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The effect of the shrinkage reducing additives on rheological properties of high-strength concrete
Červenka, Jiří ; Kucharczyková, Barbara (referee) ; Daněk, Petr (advisor)
Master’s thesis examines the effect of the shrinkage reducing additives on rheological properties of high-strength concrete. The first part is focused on high-strength concrete in terms of their composition and properties. The second part contains a detailed analysis of the cementitious composites shrinkage problems. Total shrinkage is divided into individual elementary shrinkages. For each of them there is a detailed description of causes and factors that affect their sizes. The next part describes the basic additives used to reduce the shrinkage of cementitious composites. The experimental part is focused on verifying the effectiveness of the shrinkage reducing additives during preparation of high-strength concrete. Usage of shrinkage drains for relative strain measurement enables to determine the process of shrinkage immediately after placing the concrete in the form and to obtain the overall curve of the hight-strength concrete volume changes during its setting and hardening. At the end of the thesis, there are overall analysis and summary of the results of the performed experiments.
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Influence of inorganic admixtures on shrinkage reduction of alkali activated materials
Šístková, Pavlína ; Koplík, Jan (referee) ; Kalina, Lukáš (advisor)
This bachelor thesis is focused on the influence of inorganic admixtures on shrinkage reduction of alkali activated materials. In the theoretical part the issue of alkali activated materials is explained in detail focusing on the reduction of their shrinkage. Alkali activated system is constituted by alkali activated blast furnace slag. Firstly, the effect of inorganic dashes is monitored such as low calcium fly ash and finely ground limestone. Furthermore, the influence of inorganic additives for reducing shrinkage has been studied, namely magnesium oxide and calcium oxide. The aim of this work is to determinate the mechanical properties and shrinkage of individual alkali activated mixture and then discuss whether there was a reduction of shrinkage and what the effect of added dashes and inorganic admixtures was.
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Injection moulding technology of thermoplastics
Mikulík, David ; Přikryl, Radek (referee) ; Kučera, František (advisor)
The work deals with optimization of the technological mode of injection moulding of test specimens 1A of semicrystalline PP and amorphous PS. It also explores the influence of technological mode changes on the crystallinity of a semi-crystalline PP. Was set the reference technological mode for each of the polymers and subsequently changed the value of the injection temperature, mold temperature, the volume when you switch to holding pressure, injection and holding pressure. After relaxation of injection for time 24 h, and the mouldings and dogbones were weighed and thickness were measured at selected points. From the dogbones made of PP samples were taken for differential scanning calorimetry (DSC) and crystallinity was examined. From the observed weight and thickness of dogbones were determined optimal technological modes for semi-crystalline PP and amorphous PS. Examining the influence of technological change modes on the crystallinity showed no clear dependence. Furthermore, it was found that the processing of a semicrystalline PP injection moulding reduces the value of crystallinity of the polymer, compare to starting PP granulate.
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Powder Metallurgy and Fundamentals of Sintering Process
Foltýnek, Jaroslav ; Pouchlý, Václav (referee) ; Čelko, Ladislav (advisor)
The bachelor thesis deals with the powder metallurgy and sintering process of metallic materials. The work is a recherche on this topic and includes a basic comprehensive insight into the entire production process consisting of the overview on the material powder processing techniques, introduction of the basic parameters of sintering process and mechanisms involved during sintering influencing the final compact product formation. The sintering process is in work divided into two basic categories, solid state and liquid-phase sintering.
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Volume changes of concrete based on reactive powder components and possibilities of their regulation with chemical admixtures
Hlaváček, Jaroslav ; Kalinová, Helena (referee) ; Opravil, Tomáš (advisor)
Very high strength of RPC allows them to an unusual extreme possibilities of their applications. Volume change (shrinkage) negatively affects their relatively broad range of applications, particularly in applications which are used for filling tubes or other components. In today's advanced time with plenty of chemical ingredients and additives on the market (such as the expansion component) could be a side effect of this largely eliminated, or removed entirely. Only some components of the expansion will be appropriate for RPC cements. This reaserch investigates the expansion of ingredients on the basis of sulfates and monitors not only volume changes, but also the strength characteristics and tolerability of the tested anchors tested with a matrix component of the expansion.
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Injection moulding
Heralt, Aleš ; Balej, Zdeněk (referee) ; Žák, Ladislav (advisor)
This Bachelor´s thesis is focused on construction forms for injection of thermoplastic matters. The technology for plastic products production is technology that participate more and more in production of all sorts of products - from technical components over kitchenware after as much as toys. Main part of this thesis is focused on description of the injection valve, ejector, annealing and ventilation system forms for injection with the main structural principles.
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Properties of cement composites with fiber reinforcement
Jankech, Filip ; Sitek,, Libor (referee) ; Bodnárová, Lenka (advisor)
This thesis summarizes the knowledge of the possibility of using organic fibres as dispersed reinforcement into cement composites. It is concretely a summary of knowledge about the types and properties of synthetic and cellulosic fibres, their influence on the properties of fresh and hardened cement composite and lastly a description of the fire resistance of cement composites and the effect of organic fibres on the action of those composites at high temperatures and in the presence of fire. The experimental part is supposed to verify the effect of the cellulose fibres on increasing the durability of the cement composite at high temperatures.
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Design of simple engineering structure
Macková, Lucie ; Navrátil,, Jaroslav (referee) ; Klusáček, Ladislav (advisor)
Bachelor’s thesis processes methodology of calculating the deflection according to norm EN 1992-1. First of all it deals with the theory necessary to understand the whole process and explanation of each step. Next learned lessons are applied in the model calculation of deflections, which is performed at 3 beam elements of different construction heights. The resulting values are compared to point out changes in the final deflection according to different dimensions of the structure.
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Design and production of a plastic komponent
ČÍŽEK, Václav
The theoretical part is focused on evaluation of chosen ?essential? plastics used in the car industry. The principles of construction and proportioning of plastic components, basic conception of injection moulding and measuration follow. Another section of the theoretical part presents a summary of possible CAD systems, which are used. The practical part is focused on a particular plastic moulding. It includes the main description of a component with its material choice in dependence on the component function. Another section contains evaluation of the component complexity from the viewpoint of moulding, and a possible substitution of constructions, which could be productively simpler, is shown. The whole thesis is completed for better lucidity by pictures, drawings, and mechanical drawings.
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