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Öğe Cement mortar composites including 1-tetradecanol@PMMA Pickering emulsion particles for thermal energy management of buildings(Elsevier Science Sa, 2023) Alkan, Cemil; Alakara, Erdinc Halis; Aksoy, Sennur Alay; Demir, IlhamiIn this study, a poly(methyl methacrylate) (PMMA) shell 1-tetradecanol core microencapsulated phase change material (MPCM) was produced using the Pickering emulsion technique. Characterization tests of the produced MPCMs were performed using Fourier transform infrared (FT-IR) spectroscopy, particle size distribution (PSD) analysis, differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA) techniques. The latent heat, melting temperature and encapsulation rate of MPCM were determined and they were found as 108.4 J/g, 33 degrees C, and 46.7 % for heating period, respectively. The effect of 1-tetradecanol@PMMA MPCM on the physical, mechanical, and thermal performance properties of cementitious mortars was also investigated in the study. For this reasons 1-tetradecanol@PMMA MPCMs are included in mortar mixes at 5 %, 7.5 %, and 10 % by weight of cement. As the MPCM ratio increased, the water absorption rate and porosity increased, while the workability, unit weight of the mortar, ultrasonic pulse velocity, flexural strength and compressive strength parameters decreased. The compressive strength of the mortar containing 10 % MPCM on the 28th day was measured as 34.74 MPa. The highest thermal storage capacity was found in mortars containing 10 % MPCM. When the thermal performance of the reference and 10 % MPCM-containing mortars were compared, the indoor temperature differences at the end of the heating and cooling periods were measured as 4.7 degrees C and 3.9 degrees C, respectively. The results showed that MPCM produced by the Pickering emulsion technique has the potential to increase thermal comfort in buildings, reduce fuel consumption used for heating purposes and, accordingly, reduce carbon emissions.Öğe Determination of compressive strength of perlite-containing slag-based geopolymers and its prediction using artificial neural network and regression-based methods(Elsevier Sci Ltd, 2022) Alakara, Erdinc H.; Nacar, Sinan; Sevim, Ozer; Korkmaz, Serdar; Demir, IlhamiThis study has two main objectives: (i) to investigate the parameters affecting the compressive strength (CS) of perlite-containing slag-based geopolymers and (ii) to predict the CS values obtained from experimental studies. In this regard, 540 cubic geopolymer samples incorporating different raw perlite powder (RPP) replacement ratios, different sodium hydroxide (NaOH) molarity, different curing time, and different curing temperatures for a total of 180 mixture groups were produced and their CS results were experimentally determined. Then conventional regression analysis (CRA), multivariate adaptive regression splines (MARS), and TreeNet methods, as well as artificial neural network (ANN) methods, were used to predict the CS results of geopolymers using this experimentally obtained data set. Root mean square error (RMSE), mean absolute error (MAE), scatter index (SI) and Nash-Sutcliffe (NS) performance statistics were used to evaluate the CS prediction capabilities of the methods. As a result, it was determined that the optimum molarity, curing time, and curing temperature were 14 M, 24 h, and 110 celcius, respectively and 48 h of heat curing did not have a significant effect on increasing the CS of the geopolymers. The highest performances in regression-based models were obtained from the MARS method. However, the ANN method showed higher prediction performance than the regression-based methods. Considering the RMSE values, it was seen that the ANN method made improvements by 24.7, 2.1, and 13.7 %, respectively, compared to the MARS method for training, validation, and test sets.Öğe Determination of type and ratio of superplasticizers in concrete production(2007) Şimşek, Osman; Aruntaş, Hüseyin Yilmaz; Demir, IlhamiConcrete is the most commonly used construction material. The most significant properties of the concrete are the workability and compressive strength. The use of silica fume (SF) and super plasticizers (SP) in concrete has considerably increased in recent years. In this research, three different SP in three different ratios were added to 10 % SF substitution of concrete. Slump, Ve-Be and air content properties were examined in the fresh sample concrete mixtures. In addition, the effects of 2, 7 and 28-day compressive strength and freezing-thawing resistance on hardened concrete were investigated. As a result, the highest compressive strength and freezing-thawing resistance were obtained with 1 % modification lignosulphanate SP additive concrete and 2 % modification lignosulphanate SP additive concrete, respectively.