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Öğe Comparison of the Influence of Silica-rich Supplementary Cementitious Materials on Cement Mortar Composites: Mechanical and Microstructural Assessment(Springer, 2021) Sevim, Ozer; Sengul, Cagri GoktugThe silica-rich supplementary cementitious materials (SCMs) are the key components of mechanical and microstructural properties. The use of SCMs results in improving the mechanical and microstructural properties and decreasing the environmental burden caused by cement production. In this regard, this paper reports a study to compare the influence of silica-rich supplementary cementitious materials (slag, fly ash, and bottom ash) having similar Blaine fineness on cement mortar composites in terms of mechanical and microstructural properties. The Blaine fineness of supplementary cementitious materials was chosen at cement Blaine fineness by using short grinding time due to minimize energy consumption and cost. Supplementary cementitious materials (slag, fly ash, and bottom ash) were ground at similar cement Blaine fineness (similar to 3300 cm(2)/g) and then by replacing 5 % and 20 % with cement, the 7-, 28-, 90-day mechanical and microstructural properties of cement mortar composites incorporating SCMs were examined. As a result, it was observed that the compressive strength properties of cement mortar composites incorporating 20 % slag gave similar strength of control samples (without SCM) according to samples with fly ash and bottom ash having similar fineness and this will decrease the required amount of cement and grinding time for the target strength properties, thus the number of CO2 emitted to nature will also decrease and less energy consumption, and the cost-effectiveness will be ensured by shorter grinding time for target strength.Öğe Comparison of the Influence of Silica?rich Supplementary Cementitious Materials on Cement Mortar Composites: Mechanical and Microstructural Assessment(Springer Science and Business Media B.V., 2021) Sevim, Ozer; Sengul, Cagrı GoktugThe silica-rich supplementary cementitious materials (SCMs) are the key components of mechanical and microstructural properties. The use of SCMs results in improving the mechanical and microstructural properties and decreasing the environmental burden caused by cement production. In this regard, this paper reports a study to compare the influence of silica-rich supplementary cementitious materials (slag, fly ash, and bottom ash) having similar Blaine fineness on cement mortar composites in terms of mechanical and microstructural properties. The Blaine fineness of supplementary cementitious materials was chosen at cement Blaine fineness by using short grinding time due to minimize energy consumption and cost. Supplementary cementitious materials (slag, fly ash, and bottom ash) were ground at similar cement Blaine fineness (~ 3300 cm2/g) and then by replacing 5 % and 20 % with cement, the 7-, 28-, 90-day mechanical and microstructural properties of cement mortar composites incorporating SCMs were examined. As a result, it was observed that the compressive strength properties of cement mortar composites incorporating 20 % slag gave similar strength of control samples (without SCM) according to samples with fly ash and bottom ash having similar fineness and this will decrease the required amount of cement and grinding time for the target strength properties, thus the number of CO2 emitted to nature will also decrease and less energy consumption, and the cost-effectiveness will be ensured by shorter grinding time for target strength. © 2021, Springer Nature B.V.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 Effect of Aggregate Type on Radiation Attenuation Properties of Heavyweight Concretes(Kırıkkale Üniversitesi, 2020) Gümüş, Merve; Demir, Şükrü; Sevim, OzerIt is known that the most common usage area of heavyweight concrete compared to different usage areas is nuclear power plants. Nuclear power plants are a complex of structures that are of great importance in today's world, which also lives the energy age, but also brings some dangers. The most important of these dangers is that these structures have the possibility of radiation leakage in case of any explosion situation. Therefore, the strength and durability properties of concretes that will be used in the construction of nuclear power plants should be designed meticulously. All this shows how important and worthy of study is the study subject. In the scope of the study, ultrasonic pulse velocity, compressive strength and radiation attenuation properties of concretes produced using 3 different types of aggregate, limestone crushed stone, barite and siderite were investigated. The results of the tests were interpreted comparatively. As a result, it has been determined that different aggregate types affect the ultrasonic pulse velocity, compressive strength, and radiation absorption properties of concrete.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 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 Effect of Supplementary Cementitious Materials with Similar Specific Surface Area on Cementitious Composite Systems(Amer Soc Testing Materials, 2023) Sevim, Ozer; Sengul, Cagri Goktug; Kartal, Saruhan; Toklu, Kenan; Caglar, YasinThis study investigated the effect of the mechanical and durability properties of cementitious composite systems with supplementary cementitious materials (SCMs), including fly ash (FA), ground granulated blast furnace slag (GGBS), and bottom ash (BA), with similar specific surface areas (similar to 3,300 cm2/g). FA, GGBS, and BA were ground to a specific surface area of similar to 3,300 cm2/g (about the cement-specific surface area) and then replaced with cement at 5 %, 10 %, 15 %, and 20 % replacement ratios. The compressive strength, flexural strength, length change, and rapid chloride ion permeability of the cementitious composites incorporating FA, GGBS, and BA with similar specific surface areas were recorded after 7-, 28-, and 90-day curing periods. As a result, cementitious composites containing GGBS improved the mechanical and durability properties at the maximum rate. It was shown that the properties of cementitious composites containing 20 % GGBS yielded better results than the control specimens without any SCMs.