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Possibilities of evaluation durability of the surface layer of concrete structures
Blažek, Michal ; Žalud, Oldřich (referee) ; Vymazal, Tomáš (advisor)
The thesis is focused on possibilities of durability evaluation of surface layer of concrete structures. The durability of concrete surface layer usually determines the durability of the structure as a unit. It has to be determined in what environment the structure is situated and what influences it has to face, to set the durability of the structure. There is a several normative prescription to set the resistance of the structure. There is formulated a summary of the most widely used and known prescriptions in the theoretical part of the thesis. It is a lot of effort to estimate the durability of the concrete by estimation of permeability of the concrete surface layer recently. Thus these methods are also formulated in the summary and there are compared the individual outputs of the tests. The permeability and pore structures of the concrete surface layer are crucial parameters for the durability of concrete structure. These parameters influence the construction properties of the concrete as well, thus the thesis is focused on relationship of the pore structure and the strength in press of the concrete.
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Development of concrete with high fly ash content and verification of durability in various environments
Ambruz, Pavel ; Voves, Jiří (referee) ; Hela, Rudolf (advisor)
This thesis contains two main parts: theoretical and experimental. The theoretical part deals with summarization knowledge of high-volume fly ash (HVFA) concretes. Among others, there are mentioned processes of producing of fly ash, characteristic features and resistance to aggressive environments of HVFA concretes. The theoretical part ends with a suitable example of practical application. In the practical part were tested properties of nine different mixtures containing 40%, 50% and 60% replacement by weight of the cement by fly ash. They were compared with the reference mixtures without fly ash addition. The main endpoints were long-term compressive strength, resistance to aggressive environments, the influence of fly ash on consistency, hydratation temperatures, water absorption and volume changes.
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Study of properties of concrete with "green cement"
Matyk, Tomáš ; Dorazilová, Irena (referee) ; Bodnárová, Lenka (advisor)
The thesis focuses on collecting available information about possible ways of using and usage restriction of portland blended cements and portland cements with limestone for production of concrete. The experimental part of the thesis describes the behavior of portland blended cements and portland cements with limestone in aggressive environments. Furthermore, the thesis concerns the dependence of rheological properties of cement pastes of portland cements and portland cements with limestone on type of plasticizing additives.
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Verification of durability of ash concrete in the environment XF
Kušiak, Petr ; Hela,, Vlastimil (referee) ; Hela, Rudolf (advisor)
Fly ash is now much used as an admixture to concrete. This master´s thesis focuses on the use of fly ash as an active admixture in concrete environment for XF. The thesis has two parts. The first part collected theoretical information about the origin and behavior of fly ash in fresh and hardened concrete. In the second part was experimental verification of these characteristics. The purpouse of this thesis is to demonstrate that the fly ash attribute to meet all environmental XF.
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Study of durability of binders concept on purposeful creation of ettringite
Sokolt, Stanislav ; Štenko,, Miroslav (referee) ; Žižková, Nikol (advisor)
This master thesis is focused on the binary and ternary systems with connective purposeful ettringite formation for fast hardening adhesive for ceramic tiles. It deals with the durability of these materials after exposure to the corrosive environment. It examines the physical and mechanical properties and mineralogy changes after exposure to corrosive environments. Within processing of this paper provides basic information concerning the connective concept of purposeful formation of ettringite.
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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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Possibilities for testing and improving the durability of aerated concrete
Klaudová, Dana ; Voves, Jiří (referee) ; Hubáček, Adam (advisor)
This master´s thesis studies qualities of aerated concretes, is monitoring influenece concrete composition, quantity of aerating admixture and plasticized admixture on the durability of concrete. It is monitored especially air flow and his influence on durability on concrete. In theoretical part are explained mechanisms of damage concrete, phenomena, which influence compressive strength of concrete and then there are the results of resistance against the influence of chemical defrosting substances. In experimental work were designed, mixed and tested recipe of concerete. We investigated different atribute, especially resistance of the chemical defrosting and air flow in hardened concrete. The result of master´s thesis is effect of flow air in concrete on the durability.
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The use of micro and nanotechnology to develop ultra high strength and high performance concrete with special features
Vlč, Viktor ; Ťažký, Tomáš (referee) ; Hela, Rudolf (advisor)
The use of nanotechnology has become wide spread in all branches of science. Nanotechnology help us to understand microstructure and due to the world has started to produce new materials. One of many examples carbon nanotubes (CNTs). In diploma thesis I tried to find the way of successful introduction into concrete mixture. I was studying influence of CNTs and other nano particles and I was comparing them with referential samples (without CNTs). Also I tested the improvement of mechanical characteristics of concrete. The morphology of nano particles was studied using Scanning Electron Microscopy (SEM). The results show that introduction of nanoparticles to results in increasing strength and higher density. That is why High Performace Concrete so resistant and durable.
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Influence of changes in concrerte pore structure on actually durability of reinforced and pre-stressed structures.
Kovalčíková, Hana ; Adámek, Jiří (advisor)
This master thesis deals with a durability of concrete, which has become the centre of the interests of international scientific insitutes during the last years. The resistence of reinforced concrete depends on the covercrete which the aggresive liquids and gases penetrate through from the environment to reinforcement. According to the ability of the covercrete to penetrate degradative species is possible to tell the durability of concrete constructions. In experimental part we look for the actual state of covercrete, ordinary and high strength, by combination of various experiments. We can find here the test´s results of water and gas permeability and absorbability and sorption of concrete which complete the permeability tests. In final part the impact of different concrete types on durability of reinforced concrete is discussed.
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