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The influence of the amount of sulfates on the formation of ettringite in cement-concrete covers
Mrhálková, Leona ; Palovčík, Jakub (referee) ; Opravil, Tomáš (advisor)
This bachelor´s thesis is focused on the influence of the amount of sulfates on the formation of ettringite in cement-concrete covers. For the experiments, samples of cement pastes, mortars, and concretes in the form of small beams were created. Cements of class CEM I 42.5 R – SC were used as the binder. In some mixtures, gypsum from the production of titanium dioxide was added as an additional source of sulfates. To assess the impact of ettringite formation on the properties of the samples, strength tests of the prepared materials were conducted, followed by CHRL tests. The results of these experiments were subsequently confirmed by XRD and EDX analyses along with images from a scanning electron microscope.
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Possibilities of using the secondary product from the production of titanium white as a setting retarder in Portland cements
Smirnov, Pavel ; Švec, Jiří (referee) ; Opravil, Tomáš (advisor)
This thesis is concerned with finding the possibilities of processing and application of the secondary product from the production of titanium white. The raw product, commercially known as Prestab, is currently being landfilled due to its properties, chemical composition and high moisture content. Previous research has shown that the material could have potential for use in the construction industry. The effectiveness of the work is also supported by the trends of today, where environmental requirements are becoming more stringent and more costly to implement. The use of secondary raw materials avoids the production of additional CO2 and also reduces the environmental burden. The secondary product, which is chemically a polluted chemosulfur, is investigated in this work as a setting regulator for blended Portland cements. In solving the problem, a suitable laboratory processing method for Prestab was found and subsequently a blend formulation for the preparation of admixture in Portland cements was also proposed. Three cement samples were prepared using the obtained admixtures. The samples were subsequently tested for their properties according to ČSN EN 196 and the results were compared with the CEM II class cement already in use in practice.
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Utilisation of already deposited energy by-products in cement production
Lukášek, David ; Švec, Jiří (referee) ; Opravil, Tomáš (advisor)
This bachelor thesis focuses at study of deposited high-temperatured fly ash and its utilization in production of cement. The theoretical part of the bachelor thesis deals with the production and division of cements. The individual advantages and disadvantages of high-temperature and fluid fly ash when added to cements are addressed. The theoretical knowledge was used to design subsequent experiments. The conclusion of the theoretical part of the work deals with pozzolans. The main content of the experimental part was the analysis of raw materials and subsequent analysis of the mechanical properties of the prepared mixtures. The experiments were designed in accordance with valid standards.
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Effect of ground limestone addition on properties of cement-slag binder systems
Bílek, Vlastimil ; Másilko, Jiří (referee) ; Opravil, Tomáš (advisor)
This thesis deals with the effect of ground limestone addition on properties of cement-slag binder system. The evolution of compressive and flexural strength of binary and ternary systems (pastes), where 25 % of cement was substituted by one or two admixtures in different ratio, were determined and mutually compared. Granulated blast furnace slag and three different limestones were these admixtures. Two of that limestones were natural and one was prepared by a precipitation. For comparison, mixtures, where ash was added insted of slag, were prepared. The mechanism, by which finely ground limestone participates in hydration process, was studied by conduductometric measurements of systems simulating conditions in fresh pastes, and by TG-DTA method, which was used to determination of added limestone amount which remains in its original form and the amount which participates in the formation of hydration products.
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Possibilities of using yet unused secondary products from the production of titanium white
Smirnov, Pavel ; Másilko, Jiří (referee) ; Opravil, Tomáš (advisor)
Waste products are an integral part of any production. The production of titanium white is no exception. The bachelor thesis is aimed at finding an application for a secondary product, red chemogypsum which is obtained by neutralizing waste sulfate water. The thesis aimed to find a suitable application for chemogypsum in the construction industry using experiments. The calcium sulfate dihydrate was processed by drying into monohydrate, which is the basic raw material of many products. Furthermore, the composition of the material was determined. Its properties such as onset of solidification, compressive and flexural tensile strength were investigated. Gypsum plasterboards and lightweight and insulating boards were also made. This binder was also used in filling bricks with inorganic insulating material. The knowledge gained from this work can be used to further research and improve products and hopefully make realistic use of this hitherto deposited material in the future. The thesis also provides concrete examples and suggestions for the use of this secondary raw material.
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Possibilities of using of fluid fly ash in the self-leveling systems
Zárybnická, Klára ; Bílek, Vlastimil (referee) ; Opravil, Tomáš (advisor)
The work deals with the study of possibilities of using fluid ashes in self-leveling floor systems. The task of this work is to reach a proper composition of self-leveling floor mixture with high capacity of fluid ash in binding compoment, which means replacement of portland cement primary. In the work there are monitored mechanical and durable properties of tested self-leveling systems, which are evaluated according to valid norm. Especially the work is focused on volume changes during hydratation and maturation of new designed self-leveling systems, because thanks to high capacity of free lime and anhydrite in fluid ashes there are volume changes thanks to formation of ettringite.
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Possibilities of using waste diatomaceous earth
Jonešová, Markéta ; Másilko, Jiří (referee) ; Opravil, Tomáš (advisor)
Waste diatomaceous earth is a by-product generated during a production of diatomaceous earth for filtration. It is a material with very specific properties, which has currently no use other than backfilling of mining areas. For this reason, this Bachelor thesis deals with exploration of potential utilization possibilities of this remarkable material. Analysis of the waste diatomaceous earth will be carried out, and the chemical and physical properties will be determined. During experimental part, a set of calcination tests will be carried out and evaluated with focus on properties of the waste diatomaceous earth, which could be significantly increased by the calcination process. For example, a pozzolanic activity could be significantly affected.
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Industrial sludges as alternative fuel in cement plant
Raška, Miroslav ; Kalina, Lukáš (referee) ; Opravil, Tomáš (advisor)
This thesis deals with the use of industrial sludge as an additive to alternative fuels in the cement industry. The first part is focused on solid alternative fuels, especially sewagesludge, processed and used in the firing process of Portland clinker and heatingpotential of the secondary raw materials, fuels. The second part deals with the history, production of cement and its raw material base. The last part contains information of practical measurements and draw conclusions about the appropriateness of using that type of industrial sludge in cement as a solid alternative fuel.
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Preparation of historical binders with high resistance to ambient influences
Nehybka, Josef ; Palovčík, Jakub (referee) ; Opravil, Tomáš (advisor)
This master’s thesis is focused on preparation of the mortar mixtures inspired by roman cement with a great resistivity against the corrosion environment, especially a seawater. There were prepared samples of a roman cement containing of pure lime and various artificial pozzolans and natural tuff which were used as pozzolan admixtures. The task of this work is to explore possibility of using pure lime and for example pozzolan admixture which can resist against the corrosive environment like a roman cement. There were prepared a lot of various samples which were tested separately on their mechanical characteristics before and after their exposure of the influence of the corrosive environment. There were used X-ray diffraction analysis for the characterization of a phase composition of the raw materials and some selected samples.
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