, the agricultural waste hemp shives and lauryl alcohol (LA) PCM were mixed to create shapestabilized hemp/PCM composites. The highest PCM ratio was determined in shape-stabilized composites exhibiting non-leakage properties, which was 45 wt %. These composites were then incorporated into gypsum materials at loadings of 7.5 %, 15 %, 22.5 %, and 35 wt % to produce the final composites. Morphological, thermal, and chemical characteristics of shape-stabilized composites were examined using SEM, TGA, and DSC, while the solar thermoregulation tests assessed the gypsum matrix composites. The phase change temperature of PCM was determined as 20.24 degrees C with a melting enthalpy value of 224.4 J/g. The hemp/PCM shape-stabilized composites demonstrated an impressive melting enthalpy value of 100.2 J/g, with only a slight reduction to 99.5 J/g after 750 test cycles. When the ambient temperature exceeded 50 degrees C, the central temperature of the cabins containing PCM composites was found to be at least 4 degrees C cooler than those containing only gypsum. Conversely, when the ambient temperature dropped to around 20 degrees C, it was observed that the central temperature of the cabins with PCM composites was approximately 2 degrees C warmer than those with only gypsum. This study introduces a novel approach to creating environmentally friendly gypsum/hemp/PCM composites for thermal energy storage systems.Öğe Estimation of fracture energy of high-strength steel fibre-reinforced concrete using rule-based Mamdani-type fuzzy inference system(Walter De Gruyter Gmbh, 2012) Köksal, Fuat; Şahin, Yuşa; Beycioğlu, Ahmet; Gencel, Osman; Brostow, WitoldIn this study, we worked to estimate the fracture energy of steel fibre-reinforced concrete (SFRC) according to the water/cement ratio (w/c), tensile strength of steel fibre, steel fibre volume fraction and flexural strength of concrete sample as inputs using the Mamdani-type fuzzy inference system (FIS). In the study, the values obtained from the model and experimental divided three groups (each group has six experimental results) according to the w/c ratios to evaluate the fuzzy logic (FL) model approximate reasoning ability. As a result, the Mamdani-type FIS has shown a satisfying relation with the experimental results and suggests an alternative approach to evaluate the fracture energy estimation using related inputs.Öğe Fiber-Reinforced Lightweight Calcium Aluminate Cement-Based Concrete: Effect of Exposure to Elevated Temperatures(Mdpi, 2023) Bideci, Ozlem Salli; Yilmaz, Hakan; Gencel, Osman; Bideci, Alper; Comak, Bekir; Nodehi, Mehrab; Ozbakkaloglu, TogayCalcium aluminate cements (CACs) are a group of rapid-hardening hydraulic binders with a higher aluminum composition and lower ecological footprint compared to their ordinary Portland cement (CEM) counterparts. CACs are commonly known to have higher thermo-durability properties but have previously been observed to experience a major strength loss over time when exposed to thermal and humidity conditions due to the chemical conversion of their natural hydrated products. To address this, in this study, silica fume is added to induce a different hydration phase path suggested by previous studies and utilized in conjunction with fiber-reinforced lightweight pumice to produce lightweight concrete. To closely evaluate the performance of the produced samples with CAC compared to CEM, two different types of cement (CEM and CAC) with different proportions of pumice and crushed stone aggregate at temperatures between 200 and 1000 degrees C were tested. In this context, sieve analysis, bulk density, flowability, compressive and flexural strength, ultrasonic pulse velocity and weight loss of the different mixes were determined. The results of this study point to the better mechanical properties of CAC samples produced with pumice aggregates (compared to crushed stone) when samples are exposed to high temperatures. As a result, it is found that CACs perform better than CEM samples with lightweight pumice at elevated temperatures, showing the suitability of producing lightweight thermal-resistant CAC-based concretes.