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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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The development of composite material system with focus on matrix for extreme conditions
Gratclová, Kamila ; Gross,, Tomáš (referee) ; Bydžovský, Jiří (advisor)
The thesis deals with composite systems, with a focus on matrix resistant to extreme conditions. The aim of this work was to research and development matrix, resistant to high temperatures, typical in case of fire. Used theoretical knowledge were realized with subsequent laboratory research. Attention was paid matrices based binder mixed with any alkali activation of alternative raw materials and geopolymers. Scattered reinforcement featured polypropylene fibers. The subject of the practical part of the two alternatives, including a matrix based on basic ingredients - cement, alternative raw materials - high fly ash, blast furnace slag, geopolymer and polymeric components incl. combinations thereof. Laboratory research conducted by determining the fundamental material properties such as density, strengths, etc., after heat exposure. The developed materials were subjected to a temperature 1400 ° C. The conclusion was selected several recipes that were based on the resulting values found to be optimal.
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Possibility of using of fibre-concrete at composite steel-concrete structures
Pozdíšek, Jan ; Karmazínová, Marcela (advisor)
The aim of the offered thesis is an analysis of usage of uncommon concrete matrix and its contribution to steel-concrete composites structures. It especially refers to the area of internal supports, where usually acts negative bending moments. These statical systems are very often used for bridge structures, or even for building constructions. Nowdays, the static infuence of concrete at the area of negative moment is neglected. Only the steel part of cross section and steel reinforcement are included to the static action. This work is focused on the usage of tensile strength of uncommon concrete. The improvement of tensile strength of cement matrix is due to glass fiber reinforcement acting as scattered reinforcing. The introduction is focused on common approach of design of the structures mentioned above. Next, there is a part which describes possibilites of using fibre reinforcing until nowdays.
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Study of the influence organic fibres on the fire resistance of concrete
Klobása, Jan ; Přikryl, Jan (referee) ; Sedlmajer, Martin (advisor)
The master thesis is focused on current issues of concrete behaviour under high temperatures. In the theoretical part, a search of knowledge about changes in concrete, which take place when exposed to thermal loads, which simulates the effect of fire, is performed, and summarized. It is also important to summarize the changes in the individual components that are used to produce concrete. This work describes the effect of high temperatures on mechanical and physical properties as well. There is an information about the most used fibres and their function in concrete. Emphasis is placed on describing the possibility of using recycled PET or cellulose fibres due to the positive environmental impact. In the experimental part, recipes with different types and amounts of fibres are proposed. The subject of the research was to determine how individual types and amounts of fibres affect the physical mechanical properties of concrete and their suitability for use at high temperatures. Microscopic scanning and study of changes in the structure of concrete was also performed.
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Verification of the effect of fine fibers and absorbent additives on the process of self-healing concrete
Dokoupil, Tomáš ; Ťažký, Tomáš (referee) ; Hela, Rudolf (advisor)
The diploma thesis deals with self-healing of concrete composite. In the theoretical part, it represents the effect of polymer microfibers on reducing the development of cracks and on improving self-healing properties. It also describes the most commonly used types of bacteria used to enhance the self-healing process and their effect both alone and in interaction with fibers, calcium sources and absorbent additives. It also represents auxiliary additives in the form of superabsorbent polymers. In the practical part, it verifies the influence of the above elements and describes how much the self-healing of concrete has been enhanced by the use of combinations of fibers, absorbent polymers and a source of calcium in the form of calcium lactate. It also indicates whether the self-healing properties used were not improved at the expense of deteriorating the mechanical properties of the composite.
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Influence of the type of dispersed reinforcement on selected properties of concrete
Gajdušková, Patricie ; Křížová, Klára (referee) ; Sedlmajer, Martin (advisor)
This thesis is focused on the usage of fibers in concrete. The fibers are dispersed reinforcement which may have different behaviour based on the material characteristics or the geometric shape of the fibers. Due to this, we may predict the appropriate application of fibers and possibly improve mechanical properties of concrete. At the same time, the influence of used fibers on the behaviour of the concrete when exposed to high temperatures, thus the fire resistance of material, is observed. The purpose of this thesis is to compare the properties of the individual fiber types in concrete, which are suitable for specific application of fibre reinforced concrete.
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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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Study of properties of cement composites with addition of polymer fibers
Dokoupil, Tomáš ; Hela, Rudolf (referee) ; Bodnárová, Lenka (advisor)
The bachelor thesis deals with the use of polymer fibers in cement matrix. It describes the distribution and production of the most commonly used polymer fibers as well as the requirements for their properties. A comparison of the properties of different types of polymer fibers is given. The work presents the individual components of the fiber concrete matrix, its production, testing of fresh and hardened fiber concrete and specific examples of its use in practice. Using professional research, the influence of PP, PE and PVA fibers on the properties of fresh and hardened concrete is described in detail. New trends in the use of polymer fibers are also presented. At the end of the work, a procedure of experimental verification of the properties of fiber-reinforced concrete in comparison with a reference sample of plain concrete is proposed.
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Possibility of using of fibre-concrete at composite steel-concrete structures
Pozdíšek, Jan ; Karmazínová, Marcela (advisor)
The aim of the offered thesis is an analysis of usage of uncommon concrete matrix and its contribution to steel-concrete composites structures. It especially refers to the area of internal supports, where usually acts negative bending moments. These statical systems are very often used for bridge structures, or even for building constructions. Nowdays, the static infuence of concrete at the area of negative moment is neglected. Only the steel part of cross section and steel reinforcement are included to the static action. This work is focused on the usage of tensile strength of uncommon concrete. The improvement of tensile strength of cement matrix is due to glass fiber reinforcement acting as scattered reinforcing. The introduction is focused on common approach of design of the structures mentioned above. Next, there is a part which describes possibilites of using fibre reinforcing until nowdays.
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Experimental Investigation of the Influence of the Type of Fibres on the Behaviour of Fibre Concrete
Hanuš, Petr ; Vymazal, Tomáš (referee) ; Kocáb, Dalibor (advisor)
This diploma thesis deals with the comparison of different properties of fibre-reinforced concrete according to the type of fibres. The main monitored property is flexural strength, tested on prisms with a cross section of 150x150 mm and a length of 600 mm. Four concretes of natural aggregate and four concrete of lightweight aggregate were prepared for the experiment. There were 2 reference concrete and 6 fibre-reinforced concrete. Three types of fibres were used: steel, polypropylene and glass. More than 2500 kg of concrete was produced. The aim of the thesis is to assess the influence of fibres on the flexural strength and other characteristics of fibre-reinforced concrete.
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