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 The effect of different fiber reinforcement on the thermal and mechanical properties of autoclaved aerated concrete(Elsevier Sci Ltd, 2016) Pehlivanli, Zuhtu Onur; Uzun, Ibrahim; Yucel, Zeynep Pinar; Demir, IlhamiIn this study, the changes in thermal conductivity value, compression and flexural strength of autoclaved aerated concrete were investigated experimentally by adding polypropylene, carbon, basalt and glass fibers into the G3/05 and G4/06 class autoclaved aerated concrete used as wall elements in buildings and the commercial production of which is made. Fibers were substituted with the aggregate in autoclaved aerated concrete in equal amounts volumetrically. The produced samples were subjected to autoclaved cure as in non-fibrous autoclaved aerated concrete. As a result of the experimental study; it has been seen the thermal conductivity of fiber substituted autoclaved aerated concrete changes linearly with thermal conductivity of the substituted fibers and basalt fiber reinforced autoclaved aerated concrete gives the highest thermal conductivity. But, it has been seen that the best compression and flexural strength was given by the carbon fiber reinforced samples. (c) 2016 Elsevier Ltd. All rights reserved.Öğe Effect of magnetic water on properties of slag-based geopolymer composites incorporating ceramic tile waste from construction and demolition waste(Springernature, 2023) Sevim, Ozer; Alakara, Erdinc Halis; Demir, Ilhami; Bayer, I. RaciThis study investigates the effect of magnetic water (MW) on the properties of slag-based geopolymer composites (SGCs) incorporating ceramic tile waste (CTW) from construction and demolition waste (CDW). The presented study consists of two stages. In the first stage, reference mortars without additives were produced, and optimum parameters for molarity, curing temperature and curing time were determined. Tap water (TW) was used as mixing water, and blast furnace slag (BFS) was used as a precursor in SGCs in this stage. SGCs were produced using different alkali activator concentrations (12, 14 and 16 M) and were cured for either 24 or 48 h in an oven at ranging from 60 to 110 degrees C. Ultrasonic pulse velocity (U-pv), flexural strength (f(fs)), and compressive strength (f(cs)) tests were performed on the produced SGCs. The results of these tests indicated that optimum paramaters for molarity, curing temperature and curing time parameters were determined to be 16 M, 100 celcius and 24 h, respectively. Then, TW and MW were used as mixing water, and BFS and CTW were used as precursors in the second stage. At this stage, SGCs were produced using 16 M and cured in an oven at 100 celcius for 24 h. In the mixtures, CTW was used by substituting 10, 20, 30 and 40% by weight of BFS. In the second stage, workability, U-pv, f(fs), and f(cs) tests as well as microstructure analyses, were performed on the produced SGCs. Microstructure analyses were performed with scanning electron microscopy (SEM). According to the results, U-pv, f(fs), and f(cs) increased compared to the reference SGCs when 10% of CTW was used. Additionally, when MW was used as mixing water, there were increases in workability, U-pv, f(fs), and f(cs) results compared to those produced with TW. From SEM analyses, it has been observed that MW accelerates the polymerization process of SGCs containing CTW and reduces the pore size of SGCs. As a result, it has been determined that MW can improve the fresh and hardened state properties and microstructures of SGCs containing CTW.Öğe Effect of magnetized water on alkali-activated slag mortars incorporating raw and calcined marble powder(Elsevier Sci Ltd, 2024) Demir, Ilhami; Alakara, Erdinc Halis; Sevim, Ozer; Kartal, SaruhanThis study investigates the impact of magnetized water (MW) on the fresh and hardened properties of alkaliactivated slag (AAS) mortars incorporating raw marble powder (RMP) and calcined marble powder (CMP). In the initial stage of the study, control specimens were manufactured to ascertain the optimal parameters for molarity, curing temperature, and curing time. The optimal parameters were determined based on the highest strength results: a molarity of 10, curing time of 24 hours, and curing temperature of 110 degree celsius. In the second stage of the study, while maintaining these optimal parameters, RMP and CMP were substituted in place of blast furnace slag (BFS) at rates of 10%, 20%, 30%, and 40%. In this study stage, tap water (TW) and MW were employed as the mixing water. A mini -slump test was conducted to assess the fresh state properties of the prepared AAS mortars. Subsequently, ultrasonic pulse velocity ( U p v ), flexural strength ( f f ), and compressive strength ( f c ) tests were carried out to evaluate the hardened state properties of the specimens. Finally, scanning electron microscopy (SEM) analysis was performed to examine microstructural properties. According to the results, the f f and f c values of the mortars produced with CMP substitution using TW showed an increase of up to 20.6% compared to the mortars based on RMP and produced withTW. Additionally, utilizing MW as the mixing water enhanced the workability of AAS mortars. Consequently, incorporating CMP and MW in AAS mortars further improved fresh and hardened state properties compared to RMP and TW.