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The effect of the partial replacement of natural filler by ground waste sulfur originating from the oil refining process on the fresh and hardened properties of self-compacting concrete was investigated. Properties investigated were slump... more
The effect of the partial replacement of natural filler by ground waste sulfur originating from the oil refining process on the fresh and hardened properties of self-compacting concrete was investigated. Properties investigated were slump flow, V-funnel, L-box, and sieve segregation of fresh concrete mixes; compressive, flexural, and bond (pull off) strengths, dynamic modulus of elasticity, ultrasonic pulse velocity, dynamic Poisson’s ratio, specific electrical resistance, density, and microstructure of hardened concrete. Results showed a slight decline in compressive, flexural, and bond strengths and dynamic elasticity modulus with increased addition of sulfur. Specific electrical resistance and density were higher for samples containing sulfur. Also, scanning electron microscopy indicated a slight porosity increase in the samples containing sulfur. Having in mind that, in the case of waste valorization in concrete, all properties of self-placing concrete should remain within acceptable levels or improve, this study proved that mixtures containing ground sulfur as a partial replacement for filler could be used for structural applications.
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Milica VLAHOVIĆ,, Aleksandar SAVIĆ, Sanja MARTINOVIĆ, Nataša ĐORĐEVIĆ, Zoran STEVIĆ, Tatjana VOLKOV HUSOVIĆ 1 University of Belgrade, Institute of Chemistry, Technology and Metallurgy, Belgrade, Serbia 2 University of Belgrade, Faculty of... more
Milica VLAHOVIĆ,, Aleksandar SAVIĆ, Sanja MARTINOVIĆ, Nataša ĐORĐEVIĆ, Zoran STEVIĆ, Tatjana VOLKOV HUSOVIĆ 1 University of Belgrade, Institute of Chemistry, Technology and Metallurgy, Belgrade, Serbia 2 University of Belgrade, Faculty of Civil Engineering, Belgrade, Serbia 3 Institute for Technology of Nuclear and Other Mineral Raw Materials, Belgrade, Serbia 4 University of Belgrade, Faculty of Electrical Engineering, Technical Faculty Bor, CIK Belgrade, Serbia 5 University of Belgrade, Faculty of Technology and Metallurgy, Belgrade, Serbia
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Due to the Portland cement chemical reaction, which always takes place in a hardening concrete, a certain amount of heat is released. This heat should be quantified, as it can harm or aid the concrete itself, depending on the concrete... more
Due to the Portland cement chemical reaction, which always takes place in a hardening concrete, a certain amount of heat is released. This heat should be quantified, as it can harm or aid the concrete itself, depending on the concrete components, structure element, ambient and building site conditions. There are number of possible setups for the monitoring of heat of hydration, two of which have been applied in the case presented in this paper. Four concretes were monitored with the use of the two stated techniques for 24 hours. First technique used is thermo-vision camera which monitored the surface, and the second is thermosensor - used for monitoring of interior of fresh concrete hardening mass. The potential of the applied setup lays in the ease of installation, low price, and possibilities of mass application, which could substantially aid the monitoring and prevent concrete failure.
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Mining induced the ground subsidence and consequently, damages on objects above excavation works is a serious problem all over the world. In this paper, a new approach for subsidence and deformation prediction based on the stochastic... more
Mining induced the ground subsidence and consequently, damages on objects above excavation works is a serious problem all over the world. In this paper, a new approach for subsidence and deformation prediction based on the stochastic Pataric-Stojanovic method is presented. Since the calculation using the equations of this method is very complex, the original computer program package with the title MITSOUKO has been purposely designed. The MITSOUKO program enables calculating at any point of the land surface and representing the results owing to the possibility of their integration and further processing in the Geographical Information System (GIS). The components of the GIS are used to realize the spatial analysis.
