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Influence of transmission method on the results of measurement of refractory blocks by ultrasonic pulse method
Pospíšil, Dušan ; Dufka, Amos (referee) ; Brožovský, Jiří (advisor)
Ultrasonic pulse method is a non-destructive method, which is used in the construction industry to evaluate individual parameters of building structures. The aim of the thesis was to create the prerequisites for determining the rate of ultrasonic pulse propagation on refractory silica fittings and quartz glass fittings. Selected factors influencing the speed of ultrasonic pulse propagation in the tested samples were studied, namely the influence of the sounding direction, the influence of the natural frequency of the probes and the influence of the acoustic coupling material on the ultrasonic pulse method.
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The evaluation of the effect of crystallization additives on durability cement composites
Roubal, David ; Bydžovský, Jiří (referee) ; Dufka, Amos (advisor)
This bachelor´s thesis deals with the study of crystalline materials and their effects on the durability of concrete. The theoretical part of this thesis focuses on the detailed analysis of the characteristics of crystalline materials, including their division and use. It also particularizes the main factors influencing the durability of concrete and provides an overall research of crystalline materials testing. Based on the findings, the experimantal part focuses on the examination of crystalline materials applied to self-compacting concrete. The examination included, among other things, testing in aggresive environment and strength and permeability test carried out on set SCC.
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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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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 alkali-activated matrices resistant to extreme temperatures
Ševčík, Marek ; Šácha, Libor (referee) ; Dufka, Amos (advisor)
The diploma thesis is focused on the development of composites from alkali activated materials (AAM) and their resistance to extreme temperatures. The theoretical part describes alkaline activation and precursors for the production of AAM. Furthermore, the problem of the effect of extreme temperatures on these materials is described. In the experimental part, the optimal silicate modulus with respect to the properties of AAM was gradually determined, and the effect of extreme temperatures on the AAM matrix was verified. In the next stage, the effect of the filler with respect to the behavior at extreme temperatures was tested and then the final formulation was optimized.
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Influence of transmission method on the results of measurement of refractory blocks by ultrasonic pulse method
Pospíšil, Dušan ; Dufka, Amos (referee) ; Brožovský, Jiří (advisor)
Ultrasonic pulse method is a non-destructive method, which is used in the construction industry to evaluate individual parameters of building structures. The aim of the thesis was to create the prerequisites for determining the rate of ultrasonic pulse propagation on refractory silica fittings and quartz glass fittings. Selected factors influencing the speed of ultrasonic pulse propagation in the tested samples were studied, namely the influence of the sounding direction, the influence of the natural frequency of the probes and the influence of the acoustic coupling material on the ultrasonic pulse method.
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Utilization of waste glass in cement composites
Gottwaldová, Aneta ; Dufka, Amos (referee) ; Bodnárová, Lenka (advisor)
Bachelor thesis deals with the processing of waste glass in cement composites. Bachelor thesis includes a search theoretical and experimental part. Specifically, it was verified by fluorescent waste glass and glass screen at a dose of 5, 10, 15 and 20 weight % of a batch of cement. Properties of composites were examined after 7, 28, 56 and 90 days. We monitored TG analysis and XRD analysis of cement composites with waste glass.
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Study of the interphase region of wood bonds
Chlup, David ; Dufka, Amos (referee) ; Vaněrek, Jan (advisor)
This bachelor thesis deals with summarizing knowledge on issues related to the penetration depth of the adhesive into the wood structure. In the thesis they are described all adhesion theories. We focus on the effect of viscosity and durability bond line according to varying amounts of filler adhesive. Furthermore, it is described some microscopic techniques, which measure the penetration of the adhesive into the cell structure.
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The evaluation of the effect of crystallization additives on durability cement composites
Roubal, David ; Bydžovský, Jiří (referee) ; Dufka, Amos (advisor)
This bachelor´s thesis deals with the study of crystalline materials and their effects on the durability of concrete. The theoretical part of this thesis focuses on the detailed analysis of the characteristics of crystalline materials, including their division and use. It also particularizes the main factors influencing the durability of concrete and provides an overall research of crystalline materials testing. Based on the findings, the experimantal part focuses on the examination of crystalline materials applied to self-compacting concrete. The examination included, among other things, testing in aggresive environment and strength and permeability test carried out on set SCC.
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