Öğe Effect of Molarity, Curing Time and Curing Temperature on Perlite Powder-Containing Slag-Based Geopolymers(Springer Int Publ Ag, 2024) Demir, Ilhami; Korkmaz, SerdarAs a result of the four-fold increase in the human population in the last century and the development of technology and industry, the use of natural resources, environmental protection, sustainability and the evaluation of waste materials have become one of the most important agenda items. The construction industry has also been affected by these developments, and in the last twenty years, studies have been carried out on the use of alternative binding materials instead of cement. Geopolymer production is one of the methods seen as an alternative to cement. Geopolymer production has given very positive results in terms of controlling CO2 emissions, evaluating waste materials, and protecting natural resources. At the same time, obtaining high strength at an early age by using heat curing is one of the important advantages of geopolymer. In this study, blast furnace slag (BFS), which is an industrial waste, and raw perlite powder (RPP) obtained from raw perlite, a natural aggregate, were used as binders. In this way, it is aimed to participate in the recycling of wastes and to use natural resources efficiently. Sodium hydroxide (NaOH), which does not emit CO2 in its production, was preferred as an activator. In this study, it was aimed to produce early high-strength geopolymer composites with materials with no/minimum level of CO2 emission. The molarity was chosen as 12, 14 and 16 molarities (M) in order to obtain early high strength. Curing temperature 60, 80, 100 and 110 & DEG;C was selected. Heat cure was applied for 24 and 48 h. Regression and ANOVA tests were applied on the results obtained. It has been revealed that the obtained compressive strength results are reasonable data. It has been observed that compressive strength estimation can be made with an accuracy of 82% in geopolymer composites. The internal structures of geopolymer composites were interpreted using SEM and EDX analyses. As a result, as the rate of RPP replacement instead of BFS increased, the amount of gel in the geopolymer composites decreased, and accordingly the compressive strength values decreased. The highest compressive strengths were obtained at 110 & DEG;C during the 24-h curing period. The optimum molarity was determined to be 14 M. The highest compressive strength was measured as 67.72 MPa in the sample cured at 110 & DEG;C for 24 h. Thanks to this study, it has been seen that approximately 70 MPa compressive strength can be obtained after one day by using materials with no CO2 emission/minimum level in their production. Increasing the curing time to 48 h increased the amount of microcracks and voids. Therefore, the compressive strengths of the geopolymer samples was adversely affected. It has been revealed that RPP can be used in the production of geopolymers, but research needs to be developed.Öğe Effect of sulfate on cement mortars containing Li2SO4, LiNO3, Li2CO3 and LiBr(Elsevier Sci Ltd, 2017) Demir, Ilhami; Sevim, OzerThe purpose of this study is to explore the influence of sulfate on the fresh and hardened mortars containing lithium additives added with the aim to prevent alkali-silica reaction (ASR). Four different types of lithium additives (Li2SO4, LiNO3, Li2CO3 and LiBr) were added to the cement at the ratios of 0.5%, 1%, 1.5%, and 2% by mass in order to produce mortar specimens. Influence of sulfate on the specimens was then investigated. Used in order to keep the expansion under control, expansion characteristics and mechanical properties of Li2SO4, LiNO3, Li2CO3 and LiBr were defined. Initial setting and final setting tests were conducted on the cement pastes as per the provisions of TS EN 196-3 standard. Flexure and compressive tests were conducted in accordance with TS 196-1 in order to identify the mechanical properties of cement mortars. Prisms of 25 x 25 x 285 mm in dimension were produced as per ASTM C 1012-95 in order to measure the length change of the cement bars and results were analyzed. The results showed that Li2CO3 among the other lithium additives was effective in shortening the initial setting and final setting times, while LiNO3 and LiBr additives gave the best results in terms of strength and length change when tested for 1% additive ratio by mass. The highest length change was observed for the specimens with Li2CO3 cured both in water and sulfate solution. The lowest length change was observed for the specimens with LiNO3 cured both in water and sulfate solution. 