Research Interests: Mining Engineering, Computer Science, Software Engineering, Spatial Analysis, Subsidence, and 10 moreSoftware, Geosciences, Coal Mining, Excavation, Damages, Geodesy and Surveying Engineering, Geographical Information Systems in the context of Earth Sciences, Mine Surveying, Geographic Information System, and GIS
The occurrence of subsidence caused by the underground coal mining may be a complex process that causes damage to the environment. In the last century, there was a significant development in prediction methods for calculating the surface... more
The occurrence of subsidence caused by the underground coal mining may be a complex process that causes damage to the environment. In the last century, there was a significant development in prediction methods for calculating the surface subsidence. In this paper, a new prediction method has been developed to calculate subsidence by combining a stochastic model of the ground movements and Geographical Information System (GIS). All the subsidence calculations are implemented by an original program package MITSOUKO, where the components of the GIS are used to fulfil the spatial analysis. This subsidence prediction technique has been applied to calculate the ground movements resulting from excavating 21 mining panels that are mined successively in the coal mine ''Rembas''-Resavica, Serbia. Details of movement were sequentially predicted and simulated in terms of years exploitation. Predictive calculation of the undermined terrain displacement parameters by the stochasti...
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The problem of subsidence and damages on buildings above mining works is an inevitable consequence of underground coal mining in large mining basins. Significant development of various methods for prediction of the displacement parameters... more
The problem of subsidence and damages on buildings above mining works is an inevitable consequence of underground coal mining in large mining basins. Significant development of various methods for prediction of the displacement parameters of the undermined terrain took place in the period from the middle of the last to the beginning of this century. In this paper, a new mathematical model of the stochastic Pataric-Stojanovic method for the predictive subsidence calculation is developed. A case study, as an example for the practical application of the proposed stochastic method, is given for the underground coal mine “Rembas”- Resavica, Serbia. An original MITSOUKO program package, supported by spatial analyses in the Geographic Information System (GIS), was developed for the predictive subsidence calculation based on the stochastic method proposed by the authors Pataric and Stojanovic. The comparative analysis of predicted and measured subsidence values confirms the possibility of using this stochastic method for predictive subsidence calculation in practice, which is a necessity of modern mining.
Research Interests: Mining Engineering, Geology, Spatial Analysis, Subsidence, Remote sensing and GIS applications in Landscape Research, and 11 moreGeo-spatial analysis with GIS and GPS, Earth and Environmental Sciences, Coal Mining, Spatial Analysis with GIS and Geostatistical Methods, GIS development, Terrain, Underground Coal Mining, Ground Subsidence, Geographic Information Systems (GIS), GIS, and Mine Subsidence
Pulse-reverse power modes are used in galvanotechniques in order to obtain coatings with better characteristics in terms of gloss, adhesion, tracking sharp edges and uniform distribution of deposits on complex shape objects, compared with... more
Pulse-reverse power modes are used in galvanotechniques in order to obtain coatings with better characteristics in terms of gloss, adhesion, tracking sharp edges and uniform distribution of deposits on complex shape objects, compared with the coatings produced by constant current modes. Pulse-reverse modes also allow the use of a higher current density, and thus the production speed of electroplating cells increases. Systems for standard electroplating of copper, silver and gold are optimised by the suitable choice of duration and intensity of the pulses. It is shown that coatings with satisfactory quality can be deposited using higher current density, different modes of pulsed current in a very short period of time, without expensive and often dangerous additives in the electrolyte. Parameters of the model for certain electrochemical systems were determined by modelling and computer simulation, so the system behaviour under different circumstances becomes predictive.
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Research Interests: Materials Science, Chemistry, Image Analysis, Zeolite, Cavitation, and 6 moreCeramic, Talk, Cavitation erosion, Zeolit, Tehnika, and TALC
Self-compacting concrete (SCC) contains fine mineral fillers such as limestone powder. The idea of this study was to partially replace limestone with waste sulfur since it is hydrophobic, insoluble in water and therefore chemically inert... more
Self-compacting concrete (SCC) contains fine mineral fillers such as limestone powder. The idea of this study was to partially replace limestone with waste sulfur since it is hydrophobic, insoluble in water and therefore chemically inert and to compare the properties of produced concrete samples. Fresh concrete properties included: slump-flow, t500, V-funnel time, L-box ratio, segregation ratio, density, and entrained air content. Hardened concrete was tested for compressive, flexural and bond strengths, ultrasonic velocity, dynamic elasticity modulus, dynamic Poisson’s ratio, and microstructure. Flowability and segregation increased, while bulk density, compressive and flexural strength, dynamic elasticity modulus and ultrasonic velocity slight declined. Times t500 and V-funnel time, L-box ratio and entrained air changed insignificantly. Considering that all properties should remain or improve in case of waste valorization and the criteria should set to satisfy requirements for ...
