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Modification of concrete elements for cooling towers
Mohelská, Lucie ; Šoukal, František (referee) ; Opravil, Tomáš (advisor)
This master´s thesis deals with the suppression of the growing of algae in cooling towers. Subject of the work is suggestion and testing surface modification of the existing mature concrete in order to suppress the growth of algae. In the frame surface modification, several commercially available and newly developed systems were tested. Testing systems are based on the basis of portland cement, geopolymers or formation of insoluble complex compounds containing metal elements (Zn, Cu). Experimental methods were applied in the real environment of cooling towers of Dukovany Nuclear power plant.
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Possibilities of elimination of residual ammonia content from technological water in power plants
Hajzler, Jan ; Bartoníčková, Eva (referee) ; Opravil, Tomáš (advisor)
This master thesis aims to study the possibilities of eliminating, or separation of ammonium shares from technological water of plants, where is introduced a secondary method of flue gas denitrification (SCR, SNCR). The need for elimination of ammonium shares arose after introduction of emission cap, which have been tightened since January 2015. The denitrification technologies were installed on devices that did not comply with the new limits. The theoretical part of the thesis deals with the description of combustion processes, as a fluid, and high temperature combustion of solid fuels, mechanisms of emissions and their reduction options. At the conclusion of the theoretical part is discussed the contents of the ammoniacal nitrogen in waters used in electricity and heating facilities to transport, or from which are separated by solid products of some processes such as desulphurization. There are also discussed some options for removal of ammonium salts from technological waters. Experimental part deals with finding appropriate method of determination of ammoniacal nitrogen, and the possibilities of its elimination by conversion to insoluble compound. Last but not least, the work deals with the evaluation of the sustainability of the proposed solutions. And as well as the real possibilities of their application in practice.
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Floor systems based on secondary raw materials from power industry
Kalina, Martin ; Švec, Jiří (referee) ; Opravil, Tomáš (advisor)
This thesis deals with the possibility of using secondary raw materials from the energy industry especially the solid residues of high temperature combustion of coal. These materials should be now seen as a material with wide usage especially in the construction industry. One possibility of their usage is a replacement of binding parts in floor systems. The aim is to find the optimal composition of the mixture, which fits all the technical requirements and at the same time reduces the cost of its production. An advanced methods of powder X-ray diffraction analysis, particle size laser diffraction analysis and X-ray fluorescence analysis were used to determine the raw materials. Based on these analysis the experiments were designed focusing on the mechanical properties, the observation of the evolution of hydration’s heat in prepared mixtures and their time of setting and hardening.
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Possibilities of application of meta-talc
Fridrich, Jakub ; Ptáček, Petr (referee) ; Opravil, Tomáš (advisor)
The aim of this bachelor thesis is study of physical and chemical properties of metatalk. Metatalc is delaminated and dehydroxylated form of talc which was earlier prepared and described on FCH BUT in cooperation with MRC (Material Research Center). This thesis is part of the way to find suiting use for this newly found material and it takes on proposing forms of use. Tested attributes are particle size, particle surface, volumetric mass, sorption and cation exchange capacity.
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The technology of aerated concrete
Zezulová, Anežka ; Kalina, Lukáš (referee) ; Opravil, Tomáš (advisor)
The technology of aerated concrete is a topic that is permanently studied and developed because of the incessant demand for a building material which ensures relatively high strength at low volume weight. This bachelor’s thesis examines the influence of replacing a part of sand with another silica material – microsilica. The increase of mechanical strength is expected at the same volume weight. Microsilica contents around 98 % of amorphous silicon dioxide with a high specific surface area that is substantially higher than a specific surface area of a ground sand. The reactivity of silicon dioxide increases with a higher specific surface area and also with the creation of a mineral tobermorite, which is the keeper of the strength in autoclaved aerated concrete. Three types of microsilica were chosen to examine the influence of replacing a part of sand with microsilica according to their availability for manufacture: microsilica Sikron and Elkem 971 U, microsilica Grace Davison was tested only marginally. Tests were carried out to determine volume weight, compressive strength, phase composition (by X-Ray diffraction method), and the content of tobermorit (by TG-DTA method).