1% LiNO3 additive gave the best results under sulfate effect for all test days. The length change of cement mortar with 1% LiNO3 additive was decreased by 53%, 25%, and 41% under sulfate effect for the 90th, 180th, and 360th day, respectively. It is believed that the use of LiNO3 and LiBr additives at the ratio of 1% by mass will reduce the unfavorable influence of sulfate. Li2CO3 and LiSO4 should not be used because they have negative effects on mechanical properties and length changes. (C) 2017 Elsevier Ltd. All rights reserved.Öğe Effects of High Temperature and Cooling Regimes on Properties of Marble Powder-Based Cementitious Composites(Mdpi, 2023) Bayer, Ismail Raci; Sevim, Ozer; Demir, IlhamiThe demand for cement is increasing every day worldwide. To meet this demand, natural resources are rapidly being depleted. The excessive consumption of natural resources encourages researchers to conduct studies on the use of waste materials instead of cement. Marble waste is one of the major natural wastes abundantly generated worldwide. It has been evaluated that there is a gap in the literature regarding a study comparing the effects of different cooling regimes on cementitious composites with a marble powder (MP) replacement that has been exposed to high temperatures. In this study, waste marble powder (MP) was used as a replacement for cement at percentages of 5%, 10%, 15%, 20%, and 25% by mass. The water-to-binder ratio was kept constant at 0.5 for all mixture groups. Subsequently, the prepared cementitious composites were exposed to high temperatures (300 degrees C, 600 degrees C, and 800 degrees C) and subjected to air- and water-cooling regimes. Within the scope of this study, unit weight (Uw), ultrasonic pulse velocity (UPV), flexural strength (ffs), compressive strength (fcs), and mass loss tests were conducted. Additionally, a microstructure analysis was carried out using scanning electron microscopy (SEM) to examine the effect of MP replacement and the cooling regime. When examining the results of the samples tested in the laboratory, it was observed that the mortar with 5% MP replacement exhibited better mechanical properties compared with the others. In general, it can be said that the mechanical properties of samples cooled in air after exposure to high temperatures were better than those of samples cooled in water. As a result of this study, it was determined that MP replacement could positively contribute to the resistance of cementitious composites to high temperatures. Additionally, the use of a significant amount of waste MP can lead to savings in cement usage and significant reductions in CO2 emissions.Öğe The effects of shrinkage-reducing admixtures used in self-compacting concrete on its strength and durability(Elsevier Sci Ltd, 2018) Demir, Ilhami; Sevim, Ozer; Tekin, EmrahThis study explores the effects of shrinkage-reducing admixtures (SRA) used in self-compacting concrete (SCC), a specific type of concrete which is gradually receiving widespread use, yet to be improved to the desired properties and expected to replace traditional concrete in the future, on its strength and durability. In this study, SCC mixtures with and without (reference) different SRA dosages were produced to define the optimum SRA utilization rate in SCC mixtures. After deciding the SRA dosage to be used in mixtures, properties of reference and SRA-added SCC mixtures were evaluated by focusing mainly on the workability, strength and durability properties after subjected to either direct water submersion or cyclic Na2SO4 solution. As a result of the experimental program, it was concluded that the presence of SRA has adverse effects on the mechanical properties of SCC specimens although these effects are not dramatic regardless of the harshness of environmental exposure. The influence of SRA addition on fresh-state properties was also minimal so that the workability of reference and SRA-added SCC mixtures were found to be similar. Occurrence and further development of both drying and restrained shrinkage were substantially restricted with varying rates when SRA was incorporated in SCC mixtures. Overall, this study concludes that with a proper selection of SRA dosage, SCC mixtures performing well even under very hazardous environments can successfully be produced and be taken advantage of without sacrificing much of workability and/or mechanical properties and risking the occurrence and further development of shrinkage-originated cracking. (C) 2018 Elsevier Ltd. All rights reserved.