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Abstract Pattern recognition techniques are applied to various morphological descriptors to monitor the formation and propagation of surface defects of materials subjected to thermal shock. A low-cement high-alumina castable was... more
Abstract Pattern recognition techniques are applied to various morphological descriptors to monitor the formation and propagation of surface defects of materials subjected to thermal shock. A low-cement high-alumina castable was synthesized, cured, sintered, and exposed to thermal stability testing using the water quench test. After a certain number of thermal shock cycles, photographs of the samples’ surfaces were taken and subjected to image analysis. The influence of the sintering temperature on the morphology of the detected defects was studied using principal component analysis (PCA) as a pattern recognition technique that is the most informative for extracting possible differences. The morphological descriptors of the defects correspond to the previous results regarding the influence of sintering temperature on the structure of a castable during thermal shocks.
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The intent in this paper is to define how the batch equilibrium results of copper removal from a synthetic solution on natural zeolite can be used for prediction of the breakthrough curves in the fixed-bed system for both a synthetic... more
The intent in this paper is to define how the batch equilibrium results of copper removal from a synthetic solution on natural zeolite can be used for prediction of the breakthrough curves in the fixed-bed system for both a synthetic solution and wastewater. Natural zeolite from the Vranjska Banja deposit, Serbia, has been fully characterized (XRD, chemical composition, DTA/TG, SEM/EDS) as a clinoptilolite with cation exchange capacity of 146 meq/100 g. The maximum adsorption capacity (qm) in the batch of the mono-component system (synthetic copper solution) obtained using the Langmuir isotherm model was 7.30 and 6.10 mg/g for particle size below 0.043 and 0.6–0.8 mm, respectively. Using the flow-through system with the 0.6–0.8 mm zeolite fixed-bed, almost double the adsorption capacity (11.2–12.2 mg/g) has been achieved in a saturation point for the copper removal from the synthetic solution, compared to the batch. Better results are attributed to the constant high concentration gr...
Research Interests: Materials Science, Minerals, Adsorption, Heavy metals, Wastewater, and 5 moreCopper, Zeolite, Clinoptilolite, Fixed Bed, and Batch
Abstract In this study the resistance of cordierite and zircon to the cavitation erosion was investigated with the aim of possible spreading their application. Cavitation erosion test was applied using standard ultrasonic vibratory set up... more
Abstract In this study the resistance of cordierite and zircon to the cavitation erosion was investigated with the aim of possible spreading their application. Cavitation erosion test was applied using standard ultrasonic vibratory set up with stationary sample. Weight loss and image analysis measurements including morphological analysis of the formed pits were used for monitoring degradation during the cavitation erosion testing. The obtained results were discussed in order to compare and analyze degradation mechanism and the resistance of the investigated materials to cavitation erosion. Cordierite sample underwent less serious degradation, characterized by continual forming of new pits, while zircon degradation progressed by growth and merging of already formed pits.
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In many industrial processes that include fluid flow, cavitation erosion of different engineering structures (pumps, turbines, water levels, valves, etc.) during their operation is expected. Metallic, ceramic, and composite materials are... more
In many industrial processes that include fluid flow, cavitation erosion of different engineering structures (pumps, turbines, water levels, valves, etc.) during their operation is expected. Metallic, ceramic, and composite materials are usual candidates considered for application in such extreme conditions. In this study, the idea is to synthesize refractory ceramic material based on talc with the addition of zeolite for utilization as protective coatings in cavitating conditions. Two talc-based refractories with zeolites from two Serbian deposits were produced. The behaviors of the samples in simulated cavitation conditions were examined by an advanced non-destructive methodology consisting of monitoring mass loss and surface degradation using image analysis compiled with principal component analysis (PCA), interior degradation by ultrasonic measurements, and the microstructure by a scanning electron microscope (SEM). Lower mass loss, surface degradation level, and modeled strengt...