Öğe Effects of graphene nanoplatelets type on self-sensing properties of cement mortar composites(Elsevier Sci Ltd, 2022) Sevim, Ozer; Jiang, Zhangfan; Ozbulut, Osman E.Graphene nanoplatelets (GNPs) that possess high electrical conductivity and relatively low cost have been considered to obtain self-sensing capability in cementitious composites. However, there is limited understanding on the effects of physical properties of GNPs such as particle size and surface area on the self-sensing charac-teristics of the cement composites. In this study, nine types of GNPs that have different surface areas, particle sizes, and thicknesses are considered in the development of self-sensing mortar composites. For each type of GNPs, specimens with GNP concentrations of 2.5%, 5%, and 7.5% by weight of cement were prepared. The bulk electrical resistivity of the developed mortar composites was measured at different curing ages. The compressive strength of the specimens was also evaluated. The piezoresistive behaviors of the GNP-reinforced mortar com-posites were studied through cyclic compressive loading tests at different load levels. During piezoresistivity tests, the measurements were conducted through both direct current (DC) and alternating current (AC) and the results obtained from each method were evaluated. Results reveal that GNPs with very small particle sizes and large surface areas cannot disperse effectively in the cement matrix and do not provide piezoresistive charac-teristics. For GNPs with relatively smaller surface areas, the GNPs with higher particle sizes form effective conductive paths and exhibit better piezoresistive characteristics.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 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 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 Fresh and Hardened Properties of Cementitious Composites Incorporating Firebrick Powder from Construction and Demolition Waste(Mdpi, 2023) Sevim, Ozer; Alakara, Erdinc H.; Guzelkucuk, SelahattinFirebricks are generally used in furnace basins where glass, ceramics, and cement are produced. Firebricks have an important place in construction and demolition waste (CDW). However, there is a limited understanding of the effects on fresh and hardened state properties of cementitious composites. This study investigates the mechanical, physical, and microstructural properties of cementitious composites incorporating firebrick powder (FBP) from CDW. In this regard, the FBP was used at 5, 10, 15, 20, and 25% replacement ratio by weight of cement to produce cementitious composites. The consistency, setting characteristics, and 3, 7, and 28 days compressive and flexural strength tests of produced cementitious composites were performed. In addition, ultrasonic pulse velocity, water absorption, porosity, unit weight, and microstructure analysis of cementitious composites were conducted. As a result, the 28-day compressive strength of the cementitious composite mortars containing up to 10% firebrick powder remained above 42.5 MPa. The flow diameters increased significantly with the increase of the FBP. Therefore, it has been determined that the FBP can be used up to 10% in cementitious composites that require load-bearing properties. However, FBP might be used up to 25% in some cases. Using waste FBP instead of cement would reduce the amount of cement used and lower the cost of producing cementitious composites.Öğe Graphene-reinforced cement composites for smart infrastructure systems(Elsevier, 2022) Schulte, Justine; Jiang, Zhangfan; Sevim, Ozer; Ozbulut, Osman E.In traditional strategies for structural health monitoring of concrete structures, distributed sensors are commonly utilized to monitor and evaluate the state of the structure. This requires deployment of a large number of sensors to obtain sufficient information that can help the owners and engineers to timely detect anomalies in the structural performance. Considering the challenges, such as high deployment cost, low durability, and weak compatibility, for the use of conventional sensors in the long-term monitoring of concrete structures, self-sensing cement composites with intrinsic strain- and damage-sensing capabilities can be a more practical and sustainable approach for condition monitoring. Although various nano- and microfillers have been used to develop such smart cement composites, graphene and its derivatives have gained significant attention in developing functional cement-based composites over the past decade. Graphene sheets are two-dimensional nanomaterials and offer various advantages such as excellent mechanical properties, ultrahigh specific surface area, and relatively low cost. This chapter provides a comprehensive review on the use of graphene-based nanomaterials in the development of self-sensing cementitious composites. First, different forms of graphene-based nanomaterials are described and their use for self-sensing applications is assessed. Then various techniques for the dispersion of graphene nanomaterials into a cement matrix are discussed, followed by a discussion on the experimental techniques that can be used to assess the quality of dispersion. Also, different methods used for electrical and self-sensing characterization tests of cement composites are described. A summary of earlier studies on self-sensing graphene-reinforced cement composites is provided. Next, the piezoresistive behavior of graphene-reinforced cement composites under applied loads is presented for a mortar composite filled with different types of graphene materials. Finally, opportunities for the use of these self-sensing composites in smart infrastructure applications are discussed and potential challenges are noted. © 2022 Elsevier Inc. All rights reserved.Öğe In situ determination of the mechanical performance of the steel rods anchored on an existing masonry building wall(Springer India, 2021) Dogan, Orhan; Celik, Fatih; Odacioglu, Orhan Gazi; Sevim, OzerIn order to strengthen masonry building walls against horizontal earthquake loads, steel plates or in situ reinforced concrete layers need to be attached to one or both surfaces of the walls. Because the stiffness of the wall and the stiffness of the strengthening element will be different against earthquake loads, the elastic connectors are needed to be attached to the strengthening wall to comply with an existing wall. These connectors must have sufficient and well-known strength, flexibility, spacing, diameter, and depth to resist shear and pull-out forces that will occur between the wall and the strengthening element. And it is of great importance to determine the partially interacted pull-out and direct shear performances of the widely known flexible and commonly used steel rod connectors depending on the diameter and embedment depth in strengthening analysis. In this study, since the partially interacted pull-out test on chemically anchored steel rods has shown more realistic failure in comparison to the fully interacted pull-out test and both the partially interacted pull-out test and the shear test are quite difficult and time-consuming in comparison to the fully interacted pull-out test, the steel rods were anchored on an existing a five stories masonry building constructed using clay block bricks, mortar and plaster in Turkey and then three different types of tests were conducted on steel rods to determine the relation between the fully and partially interacted pull out performances and also between fully interacted pull out and shear performances. Very significant linear equations were obtained for the shear performance and partially interacted pull-out performance of the anchor rods in accordance with the fully interacted pull-out performance of the steel rod connectors for different embedment depth and hole.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.
