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Öğe Effect of Alternative Expanded Perlite Using on Properties of Raw Perlite Aggregated Light-Weight Concrete(Gazi Univ, 2010) Gokce, H. Suleyman; Simsek, Osman; Durmus, Gokhan; Demir, IlhamiPerlite is a natural building materials contribute to global warming positive thanks to its isolation and lightness characteristics as concrete aggregate with usage of in construction sector. In research results, about %74 of world perlite reserves was determined to be in Turkey. It is thought that energy of fairly hard obtained will provide more efficient usage thanks to efficient usage of the natural reserves. Such approaches will provide to reduce of environment pollution in the usage of energy. In this study, with different characteristic usability of expanded perlite aggregate was researched in raw perlite aggregated light weight concrete. 7 different mixtures were prepared in volume at 10% ratio by using 3 different expanded perlite aggregate instead of raw perlite aggregate. With prepared light weight concrete mixtures 100x100x100 mm sized cube samples were produced. 28 days compressive strength, unit volume weight and water absorption ratio of these sample were researched. As a result, with suitable characteristic usage of expanded perlite aggregate was understood to be effective on the mechanical and physical properties of perlite aggregated light weight concrete.Öğe Estimating the Properties of Ground-Waste-Brick Mortars Using DNN and ANN(Tech Science Press, 2019) Karaci, Abdulkadir; Yaprak, Hasbi; Ozkaraca, Osman; Demir, Ilhami; Simsek, OsmanIn this study, deep-neural-network (DNN)- and artificial-neural-network (ANN)- based models along with regression models have been developed to estimate the pressure, bending and elongation values of ground-brick (GB)-added mortar samples. This study is aimed at utilizing GB as a mineral additive in concrete in the ratios 0.0%, 2.5%, 5.0%, 7.5%, 10.0%, 12.5% and 15.0%. In this study, 756 mortar samples were produced for 84 different series and were cured in tap water (W), 5% sodium sulphate solution (SS5) and 5% ammonium nitrate solution (AN5) for 7 days, 28 days, 90 days and 180 days. The developed DNN models have three inputs and two hidden layers with 20 neurons and one output, whereas the ANN models have three inputs, one output and one hidden layer with 15 neurons. Twenty-five previously obtained experimental sample datasets were used to train these developed models and to generate the regression equation. Fifty-nine non-training-attributed datasets were used to test the models. When these test values were attributed to the trained DNN, ANN and regression models, the brick-dust pressure as well as the bending and elongation values have been observed to be very close to the experimental values. Although only a small fraction (30%) of the experimental data were used for training, both the models performed the estimation process at a level that was in accordance with the opinions of experts. The fact that this success has been achieved using very little training data shows that the models have been appropriately designed. In addition, the DNN models exhibited better performance as compared with that exhibited by the ANN models. The regression model is a model whose performance is worst and unacceptable; further, the prediction error is observed to be considerably high. In conclusion, ANN- and DNN-based models are practical and effective to estimate these values.Öğe Experimental study on firebrick powder-based cementitious composites under the effect of elevated temperature(Elsevier, 2022) Alakara, Erdinc Halis; Sevim, Ozer; Demir, Ilhami; Simsek, OsmanThis study investigates the effect of elevated temperature on cementitious composites with 5, 10, 15, 20, and 25% firebrick powder (FBP). In this regard, cementitious composite mortars with di-mensions of 40 x 40 x 160 mm, which were water-cured at 20 +/- 2 degrees C for 56 days, were pro-duced. Produced samples were exposed to 300, 600, 750, and 900 degrees C, then air-and water-cooling processes were applied. Cooling processes were continued until the samples reached the labora-tory temperature. Unit weight, ultrasonic pulse velocity, compressive strength, and mass loss of the FBP-based cementitious composite samples were measured after both air-and water-cooling regimes. Finally, microstructural analysis was performed for reference samples and samples with 20% FBP. As a result, the compressive strengths of the samples exposed to 600, 750, and 900 degrees C showed that up to 15% of FBP-based cementitious composite samples had better results com-pared to the reference samples. The compressive strengths of the water-cooled samples were lower than those of the air-cooled samples. The mass loss results of FBP-based samples decreased with the increase in temperature. The mass loss of the air-cooled samples was higher than that of the water-cooled samples.