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Concrete is a material that has been used for centuries and is often modified using polymers. In the last fifty years, synthetic polymers have been used for the modification of concrete, but also for the production of concrete. In recent... more
Concrete is a material that has been used for centuries and is often modified using polymers. In the last fifty years, synthetic polymers have been used for the modification of concrete, but also for the production of concrete. In recent decades, sulfur concrete has been an interesting product that can be used mainly in low-rise construction due to its characteristics. In this work, we used the starting mixture for the preparation of sulfur concrete (sand, elemental sulfur with the addition of modified sulfur and fillers) heated to a temperature of 120 ºC to 170 ºC and homogenized. The results of previous research on the production of sulfur concrete showed that the density of the obtained product changes depending on the type as well as the amount of filler added to the basic mixture based on raw materials. Talc, microsilicon, plate alumina and fly ash were used as fillers. The amounts of fillers were 0%, 1%, 3%, 5%, 7% and 10%.
Two types of concrete will be shown in this paper. First type of concrete is sulfur concrete, where part of Portland cement was replaced with sulfur. Second type of concrete is selfcompacting concrete, where sulfur replaced part of the... more
Two types of concrete will be shown in this paper. First type of concrete is sulfur concrete, where part of Portland cement was replaced with sulfur. Second type of concrete is selfcompacting concrete, where sulfur replaced part of the filler, with different contents. Analysis of the required amount of sulfur for these types of concretes, as well as the influence on the quality achieved and potential application in objects for Renewable energy, will be discussed
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Microstructural and cavitation erosion testing was carried out on Cu-12.8Al-4.1Ni (wt. %) shape memory alloy (SMA) samples produced by continuous casting followed by heat treatment consisting of solution annealing at 885 °C for 60 min... more
Microstructural and cavitation erosion testing was carried out on Cu-12.8Al-4.1Ni (wt. %) shape memory alloy (SMA) samples produced by continuous casting followed by heat treatment consisting of solution annealing at 885 °C for 60 min and, later, water quenching. Cavitation resistance testing was applied using a standard ultrasonic vibratory cavitation set up with stationary specimen. Surface changes during the cavitation were monitored by metallographic analysis using an optical microscope (OM), atomic force microscope (AFM), and scanning electron microscope (SEM) as well as by weight measurements. The results revealed a martensite microstructure after both casting and quenching. Microhardness value was higher after water quenching than in the as-cast state. After 420 min of cavitation exposure, a negligible mass loss was noticed for both samples. Based on the obtained results, both samples showed excellent cavitation resistance. Mass loss and morphological analysis of the formed p...
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Secondary sulfur obtained as a by-product in the oil refining process is a major problem as an environmental pollutant. One of the possibilities of environmental protection is the use of sulfur obtained in this way as a component of... more
Secondary sulfur obtained as a by-product in the oil refining process is a major problem as an environmental pollutant. One of the possibilities of environmental protection is the use of sulfur obtained in this way as a component of sulfur concrete. Mixing of sulfur with suitable additives can provide longer working lifetime of sulfur concrete, as well as maintenance of the former physical, chemical, and mechanical properties of concrete. Such mixtures are usually called modified sulfur or sulfur cement. Secondary sulfur produced in the oil refining process by the Klaus process (approval of crude oil) cannot be used in this form. In order to be ready for the use of sulfur concrete and asphalt, it is necessary to modify elemental sulfur from cyclic to chain form, obtaining of modified sulfur whose application is as a binding agent in a concrete instead of portland cement is described in this paper. Influence of dicyclopentadien, an organic additive, on sulfur modification has been st...
