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Study of the behavior of selected rocks at high temperatures
Holanec, Aleš ; Sitek,, Libor (referee) ; Bodnárová, Lenka (advisor)
The diploma thesis deals with the observation and diagnostics of transformations that take place in stone slabs of different mineralogical composition during heating to high temperatures. The theoretical part of the thesis deals with a summary of available information about selected types of rocks. Furthermore, it presents findings from the experimental thermal loading of a granite sample. The principles and instruments of laboratory experimental methods that are used to judge the resistance of rocks are described in detail. In the experimental part, the testing methodology is proposed, the procedure of production of rock test specimens is described and the way in which the thermal loading of stone slabs took place is explained. The results of the experiments are shown in the tables and graphs. A comparison of individual tests and properties of selected samples and evaluation of the obtained results is performed.
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The issue of concrete resistance to high temperatures
Krejčík, Jakub ; Hela, Rudolf (referee) ; Bodnárová, Lenka (advisor)
Bachelor´s thesis deals with resistance of cement concrete to high temperatures. Theoretical part of bachelor´s thesis describes changes that occures in concrete at thermal loading and behavior of each component of concrete. Next there were discribed ways to improve resistance of concrete to high temperatures, by choosing the right component or by adding fibre reinforcement. In experimental part composites with bassalt and polypropylen fibre and with bassalt aggregates were tested. In these composites changes of compressive strenght and changes of density were mesured according to the thermal loading. Next individual fibre reinforcement polypropylen, celulose and bassalt fibres were exposed to the thermal loading and their changes were observed.
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Properties of Fiber Reinforced Plastics
Jastrzembská, Alena ; Petránek, Vít (referee) ; Bodnárová, Lenka (advisor)
This thesis deals with the theoretical part of raw materials, production and properties of composite materials with fiber reinforcement and polymer matrix. It also gives a brief overview of selected prominent Czech and foreign producers of composite materials with polymer matrix and fiber reinforcement. The practical section deals with testing the durability of selected composite profiles immersion in aggressive environments and testing of compressive strength.
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Fibre reinforcement with plasma in cement composites
Žižková, Lucie ; Hela,, Rudofl (referee) ; Bodnárová, Lenka (advisor)
The usage of polymer fibres can be increased by the new progressive method of the plasma treatment. This thesis is focused on verification of the influence of the low-temperature treatment on polymer fibres´ surface used in concrete. The treatment of polypropylene fibres in low-temperature plasma is described in the theoretical part. The impact of the treatment on the volume differences of cement composites is also evaluated. The influence of the addition of commercially available fibres and plasma treated fibres on the volume differences of cement composites is also experimentally verified.
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Usability of hig speed water jet in civil engineering
Boucníková, Veronika ; Sitek,, Libor (referee) ; Bodnárová, Lenka (advisor)
The bachelor thesis deals with possibilities of using high-speed water jet in construction industry. In the theoretical part, water jet technology was generally described and a research for use in the construction industry with an emphasis on the application of concrete structures redevelopment and the process of interaction of water jet with concrete was done. Furthermore, the safety risks during work with high-speed water jet and the possibilities of recycling of waste generated by the use of this technology were evaluated. In the experimental part were prepared concrete samples with dispersed concrete reinforcement. The characteristics of the concrete samples were determined and the depth and appearance of the cross-section after interaction with the high-speed water jet was evaluated.
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Study of FRP for concrete reinforcement
Blahová, Aneta ; Prokeš,, Jan (referee) ; Bodnárová, Lenka (advisor)
The diploma thesis aims to analyze bent FRP reinforcements. It describes the method of production of bent FRP reinforcement, examples of application of FRR reinforcement in structures and mentions aggressive influences influencing the durability of FRP reinforcement. Furthermore, an experiment is proposed to monitor changes in straight and bent FRP reinforcement stored in an aqueous environment at 20 °C and an alkaline environment at 20 °C and 40 °C. The output of the diploma thesis is the evaluation of changes in mechanical properties and durability. The condition of the FRP reinforcement is documented using optical and electron mocroscopy.
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The issue of the use of carbon nanotubes in cement composites
Pacltová, Klára ; Hela, Rudolf (referee) ; Bodnárová, Lenka (advisor)
The bachelor thesis deals with the analysis of the efficiency of carbon nanoparticles in cement composites. The theoretical part of the bachelor thesis is focused on the research of information about carbon nanotubes and their influence on cement composites. The practical part follows the research of the theoretical part, where is verified the effectiveness of carbon nanotubes in cement composites at different dosages.
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Studying the behavior of concrete at high temperatures
Tillová, Jana ; Herka, Petr (referee) ; Bodnárová, Lenka (advisor)
This master‘s thesis is focused on the study of the behavior of cement concrete at high temperatures with a focus on monitoring the impact of aggregate and cement type. This work describes the processes in aggregates and cement matrix at high temperatures. The theoretical part describes the selestion of a suitable aggregate and cement for the surroundings with potential exposure to high temperatures. In the experimental part is given design of composition of a concrete with two types of aggregates and four cements. It has been suggested 8 recipes. Changes were observed densities, compressive strength and tensile strength in bending, calculate the velocity of propagation of waves with ultrasonic pulsed method. Also evaluated the appearance of the surface samples after thermal load – cracks on the surface and measure the maximum crack width.
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Study of the properties of cement composites with polypropylene fiber modified low-temperature plasma
Žižková, Lucie ; Herka, Petr (referee) ; Bodnárová, Lenka (advisor)
Plasma treatment of polypropylene fibers presents a new progressive method, how to increase the utility properties of these fibers. The thesis is focused on verifying the effect of surface treatment of polypropylene fibers in concrete with low-temperature plasma discharge in the normal atmosphere. The paper describes the procedure for treatment of polypropylene fibers with low-temperature plasma and evaluate the impact of this adjustment on the volume changes of cement composites. It should also be emphasized that the thesis is focused on the initial volume changes, ie volume changes in the early stages of solidification and only for your own mixture, which is not considered an external load. Subsequently, the experimental verification of the effect of the addition made commercially available fibers and fibers treated plasma volume changes to a selected physico-mechanical properties of the test compounds.
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Studying the behavior of high strength concrete at high temperatures
Sovová, Kateřina ; Kirnbauer, tech Johannes (referee) ; Bodnárová, Lenka (advisor)
This master’s thesis is divided into two parts; practical and theoretical. The theoretical part of this study describes the influence of high temperature on concrete structure and chemical, mechanical and physical changes, which take place during the exposure to high temperatures. The thesis also evaluates spalling of concrete and the methods to prevent it, as well as the function of polypropylene and cellulose fibers in the concrete. The practical part deals with design, production and testing of the cement-based concrete with the use of different fibers (polypropylene fibers and cellulose fibers). The properties and the means of applications in high temperatures are also included. The practical part also assesses the influence of high temperature on strength, porosity, visual changes of specimens, changes of surface and degradation of testing specimens due to heat loads according to normative heat curve (ISO 834) and also according to hydrocarbon curve. For clearer arrangement, the experimental tests are divided into two parts and the measured values are evaluated at the end of each part. The conclusion resumes all data obtained by testing and evaluates what is the most suitable formulation. The approach for further research is also discussed.
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