Öğe Glass fiber reinforced gypsum composites with microencapsulated PCM as novel building thermal energy storage material(Elsevier Sci Ltd, 2022) Gencel, Osman; Hekimoğlu, Gökhan; Sarı, Ahmet; Ustaoğlu, Abid; Subaşı, Serkan; Maraşlı, Muhammed; Erdoğmuş, ErtuğrulA comprehensive study involving the fabrication and characterization of gypsum plasterboards combined with microencapsulated phase change material (mPCM) is introduced to evaluate their benefits regarding thermoregulation management and energy saving performance in buildings. For this purpose, the produced new type of gypsum plasterboard was subjected to the detailed chemical, morphological, mechanical, physical and thermal tests. The gypsum plasterboard incorporated with mPCM (7.5 wt%) and reinforced by glass fiber has latent heat capacities as high as 16.7 and 16.6 J/g at onset melting and solidification temperature of 11.90 ? and 12.09 ?, respectively. TGA analyzes revealed high thermal stability of gypsum plasterboard up to about 140 ?. Outcomes exhibited that mPCM-gypsum plasterboard can substantially diminish cooling load of a building during the daytime even at the high room temperature and offer decline in heat necessity of a house during night-time. During peak room temperature hours, the mPCM-gypsum plasterboard achieved 3 ? lower temperatures than the reference room, and it provided a cooler room temperature for about 7 h during the daytime while a warmer temperature of 0.3 ? was achieved at the cold weather. As a result, the produced gypsum-based composites can be considered as an energy-saving and indoor temperature regulating material in buildings.Öğe Investigation of electromagnetic interference shielding performance of ultra-high-performance mortar incorporating single-walled carbon nanotubes and steel fiber(Elsevier, 2024) Subasi, Serkan; Seis, Muhammet; Tekin, Ilker; Kazmi, Syed Minhaj Saleem; Munir, Muhammad Junaid; Gencel, Osman; Ozbakkaloglu, TogayFor security amenities and key infrastructure, construction materials with extraordinary mechanical, durability, and electromagnetic interference (EMI) shielding performance are essential. This study investigates the EMI shielding performance of ultra-high performance mortar (UHPM) incorporating single-walled carbon nanotubes (SWCNT) and steel fibers. Currently, no such work is present in the existing literature. Eight mixtures were prepared with varying SWCNT dosages (0%-0.03 % by weight of cement) and steel fiber additions (1.2 % of the volume of the UHPM mixture). The performance of UHPM incorporating SWCNT and steel fibers was evaluated through flow diameter, compressive strength, flexural strength, Schmidt hardness, ultrasonic pulse velocity, EMI shielding performance, and scanning electron microscopy analysis tests. It is observed that increasing the SWCNT content enhances the compressive strength, flexural strength, ultrasonic pulse velocity, and Schmidt hardness of UHPM. The addition of steel fibers further enhances compressive (up to 22 %) and flexural (up to 92 %) strengths. In terms of the transmittance behavior, the improved EMI shielding performance of UHPM with the increasing SWCNT content is observed prominently at high electromagnetic frequencies (i.e., 2500 MHz-5100 MHz). However, the improved shielding performance is observed to be quite low, limited to 10 dB. Moreover, combining steel fibers and SWCNT enhances the EMI shielding performance of UHPM in terms of the transmittance behavior. As a result, UHPM incorporating SWCNT and steel fibers behaves as an absorbent material, shielding a significant amount of energy, approximately 45 dB, at a frequency of 5000 MHz. Based on the results, UHPM incorporating SWCNT and steel fibers can be used effectively as EMI shielding material. The findings of this study will enhance the practical applications of UHPM incorporating SWCNT and steel fibers.Öğe Light transmitting glass fiber reinforced cementitious composite containing microencapsulated phase change material for thermal energy saving(Elsevier Sci Ltd, 2022) Gencel, Osman; Sarı, Ahmet; Subaşı, Serkan; Bayram, Muhammed; Danish, Aamar; Maraşlı, Muhammed; Hekimoğlu, GökhanThe energy utilization for artificial lighting, cooling, heating, and air conditioning in buildings results in the release of greenhouse gases and causes climate crises. In this regard, a novel light-transmitting cementitious composite (LTCC) was developed by substituting microencapsulated phase change material (MPCM) to reduce the building energy utilization via transmitted light through the composite and improve the solar thermal energy efficiency. The cementitious matrix is produced with cement, kaolin, silica sand, water, superplasticizer, adhe-sive polymer, glass fiber, different ratios of MPCM, and plastic optical grids to let inward sunlight transmittance. The current study thoroughly investigates the characteristics of light-transmitting composite, including MPCMs, via physico-mechanical, chemical, microstructural, thermal, light transmittance and solar thermoregulation tests. The thermal conductivity of the composite with 0 wt% MPCM decreased from 1.09 W/mK to 0.96 W/mK with 15 wt% MPCM addition. Incorporating 10 wt% of MPCM reduced the 28 days-compressive strength of specimens by almost 28 % due to the lower strength and density of microcapsules, as well as the voids formed by damaged MPCMs. On the other