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Evaluation of properties of coal combustion solid residues
Cesnek, Ľuboš ; Bílek, Vlastimil (referee) ; Opravil, Tomáš (advisor)
The bachelor’s thesis focuses on condition monitoring of a stored high-temperature fly ash and its properties over time. The high-temperature fly ash comes from a dumping where it has been aggregated over several years. Samples of fly ash used for our analysis were taken from a bore-hole with a depth of 38 meters. Subsequently, detailed analyses of the fly ash from individual depth levels were performed. Furthermore, mechanical properties, volume stability and changes in weight of the prepared test beams were tested. The aim of the experiment was to evaluate suitability of using fly ash from a dumping site as a pozzolanic admixture in cement pastes.
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Study of microstructure of autoclaved aerated concrete with using of secondary raw materials
Martanová, Jana ; Suchý, Peter (referee) ; Kulísek, Karel (advisor)
Autoclaved aerated concrete is a used building material, especially for its thermal insulating properties. During autoclaving, an aerated concrete microstructure produces crystalline CSH phases, primarily tobermorite. The ingoing substances are calcium oxide and silica. In addition to commonly used raw materials, secondary raw materials rich in silicon dioxide can be used for production. The use of secondary raw materials gives the opportunity for the construction industry to be more environmentally friendly. Another benefit is the reduction of financial costs. The work explores the influence of individual secondary raw materials on the microstructure. High-temperature fly ash, fluid fly ash, cinder, ground glass and zeolite were used The raw materials were mixed with unalloyed lime at a molar ratio of calcium oxide to silicon dioxide of 0.73 and 1.0. Autoclaving capsules were used to synthesize tobermorite under laboratory conditions. Autoclave was performed at 170 °C and 190 °C with hydrothermal durations of 4, 8 and 16 hours. The most important influence on the microstructure was high-temperature fly ash, on the contrary, the greatest influence on the mechanical properties is attributed to the ground glass.
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Optimisation of cement-bonded particleboard matrix composition by using alternative raw material sources
Roháček, Lukáš ; Vacula, Miroslav (referee) ; Bydžovský, Jiří (advisor)
The diploma thesis deals with possibility of utilization raw materials from alternative sources for production of cement-bonded particleboards. In theoretical part the possibilities of modifying composition of cement-bonded slabs with emphasis on their matrix are discussed in detail. On basis of the findings and their evaluation, waste from the formatting of cement-bonded particleboards, micronized limestone, heat sink and high temperature fly ash were selected to the composition modification. The mentioned raw materials were analyzed and subsequently tested as substitutes for the matrix of cement-bonded particleboards in the experimental part. The properties of the proposed materials were tested even in the longer term, including the microstructure.
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Development of phase composition in silicate systems by available methods and their optimalization
Opravilová, Lenka ; Palou, Martin (referee) ; Škvára, František (referee) ; Havlica, Jaromír (advisor)
One of the most prominent measurable parameters of the development of phases and phase transformations in inorganic systems are undoubtedly the volume changes of silicate matrix. The study of volume changes is crucial in the terms of usable durability of final product. They represent shrinkage or expansion of the material and may lead to significant decrease of technological and ecological parameters and often to complete destruction of these materials. Most often the volume changes can be observed when cement is used as a binder and in concretes, mortars, artificial aggregates and other similar materials. There are many methods to detect, define and determine the volume changes qualitatively or quantitatively. The development of phases was investigated as a part of the dissertation thesis and hence the volume changes were observed under the conditions closest to the real state in the construction industry. The raw materials and admixtures were selected which model the content of hazardous components present in conventional materials (both natural and secondary), used in construction and the relationship with volume changes was searched and demonstrated. The contacts for measuring the volume changes were attached to test surfaces of specimens and the physical - mechanical tests (volume changes, phase changes, strength, etc.), chemical analysis and ecotoxicity tests depending on the length of hydration were performed.
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Possibilities of reducing shrinkage of concrete and development of concrete recipes with limited shrinkage.
