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Application of fly ashes from fluid bed coal combustion within refractory materials
Kotrla, Jan ; Bartoníčková, Eva (referee) ; Šoukal, František (advisor)
The thesis deals with the possibility of utilization of fluid ash in refractory materials and its influence on resulting properties. This work studies the effect of bed and filter ash addition on properties of the droplet and resulting mechanical properties, bulk density, shrinkage and firing temperature of stove fireclay. The subject of this thesis is also reduction of SO2 emissions evolved burning of fireclay containing fluid ash rich of anhydrite. Emissions of SO2 were observed by TG-TDA-EGA method. Characterization of prepared samples and study of heat treatment processes was based on XRD, TG-DTA-EGA, TDA, SEM–EDS, heating microscope and isothermal calorimetry.
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The importance and role of greenery in historic city centers
Tašnerová, Lucie ; Kotrla, Jan (referee) ; Májek, Jan (advisor)
The thesis focuses on the urbanistic analysis, public space and greenery situation in Litomyšl’s historic town centre with regard to an improvement of public space quality. Urban greeneary is an integral part of the urban environment of the city. Beside buildings, technical infrastructure and services, urban greenery is an important component of any urban space. It is a part of environment of human and it is a great part of good psychical ease of man. Many features and kinds of public green are known. Trees and shrubs create architectural elements in grassy areas. Planting, maintaining and resorting vegetation must belong amongst priorities of development of any city. The first part work describes the terminology, distribution and development of urban greenery. The second part focuses on the analysis of the area of the historic center of the city Litomyšl with regard to greenery. Current problems and limits due to which the public space loses its quality and future development is no more possible. At the end of the work is the best solution for revitalization og the green area suggested in order to develop public space with preserving the urban concept of the historic town centre.
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The binder based on the high-calcium ash - the influence of the alkali activator
Šichnárek, Vojtěch ; Kotrla, Jan (referee) ; Koplík, Jan (advisor)
The aim of this thesis was examination of the influence of different alkali activators to final properties of binders based on fluidized bed combustion fly ash. There were prepared mixtures containing sodium waterglass or sodium carbonate. Curing time, consistence, and strengths after 2, 7, 14 and 28 days were measured. X-ray diffraction and X-ray fluorescence were used to find out the composition of samples. There were taken images and element spectra using scanning electron microscope and isothermal calorimetry was used to determine the heat flow during the time of curing. The results indicate that the use of water glass achieves better initial workability and pressure strengths are higher than besides sodium carbonate. However, when sodium carbonate is used, pressure strengths are lower, but they are less dependent on the amount of the activator and do not change as much with time. Crystallographic composition is dependent to the activator used – by using sodium waterglass there was more of ettringite and portlandite in the sample.
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The influence of different anions on fixation of Cu in alkali-activated blast furnace slag
Böhm, Petr ; Kotrla, Jan (referee) ; Koplík, Jan (advisor)
The work deals with the fixation of copper in alkali activated blast furnace slag and with the influence of anionts (sulphate, nitrate, chloride and oxide) to its immobilization. This is tested according to leaching tests ČSN EN – 12457 4. The concentration of copper in leachates was determined by inductively coupled plasma optical emission spectrometry. The aim of this work is to check the influence of addition (copper) to the resulting mechanical properties and also specify, how the heavy metal is bonded in the matrix. The structure was examined by scanning electron microscopy.
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Effect of curing conditions on shrinkage of alkali activated systems
Pragerová, Barbora ; Kotrla, Jan (referee) ; Kalina, Lukáš (advisor)
This bachelor thesis deals with the determination of optimal curing conditions of alkali-activated systems in order to reduce shrinkage. Hardened alkali-activated blast-furnace slag pastes activated by sodium silicate were tested in the empirical part. Six varieties of curing conditions were compared. Immediately after demolding process, three sets of samples were stored in air, water and plastic film. Another three sets were first placed in water for 14 days, then removed and two of them impregnate with lithium silicate and acrylate-based coatings. The formation and the number of cracks were monitored by an optical method. The percentage of cracks was evaluated by the ImageJ program. The highest number of cracks was formed after 7 days of curing, given the samples placed in the open air. Some them were filled later. Samples placed in the open air after being submerged in water for 14 days showed a rapid increase of cracks as well, but the percentage of cracks was reduced to 50 %. Treating agents reduced the development of cracks but have not stopped their formation. After 36 days of curing, the results of these types of curing conditions were comparable. Only the samples wrapped in plastic foil showed a minimum number of cracks and no cracks were observed if the samples were submerged in water. The lowest levels of shrinkage were reached with the samples placed in water, and with the ones wrapped in plastic foil. Samples stored in water for the first 14 days showed the identical tendency of high-level shrinkage, as did the ones placed in the open air.