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Enamels containing recycled brick waste
Tmejová, Jana ; Ptáček, Petr (referee) ; Opravil, Tomáš (advisor)
The diploma thesis deals with the possibilities of using recycled brick as a component in the preparation of glazes. Recycled brick is a mixture of crushed bricks, it can also contain a brick tablecloth, its composition and color makes this material practically identical to a brick shard. Due to these properties, it can be assumed that recycled brick can be used to prepare technical glazes with a specific color. The aim of the diploma thesis is to verify the possibilities of using recycled brick for the preparation of technical glazes. For prepared glazes, then evaluate their properties and estimate for which type of product these alternative glazes could be used.
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Utilization possibilities of industry gypsum and secondary materials containing for preparation of composites
Weiglová, Jana ; Šoukal, František (referee) ; Opravil, Tomáš (advisor)
The work studies the possibilities of the utilization of secondary raw materials produced by power industry. It addresses mainly the gypsum by-products and fluidized coal combustion ash. As for the secondary raw materials the content of sulphites is observed and the dependences of their transformation to sulphides via natural oxidation by air oxygen or by addition of adequate oxidant are studied. The work follows with describing the effect of sulphides contained in raw materials on the mechanical properties of composites prepared from several various matrices such as alumina or portland cement, lime or portland clinker. As for pure portland clinker the ability to retard the setting is also observed. The amount of contained sulphites is measured volumetrically via indirect titration of iodine surplus by sodium thiosulphate with the starch size as the indicator.
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Utilization possibilitiesof foundry sands in geopolymers systems
Kopecký, Filip ; Másilko, Jiří (referee) ; Opravil, Tomáš (advisor)
Considering increasing manufacture of cast iron, steels and other metallic materials made in foundries increases also production of waste foundry sands. Foundry sands that remain after moulding and can not be reused in the prouction process are usually not recycled nowadays and in the better cases they are clasified as a fill materials. Becouse these secondary raw materials are produced in relatively big amounts it is apropriate to search for their effective reuse. One of the possibilities is using of this materials in buliding industry. Thanks to their constitution and properties we can consider the possibilties of an alkaline activation. Thats why this work discusses the possibilities of the alkaline activation of the waste foundry sands.
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Utilization of mica separated from washed kaolin
Vaculík, Josef ; Ptáček, Petr (referee) ; Opravil, Tomáš (advisor)
The Master’s Thesis aims to laboratory test the possibilities of utilization mica separate, which arises during the process of floating kaolin as a by-product together with sand. Mica and sand are then separated by flotation or vibration. The mica separate thus formed was subjected to analysis. XRD and heating microscopy methods were used for analysis. Subsequently, experiments with mica separation as a filler in composites based on epoxy resins were set up and performed. Furthermore, the separate was tested as a part of plasters and visual building elements. Last but not least, the separate was mixed into the ceramic, which was then subjected to firing in the selected mode. The diploma thesis provides a comprehensive overview of the above-mentioned possibilities of using mica separation, which is based on a sufficient amount of experimental data.
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Possibilities of affecting the portland cement hydration by the addition of fluidized ash
Nehybka, Josef ; Bartoníčková, Eva (referee) ; Opravil, Tomáš (advisor)
This work is focused on study of possibilities of influence of hydration of Portland cement with an admixture of fluid ashes. The work deals with the tests with fluid filter ashes and milled fluid bed combustion ashes. Predominantly, a calorimetric measurement is used for study of admixtures. The prepared samples were found out on their mechanical parameters as the tensile bending strength and compressive stress. X-ray powder diffraction was used to determine of phase composition of the raw materials and created samples after hydration.
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