Sürdürülebilir Kalkınma Amaçları

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• MakaleYalnız künye2026Scopus SJRQ2/r/munzur/1112
  Drying Shrinkage and Microstructural Properties of Geopolymers Including Steel and Iron Particles

  Gulmez, Nihan; Kockal, Niyazi Ugur

  Geopolymer mortars show significantly higher shrinkage than normal Portland cement mortars. So, one of the most important disadvantages of these promising alternative binding materials for their wider applications is the cracking occurring by shrinkage. Different inserts and fibers are used in fresh mixtures in order to control drying shrinkage cracks and to provide mechanical capacity. The aim of this study is to investigate the effectiveness of using both metal particles (iron particles) and metallic fibers (steel particles) in geopolymer composites to reduce drying shrinkage. In addition, microstructural properties of composites were determined by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses and causes of shrinkage were investigated in detail. Mixtures containing 20% ​​silica fume have 38.4% lower drying shrinkage than slag-based mixtures. In slag-based composites, decreases in drying shrinkage were found as 18.8% and 49.1% when adding 10% iron particles or 10% steel particles compared to metal-free composites.

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• MakaleYalnız künye2025Scopus SJRQ2/r/munzur/924
  Using Meta-Heuristic Optimization Algorithms to Determine Baseflow and Comparing Their Temporal Performance

  Acar, Ramazan; Sapliogu, Kemal

  Accurate and simple determination of baseflow is an extremely important issue. In this study, the baseflow levels of Göksu station number 1805 in the Seyhan basin were determined by calibrating the Lyne and Hollick, Chapman, Chapman and Maxwell methods available in the literature using meta-heuristic optimization methods. The meta-heuristic algorithms used for calibration in the study were run thirty times each. Thus the reliability, the reliability of the algorithms was tested with the standard deviations obtained. The study also measured the temporal performance of the algorithms. In addition, the baseflows of Göksu station were determined and their percentage rates were found separately according to all three methods and intuitive methods, and the results obtained were compared. By examining the results obtained in this section, the average baseflow rate of the basin was also determined. Furthermore, each phase of the study was repeated over a five-year period, with the objective of measuring its sustainability. Consequently, it has been demonstrated that the method can be employed over extended periods.

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  AtıfOpenAlex1

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• MakaleYalnız künye2024Scopus SJRQ2/r/munzur/2191
  Factors Affecting the Setting Times of Pumice Based Alkali-Activated Hybrid Cements

  Balun, Bilal; Karataş, Mehmet

  The environmental impacts of ordinary Portland cement (OPC) production have led researchers to produce alternative binders. Binders with aluminosilicate structure, such as pumice, can be used to produce one of these alternatives, alkali-activated cements. In addition, alkali-activated hybrid cements have become a type of material that combines the positive aspects of geopolymers and Portland cement. Especially in the activation of low CaO containing materials such as pumice with alkalis, the use of a small amount of OPC ensures that the alkali-activated materials can both be produced under ambient conditions and improves its strength properties. In this study, setting times of pumiced based alkali-activated hybrid cements were evaluated based on OPC amount (0%, 5%, 10%, 15% and 20%), alkaline solution/binder ratio (0.47, 0.50 and 0.53) and sodium silicate/potassium hydroxide (1, 2 and 3) ratio. In experiments carried out under ambient conditions, the silica module (2.0) of the sodium silicate solution was kept constant. As a result of the experimental studies, the increase in the OPC amount and the sodium silicate ratio shortened the setting times of the pumiced based alkali-activated hybrid materials while the alkali solution/binder ratio increased the setting times. It was determined that the factor most affects the setting times was the OPC amount. The setting time of the OPC-free pumice-based alkali-activated binders without OPC takes more than one day. As a result, increasing the amount of OPC up to 20% significantly reduced the setting times. A decreasing trend was observed in compressive strengths with increasing setting times.

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  AtıfScopus5·WoS4·OpenAlex5

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• MakaleYalnız künye2023Scopus SJRQ2/r/munzur/2333
  Effect of Using Eccentric Braces with Different Link Lengths on the Seismic Demand of CFST Column-Composite Beam Frames Subjected to Near-Field and Far-Field Earthquakes

  Etli, Serkan; Güneyisi, Esra Mete

  In recent years, in the light of technological developments, the utilization of composite members that enable the use of superior properties of concrete and steel together in earthquake-resistant building design has become widespread. In this study, 5-, 8-, 10-, 13- and 15-story composite moment-resisting framed buildings were designed using composite beams and concrete filled steel tube columns. The effect of using steel braces and the variation of the link length of the eccentric steel braces on the seismic demand of the composite buildings were investigated. For this, eight different cases with braces were considered and compared with the bare structure. The first case had concentric braces (having no link), and the other seven cases had eccentric steel braces with different link lengths classified as short, medium and long. The nonlinear dynamic response of braced and non-braced composite structures was evaluated under the effect of earthquake groups of far-field, near-field with and without pulse effects. Each earthquake group includes ten different ground motion records. SeismoStruct which is a fiber element-based software was used in modeling and analysis of the structures. Seismic behavior of the case studied structures was investigated comparatively through the demand parameters such as the maximum inter-story drift ratios, the maximum roof drift ratios and the deformation states in the structural elements. It was observed that the inclusion of the steel braces provided significant gains in dissipating seismic energy acting through composite buildings and the beam/column deformations decreased considerably, depending on the length of the link and the height of the structure. In some cases, significant damage was monitored in the link members; however, this type of deformation was limited.

