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Optimization of aggregate composition with max. grain 22 mm for concretes
Opat, Lubomír ; Vojtek, Miroslav (referee) ; Hela, Rudolf (advisor)
This bachelor thesis deals with the issue of aggregate curve design, proportional representation of the individual separated aggregate sizes in the formula for concrete mixture. It clarifies the origin of aggregate types, from their mother rocks. It describes tests on aggregates, including the test of the shape suitability. In the practical part, there are nine formulas, two of them mixed with the maximum grain size of 16 mm, seven with the grain size of 22 mm. They are instances of fine curves or mixture of coarse curve. Aggregate dust or crushed fine aggregate was also used.
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Interaction between asphalt binder and filler
Indráková, Kristýna ; Hýzl, Petr (referee) ; Dašek, Ondřej (advisor)
The thesis is mainly focused on comparison of properties of mastics, that were mixed in lab. The samples of mastics were mixed of paving bitumen in combination with 9 samples of backhouse filler, 1 inappropriate sample containing mica and 1 sample of additive filler. The folowing tests were used for assessment of samples: The particle density of filler-pyknometer method, The delta ring and ball test, The complex shear modulus and phase angle, The multiple stress creep and recovery test. The tests results were evaluated and compared. The results of the thesis are listed in the conclusion.
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Development of polymer repair materials using secondary raw materials
Juřička, Viktor ; Vyhnánková, Michaela (referee) ; Drochytka, Rostislav (advisor)
The diploma thesis deals with the development of polymeric repair mortars in two qualitative levels ECONOMY and PREMIUM, designed especially for heavy engineering plants and the energy industry. In order to effectively withstand difficult industrial conditions, the developed materials should meet the highest requirements such as increased chemical and heat resistance, excellent adhesion to the concrete substrate, minimal shrinkage and other physical and mechanical properties. The PREMIUM level is aimed to achieve maximum physical and mechanical properties. Within the economy version, the emphasis is placed not only on very good properties, but also the possibility capability of reducing price of the resulting material. The partial aim of this work is the efficient use of secondary raw materials, mainly based on industrial waste in the form of fillers to the developed polymeric repair mortars.
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Long-term tests for examination of surface treatments in various adverse environments simulating real effects
Hudečková, Petra ; Vacula, Miroslav (referee) ; Bydžovský, Jiří (advisor)
Cement bonded particleboards contain organic base and as they are set outside, extreme weather condition, such as frost, chemical defrosting substances or sulphates, cause their degradation. The presence of the organic base in the matrix of the material could be the reason why there is higher probability of degrading when compared with materials containing an inorganic base. It could be partially eliminated by an appropriate surface modification of the slab, which main goal is to weaken the impact of an aggressive environment and to extend the lifespan of the board. On the other hand, the surface modifications based on a polymer base are prone to degrade because of other unfavourable conditions such as UV radiation when compared with the cement bonded particleboard. The classification of the surface modifications and the way of their degradation caused by the aggressive environment in real applications are presented in the theoretical part of the thesis. In the experimental part, appropriate methodical ways of testing the resistance of cement bonded particleboard’s coating system were chosen. Then, the testing and comparing of the physical, mechanical and aesthetic properties of different types of coatings were done. Moreover, a spectrophotometric analysis of the colour shade changes for the different aggressive environment were carried out. Furthermore, microstructures of chosen surface modifications were assessed by using an optical and an electron microscope.
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Hybrid Blends of Recycled Plastics
Černý, Miroslav ; Lehocký, Marián (referee) ; Balgová,, Vendula (referee) ; Jančář, Josef (advisor)
Work describes the relationship between structure and mechanical properties in case of hybrid mixtures. They are composed from polyurethane matrices (eventually polyurethane-urea or polyurethane-inorganic filler mixtures), different rubber fractions as filler and eventually reinforcement made from PET monofilaments. Mechanical behaviour was studied by tensile testing. Studied mechanical properties include tensile modulus, ultimate strength and strain and also specific energy need neccessary for ultimate strength achievement. Prepared materials are naturally porous. Therefore their mechanical behaviour has to be described generally for porous composites. The porosity occurence means, that it is difficult to describe them by models valid for mechanical behaviour (mainly elastic modulus) of nonporous composites. Models are also based on idealized structures on microscopic level. In case of porous composites, it is very difficult to create any idealized structure. The structure is changed with modifications of composition (change of components or their rates). These conditions have lead to utilizing of different approach how to describe the relationship between structure and mentioned mechanical properties. The chosen approach comes from knewledge about structural parametres coming from porosity. Structural parameters describe the structure on macroscopic level. They include interspace volume (volume lying between filler particles), interspace filling (how the matrix fills the interspace volume) and matrix volume fraction. Proposed parameters are used in relations, where they are fitted by exponents to interlay values of chosen mechanical properties for composites containing discrete matrix and filler. Found exponents are then described by properties of matrices to obtain relations describing properties of filled porous materials. Very similar approach was chosen for description in the case of reinforced composites. Proposed relation are potentially valid for materials containing binding matrix, infinity count of fillers and one kind of reinforcement.
