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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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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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Study of the influence of additions on the durability of aerated concrete
Halešová, Adéla ; Voves, Jiří (referee) ; Hubáček, Adam (advisor)
The aim of this work is to summarise and consider the possibilities of using admixtures and their influence on the durability of aerated concrete.This bachelor's thesis is based on research findings concerning aerated concrete. Furthermore, it deals with the study of inert and active additions. The experimental part is focused on testing trial samples with the addition of admixtures. It examines what is the rate of the possible chosen physically-mechanical features such as the rate of air density, the durability of surface against the effect of water and chemical defrosting substances and achieving the required strength.
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Issues of design and testing of waterproof concrete fot tunnel lining
Merta, Michael ; Voves, Jiří (referee) ; Hubáček, Adam (advisor)
The diploma thesis deals with the issue of waterproof concrete and testing its properties. The theoretical part is conceived through research on existing knowledge relating to waterproof concrete. Emphasis is placed on the possibility of using a waterproof concrete for structures, such is e.g. tunnel lining. The experimental part is focused on the laboratory testing of waterproof concrete. Particulary examined was the effect of various admixtures as a partial replacement of cement. Monitored was the development of compressive strength and flexural strength, development of temperature during hydration in the early stages of maturation of concrete, water resistance of concrete, concrete surface resistance to water and chemical de-icing agents, as well as development of shrinkage during concrete maturation.
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Comparison of calibration relationships for determining the compressive strength of various types concrete of non-destructive testing
Kaplan, Václav ; Voves, Jiří (referee) ; Brožovský, Jiří (advisor)
The bachelor thesis deals with the copmarison of calibration relationships for compressive strength of concrete by non-destructive testing. The work describes the methods for the determination of compressive strength of concrete obtained by non-destructive methods, including rebound hammer method, ultrasonic pulse method and combined SonReb method for various types of concrete. In thesis are described species tested concretes obtained normalweigt concrete, high-performance and high-strenght concrete, light-weight concrete and self-compacted concrete. In this work are described below used types of non-destructive testing, terms of use and czech technical standarts related with non-destructive testing. For the comparisons are utilized calibration relationships of technical standarts manufacturers of test equipment and specialised literature.
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The possibility of using admixtures for waterroof concrete
Roháček, Lukáš ; Voves, Jiří (referee) ; Hubáček, Adam (advisor)
Bachelor thesis is mainly focused on additions, that have impact on water impermeability and other properities of fresh and hardened concrete. This issue is also described in short section, which is took from foreign reaserch. Thesis further discusses about the standards and regulations that determine, what properties should have waterproof constructions. Experimental part is showing influence of fly ash, slag and silica fume on conzistency, hydratation heat development, strenght, water impermeability, frost resistance and volume changes of the concrete.
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Modeling of Microwave Semiconductor Structures
Pokorný, Michal ; Mazánek, Miloš (referee) ; Voves, Jan (referee) ; Raida, Zbyněk (advisor)
Tato dizertační práce se zabývá modelováním mikrovlnných polovodičových struktur. Stále vyšší pracovní kmitočty komunikačních systémů zvyšují nároky na aktivní prvky a přenosová vedení, realizované zpravidla v monolitické integrované podobě. Přenosová vedení s rozprostřeným zesílením představují perspektivní řešení nejen jako zesilovací prvky, ale také jako aktivní napáječe mikrovlnných antén. V součastné době neexistuje vhodný softwarový nástroj pro jejich efektivní simulaci a návrh. První část této práce je zaměřena na implementaci termodynamické formulace modelu driftu a difuze pro numerickou simulaci transportních procesů polovodičových struktur v komerčním programu COMSOL Multiphysics. Další část je věnována implementaci Gunnova jevu v makroskopické aproximaci a vypracování simulační procedury pro analýzu struktur využívajících tento jev. Poslední část je věnována návrhu a analýze aktivních přenosových vedení a zlepšení jejich vlastností.
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Study of effect of the introduced parameters to aerate of aerated concrete
Urbánek, Libor ; Voves, Jiří (referee) ; Hubáček, Adam (advisor)
Bachelor thesis is focused on aerated concrete, their parameters of composition and properties. Further, the thesis focuses on the study of the effect of the introduced aeration on fresh concrete on its properties in both fresh and hardened state. Emphasis is placed on the assessment of the aeration rate in fresh concrete, as compared to the various parameters of hardened concrete, especially the content of hardened concrete and the durability of concrete. The study is complemented by a description of air pore distribution tests in fresh and hardened concrete, a description of individual aeration additives and a study of the influence of aeration additives on the durability of concrete.
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Study of properties of concrete and brick recycled aggregate and its use for structures
Lípová, Sabina ; Voves, Jiří (referee) ; Hubáček, Adam (advisor)
This bachelor thesis studies the existing knowledge on recycled aggregates, particularly brick and concrete recyclates. It describes the properties and parameters of different types of recyclates and their possible applications in structures such as concrete, base courses, non-structural parts of pavements, etc. It also deals with the development of a methodology for selecting and testing recycled aggregates with the possibility of using them to meet the requirements of aggregate standards. Geometric, physical and mechanical parameters of aggregates that could affect the properties of the materials for structures made from them have been studied
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