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  AtıfScopus3·WoS3·OpenAlex18

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• MakaleYalnız künye2023Scopus SJRQ2/r/munzur/1825
  An Estimation Proposal for Engineering Properties of Modified Concrete by using Standalone and Hybrid GRELM

  Cemalgil, Selim; Onat, Onur; Aruntaş, Hüseyin Yılmaz

  The presented study pertains to an attempt to propose a novel prediction model to predict the flexural and compressive strengths of concrete modulated using steel fiber (SFb) and silica fume (SF). A completed experimental investigation is adopted for the current study, and a research plan is employed. Three different superplasticizers amount (SP), different SF replacement ratios, and a constant amount of SFb were used by the weight of cement to meet the C25 target strength. A sum of 16 distinct mixtures designed by changing SP and SF ratios were developed. Furthermore, SFb was added at a fixed rate of 65 kg/m3 to all planned concrete mixes. In addition, SFb was used to create a 16-mix design. Finally, a total of 32 distinct mix designs were created. Produced, hardened specimens were exposed to two different curing conditions. This research uses the mechanical characteristics of concrete treated with SF, SP, and SFb to estimate by conducting standalone and hybridized generalized extreme learning machine (GRELM) algorithms based on available experimental data in terms of the metaheuristic aspects of this work. With continuous input data, four separate data sets were constructed. Compressive strength and flexural strength were estimated separately. With the aid of the Grey Wolf Optimization (GWO) and Particle Swarm Optimization (PSO) algorithms, binary and ternary hybrid approaches were developed and tested on the data. Four distinct estimation models were suggested. Two quality metrics were used to evaluate the estimation performance: Root Mean Square Error (RMSE) and correlation of determination (R2). The estimation results showed that the hybridized GRELM-PSO-GWO estimation model that was built for prediction was relatively successful in all sets.

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  AtıfScopus4·WoS3·OpenAlex2

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• MakaleYalnız künye2023Scopus SJRQ2/r/munzur/1686
  Engineering Properties of Geopolymer Mortars Containing Industrial Steel Shavings

  Gülmez, Nihan; Koçkal, Niyazi Uğur

  The purpose of using waste materials is to prevent the unnecessary use of resources and to reduce the amount of waste. Geopolymer, developed as an alternative to cementitious materials, prevents the depletion of natural resources and saves a large amount of energy. This paper presents the effect of waste steel shavings on the improvement of physical and mechanical properties of geopolymer mortars. For this purpose, geopolymer mortars were produced by using two binder types [slag (BFSb) and silica fume] as well as steel shavings in five different replacement percentages (0%, 2.5%, 5%, 7.5% and 10%) by volume instead of aggregate. A series of experiments on geopolymer mortars were carried out to determine properties such as bulk density, water absorption, apparent porosity, sorptivity coefficient, splitting tensile strength, flexural strength and compressive strength. Results showed that steel shavings recovered from metal processing and forming sector were highly effective at improving engineering properties of geopolymer mortars. Furthermore, although replacement of 20% by volume of BFSb with silica fume improved properties of geopolymer mortar, it was observed that the use of silica fume at higher ratios reduced mechanical properties by increasing porosity and sorptivity of BFSb-based geopolymer mortars.

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  AtıfScopus1·OpenAlex1

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• MakaleYalnız künye2023Scopus SJRQ2/r/munzur/1601
  Computer-aided Optimization of Geopolymer Mortars

  Gülmez, Nihan; Koçkal, Niyazi Uğur

  The optimum mix design of geopolymers involves the purpose of determining which mixture will have high engineering properties without compromising the importance of each variable. This experimental study aimed to investigate the effects of some critical geopolymer mixture parameters on engineering properties by using historical data design in response surface methodology (RSM). Statistical models were developed between factors (binder and aggregate content, curing conditions and aggregate type) and their response surfaces (oven dry (OD) bulk density, water absorption, compressive strength and flexural strength). The final mathematical models for the response surfaces were constructed in terms of coded factors defined as dimensionless. In addition, a multipurpose optimization technique was used to achieve the desired design with the desired maximum strength.

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• MakaleYalnız künye2022Scopus SJRQ3/r/munzur/2919
  The Effect of Using Waste Tire as a Fine Aggregate on Mechanical Properties of Fly Ash-Substituted Self-Compacting Concrete

  Cemalgil, Selim

  Wasted tyres are commonly used in civil engineering applications for a variety of purposes, including as concrete ingredients. Wasted tires that are mechanically sheared into shreds ranging in size from 25 to 300 mm and intended for use in concrete are called " Waste Shreded Tyre Aggregate" to make a contribution to sustainable waste management. Currently, at this point, the basic philosophy of this study is to investigate the effects of Waste Tire Aggregate (WTA) on the mechanical and durability properties of Self Compacting Concrete (SCC) to provide a contribution to reusing waste tires in the construction industry. WTAs with 5, 10, and 15% volume ratios are substituted for fine aggregate in SCC production. In addition, 15% mixtures with a binder quantity of 550 kg/m3, including 20 and 30% fly ash (FA) were substituted and prepared to be compared with the control concrete. To measure the rheological properties of SCCs, slump flow, V-funnel and L-box tests were performed. Then, the produced concrete samples of different sizes were cured under laboratory conditions for 28 days and then subjected to hardened concrete tests on the 28th, 56th and 90th days. The hardened concrete tests were composed of axial compressive strength, flexural strength, splitting tensile, diagonal tensile, abrasion resistance, modulus of elasticity. Finally, a durability test was performed as chlorine penetration depth. The test results show that WTA positively affects the properties of fresh and hardened SCC. Only, the increase in the substitution rate of WTA in concrete mixtures decreased the hardened state strength of the SCC. However, the addition of WTA to up to 15% of the total fine aggregate volume indicates that it is possible to apply recycled WTA to SCC and successfully satisfy both fresh and hardened SCC specifications.

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