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Architectural concrete
Novosad, Petr ; Ďurica,, Tibor (referee) ; Dulenčín, Juraj (referee) ; Klečka,, Tomáš (referee) ; Hela, Rudolf (advisor)
In the development of concrete structures and its finishes we are constantly looking for new ways to highlight the aesthetic value of the concrete. With all the possibilities of shapes, textures and colours, an architectural concrete in the hands of an architect and designer becomes a material, which can be used to express different individual and specific ideas. It is necessary to recognize and cope with these possibilities, but also the limits, which determine the properties of concrete as the proper design and implementation creates excellent finishes that are otherwise inaccessible to other materials and technologies. The theoretical part includes an extensive summary carries out a research on issues of architectural concrete and its production. From this research comes a new definition of architectural concrete and the newly redesigned and determined classes of architectural concrete with respect to the continuous development of technologies and production possibilities, rendering and surfacing. The aim of the thesis is to verify the possibilities of producing quality architectural concrete and additional treatment of the surface with respect to the desired aesthetic quality.
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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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Study of the influence of feedstock composition and the values of the modulus of elasticity of concrete
Šafrata, Pavel ; Křížová, Klára (referee) ; Hela, Rudolf (advisor)
Modulus of elasticity is significantly reflected feature of concrete, besides the compressive strength in static design nowadays. Low modulus of elasticity can cause unacceptable deflections for subtle skeletal structures. It is at least irresposible to count with empirical formulas since there is a wide range of materials and additives in production of concrete. The aim of this thesis is to study the influence of large fraction aggregate on static and dynamic modulus of elasticity of concrete and recommendation for appropriate measures to produce concrete with high modulus of elasticity. The experimental part is further following up the influence of air content in concrete on the modulus of elasticity.
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Technology of translucent architectural concrete
Adámková, Aneta ; Novosad,, Petr (referee) ; Hela, Rudolf (advisor)
The bachelor thesis deals with problems of light transmitting concrete. The aim was to design a process for the production of light transmitting concrete. The theoretical part was compiled from foreign knowledge, which led to an assessment of the availability and price of optical fibers in the Czech Republic. The experimental part deals with the issues of different types of anchores in production and the selection of adequate diametr of the optical fiber from the three tested diameters. In the conclusion are the findings that led to the design of the production proces that is also described.
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Activation admixtures in concrete
Eger, Lukáš ; Hela, Vlastimil (referee) ; Hela, Rudolf (advisor)
The aim of my bachelor´s work is the summarization and focus on admixure concrete,and the active and inert admixure, which have some positive characteristies for fresh and hardened concrete. Theoretically, I tried to study the increase of their joining potential while this characteristic can be used by either chemici or mechnical way, their combination as well. I also Works on evaluetion of physically mechanical influence for fresh and hardened concrete that can up to 60 days old while the cement was partly substituted by admixure of different character.
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Development of ultra lightweight concretes
Popelková, Adéla ; Hubertová,, Michala (referee) ; Hela, Rudolf (advisor)
This bachelor thesis deals with the technology of production of ultralight concretes using direct lighten cementing compound and at the same time indirect lighten using lightweight aggregate. Further work deals with the choice of suitable raw materials for these concretes. The practical part consists of a proposal of several different recipes, experimental verification and by comparing their properties in a fresh or hardened state.
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Development of structural concrete with power plant ash
Ťažký, Martin ; Sokol, Pavel (referee) ; Hela, Rudolf (advisor)
Worldwide production of concrete is increasing, what has a negative environmental load of cement production. That is due to effort in building construction, also concrete production, greater use of the secondary raw materials. Fly ash is the most commonly used secondary raw material. His used has a very good impact on the economy and ecology of production and positively affects on the properties of concrete in both the fresh and hardened state. The aim of this bachelor's thesis was to improve its use in concrete, using a minimum void fraction of dry mix cement-fly ash.
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Optimization of the concrete composition with the use of recycled concrete aggregates
Skriňáková, Eva ; Holák, Michal (referee) ; Hela, Rudolf (advisor)
Concrete as a building material is subject to continuous innovation and thanks to advanced technology and quantum of research, its properties are still improved. It is logical that the more concrete we produce, the more waste it arises. The volume of this waste can not be stored in landfills endlessly, nowadays most of the waste economies in the world are trying to recycle concrete rubble. The recycling is not such a problem, the technology has been long verified but the quality of the recycled concrete aggregate is unquestionably one of the primary assumption which leads to accomplish required properties of concrete. In fact, the recycling process is „crushing“ the concrete into particles with an effort to eliminate the cement paste on the surface of the aggregate. An ideal solution would be create a resistant and firm coating that would adhere perfectly to the cement matrix. This diploma thesis is focused on the properties of recycled concrete aggregate and methods of improvement and optimization of the concrete mix composition.
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SCC with secondary raw materials
Ťažká, Lucia ; Ťažký, Tomáš (referee) ; Hela, Rudolf (advisor)
Bachelor thesis is focused on the possibility of using secondary raw materials and their application to the production of SCC. Large part deals with impurities of type I and its application results mainly from abroad. Furthermore, this work examines the impact of different types of impurities on the resulting concrete durability in various aggressive environments. The practical part is focused on the use of chemically non-reactive additives of type I instead of the commonly used additives of type II which are used to replace part of cement and the resulting design and manufacture of low-strength SCC using appropriate additives.
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Study of the effect of the addition of the cellulose fibers on the selected properties of concrete
Blaha, Lukáš ; Hela, Rudolf (referee) ; Bodnárová, Lenka (advisor)
This dissertation desribes the behavior of cellulose fiber reinforced concrete. In the theoretical section one can find basic information on cellulose fiber and its methods of production and usage in concrete structures. One can find the information about the effect of high temperature on the mechanical and physical attributes of cellulose fiber reinforced concrete, and also a comparison with other fibers used in concrete based on the research done using scientific literature. Furthermore the details about particular cellulose fibers are provided. In the experimental section the formulas for CHRYSO and GREENCEL concrete are designed. The influence of the addition of various types of cellulose fibers into both liquid and solid states of concrete was researched. Tests were also done on the effect of high temperatures (600 °C and 800 °C) on the firmness and densitiy of concrete, its deformations and visual changes. Furthermore, the resistance of cellulose fibers was monitored by monitoring the development of the pH environment (from pH 4 to pH 12) with long-term deposition of different types of cellulose fibers in these environments.
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