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Ultralight concrete with high utility properties
Popelková, Adéla ; Hubertová,, Michala (referee) ; Hela, Rudolf (advisor)
This diploma 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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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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The effect of fly ash aerated concrete production technology to formation of tobermoritic phases
Fleischhacker, Ján ; Kulísek, Karel (referee) ; Drochytka, Rostislav (advisor)
Autoclaved aerated concrete is long-time ecological building material with usefull properties. There needs to be done research of its mineralogical compound for reengineering the production. The main mineral compound of AAC is tobermorite, it increases its mechanical properties. In the presence study, we examine the usage of nature and artificial silicious materials. Also, we investigate the influence of sulfate and alumina admixtures, as well as fluidized bed combustion ash, which can be used as the lime and gypsum replacement. Closure of the study is design of the optimal raw material composition, also hydrothermal treatment of autoclaved aerated concrete. In relation to its mechanical properties, mineralogical composition and cost.
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Change in the durability of concrete made of recycled concrete by alternative addition of ceramic admixtures
Stavař, Tomáš ; Hoffmann, Oldřich (referee) ; Stehlík, Michal (advisor)
The master thesis dealing with problematic about durability of concrete, with use of recycled concrete and addition of silica additions. Predominant for resistance of concrete constructions is surface layer, through which aggressive gasses and liquids penetrate from surrounding environment. The most important indicator of concrete durability is ability of surface layer transmissions of aggressive substants. In experimental part will be defined the actual state of surface layer by normal testing methods. The transmissions of surface layer will be tested on concrete cubes. Tests for transmissions of air (method TORRENT), of water (method ISAT), of acid gases (dept of carbonation by quick test in 98% CO2) will be carried out and also strength tests. Assessment of positive or negative influence of additions and amount of cement on durability and mechanical properties of concrete will be discussed in conclusion.
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Studying the properties of high strength concrete using micro and nano admixtures
Gabko, Miroslav ; Bodnárová, Lenka (referee) ; Hela, Rudolf (advisor)
The objective of this bachelor thesis is to examine the properties of high strength concretes with the main focus on application of mikro or nano admixtures. In theoretical part their production, the properties and the influence on fresh and hardened properties of cement composites are described. In addition, it explores the influence of plasticizer type, some properties of aggregate and cement types. The practical part focuses on testing cement mortars in which fine cements were added. The compressive and flexural strengths were examined after 7 and 28 days of curing, moreover, rheological properties and heat hydration of cements were also observed. Furthermore, the influence of high speed mixing on cement mortars properties was studied.
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Possibilities of using different types of admixtures in shotcrete technology
Berčík, Martin ; Brožovský, Jiří (referee) ; Hubáček, Adam (advisor)
The Bachelor’s thesis is conceived in the form of research findings on current knowledge of inert and active ingredients and their effects on the shotcrete. It focuses mainly on the composition of individual ingredients, their function executing in the concrete mix and explains how they affect the selected physical and mechanical properties. The work enlightes the importance of using co-products from the industry production as an additive to concrete in terms of both ecological and partly economical.
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Study of the development, trends and innovations in shotcrete technology
Záruba, Jiří ; Hela, Vlastimil (referee) ; Hubáček, Adam (advisor)
The Bachelor thesis is focused on the study of development, trends and innovations in shotcrete technology. The main target of this thesis is to summarize new procedures in shotcrete technology. Secondary targets include a description of basic properties of sprayed concrete, introducing new trends and technology in recent years. The next sub-goal is to propose experiment that will try new ways of testing shotcrete. Based on these secondary targets is possible to evaluate the current situation in shotcrete technology and fulfil the main objective of this thesis.
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ultra-high-strength concretes
Ambruz, Pavel ; Hubáček,, Adam (referee) ; Hela, Rudolf (advisor)
Thesis deals with summarizing knowledge about production methods of ultra – high – strength concrete (UHSC) and their possible use in practice, which is documented on the existing building. Further work shows suitable raw materials for production UHSC and their availability on the Czech market. The practical part results an experiment whose outcome should be concrete with a compressive strength of 150 MPa.
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