Öğe Effects of sulfate on cement mortar with hybrid pozzolan substitution(Elsevier - Division Reed Elsevier India Pvt Ltd, 2018) Demir, Ilhami; Guzelkucuk, Selahattin; Sevim, OzerSulfate is one of the most important chemical risks which affect the durability of concrete and reinforced concrete structures. Therefore, this study investigates the effects of sulfate on blended cement mortars. In this paper, cement mortar specimens were prepared with the substitution of CEM I 42.5 R cement with Fly ash + Bottom ash + Blast-furnace Slag at the ratios of 5%, 10%, 15%, and 20% along with a control specimen without additives. These prepared cement mortar specimens were then cured for 2, 7, 28, 90, 180, and 360 days either in potable water or 10% sodium sulfate (Na2SO4) solution. Cement paste specimens were subjected to the initial setting, final setting, and volumetric expansion tests in accordance with the TS EN 196-3 standard. Cured for 2, 7, 28, 90, 180, and 360 days, cement mortars were subjected to compressive strength tests as per the TS EN 196-1 standard while length change tests were conducted as per the ASTM C 1012 standard. It was found that the compressive strength of cement mortars blended with 5% Fly ash + Bottom ash + Blast-furnace Slag cured in sodium sulfate for 360 days was approximately 2% higher than that of the cement mortar without additives. The length change of specimens obtained from cured in sodium sulfate solution shows best results in higher additive ratio. These all length changes ratio are greater than 0.087% ratio which is maximum length change expansion in potable water. This study suggests that 15% and 20% additive ratios are effective in reducing unfavorable effects of sulfate. (C) 2018 Karabuk University. Publishing services by Elsevier B.V.Öğe Effects of the sole or combined use of chemical admixtures on properties of self-compacting concrete(Springernature, 2021) Sevim, Ozer; Kalkan, Ilker; Demir, Ilhami; Akgungor, Ali PayidarChemical additives are very important in determining the behavioral characteristics of self-compacting concrete. For this reason, determining the building materials that make up the chemical structure of self-compacting concrete and the interactions of these materials is of great importance. The present study pertains to the effects of the use of different chemical admixtures (high-range water-reducing, i.e., superplasticizer, hydration accelerating, air-entraining, shrinkage reducing, and hydration heat reducing admixtures) on the fresh and hardened properties of self-compacting concrete. The influence of using a single one or a hybrid combination of the air-entraining, hydration-accelerating, heat-reducing, and shrinkage-reducing admixtures on the mechanical properties of fresh and hardened SCC was investigated through a set of tests. For this purpose, sixteen different SCC mixtures with different combinations of chemical additives were prepared and tested. The properties of fresh concrete were examined as well as the compressive and tensile strengths of the mixtures. SCC mixtures with shrinkage-reducing admixtures were evaluated in terms of shrinkage development. The effect of the use of admixtures was found to be more pronounced on the early-age concrete strength. The use of any type of additive in addition to the shrinkage-reducing admixture increased the speed of flow of fresh concrete.Öğe Engineering Properties of Granite Aggregates in Kaman, Kirsehir Region(Gazi Univ, 2007) Demir, Ilhami; Onal, M. MustafaIn this research, the engineering properties of granite crushed stone aggregates obtained from block stone quarries in Kaman, Kirsehir region were examined. Forthis aim; samples were taken from Yelek, Savcili I, Omerhacili and Savcili II stone quarries. Granulometry, specific density, water absorption, unit weight, freeze-thaw, abrasion resistance, sulphate, and choloride quantity, particle shape and alkali-aggregate reaction properties of the samples were tested. As a result it was seen that Savcili I region samples had the most convenient engineering properties among all sample aggregates.Öğe Enhancement on mechanical and durability performances of binary cementitious systems by optimizing particle size distribution of fly ash(SPRINGERNATURE, 2020) Filazi, Ahmet; Demir, Ilhami; Sevim, OzerFly ash is a well-known supplementary cementitious material that is the by-product of coal-fired thermal power plants. The contribution of fly ash to the enhancement of the mechanical and durability properties of cementitious materials has been documented in concrete technology for many years. In this study, to allow superior mechanical and durability properties, fly ash-based mixtures have been produced after optimization of particle size distribution (PSD) of Class F and Class C fly ash according to the formula of Fuller-Thompson. Different distribution modulus values ranging from 0.3 to 0.6 were used to achieve ideal PSD in accordance with the Fuller-Thompson equation. 