hand, the incorporation of MPCM did not dramatically affect the flexural strength of the cementitious composite. DSC analysis results revealed that the composite containing 15 wt% MPCM shows a latent heat of fusion of 14.6 J/g with a melting point of 17.65 degrees C. FTIR analysis disclosed that MPCM maintains its chemical structure in the composite. Composite slabs exhibited up to 12.4 % artificial light transmittance, which would translate to a considerable increase in the lighting efficiency of commercial and residential buildings. Thermoregulation performance test under ambient conditions indicates that the specimen containing 15 wt% MPCM can provide a cooler room temperature for 6.5 h when the room or surface temperatures increase above 21-23 degrees C, and a warmer room when the temperature decreases below these temperatures. The findings of the current study can be applied to enhance thermal energy saving and artificial lighting efficiency in buildings that inspire the design of environment-friendly constructions.Öğe Mechanical and radiation shielding properties of SWCNT reinforced polymer/glass fiber fabric-based nanocomposite containing different filler materials: A comparative study(Wiley, 2022) Surucu, Ali Murat; Subaşı, Serkan; Danish, Aamar; Gencel, Osman; Subaşı, Azime; Özbakkaloğlu, TogayIn this study, polymer/glass fiber fabric-based nanocomposite plates were fabricated with 0.01%-0.1% single-walled carbon nanotubes (SWCNTs) and filler materials (barite, magnetite, and colemanite) using a hand layup process. Mechanical properties (e.g., tensile strength, flexural strength, and Charpy impact strength), thermal conductivity, and radiation shielding properties (e.g., gamma radiation and neutron radiation) of the specimens were determined. The results revealed that the specimens containing barite and magnetite managed to exhibit adequate mechanical properties (especially Charpy impact strength). Among different filler materials used, barite-filled specimens outperformed colemanite and magnetite-filled specimens in terms of mechanical properties. The mechanical performance of filler-modified specimens can be further enhanced by adopting efficient dispersion techniques to disperse filler material and SWCNTs throughout the composite plates. The thermal conductivity of barite, magnetite, and colemanite-filled specimens (with/without SWCNTs) increased by 30.56%-60% as compared to specimens only containing SWCNTs and neat polymer, which avoids the accumulation of heat required for radiation shielding applications. Similar to thermal conductivity, specimens containing filler materials (with and without SWCNTs) provided higher gamma and neutron radiation shielding properties as compared to neat polymer- and SWCNT-modified specimens. In the case of gamma and neutron radiation shielding, barite- and colemanite-filled specimens provided better results, respectively.Öğe Mechanical properties of blended cements at elevated temperatures predicted using a fuzzy logic model(Techno-Press, 2017) Beycioğlu, Ahmet; Gültekin, Adil; Aruntaş, Hüseyin Yılmaz; Gencel, Osman; Dobiszewska, Magdalena; Brostow, WitoldThis study aimed to develop a Rule Based Mamdani Type Fuzzy Logic (RBMFL) model to predict the flexural strengths and compressive strengths of blended cements under elevated temperatures. Clinoptilolite was used as cement substitution material in the experimental stage. Substitution ratios in the cement mortar mix designs were selected as 0% (reference), 5%, 10%, 15% and 20%. The data used in the modeling process were obtained experimentally, after mortar specimens having reached the age of 90 days and exposed to 300 degrees C, 400 degrees C, 500 degrees C temperatures for 3 hours. In the RBMFL model, temperature (C degrees) and substitution ratio of clinoptilolite (%) were inputs while the compressive strengths and flexural strengths of mortars were outputs. Results were compared by using some statistical methods. Statistical comparison results showed that rule based Mamdani type fuzzy logic can be an alternative approach for the evaluation of the mechanical properties of concrete under elevated temperature.