Öğe Influence of freeze-thaw cycling on properties of cementitious systems doped with fly ash having optimized particle size distribution(Springernature, 2022) Demir, Ilhami; Filazi, Ahmet; Sevim, Ozer; Simsek, OsmanIn this study, the particle size distribution (PSD) of class F and C fly ash (FA) was optimized using theory of the Fuller-Thompson. After defining the optimal size distribution, the distribution modulus (q) of 0.4 yields the best mechanical property results. The freeze-thaw up to 300 cycles on mechanical and permeability properties of 90-day cementitious composites incorporating optimized class F and C fly ash (5, 10, 15, 20, 25, and 30% by weight of cement) were investigated. Optimized FA has improved the mechanical and permeability properties of cementitious composites under freeze-thaw cycling by ensuring a better filler effect. The cementitious composite mortars with 20% optimized class C fly ash and class F fly ash replacement yielded high compactness and better mechanical properties than the control cementitious composite mortars without any fly ash replacement after 90 days. Finding the best particle size distribution of FA providing high compactness will save cement, reduce the carbon dioxide (CO2) emission that pollutes the environment in cement production, and contribute to the economy and environment.Öğe Influence of freeze–thaw cycling on properties of cementitious systems doped with fly ash having optimized particle size distribution(Springer Science and Business Media Deutschland GmbH, 2022) Demir, İlhami; Filazi, Ahmet; Sevim, Ozer; Simsek, OsmanIn this study, the particle size distribution (PSD) of class F and C fly ash (FA) was optimized using theory of the Fuller-Thompson. After defining the optimal size distribution, the distribution modulus (q) of 0.4 yields the best mechanical property results. The freeze–thaw up to 300 cycles on mechanical and permeability properties of 90-day cementitious composites incorporating optimized class F and C fly ash (5, 10, 15, 20, 25, and 30% by weight of cement) were investigated. Optimized FA has improved the mechanical and permeability properties of cementitious composites under freeze–thaw cycling by ensuring a better filler effect. The cementitious composite mortars with 20% optimized class C fly ash and class F fly ash replacement yielded high compactness and better mechanical properties than the control cementitious composite mortars without any fly ash replacement after 90 days. Finding the best particle size distribution of FA providing high compactness will save cement, reduce the carbon dioxide (CO2) emission that pollutes the environment in cement production, and contribute to the economy and environment. © 2022, Wroclaw University of Science and Technology.Öğe Investigation of the Effect of Seawater and Sulfate on the Properties of Cementitious Composites Containing Silica Fume(Springer, 2022) Simsek, Osman; Aruntas, H. Yilmaz; Demir, Ilhami; Yaprak, Hasbi; Yazicioglu, SalihConcrete consumes over two billion tons of freshwater every year and 75 % of regions of the world will become water shortages in 2050. Because of increasing freshwater scarcity seawater may become reasonable as an alternative mixing and curing water for concrete. In this study, seawater (SW) was utilized for mixing and curing of concrete and investigated the seawater and sulfate on the properties of cementitious composites containing silica fume (SF). Hence, SF was replaced with the cement at ratios corresponding to 0 %, 2.5 %, 5 %, 7.5 %, 10 %, 12.5 %, and 15 % by weight of cement, and SW and tap water (TW) were used as mixing water in the production of cementitious composites. Thus, the effect of SW on the properties of fresh cement pastes and the flexural and compressive strengths of 7-day, 28-day, and 90-day old cementitious composites were examined. Additionally, the lengthening change values of cementitious composites containing SF that were kept in 5 % Na2SO4 solution for 7-day, 28-day, and 90-day were determined. The SF delayed the setting period while increasing the water requirement of the cement paste. It is determined that the SW accelerated the setting period of cement. In the case when 10 % SF in cementitious composites was used, the maximum compressive and flexural strengths were obtained for cementitious composites produced by mixing with SW and SF fume at an age corresponding to 28-day and 90-day. It was observed that the length change of the cementitious composites decreased due to the increase in the SF replacement ratio.