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The research of the behavior of composites based on inorganic matrices in extreme conditions
Ballon, Marek ; Bydžovský, Jiří (referee) ; Dufka, Amos (advisor)
Alkali activated materials have great potential to be a material that could compete with Portland cement. Compared to concretes based on Portland cement they often exhibit greater durability and resistance to aggressive agents such as sulphates. Also their resistance to high temperature is substantial. This work is devoted to research on behavior of alkali-activated materials, particularly fly ash activated by sodium water glass and sodium hydroxide, exposed to these extreme conditions. The evaluation of properties was performed based on the detection of physico-mechanical parameters and microstructure examination by RTG diffraction analysis and scanning electron microscopy (SEM).
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The research of cause of failure of concrete elements Face Block
Eger, Lukáš ; Husařík, Petr (referee) ; Dufka, Amos (advisor)
This master thesis focus on the analysis of effects that cause defects in concrete blocks. Experiences show that the defect of the blocks are often manifested in the form of cracks. Great rate of occurrence of defects is attributed to volume changes of poor quality concrete filler. The aim of this master thesis is to analyze the finding from the practical use and exploration of the requirements for the actual blocks and especially the concrete filler which is used to make monolithic structures built from these blocks. The attention will be paid to the interaction between the block and the concrete filler. Here we focus mainly on the volume changes caused by a change of moisture level and especially the cyclic moisture.
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The development of composites based on inorganic binders designed for the extreme applications
Janoušek, Petr ; Šácha, Libor (referee) ; Dufka, Amos (advisor)
The topic of this master's thesis is the development of composite materials based on inorganic binders for use in extreme conditions. It means especially geopolymeric or alkali activated materials (AAM) based composites. The theoretical part of this thesis summarizes knowledges about the development and use of alkali-activated materials, their structure and mechanisms of their formation. It also deals with the applicable raw materials for AAM and their exciters, which are in particular water glass and sodium hydroxide. There also have been a summary of the effects of high temperatures and chemicals on the mechanical properties of AAM and the requirements of standard EN 1504-3 for repairing materials. The task of the practical part was to develop a repair mortar for concrete structures based on AAM so that its production was as simple as possible, ie one-component materials. Gradually six recipes have been develeoped. Test specimens made from these recipes have been putted to selected tests according to the requirements of ČSN EN 1504-3.
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Possibilities of increasing the durability of shotcrete
Merta, Michael ; Dufka,, Amos (referee) ; Hubáček, Adam (advisor)
This thesis deals with an issue of shotcrete and possibilities of increasing its durability. Theoretical part of the thesis is conceived in a form of summary of current knowledge concerning shotcrete. The emphasis is mainly on the possibilities of using shotcrete in exposure classes XA and XF. The experimental part focuses on laboratory testing of shotcrete. Waterproofness of shotcrete, its surface resistance to water and chemical de-icing agents was tested with regard to a development of its compresive strength during maturation.
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