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Influence of high temperatures on concrete properties
Klobása, Jan ; Křížová, Klára (referee) ; Sedlmajer, Martin (advisor)
The aim of this bachelor thesis is to study the problem of the behavior of concrete under high temperatures. The theoretical part of the work summarizes the knowledge about the changes that take place in concrete when it is exposed to a high thermal load that simulates the effects of fire. It also summarizes the effect of high temperatures on the behavior of the individual components that make up concrete. Emphasis is placed on describing the possibilities of eliminating concrete damage at high temperatures. Furthermore, the principles of changes and events due to high temperatures simulating the effect of fire are described. The experimental part summarizes the knowledge related to the composition of concrete, the use of different types of fibers, and other measures in loading concrete at high temperatures. Steps influencing the negative impact on the properties and resistance of concrete to high temperatures are also described. Based on the summarized findings, conclusions are formulated.
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The effect of appication of fine organic fibers to cement composites
Kavka, Lukáš ; Hela, Rudolf (referee) ; Bodnárová, Lenka (advisor)
This bachelor thesis describes the effect of using fine organic fibers in cement composites. In the theoretical part of bachelor thesis a composite material was defined and his individual components were described. Then was created a research of information about organic fibers focused on natural fibers. The basic parameters of cellulosic fibers and polypropylene fibers, the effect on the properties of cement composites and their application in practice were described. In the practical part there were created a reference concrete and 3 types of concrete with the addition of various types of organic fibers. The influence of fiber addition on the properties of fresh and hardened concrete were investigated. Another task of practical part was monitored the resistance of cellulose fibers in acidic and alkaline media in which the tested fibers were deposited. The development of pH solutions was examined over time.
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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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Studying the behavior of concrete at high temperatures
Čonka, Ladislav ; Sitek,, Libor (referee) ; Bodnárová, Lenka (advisor)
The thesis is focused on the current issues of concrete resistance to high temperatures. The theoretical part has been processed the changes taking place in the individual components of concrete and changes affecting the physical - mechanical properties of concrete and color-changing effects manifesting high. In the experimental part of the load was, carried concrete test samples to a temperature of 400 ° C, 600 ° C and 800 ° C. After the thermal load, has been on test samples tested changes in physico - mechanical properties, especially concrete compressive strength, water absorption but also a visual assessment of the concrete surface
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