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Study of usabiliti of sands for preparation of aeroconcrete in hydrotermal condition
Straka, Radek ; Ptáček, Petr (referee) ; Opravil, Tomáš (advisor)
A building industry is expanding branch all the time and it intervenes in the life of everyone. Aeroconcrete is very attractive and actual subject nowadays because economy is important point of view of production. This material finds a wide-spread use thanks to its specific properties. The good manipulation and great thermal insulating properties are secured by its porous structure. Furthermore, proper material selection provides a saving of power of house for every customer demands. Due to aeroconcrete's sufficient compressive strength it is useful for both constructions and internal walls. Fundamental and very important for final material properties is raw material composition of aeroconcrete. A relationship between composition of filler (quartz sand) and resultant properties of aeroconcrete is an objective of the thesis.
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The technology of aerated concrete
Zezulová, Anežka ; Kalina, Lukáš (referee) ; Opravil, Tomáš (advisor)
The technology of aerated concrete is a topic that is permanently studied and developed because of the incessant demand for a building material which ensures relatively high strength at low volume weight. This bachelor’s thesis examines the influence of replacing a part of sand with another silica material – microsilica. The increase of mechanical strength is expected at the same volume weight. Microsilica contents around 98 % of amorphous silicon dioxide with a high specific surface area that is substantially higher than a specific surface area of a ground sand. The reactivity of silicon dioxide increases with a higher specific surface area and also with the creation of a mineral tobermorite, which is the keeper of the strength in autoclaved aerated concrete. Three types of microsilica were chosen to examine the influence of replacing a part of sand with microsilica according to their availability for manufacture: microsilica Sikron and Elkem 971 U, microsilica Grace Davison was tested only marginally. Tests were carried out to determine volume weight, compressive strength, phase composition (by X-Ray diffraction method), and the content of tobermorit (by TG-DTA method).
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The technology of aerated concrete
Koutný, Ondřej ; Repka, Martin (referee) ; Opravil, Tomáš (advisor)
Civil engineering is integral part of industry in each developed country. Naturally the construction point does not play the main role here, but also the material of building segments. In last fifty years the new possibility has been discovered against classic brick in form of autoclaved aerated concrete. This material gathers its customers not only due to low weight and easy application with sufficient strength, but particularly due to excellent heat-insulation properties. Contemporary trend in research of aerated concrete points to application of alternative raws, as for example metakaoline, to improve final properties of product by preserving of current technology and price.
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Monitoring of the wheat quality for food production
Slavíčková, Radka ; Hýsková, Eva (referee) ; Omelková, Jiřina (advisor)
The aim of this study was to monitor the quality of wheat Triticum aestivum, imported into the laboratory MORAGRO after harvest by eight different suppliers, and to evaluate the main quality parameters decisive for the final use of cereal crops. The introduction of the theoretical part was devoted to understanding commercial and agricultural importance of wheat and description of morphological and physiological characteristics of wheat grain. The core of the theoretical part has been focused on the description and explanation of physical and chemical properties of the wheat grain, which largely affect the final product quality of wheat. External factors affecting final quality and yields of wheat were also commented. The experimental part was based on measurements of main quality parameters of wheat (moisture content, bulk density, falling number, amount of gluten and the wheat proteins, sedimentation value and content of additives and impurities). In most cases, measurements were carried out using automated instruments. The quality of wheat was determined based on the obtained results, which allows deciding, whether it is appropriating for food production.
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Changes in physical properties of the subsurface soil layers depending on the technology tillage
Bažantová, Adéla ; Larišová, Lucie (referee) ; Kameníčková, Ivana (advisor)
For the correct course of soil processes, plant growth and development is necessary the tillage of soil. Usually we choose between two technologies, that those adjustments are cariied out by. Both are conventional tillage, which uses plowing and minimization tillage, wherein is excluded plowing. Objective of this work is to determine the impact of these tillage treatments on selected physical properties of soil, i. e reduced bulk density of the soil, porosity, momentary contents of water and air in the soil. Soil samples were collected by Kopecky rollers (V = 100 cm3) taken from depths of 0,1; 0,2 and 0,3 m that were used to evaluate. Two samples were collected each July. This period is referred as a critical due to higher soil compaction (movement of mechanization, root system of plants and rainfall totals). Experimental research was conducted in years 2008 – 2011 in the village Bohaté Málkovice.
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Influence of dosage of steel fibres on the loss of consistency of fresh concrete and compresive strength of hardened concrete.
Kuře, Václav ; Źalud, Oldřich (referee) ; Vymazal, Tomáš (advisor)
Bachelor work is focused on problems of a consistency of fresh fiber reinforced concrete. The consistency was characterized by a slump test and by a test of spilling how is it described in ČSN EN 12350. Obtained results are compared with a reference sample of a fresh concrete and between themselves. Further the work is focused on volumetric changes during maturation which are integral part of physical properties of the concrete. Influence of a dispersed reinforcement was monitored on the cube strength in plain pressure of individual mixed sample too. Total evaluation of tested parameters is states at the end of the work including comment about possible ways of interference of tests.
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Energy demands balers with fixed and variable compression chamber
SKALICKÝ, Martin
This bachelor thesis focuses on the comparison of energy demands of fixed- and variable- chamber silage balers. The first part of the thesis deals with the fodder plants (importance, crop and agrophysical characteristics) and pick-up balers (agrotechnical requirements, division, description and construction of balers). The second part contains measured values and results. To compare the energy demands I have chosen the fixed-chamber silage baler CLAAS ROLLANT 250 ROTOCUT and the variable-chamber silage baler KRONE VARIOPACK 1800 MULTICUT. With both balers I compared their unit weight, performance and fuel consumption measuring. The measuring took place during the hey and silage crops (three cuttings). The gathered data was used for further calculations.
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