30% of F- and C-class fly ash by weight of cement were used to replace with cement in cementitious composites by optimizing PSD with help of air jet sieve. The recommended optimization technique improved the 7-, 28- and 90-day compressive and flexural strength results of mortars. Compressive and flexural strength tests and rapid chloride permeability test of cement-based systems incorporating fly ash up to 15% replacement ratio with optimized PSD at 90-days exhibited better results than those of plain samples owing to the filler effect.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 Evaluation of Mechanical and Microstructural Properties of Engineered Geopolymer Composites with Construction and Demolition Waste-Based Matrices(Asce-Amer Soc Civil Engineers, 2024) Kul, Anil; Ozcelikci, Emircan; Ozel, Behlul Furkan; Gunal, Muhammed Faruk; Yildirim, Gurkan; Bayer, Ismail Raci; Demir, IlhamiThe main purpose of this work was to combine the advantages of increased material greenness, waste upcycling, reduced raw material demand, and the superior characteristics of traditional engineered cementitious composites (ECCs). To this end, engineered geopolymer composites (EGCs) with matrices based entirely on components from construction and demolition waste (CDW) as precursors and aggregates were developed. The CDW-based precursors included roof tiles, red clay bricks, hollow bricks, glass, and concrete. Different combinations of sodium hydroxide, sodium silicate, and calcium hydroxide were used as alkaline activators. Hybridized polyethylene and nylon fibers were used as fibers. To investigate the influences of the additional calcium source, slag-substituted versions of the same mixtures were produced. At the fresh state, Marsh cone and mini-slump tests were performed. At the hardened state, mechanical property tests (compressive strength and four-point bending) and microstructural characterization tests (X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy) were conducted. The findings revealed that, regardless of the mixture composition, all EGCs exhibited a deflection-hardening response coupled with multiple microcracking behavior. The 28-day average ranges for compressive strength, flexural strength, and midspan deflection results were 25.2-42.1 MPa, 6.2-9.5 MPa, and 14.1-28.3 mm, respectively. Slag substitution mostly improved the mechanical performance of EGCs. The main geopolymerization products were sodium aluminosilicate hydrate (NASH), calcium aluminosilicate hydrate (CASH), and C-(N)-ASH gels, the formation of which varied depending on the type of precursor and activator.Öğe Experimental Evaluation of New Geopolymer Composite with Inclusion of Slag and Construction Waste Firebrick at Elevated Temperatures(Mdpi, 2023) Sevim, Ozer; Demir, Ilhami; Alakara, Erdinc Halis; Bayer, Ismail RaciThis study investigates the effect of elevated temperatures on slag-based geopolymer composites (SGC) with the inclusion of firebrick powder (FBP). There is a limited understanding of the properties of SGC with the inclusion of FBP when exposed to elevated temperatures and the effects of cooling processes in air and water. In this regard, in the preliminary trials performed, optimum molarity, curing temperature, and curing time conditions were determined as 16 molarity, 100 degrees C, and 24 h, respectively, for SGCs. Then, FBP from construction and demolition waste (CDW) was substituted in different replacement ratios (10%, 20%, 30%, and 40% by slag weight) into the SGC, with optimum molarity, curing temperature, and curing time. The produced SGC samples were exposed to elevated temperature effects at 300, 600, and 800 degrees C and then subjected to air- and water-cooling regimes. The ultrasonic pulse velocity, flexural strength, compressive strength, and mass loss of the SGCs with the inclusion of FBP were determined. In addition, scanning electron microscopy (SEM) analyses were carried out for control (without FBP) and 20% FBP-based SGC cooled in air and water after elevated temperatures of 300 degrees C and 600 degrees C. The results show that the compressive and flexural strength of the SGC samples are higher than the control samples when the FBP replacement ratio is used of up to 30% for the samples after the elevated temperatures of 300 degrees C and 600 degrees C. The lowest compressive and flexural strength results were obtained for the control samples after a temperature of 800 degrees C. As a result, the elevated temperature resistance can be significantly improved if FBP is used in SGC by up to 30%.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.
