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Lightweight composites based on fluid filter ashes
Palovčík, Jakub ; Másilko, Jiří (referee) ; Opravil, Tomáš (advisor)
This Bachelor’s thesis deals with preparation, study and analysis of binders based on fluid filter ashes. Binders were doped with various additives to alter the rheological properties, reduce volumetric weight and increase flexural compressive and tensile strength. Next, a possibility of using waste polyester fibres for reinforcement in matrices based on above mentioned binders was determined. The prepared samples were tested for compression and flexural strength after 28 days. Phase composition was analysed by means of X-ray diffraction analysis.
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The effect of particles size on the properties of mortars.
Sehnal, Tomáš ; Krátký, Josef (referee) ; Šiler, Pavel (advisor)
The consumption of concrete as a building material is still increasing over the world. Concrete production is closely associated with CO2 and other greenhouse gases emissions. The reduction of these emissions can be achieved by a higher utilization of secondary raw materials in cement mixtures. This bachelor work is focused on the using of secondary raw material, finely ground granulated blast furnace slag and fly ash from fluidized bed combustion and high temperature combustion. The properties of milling pure cement and cement mortars with addition of secondary raw material will be measured. Compressive strength, flexural strength, and calorimetric measurement will be performed for these prepared mortars.
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Possibilities of utilization of solid residues from fluidized bed combustion for preparation of composite Portland cements
Beranová, Denisa ; Šiler, Pavel (referee) ; Opravil, Tomáš (advisor)
The bachelor thesis deals with possibilities of utilization of solid residues from fluidized bed combustion of coal, bed and filter ash, to be used in the production of composite Portland cements. 6 ash types were investigated, of which 3 were bed ash (finely ground) and 3 were filter ash colected from Ledvice, Tisová and Poříčí K8 power plants. The chemical composition of the ash collected was determined and the progress of a hydration reaction monitored, and then samples mixed with Portland clinker were prepared. Their respective compressive strength and flexural strength were then analysed and observations made on the hydration and composition of products of the hydration reaction. Finally the results of selected mixtures were verified with prepared standardized mortars.
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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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The composites materials based on the solid residues of fluidized combustion
Kalina, Martin ; Koplík, Jan (referee) ; Opravil, Tomáš (advisor)
This bachelor thesis deals with a study of possible preparation of composite materials based on the solid residues of fluidized bed combustion. It focuses mainly on the strength properties of prepared materials and the phase composition of incurred hydration products. A powder X-ray diffraction analysis was used to determine the phase composition of prepared stiffened samples. Based on analysis of raw materials (fluid ash), various ingredients and additives were added to the mixtures in order to modify the composition or rheological properties of the fresh mixtures. After 28 days of maturation, the phase composition of prepared samples and the development of compressive and tensile strength in bending were monitored.
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The effect of fly ash on the properties of cement mortars.
Bayer, Petr ; Brandštetr, Jiří (referee) ; Šiler, Pavel (advisor)
The consumption of the cement for construction industries is increased every year. That is associated with greenhouse gas emissions, especially carbon dioxide CO2. Reduction of greenshouse gas emissions can be achieved by maximisation of the use of cementitious and pozzolanic by-products. As by-product could be used blast furnace slag and fly ash. My bachelor’s thesis is focused on the possibility of the partical replacement of the cement by fly ash. High temperature and fluidized fly ashes will be tested. The goal is to examine the behavior of the cement mortars in compensation of 10, 20, 40 and 60 % by weight of cement by fly ash. The compressive and flexural strength and isoperibolic calorimetry measurement were performed.
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Modern Inorganic Building Materials Free of Portland Cement
Sadílek, Jakub ; Opravil, Tomáš (referee) ; Zmrzlý, Martin (advisor)
This bachelor’s thesis is focused on properties of modern construction inorganic ma-terials – geopolymeric concretes. In introductional part of work it is described basic theoretical background, as properties of binders, principles of setting and hardening. For preparation of geopolymer matrix was used secondary or waste materials of energetic and metallurgical industry – fly ashes and slags. In laboratory were prepared four com-positions of geopolymeric concretes combined from geopolymeric matrix with constant compostition and variable composition of aggregates. As aggregates these materials were used: three fractions of quartz sand, steel furnace slag and in one composition also crystals of mineral wollastonit. It was discovered that the use of steel furnace slag as aggregate in geopolymeric concrete has positive influence mainly to compressive strength, but the addition of wollastonite mineral do not evocate expectable increase of mechanical properties of samples.
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Testing early strength concrete by electronic tester
Holbová, Monika ; Kocáb, Dalibor (referee) ; Cikrle, Petr (advisor)
This project solves the creation of calibration relations for determining the compressive strength of early age concrete. It deals with news in the field of hardness methods. 36 samples were made for this experiment and tested by ultrasound and by impact hammer SilverSchmidt type L with Mushroom Plunger. The result is set of calibration relations for determining of compressive strength for different methods and their combinations.
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Modulus of elasticity of natural stone
Hoduláková, Michaela ; Cikrle, Petr (referee) ; Kocáb, Dalibor (advisor)
The value of the modulus of elasticity of concrete depends on the concrete composition (particularly on the aggregate used). The contemporary construction industry literature lacks comprehensive studies of the modulus of elasticity for each type of the rock stone. Therefore, this study focuses on testing and comparing the modulus of elasticity of selected types of rock stones used for the production of crushed coarse aggregates into the concrete. The modulus of elasticity are determined by static and dynamic methods. The work also deals with the modulus of elasticity of granite in different stages of weathering.
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