Stoklásek, Martin ; Louda,, Pavel (referee) ; Hela, Rudolf (advisor)
The bachelor thesis deals with the issue of volume changes of concrete and their causes. The theoretical part describes the various types of volume changes in concrete and the causes of their occurrence. Influence of concrete mix design and concreting conditions on volume changes. Methods for reducing volume changes are also addressed. The experimental part is focused on the development of recipes with limited volume changes. In which the development of shrinkage is monitored from an early age up to 60 days and at the same time the development of compressive strengths at 2, 7, 28 and 60 days is also monitored.
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Comparision of leachability of heavy metals from various types of alkali-activated alumino-silicate systems
Smolková, Miroslava ; Kalina, Lukáš (referee) ; Koplík, Jan (advisor)
The work deals with the determination and comparison of leaching of heavy metals from various types of alkali-activated alumino-silicate systems (high-temperature fly ash, blast furnace slag). Such alkali activated materials are capable in their structure effectively encapsulate heavy metals, toxic chemicals or other contaminants, which can be beneficial for the environment. The aim of this work is to obtain a mixture with acceptable mechanical properties that could be useful for the inhibition of these substances. Leachability was tested according to norm ČSN EN - 12457-4, followed by analysis by ICP-OES. The structure of the matrix was investigated using SEM equipped with EDS.
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Development of new grouting materials for reverse grouting of sewers
Dolák, Martin ; Dohnálek,, Pavel (referee) ; Drochytka, Rostislav (advisor)
ABSTRACT This thesis deals with the development of silicate based reverse grouts for the purpose of rehabilitation of sewers. The work also examines the possibility of substitution of basic input raw materials with secondary raw materials, meaning replacements of both filler components and binder components. As secondary raw materials, we refer to wastes from the production process which, after the necessary treatment, are used in another production. The development and experimental verification of the functionality of the developed grout was focused mainly on the use of secondary raw materials as much as possible, while maintaining or even improving its physical and mechanical properties. Based on the results of the work, it can be stated that with a 100% replacement rate of filler components in combination with 20% replacement rate of binder components, it is possible to largely maintain the properties of the material, or even optimize them. The results of the thesis also point to the possibility of reducing the economic and environmental demands of production of building materials.
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: Development of special high strength concrete with low volume changes
Meruňka, Milan ; Hela,, Vlastimil (referee) ; Hela, Rudolf (advisor)
The bachelor thesis deals with problems of volume changes of concrete, especially shrinkage of concrete. Types of concrete changes, causes, occurrences, and ways to eliminate them are described. The experimental part is focused on monitoring the volume changes of concrete within 28 days of maturing using a different type and dose of shrinkage reducing additions, a summary of cement pastes within 24 hours of mixing, the development of temperatures of the hydration temperatures of concrete and cement pastes.
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Possibilities of classical fly ash utilization after denitrification of flue gas
Snop, Roman ; Dvořák, Karel (referee) ; Bílek, Vlastimil (referee) ; Havlica, Jaromír (advisor)
This doctoral thesis, "Possibilities of using conventional fly ash after flue gas denitrification", deals with the solution and processing of data on the issue of ammonia / contaminated fly ash after selective non-catalytic reduction (SNCR) technology in coal-fired power plants. Also this thesis is focused on experimental verification of the effect of ammonium salts on the properties of fly ash and the effect on the working environment. Basic data on the issue of ammonia ash were collected. Specifically, these are several main areas of research. The binding of ammonia in fly ash produced after SNCR is described, the problem of determination of ammonium ions in fly ash, mortars and concretes is solved. Furthermore, the effects of the use of ammonia fly ash on the properties of concrete are experimentally verified, and the work also deals with the leachability of ammonia fly ash
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Possibilities of reducing shrinkage of concrete and development of concrete recipes with limited shrinkage.
Stoklásek, Martin ; Louda,, Pavel (referee) ; Hela, Rudolf (advisor)
The bachelor thesis deals with the issue of volume changes of concrete and their causes. The theoretical part describes the various types of volume changes in concrete and the causes of their occurrence. Influence of concrete mix design and concreting conditions on volume changes. Methods for reducing volume changes are also addressed. The experimental part is focused on the development of recipes with limited volume changes. In which the development of shrinkage is monitored from an early age up to 60 days and at the same time the development of compressive strengths at 2, 7, 28 and 60 days is also monitored.
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