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Verbal padding in spoken language on the Czech media scene exemplified by reporters of the Czech television and the Czech radio
Švejkovský, Jakub ; Šoltys, Otakar (advisor) ; Němcová Tejkalová, Alice (referee)
Speaking is an immensely complex area of human communication. Speakers whose speech is fluent, without hesitation, pauses and any other shortcomings, have been and are still admired most of all speakers. Most people are encouraged by the effects of fillers and performance additions. However, the two means that fill the language to be more coherent are, of course, considered to be significant language flaws. Still, the oral speech is inherent to us. The author of the bachelor thesis used it to prove that the fillers and performance additions are not spoken only by ordinary people, but also by those for who the language is living. Since neither oral speech by professional speakers is completely coherent in any circumstances, even the best speakers are occasionally forced to use paradoxically language flaws for smoother speech. In order to confirm this theory, the author chose a media scene environment where he analyzed the speeches of Czech TV and Czech Radio editors.
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Preparation and characterization of highly filled composite materials for dental applications
Gavroňová, Ivana ; Bystřický, Zdeněk (referee) ; Poláček, Petr (advisor)
Master thesis deals with highly filled particulate composite materials for dental applications. In the practical part, the dimetacrylate matrix was filled with a mixture of particles of different types and different sizes to achieve the maximum possible packing. Moreover, filler content and the influence of filler on composite material was studied. Hydrolytic stability was also tested on composite materials. The methods used to characterize composite materials were bending test, thermogravimetric analysis (TGA), differential scanning photocalorimetry (DPC), dynamic-mechanical analysis (DMA) and scanning electron microscopy (SEM). Curing of the matrix was characterized by the degree of conversion, the heat of polymerization and the polymerization rate. Furthermore the polymerization shrinkage was measured. The glass transition temperature, the dynamic modulus at 40 °C and 100 °C, the modulus of elasticity, the strength, the critical value of the stress factor and the critical energy release rate were found in the tested samples.
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Brickmaking grogs and their thermo-dilatometric determination
Hladík, Václav ; Skotal, Zbyněk (referee) ; Sokolář, Radomír (advisor)
Main focus of the bachelor´s thesis is use of rock waste fraction as an alternative raw material to traditional quartz sand. Effect of this substitution on ceramic produts properties is outlined. Key properties are water absorption, flexural strength and compressive strength. The practical part traces the potential of alternative grogs. Their behavior is monitored by DKTA analysis, water absorption tests and strength tests. Thesis includes author´s suggestion of an optimal grog based on publications and results of the practical part.
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Analysis of filler types onto the wood plastics composites
Blaha, Lukáš ; Pospíšil,, Ladislav (referee) ; Vaněrek, Jan (advisor)
Wood polymer composite (WPC) is a material that combines the wood material and the thermoplastic matrix. As filler to be used as wood flour and thermoplastic matrix will be used in primary or recycled polypropylene. WPC will be made by injection molding. The aim of the thesis is to find the optimal ratio between primary and recycled polymer in which the result will be the best physical and mechanical properties.
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Modification of epoxy resin effecting ductility of wood bonds
Hudečková, Petra ; Drochytka, Rostislav (referee) ; Vaněrek, Jan (advisor)
This bachelor thesis is focus on a jointing process of wood parts, the basic kinds of adhesives that are used for wood constructions, and also deals with an important demands on a bonded wood joint. Then there is briefly described an issue of fracture toughness and the ways of epoxy adhesives filling, primarily filling with the rubber, the thermoplastics and other fillers. In the experimental part the reinforcing of epoxy matrix with the different quantity of rubber was carried out. The mixture was prepared by an ultrasound homogenizer. Firstly, the tensile strength test with epoxy samples was carried out. Secondly, the Young modulus was calculated and in the last part the fracture surface was analyzed with the scanning electron microscope.
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