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The influence of parameters on the quality of the dispersion medium mixed nanoparticles
Kutová, Lenka ; Hela, Rudolf (referee) ; Bodnárová, Lenka (advisor)
The thesis deals with monitoring the characteristics of cement composite using nanoparticles. The theoretical part describes nanoparticles production, their characteristics and influence on cement composites, both in fresh and hardened state. In the practical part of the thesis physically-mechanical characteristics of cement composites with nanoparticles are determined. The microstructure of the composites was monitored on a scanning electron microscope for 1, 3, 7 and 28 days of maturing. And finally mechanical characteristics of the composite and the reference samples without nanoparticles were compared.
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RESEARCH AND DEVELOPMENT COMPOSITE MATERIAL WITH A HIGHER RESISTANCE TO HIGH TEMPERATURES
Válek, Jaroslav ; Durica,, Tibor (referee) ; Kolář,, Karel (referee) ; Sitek,, Libor (referee) ; Bodnárová, Lenka (advisor)
Concrete has many advantageous properties as regards resistance to fire. It is non-flammable and it has a low thermal conductivity. However, concrete structures, which are not designed for resistance against fire, show significant damage after heating. In particular, the explosive flaking with the consequence of weakening the reinforced concrete cross-section and exposing the steel reinforcement to the temperatures higher than critical temperature of reinforcement. There are only a few possible measures of preventing or mitigating the effects temperature load used. Ways of protection can be divided into two systems: active and passive. Active systems are designed to ensure the greatest possible reduction of temperatures the concrete is exposed to. Passive systems directly resist to high temperatures and fire. Design of composition of concrete with the aim of higher resistance to exposition to high temperatures belongs among the passive systems. A part of the work focuses on summary searches of the problems of concrete and reinforced concrete structures exposed to high temperatures and fire. The goal of the work is defining requirements for cement matrix based composite material and its design ensuring the highest possible resistance to high temperatures or direct fire.
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Durability of repair materials with higher fire resistance for concrete structures
Počekajlo, Václav ; Dohnálek,, Pavel (referee) ; Bydžovský, Jiří (advisor)
This dissertation deals with the study of durability and degradation repair mortars for reinforced concrete structures. In its theoretical part, there are the research findings on the behavior of repair mortars exposed to corrosive environments with different exposure time and selected high temperatures. Processes occurring in repair mortars during their loading at high temperatures or when exposed to chemically aggressive environments are described, We can find recipes designed for cementitious binder based with a specific replacement using slag or fly ash in its practical part. The object of the research was to determine the durability of the proposed repair mortars, and determine their suitability for use on concrete structures, which may be exposed to a synergistic effect of chemically aggressive environments with high temperatures simulating fire.
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Possibilities of dispersed reinforcement for lightweight concrete
Novotná, Aneta ; Žítt, Petr (referee) ; Láník, Jaromír (advisor)
Master´s thesis deals with some problems associated with utilisation of lightweight concrete from the porous aggregates in the load – carrying structures. The thesis focuses on the possibilities of the increase of the cement composites toughness using dispersed reinforcement. Lightweight concretes were reinforced with a combination of different lengths of polypropylene fibers Forta Ferro. There were used polypropylene fibers of three lengths 19, 38, 54 mm. The thesis is divided into theoretical, experimental and static part.
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The behavior of cementitious composites with fiber reinforcement at high temperatures
Fichtová, Zlata ; Herka, Petr (referee) ; Bodnárová, Lenka (advisor)
This master’s thesis studies the influence of dispersed reinforcement on the behaviour of cement composites at thermal loading. In the theoretical part of the research was performed knowledge of the behaviour of concrete at high temperatures. The paper describes the on-going happening in the individual components of concrete and benefits of using dispersed reinforcement. In the practical part were designed concrete mixtures with different types and quantities of fibers. The object of the research was to determine how different types and amounts of fibers affect the physical - mechanical properties of concrete and their suitability for use in high temperatures.
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Properties of cement composites with fiber reinforcement
Jankech, Filip ; Sitek,, Libor (referee) ; Bodnárová, Lenka (advisor)
This thesis summarizes the knowledge of the possibility of using organic fibres as dispersed reinforcement into cement composites. It is concretely a summary of knowledge about the types and properties of synthetic and cellulosic fibres, their influence on the properties of fresh and hardened cement composite and lastly a description of the fire resistance of cement composites and the effect of organic fibres on the action of those composites at high temperatures and in the presence of fire. The experimental part is supposed to verify the effect of the cellulose fibres on increasing the durability of the cement composite at high temperatures.
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Cement composite materials with polypropylene fibers
Preisner, Martin ; Hela, Rudolf (referee) ; Bodnárová, Lenka (advisor)
This thesis deals with summarizing the possible effects of the addition of polypropylene fibers, especially low temperature plasma treated on the properties of cement composites and concrete. They are given basic information and distribution of polypropylene fibers. It describes the finish polypropylene fiber low-temperature plasma. The experimental part focuses on the effect of dispersion of polypropylene fibers treated plasma in the cement matrix.
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Properties of cementitious composites with plasma treated polymer fibers
Počekajlo, Václav ; Hela, Rudolf (referee) ; Bodnárová, Lenka (advisor)
Modification of polymer fiber low temperature plasma is one of the ways to enhance the properties of modified fibers as follows. This work aims to evaluate the effect of plasma treated polypropylene fibers on the rheological properties of cement composites. The theoretical part describes the treatment and the effect of plasma treatment on polymer fibers. The influence of polypropylene fibers treated by low-temperature plasma on the workability of concrete. The practical part is described and evaluated experimental verification of the influence of the addition of commercially available fibers and fibers treated plasma on the rheological properties of fresh cement composite.
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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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