Öğe Investigation of thermal and mechanical properties of perlite-based lightweight geopolymer composites(Springernature, 2023) Demir, Ilhami; Guzelkucuk, Selahattin; Sevim, Ozer; Simsek, OsmanThe objectives of this study include minimizing the thermal conductivity of the produced materials, reducing dead loads of structures through lightweight composite material production, and increasing perlite use in areas close to material deposits. To this end, lightweight geopolymer composites were produced using ground raw perlite as a precursor, expanded perlite as an aggregate, and sodium hydroxide (NaOH) as an activator. The produced samples were cured in an oven at 110 degrees C for 24 h. Within the scope of this study, unit weight, compressive strength, and thermal conductivity coefficient tests were conducted. Additionally, microstructure analysis was carried out using scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP). As a result, it has been shown that ground raw perlite can be used as a precursor in geopolymer composites, while expanded perlite demonstrates suitability as a lightweight and porous aggregate for heat insulation applications.Öğe Performance of cement mortars replaced by ground waste brick in different aggressive conditions(Univ Chemistry & Technology, Prague, 2011) Demir, Ilhami; Yaprak, Hasbi; Simsek, OsmanThis article investigates the sulphate resistance of cement mortars when subjected to different exposure conditions. Cement mortars were prepared using ground waste brick (GWB) as a pozzolanic partial replacement for cement at replacement levels of 0%, 2.5%, 5%, 7.5, 10%, 12.5 and 15%. Mortar specimens were stored under three different conditions: continuous curing in lime-saturated tab water (TW), continuous exposure to 5% sodium sulphate solution (SS), and continuous exposure to 5% ammonium nitrate solution (AN), at a temperature of 20 +/- 3 degrees C, for 7, 28, 90, and 180 days. Prisms with dimensions of 25x25x285 mm, to determine the expansions of the mortar samples; and another set of prisms with dimensions of 40x40x160 mm, were prepared to calculate the compressive strength of the samples. It was determined that the GWB replacement ratios between 2.5% and 10% decreased the 180 days expansion values. The highest compressive strength values were found for the samples with 10% replacement ratio in the TW, SS, and AN conditions for 180 days. The microstructure of the mortars were investigated using scanning electron microscopy (SEM) and the Energy dispersive X-ray (EDX).Öğe The Effect of Fiber Type and Ratio on the Physical and Mechanical Properties of Marble Powder Added Fiber Concrete(Gazi Univ, 2022) Simsek, Osman; Demir, SukruIn this study, it is aimed to determine the effect of steel and macro synthetic fibers used in different ratios and types on the physical and mechanical properties of concrete. For this purpose; Macro synthetic fiber was used at 0.25%, 0.30% and 0.35% by volum4, steel fiber at 0.50%, 0.75% and 1.00% by volume. Chemical additives and marble powder were used in fixed proportions. In the study, the water / cement ratio was taken as 0.54 constant according to the fiber concrete TS 802 mixture. In this research, beams of 10 x 10 x 40 cm and 15 cm cube samples were produced for fresh and hardened concrete properties. The effect of fiber type and ratio was investigated by performing physical and mechanical tests on the produced samples. As a result of the study, as the fiber ratio of fiber mixes in fresh concrete increased, workability and unit volume weights decreased. As a result, as the fiber ratio in fresh concrete increases, the fiber ratio has negatively affected the workability and the unit volume weights decreased. In hardened concrete; In hardened concrete; As the fiber ratio increased, the initial crack stress and bending stress increased. The highest mechanical and physical properties were given by 1.00% steel fiber and 0.35% macro synthetic fiber concretes.Öğe The effect of sea water on the properties of concrete with silica fume admixture(Stowarzyszenie Producentow Cementu, 2010) Demir, Ylhami; Yaprak, Hasbi; Simsek, OsmanTwo series of concrete samples with silica fume addition were produced from the mixtures with tap water or sea water, as mixing water. It was found that sea water has no harmful influence on the concrete mix properties, but increase the rate of concrete hardening. This caused the increase of concrete strength, which was observed till the end of measurements i.e. till 90 days. However the increase of strength after 90 days was smaller than after 28 days.