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Modification of polyvinylalcohol of lower saponification degree for preparation of MDF composites
Kotrla, Jan ; Švec, Jiří (referee) ; Šoukal, František (advisor)
The subject of the bachelor thesis is modification of polyvinylalcohol of lower saponification degree for preparation of MDF composites. MDF composites are characterized by their extreme mechanical properties. However, their low resistance to moisture is a significant disadvantage. Increased moisture resistance could be achieved by grafting suitable functional groups on the polymeric chain and the subsequent cross-linking. The study is focused on optimization of the number of functional groups and the cross-linking conditions. The number of grafted functional groups was determined by UV – VIS, XPS analysis and IR spectrophotometry. The solubility of the crosslinked samples was measured by rheological measurements.
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The binder based on the high-calcium ash - the influence of the alkali activator
Šichnárek, Vojtěch ; Kotrla, Jan (referee) ; Koplík, Jan (advisor)
The aim of this thesis was examination of the influence of different alkali activators to final properties of binders based on fluidized bed combustion fly ash. There were prepared mixtures containing sodium waterglass or sodium carbonate. Curing time, consistence, and strengths after 2, 7, 14 and 28 days were measured. X-ray diffraction and X-ray fluorescence were used to find out the composition of samples. There were taken images and element spectra using scanning electron microscope and isothermal calorimetry was used to determine the heat flow during the time of curing. The results indicate that the use of water glass achieves better initial workability and pressure strengths are higher than besides sodium carbonate. However, when sodium carbonate is used, pressure strengths are lower, but they are less dependent on the amount of the activator and do not change as much with time. Crystallographic composition is dependent to the activator used – by using sodium waterglass there was more of ettringite and portlandite in the sample.
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Effect of curing conditions on shrinkage of alkali activated systems
Pragerová, Barbora ; Kotrla, Jan (referee) ; Kalina, Lukáš (advisor)
This bachelor thesis deals with the determination of optimal curing conditions of alkali-activated systems in order to reduce shrinkage. Hardened alkali-activated blast-furnace slag pastes activated by sodium silicate were tested in the empirical part. Six varieties of curing conditions were compared. Immediately after demolding process, three sets of samples were stored in air, water and plastic film. Another three sets were first placed in water for 14 days, then removed and two of them impregnate with lithium silicate and acrylate-based coatings. The formation and the number of cracks were monitored by an optical method. The percentage of cracks was evaluated by the ImageJ program. The highest number of cracks was formed after 7 days of curing, given the samples placed in the open air. Some them were filled later. Samples placed in the open air after being submerged in water for 14 days showed a rapid increase of cracks as well, but the percentage of cracks was reduced to 50 %. Treating agents reduced the development of cracks but have not stopped their formation. After 36 days of curing, the results of these types of curing conditions were comparable. Only the samples wrapped in plastic foil showed a minimum number of cracks and no cracks were observed if the samples were submerged in water. The lowest levels of shrinkage were reached with the samples placed in water, and with the ones wrapped in plastic foil. Samples stored in water for the first 14 days showed the identical tendency of high-level shrinkage, as did the ones placed in the open air.
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The influence of different anions on fixation of Cu in alkali-activated blast furnace slag
Böhm, Petr ; Kotrla, Jan (referee) ; Koplík, Jan (advisor)
The work deals with the fixation of copper in alkali activated blast furnace slag and with the influence of anionts (sulphate, nitrate, chloride and oxide) to its immobilization. This is tested according to leaching tests ČSN EN – 12457 4. The concentration of copper in leachates was determined by inductively coupled plasma optical emission spectrometry. The aim of this work is to check the influence of addition (copper) to the resulting mechanical properties and also specify, how the heavy metal is bonded in the matrix. The structure was examined by scanning electron microscopy.
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Application of fly ashes from fluid bed coal combustion within refractory materials
Kotrla, Jan ; Bartoníčková, Eva (referee) ; Šoukal, František (advisor)
The thesis deals with the possibility of utilization of fluid ash in refractory materials and its influence on resulting properties. This work studies the effect of bed and filter ash addition on properties of the droplet and resulting mechanical properties, bulk density, shrinkage and firing temperature of stove fireclay. The subject of this thesis is also reduction of SO2 emissions evolved burning of fireclay containing fluid ash rich of anhydrite. Emissions of SO2 were observed by TG-TDA-EGA method. Characterization of prepared samples and study of heat treatment processes was based on XRD, TG-DTA-EGA, TDA, SEM–EDS, heating microscope and isothermal calorimetry.
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