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Following the global trends and accordingly to the energy conditions, wind turbines are being succesfully built in Serbia, which leads to an increase in the fund of knowledge in this field. In the paper, on the basis of general... more
Following the global trends and accordingly to the energy conditions, wind turbines are being succesfully built in Serbia, which leads to an increase in the fund of knowledge in this field. In the paper, on the basis of general geotechnical conditions in Serbia, the most common types of wind turbine foundations will be presented. Problems of the load analysis of these structures will be presented in brief, and also the conceptual requirements in their design. Connection between the tower and the foundation will be briefly described as well. Despite the global aspiration to generalize and industrialize this aspect of the construction of wind turbines, in specific cases remains a number of issues, regarding component materials, the application of standards and design codes, which are usually not adjusted to the design of wind turbine foundations.
Research Interests: Engineering, Design, Foundations, Wind Power, Turbine, and 3 moreWind Turbines, Application, and Tower
Throughout its historical development, mining has faced the problem of moral and material responsibility due to various types of endangerment and damage to the environment. As a result of the underground coal exploitation, a movement of... more
Throughout its historical development, mining has faced the problem of moral and material responsibility due to various types of endangerment and damage to the environment. As a result of the underground coal exploitation, a movement of the rock massif above the coal seam, and changes on the terrain surface due to the process of massif stabilizing take place. The process occurs in space and time, from the moment of balance disturbance in the massif, i.e., the beginning of excavation, during excavation, and after the final excavation of deposit, when the equilibrium state is reestablished in the massif. The character and intensity of these movements and principles according to which they are performed, depend on numerous natural and mining-technological conditions, and are specific to each individual coal deposit. Deformations on the terrain surface in the sinkhole occur in the horizontal and vertical directions. Their values serve to determine the vulnerability level of individual o...
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Thermal shock stability plays a great role in the selection of optimal refractory material. Different methods of characterization were developed for this purpose, including the implementation of nondestructive testing. Image analysis is a... more
Thermal shock stability plays a great role in the selection of optimal refractory material. Different methods of characterization were developed for this purpose, including the implementation of nondestructive testing. Image analysis is a very well method for characterization of different materials structures, as well as changes and occurred defects in structure caused by different influences. In this paper, possible application of image analysis will be presented related to the monitoring thermal shock behavior of selected refractory materials. Different parameters such are R parameter, level of destruction, as well as determination of morphological descriptors (area, perimeter, diameter, roundness) using Image analysis, will be presented.
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During mechanical activation, qualitative changes that can produce various phenomena occur in the material. In this study, anhydrous sodium carbonate was mechanically activated for 2, 7, 14, and 28 minutes in a vibro mill at a frequency... more
During mechanical activation, qualitative changes that can produce various phenomena occur in the material. In this study, anhydrous sodium carbonate was mechanically activated for 2, 7, 14, and 28 minutes in a vibro mill at a frequency of 3000 oscillations per minute. After activation, four series of activated samples were stored in the air at room conditions for 31 days (relaxation period). To monitor the kinetics of the transformation process of activated sodium carbonate samples, i.e. the mechanism of sodium bicarbonate formation during relaxation, Fourier-transform infrared (FTIR) spectroscopy analysis was used. FTIR testing was performed as a function of relaxation time for all four series of samples, with characteristic groups observed: CO32-, HCO3- and OH-. The obtained results provided kinetics parameters for the transformation of sodium carbonate into sodium bicarbonate due to the chemisorption of moisture and carbon dioxide from the atmosphere.
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International audienc
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International audienc
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International audienc
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Thermal power plants in Serbia use lignite for electrical power production The secondary product of coal combustion is fly ash in the amount of 17%. Fly ash causes the pollution of air, water and soil, and also cause many human,... more
Thermal power plants in Serbia use lignite for electrical power production The secondary product of coal combustion is fly ash in the amount of 17%. Fly ash causes the pollution of air, water and soil, and also cause many human, especially lung diseases. Secondary sulphur is a product of crude oil refining. The aim of this study was to investigate the use of sulphur as a bonding material in ultra fine particle agglomeration (smaller than 63 ?m) in fly ash. The agglomeration should make the ash particles larger and heavy enough to fall without flying fractions. The experiments showed that during the homogenization of the ashes and sulphur from 150 to 170 ?C in a reactor with intensive mixing, an amount of 15% sulphur was sufficient to bond particles and cause agglomeration without visible flying fractions.