Öğe Microencapsulated phase change material incorporated light transmitting gypsum composite for thermal energy saving in buildings(Elsevier, 2023) Gencel, Osman; Bayram, Muhammed; Subasi, Serkan; Hekimoglu, Gokhan; Sari, Ahmet; Ustaoglu, Abid; Marasli, MuhammedThe increased energy consumption for specific applications, including heating, cooling, air conditioning and lighting of residential and commercial buildings accelerate the research efforts concentrated on developing thermal energy storage capacity of buildings materials in recent years. Likewise, the development of light-transmitting building elements is a novel energy-saving technique that enhances lighting efficiency in build-ings. In light of these, the current study seeks to design an untried microencapsulated phase change material (MPCM) integrated glass fiber reinforced gypsum composite with sufficient light-transmitting properties and thermal energy storage capacity. In this research, a multi-scale investigation of light-transmitting gypsum composite was conducted experimentally with physical, mechanical, chemical, microstructural, thermal, light transmittance and solar thermoregulation tests. The gypsum composite is formed from alpha-gypsum, water, polymer admixture, alkali-resistant glass fiber (AR-GF), several concentrations of MPCM, and plastic optical grids to allow light to transmit through the board. Although higher fractions of MPCM yielded an apparent decrease in me-chanical strength test results, 5 wt% introduction of MPCM to the reference matrix reduced the compressive and flexural strength of specimens by 1 and 8 %, respectively. The results verified a reduction trend in thermal conductivity of composites with MPCM loading. DSC investigations revealed that the melting temperature and the regarding latent heat storage capacity of gypsum composite with 15 wt% of MCPM are 17.76 degrees C and 19.2 J/g, respectively. Light-transmitting gypsum composites showed up to similar to 10 % light transmittance, that can greatly increase the efficiency of lighting in buildings. The produced gypsum composites with MPCM kept the test room cooler during the highest temperature, while it provided a warmer room during the nighttime for an extended time. The study's findings are applicable to increase thermal comfort by reducing the significant temperature variations in buildings and improving artificial lighting efficiency, encouraging the design of sustainable building applications.Öğe Polymer concrete reinforced with luffa fibers: Effect of gamma radiation(Revista Tecnica de la Facultad de Ingeniera, 2014) Barrera, G. Martínez; López, M. Martínez; Santiago, E. Vigueras; Gencel, Osman; Beycioğlu, Ahmet; Reis, JoãoThe interest of many research groups regarding manufacture of composite materials by using natural fibers is increasing world-wide. The main objectives involve the improvement of mechanical properties, mainly those related to resistance and elasticity. In the present study in a first stage, polymer concrete specimens were elaborated by using an unsaturated polyester resin, silica sand and luffa fibers; after, they were gamma irradiated at different doses and their mechanical properties were evaluated. Two different silica particle sizes (0.15 mm and 0.6 mm), and four different luffa fiber concentrations (0.3, 0.6, 0.9 and 1.2 wt%) were used, as well as 50 and 100 kGy of radiation dose. The results show a gradually diminution of compressive strength and modulus of elasticity when adding luffa fiber concentration. Nevertheless, such mechanical features are increasing when polymer concrete is gamma irradiated.Öğe The use of natural (coconut) and artificial (glass) fibers in cement - polymer composites: An experimental study(Elsevier Sci Ltd, 2024) Demirdag, Caner; Nodehi, Mehrab; Bideci, Alper; Bideci, Ozlem Salli; Tuncer, Metin; Gencel, Osman; Ozbakkaloglu, TogayFiber reinforced concrete composites are a group of high-performance materials with considerably enhanced stress-strain properties. Similar effects can also be achieved using polymeric binders whereby the inclusion of the polymers as binder can significantly enhance the physical-mechanical properties of the resulting concretes. In this regard, the following study investigates the impact of utilizing natural (e.g., coconut) versus artificially manufactured fibers (e.g., glass fiber) in polymer-cementitious composites. In doing so, 14 mixes were produced using various ratios of the two fibers. To evaluate the properties of the produced samples a series of tests including flow diameters, unit weights, water absorption values, compressive strengths, flexural strengths and ultrasound transmission rates were determined. Also, to evaluate the microstructural cohesion of polymercement and polymer-coconut samples, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) has also been used. The results show that the surface texture of fibers can play a key role in major engineering properties of the fiber reinforced concretes and that the natural fibers have great potential to be used as high-performance materials in cementitious composites. Also, it is found that the use of polymer as the main binder can provide higher adhesion with fibers containing smoother surface (e.g., glass fiber) at the interfacial transition zone (ITZ). In the end, recommendation for future studies is also included.
