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The development of high-strength concrete with a high content of el. fly ash
Roubal, David ; Ťažký, Tomáš (referee) ; Hela, Rudolf (advisor)
This diploma thesis deals with the study of high-strength, high-volume fly ash concrete. The theoretical part of this thesis focuses on the detailed characteristic and main principles of high-strength concrete, high-volume fly ash concrete. In addition, according to the findings, the technology of high-strength and high-volume fly ash concrete, including principles of high strength, has been described. On the basis of the findings, high-strength, high-volume fly ash concrete for specific compressive strengths has been designed and created in the experimental section. These concretes were then subjected to a number of tests.
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Monitoring the influence of concrete composition on abrasion resistance
Černá, Hana ; Novosad, Petr (referee) ; Bodnárová, Lenka (advisor)
This diploma thesis focuses on the resistance of concrete to abrasion with regard to the raw materials used for their production. In the theoretical part of the thesis are described admixtures, different types of aggregate and aggregate composition which influence the resistance of concrete to abrasion. In the experimental part, 15 different C30 / 37, S4 concrete formulations were proposed. Different types of aggregates - fecal gravel (Žabčice), biotic granodiorite (Olbramovice) and amphibolite (Želešice) have always been used in the recipes. Fine ground limestone, micro-silica, high-temperature fly ash and finely ground slag were ingredients that were added to the proposed recipes. Consistency was determined by the method of cone seating and the density of fresh concrete. In the hardened state, concrete density, compressive strength, bending tensile strength, tensile strength, watertightness, concrete absorption, and abrasion resistance were determined using the Böhm method and wide wheel method. The test specimens were tested after 7, 28, and 90 days of maturation.
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Study of the influence of additions on the durability of aerated concrete
Halešová, Adéla ; Voves, Jiří (referee) ; Hubáček, Adam (advisor)
The aim of this work is to summarise and consider the possibilities of using admixtures and their influence on the durability of aerated concrete.This bachelor's thesis is based on research findings concerning aerated concrete. Furthermore, it deals with the study of inert and active additions. The experimental part is focused on testing trial samples with the addition of admixtures. It examines what is the rate of the possible chosen physically-mechanical features such as the rate of air density, the durability of surface against the effect of water and chemical defrosting substances and achieving the required strength.
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Study of shrinkage reducing admixture efficiency in alkali activated systems
Fojtík, Ondřej ; Koplík, Jan (referee) ; Bílek, Vlastimil (advisor)
Significant drying shrinkage is one of the major issues for the wider application of materials based on alkali-activated slag (AAS). Some shrinkage reducing admixtures (SRA) were developed for the ordinary portland cement systems. A couple of previous studies focused on the efficiency of these SRA in alkali-activated materials. The studies were mainly concentrated on the SRA based on polypropylene glycol. This thesis deals with efficiency of the SRA based on 2 methyl-2,4-pentanediol in AAS pastes and mortars. Influence of the SRA and activator (waterglass) dose on the drying shrinkage and other properties of AAS (flexural and compressive strength, autogenous shrinkage, workability, setting time and microstructure) were investigated. It was found, that at the activator dose when Na2O/slag mass ratio equals 4 or 6 %, SRA causes retardation of hydration, which leads to shrinkage reduction, however strength is reduced significantly, weight lost during the drying is increased and the coarsening of the pore structure occurs. At the activator dose when Na2O/slag mass ratio reaches 8, 10 or 12 %, in the presence of SRA the drying shrinkage is reduced, weight lost during the drying is similar to the reference, strength is increased and microstructure is unchanged against reference. It has been proved that SRA works properly in AAS only at higher activator doses.
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Development of structural concrete with power plant ash
Ťažký, Martin ; Sokol, Pavel (referee) ; Hela, Rudolf (advisor)
Worldwide production of concrete is increasing, what has a negative environmental load of cement production. That is due to effort in building construction, also concrete production, greater use of the secondary raw materials. Fly ash is the most commonly used secondary raw material. His used has a very good impact on the economy and ecology of production and positively affects on the properties of concrete in both the fresh and hardened state. The aim of this bachelor's thesis was to improve its use in concrete, using a minimum void fraction of dry mix cement-fly ash.
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Effect of partial replacement of Portland cement by diatomaceous earth on selected parameters of cement mortar
Rousková, Jana ; Sedlmajer, Martin (referee) ; Rovnaníková, Pavla (advisor)
The subject of this thesis is selected parameters cement mortars with partial replacement of Portland cement diatomaceous earth. This work provides information on the basic properties of diatomaceous earth and its deposits with a focus on deposit in Borovany. From the properties is very important pozzolanic activity due to the high content of amorphous silica of this soil. The main use of diatomaceous earth is in the area filtration and is used widely as a nutritional supplement. In the building industry, diatomite can be applied as an admixture to mortar and concrete, where it can, with its abilities, improve some physical mechanical properties. In the experimental part was diatomaceous earth, in its raw and calcined form, tested as admixture for cement pastes and mortars. The main criterion for evaluating these composites was bulk density, flexural and compressive strength. It was also investigated mineralogical composition, microstructure, freeze–thaw resistance and sulfate resistance.
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Technical and economic comparison of usability of different types of cements
Kováč, Michal ; Ťažký, Tomáš (referee) ; Hela, Rudolf (advisor)
This bachelor thesis deals with comparison of properties of different types of cements. The theoretical part is devoted to the distribution of cements, their composition and production. Various properties of cements are detected and compared in the practical part. Furthermore, concrete formulas are created which are also mixed and tested. Finally, the proposed area for the test cements and economic evaluation per 1 m3 of concrete mix.
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Design and development of the electrostatic precipitator
Kvasnička, Karel ; Radil, Lukáš (referee) ; Ptáček, Michal (advisor)
This bachelor thesis deals with the design of an electrostatic precipitator and familiarization with the problems of separation on these separators. The aim of this work is to construct a functional model of an electrostatic precipitator. The principle of operation and design will be described. In addition, the design of a separator is elaborated, which was subsequently realized and experimentally verified in the CVVOZE Power Laboratories Research Infrastructure. The first part deals with the description of the legislation on air protection, the most frequent input material of separators and descriptions of the basic types of separators. In addition, the electric separator, its area of use, construction and individual components, as well as the undesirable operating state of the separator, are further elaborated. In the second part are presented the equations and calculations for the design of the separator. In the next part, the separator designer and his laboratory tests are described. The separator was subjected to basic voltage tests from the viewpoint of its operating voltage. Its functionality fits the realized experiments up to 30 kV. On the basis of this work and the production of the equipment, it is possible in the future to test the properties of flue gases and other gases.
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The possibility of using admixtures for waterroof concrete
Roháček, Lukáš ; Voves, Jiří (referee) ; Hubáček, Adam (advisor)
Bachelor thesis is mainly focused on additions, that have impact on water impermeability and other properities of fresh and hardened concrete. This issue is also described in short section, which is took from foreign reaserch. Thesis further discusses about the standards and regulations that determine, what properties should have waterproof constructions. Experimental part is showing influence of fly ash, slag and silica fume on conzistency, hydratation heat development, strenght, water impermeability, frost resistance and volume changes of the concrete.
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