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ABSTRACT The purpose of this study was to investigate behavior and degradation level of refractory concrete sintered at different temperatures during the thermal stability testing. Alumina based low cement castable was synthesized, cured,... more
ABSTRACT The purpose of this study was to investigate behavior and degradation level of refractory concrete sintered at different temperatures during the thermal stability testing. Alumina based low cement castable was synthesized, cured, and then sintered at 1100, 1300, and 1600 °C with dwell time of 3 h. Prepared samples were subjected to the water quench test. Behavior of the refractory concrete and determination of surface and internal degradation level during the testing were monitored by ultrasonic measurements and image analysis. Overall material degradation was determined by measuring the strength degradation of samples using the standard laboratory procedure. The samples sintered at 1300 °C showed the best behavior under thermal shock, since they withstood 110 cycles of water quench without breaking. It was evident that during the thermal shock, surface and interior of the samples sintered at 1600 °C behave differently compared with those sintered at 1100 and 1300 °C.
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Abstract In order to predict service life of the sulfur–polymer composite, the samples were subjected to the induced destruction using 10% hydrochloric acid solution. Control specimens were prepared using Portland cement binder.... more
Abstract In order to predict service life of the sulfur–polymer composite, the samples were subjected to the induced destruction using 10% hydrochloric acid solution. Control specimens were prepared using Portland cement binder. Sulfur–polymer composite showed limited mechanical strength and mass loss, while physico-mechanical properties of Portland cement composite regressed rapidly. The Image Pro Plus software was used for surface destruction monitoring. The simulations for composites were applied to the previously reported model for predicting the mechanical strength degradation during durability testing, based on the image analysis results. The results proved that the time gradient of structural change was useful for quantification of service life, therefore it can be accepted as a parameter that represents service life.
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The majority of refractories used today are associated with the iron and steel industries. Typically, the refractory lining of a blast furnace consists of a combination of different refractory materials chosen for different portions of... more
The majority of refractories used today are associated with the iron and steel industries. Typically, the refractory lining of a blast furnace consists of a combination of different refractory materials chosen for different portions of the furnace, as well as distinct process conditions and temperature ranges. Knowledge and requirements for the iron manufacturing system in conjunction with the physical, mechanical, and chemical qualities of the proposed refractories determine the choice of refractory combination. Inadequate understanding of the aforementioned components frequently results in refractory failure, which then becomes a difficult problem to tackle. A blast furnace's refractory liner typically fails owing to any number or combination of these variables. To facilitate comprehension, we will explain the types of refractory lining required in a blast furnace by region, as well as the observed trend in refractory lining patterns over the past few decades.
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High-temperature materials are used in a wide range of industries and applications such as gas turbine engines for aircrafts, power and nuclear power plants, different types of furnaces, including blast furnaces, some fuel cells,... more
High-temperature materials are used in a wide range of industries and applications such as gas turbine engines for aircrafts, power and nuclear power plants, different types of furnaces, including blast furnaces, some fuel cells, industrial gas turbines, different types of reactors, engines, electronic and lighting devices, and many others. Demands for high-temperature materials are becoming more and more challenging every year. To perform efficiently, effectively and at the same time to be economically viable, the materials used at high temperatures must have certain characteristics that are particularly expected for applying under such extreme conditions, for example, the strength and thermal resistance. In the present review, some important requirements that should be satisfied by high temperature materials will be discussed. Furthermore, the focus is put on refractory concretes, ceramics, intermetallic alloys, and composites as four different categories of these materials, which...
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This study analyzes the feasibility of valorizing industrial by-product, fly ash from a thermal power plant as a partial replacement of mineral filler-limestone for the production of self-compacting concrete (SCC). Three types of SCC... more
This study analyzes the feasibility of valorizing industrial by-product, fly ash from a thermal power plant as a partial replacement of mineral filler-limestone for the production of self-compacting concrete (SCC). Three types of SCC mixtures with different portions of fly ash and the reference mixture with limestone were designed. The synthesized SCCs in the fresh state were examined for density, entrained air content, flowability (Slump flow, Slump flow time (t500), V-funnel time (tv)), passing ability (L-box), and segregation resistance, while hardened state testing included: density, compressive and flexural strength, static modulus of elasticity, water permeability, resistance against freezing in the presence of deicing salt, and SEM analysis. Taking into account the obtained results it can be concluded that the addition of fly ash has a positive impact on the concrete properties and that the optimal content of fly ash is 20 % with respect to the total filler mass.
