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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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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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Impact of uncoventional technologies of soil cultivation on soil quality
Suchá, Kateřina ; Doležal, Petr (referee) ; Kameníčková, Ivana (advisor)
Agricultural land is being handled by various tillage of soil which affects properties of soil. There are two types of tillage treatment. These are conventional (classic) tillage with plowing and minimization tillage (plowing is excluded). The aim of this particular work is to assess the quality of the soil near the village of Bohaté Málkovice, which is being (long-term) handled by minimization tillage. As indicators of soil quality, we used selected physical and physico-chemical characteristics, which are determined from analysis of disturbed and undisturbed soil samples from the top soil layer (0-10 cm) by standard methods in laboratory conditions. The theoretical part describes the basic physical properties of the soil and the ways of their determination. The practical part is devoted to the presentation of the examined locality and the results of selected physical and physico-chemical properties of the soil are presented and subsequently evaluated. In the conclusion, the impact of used tillage in Bohaté Málkovice on the selected soil properties is assessed.
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Influence of fine particles granulometry on the physico-mechanical properties of concrete
Louda, Pavel ; Klečka,, Tomáš (referee) ; Ďurica,, Tibor (referee) ; Hubáček, Adam (referee) ; Hela, Rudolf (advisor)
The theoretical part describes the properties of fine-grained admixtures and the ways how these admixtures modify concrete properties. There are also described ways to assemble grain curves in the range 0-1000 m. The practical part describes the properties of all the concrete components used for the tests. From the admixtures and cement, the individual grain curves were compiled. Curves were assembled in the first stage manually by using MS Excel. Subsequently, a simple program was developed based on the knowledge of composing grain curves, which automatically compiles the grain curve according to the given limits. The maximum cement replacement was set at 25% by weight. The physical and mechanical properties of the graded curves thus established were first verified on mortar mixtures where the workability, bulk density and strength were verified at the age 7, 28 and 90 days. In addition, the porosity of cement cement with mercury porosimetry has been verified for selected recipes. The acquired knowledge was subsequently applied to the concrete in the laboratory. Here the maximum cement compensation was set at 30%. In particular, concrete consistency over time, air content in the concrete and compresive strength of concrete at the age 3, 7, 28 and 90 days were verified. Verification was also carried out in practice on the optimization of self-compacting concrete. Mechanical properties have been retained for optimized recipe but there were financial savings and CO2 emissions reductions compare with the original recipe.
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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 Combustion of Organic Lightweighting Agents in the Chamotte Materials
Smékalová, Veronika ; Keršner, Štěpán (referee) ; Sokolář, Radomír (advisor)
Lightweight chamotte products are popular building material. There are many types of lightweight chamotte on the market, but the most popular lightening options are organic ingredients. This brings some problems to the production of these products. This thesis deals with the burning of various types of lighters from shards of fireclay materials. In the theoretical part are summarized raw materials, which are necessary for production of lightweight chamotte. The results of the published research studies on the topic of lightening of organic lightening products are being described here. The practical part deals with properties of products made of clay or kaolin with the addition of a certain amount of lighter. These added lighters are spruce sawdust, beech sawdust, peat, bran, paper slurry and anthracite. All these lighters are direct. For comparison, the cenospheres, which represent indirect lightweights, were also included in the research. For all specimens, the temperature interval of burnout of specimens, refractoriness, classification temperature, bulk density, thermal conductivity coefficient and other properties were defined.
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Survey and Diagnostics of Reinforced Concrete Structure
Richterová, Dominika ; Heřmánková, Věra (referee) ; Anton, Ondřej (advisor)
The main theme of this diploma thesis is a building survey and diagnostics of a reinforced concrete construction. In the first, theoretical part the focus lies on a description of each method for testing constructions and their evaluation. The second, practical part focuses mainly on finding of material characteristics and reinforcement of particular parts of the construction. On basis of obtained information, the final part of this paper focuses on static assessment of chosen parts of the construction.
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Effects of water erosion on selected physical properties of soil
Larišová, Lucie ; Toman,, František (referee) ; Hlavčová,, Kamila (referee) ; Dumbrovský, Miroslav (advisor)
The aim of the dissertation thesis is the assessment of the degradation of selected soil properties due to water erosion, including the temporal dynamics of these properties and the assessment of how this change affects the cumulative infiltration of the soil in watershed. Between 2012 and 2015, undisturbed and disturbed soil samples were collected on three experimental areas and the cumulative infiltration of the soil was measured. Experimental areas were selected on sloping, erosion-endangered blocks of arable land, in three cadastral territories of the Czech Republic, and this in the cadastral areas of Větřkovice, Čejkovice and Hustopeče. The cumulative infiltration was measured in three landscapes positions of the slope and soil samples were collected in three landscapes positions of the slope, at soil crust, topsoil and subsoil. In the Pedological Laboratory at the Institute of Landscape Water Management, Brno University of Technology, the particle density, bulk density, porosity, soil texture and water stable aggregates were determined from the samples taken. The cumulative infiltration of the soil was measured using the Double Ring Infiltrometer, the Mini Disc Infiltrometer and the mobile rainfall simulator. Using one-way analysis of variance to analyze the differences among soil samples and infiltration test. In addition, the dependence of soil crust formation, its physical properties and its influence on the cumulative infiltration of the soil were monitored on the areas.
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The preparation of cellular concrete for insulating purposes
Koutný, Ondřej ; Šiler, Pavel (referee) ; Opravil, Tomáš (advisor)
In these days of economic crisis subsiding, in the civil engineering the attention is pointed especially to the systems, which effectively reduce energy and decrease costs associated with using of residential or industrial premises. Especially the heat-insulating systems are mentioned, because of their characteristics and construction which will be applied economical solutions. It is possible to use the materials based on aerated concrete which excel within construction materials due to its heat-insulating properties. The use of this material for clearly heat-insulations seems to be fully-fledged alternative to standard heat-insulating systems also due to combination of nature character and sufficient strength. This work deals with possibility of preparation non-bearing, heat-insulating material based on autoclaved aerated concrete with volume weight under 200 kg/m3.
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Innovative wood-based materials
Buriánek, Vlastimil ; Brožovský, Jiří (referee) ; Vaněrek, Jan (advisor)
This bachelor’s thesis deals with the issue of optimizing the modification process for plywood boards. Optimization consists mainly in evaluating different densification methods with different parameters of plasticization and stabilization. Psychical parameters (bulk density, swelling, water absorption) and strength parameters (bending strength, modulus of elasticity) of modified plates were chosen for the evaluation parameters. The practical part involved the verification of two thickening treatments on birch plywood.
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