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High-temperature materials are used in a wide range of industries and applications such as gas turbine engines for aircrafts, power and nuclear power plants, different types of furnaces, including blast furnaces, some fuel cells,... more
High-temperature materials are used in a wide range of industries and applications such as gas turbine engines for aircrafts, power and nuclear power plants, different types of furnaces, including blast furnaces, some fuel cells, industrial gas turbines, different types of reactors, engines, electronic and lighting devices, and many others. Demands for high-temperature materials are becoming more and more challenging every year. To perform efficiently, effectively and at the same time to be economically viable, the materials used at high temperatures must have certain characteristics that are particularly expected for applying under such extreme conditions, for example, the strength and thermal resistance. In the present review, some important requirements that should be satisfied by high temperature materials will be discussed. Furthermore, the focus is put on refractory concretes, ceramics, intermetallic alloys, and composites as four different categories of these materials, which...
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This study analyzes the feasibility of valorizing industrial by-product, fly ash from a thermal power plant as a partial replacement of mineral filler-limestone for the production of self-compacting concrete (SCC). Three types of SCC... more
This study analyzes the feasibility of valorizing industrial by-product, fly ash from a thermal power plant as a partial replacement of mineral filler-limestone for the production of self-compacting concrete (SCC). Three types of SCC mixtures with different portions of fly ash and the reference mixture with limestone were designed. The synthesized SCCs in the fresh state were examined for density, entrained air content, flowability (Slump flow, Slump flow time (t500), V-funnel time (tv)), passing ability (L-box), and segregation resistance, while hardened state testing included: density, compressive and flexural strength, static modulus of elasticity, water permeability, resistance against freezing in the presence of deicing salt, and SEM analysis. Taking into account the obtained results it can be concluded that the addition of fly ash has a positive impact on the concrete properties and that the optimal content of fly ash is 20 % with respect to the total filler mass.
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To provide the quality required for its use, raw kaolin must be subjected to certain processing procedures like delamination which is applied to the layered structure materials. The aim of this research is to determine the possibility of... more
To provide the quality required for its use, raw kaolin must be subjected to certain processing procedures like delamination which is applied to the layered structure materials. The aim of this research is to determine the possibility of performing delamination in the extruder and to estimate the effects of this process on the physico-chemical properties of kaolin. The results showed that delamination can be efficiently realized in the extruder by shearing densely packed layers under the influence of friction force and added Na2CO3 electrolyte. The crystal structure of the system was thus disrupted. This was confirmed by the Hinckley index (HI) decrease and by the dilatometric characteristics changes during heating. The particle size was reduced and, furthermore, new adsorption centers were formed, which led to an increase in the total cation exchange capacity (CEC). The plasticity of kaolin decreased with the increasing delamination degree, as well as the amount of water required f...
This paper is occupied by track and control of single component raw materials melting process. Experiments were performed in an electric-resistance furnace with a horizontally placed movable graphite electrode (heater). Used raw material... more
This paper is occupied by track and control of single component raw materials melting process. Experiments were performed in an electric-resistance furnace with a horizontally placed movable graphite electrode (heater). Used raw material was floated quartz sand, while obtained material was electrofused SiO2, also called quartz glass. Height of the electrode elevation and total melting time were varied. The process is considered as non-stationary process due to existence of captured gas bubbles in the viscous melt and many accompanying effects, as well. Tracking of processing parameters was enabled by thermovision as the source of information. In that regard, infrared camera was used. On the basis of these measurements, temperature profiles in the system during the melting process were obtained. Working models of the process were defined by correlation of the temperature changes with time at distances of 1, 3 and 5 cm from the heater. The “black box” method that correlates temperatur...