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The influence of hydration accelerators on cement doped with zinc
Beneš, Pavel ; Šilerová,, Iva (referee) ; Šiler, Pavel (advisor)
Zinc in cement has negative properties mainly due to a significant delay in hydration. This bachelor thesis deals with the study of hydration of cements containing zinc. The course of cement hydration was monitored by isoperibolic calorimetry. Zinc was doped to CEM I 42.5 R in the form of 1 weight percent zinc oxide. Calcium oxide, formic acid and calcium formate were used in various proportions as accelerators. The obtained results were compared with the measured strengths and finally the suitability of the given accelerators was discussed for use in construction application.
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Study of the properties of the ettringite which was produced synthetically
Hučínová, Lenka ; Jiroušková, Kateřina (referee) ; Fridrichová, Marcela (advisor)
Up to present, ettrigite has been prepared by two means in the Institute of Technology of Building Materials and Components of the BUT Faculty of Civil Engineering: originally by the hydration of the yeelimite clinker; recently by the direct synthesis of ettringite from calcium hydroxide and aluminum sulfate, the latter being considered more suitable in qualitative and quantitative terms. This diploma thesis focuses on the comparison of both means, using ettringite produced by the latter as control sample. This endeavor focuses on monitoring the stability of ettringite and its possible conversion to other minerals using X-ray diffraction analysis, thermal analysis and scanning electron microscopy (SEM).
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Study of new types of admixtures for waterproof concrete
Sikorová, Věra ; Másilko, Jiří (referee) ; Kalina, Lukáš (advisor)
This bachelor thesis is focused on the influence of crystallizing admixture for waterproof concrete. Reference concrete samples and modified concrete samples were prepared with different dosing of the crystallizing admixture, on which the standard test – the depth of penetration of water under pressure was carried out. The rheological properties of fresh concrete were verified by a slump test. The mechanical properties of the hardened concrete were examined by a compressive strength test. The mechanism of effect of the crystallizing admixture has been studied by scanning electron microscopy and X-ray diffraction analysis.
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Cement mixtures and their utilization in castings production to improve working environment
Svobodová, Radka ; Cupák, Petr (referee) ; Burianová, Klára (advisor)
This bachelor thesis describes the production of cement, its subdivision and use in industy, its chemical, physical and technological properties. Here it is writen about its virtues and qualities, but also about drawbacks and deficiencies. For the cement mixtures is important their porosity and total recovery in cement mixtures. As a result of the environmental protection, it is written about recovery and recycling of cement and its subsequent use as well. This thesis also involves laboratory measurement of mechanical properties.
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The possibilities regulation of production hydration heat of concrete with plasticizer
Hermann, Radek ; Halas, Vladimír (referee) ; Sedlmajer, Martin (advisor)
This thesis studies the problematics of water reducing and high range water reducing admixtures and their influence on the process of hydration of cement pastes. The process of hydration is examined in this thesis both in terms of hydration heat and hydration temperature rise. Attention is also paid to the influence of plasticizers in combination with retarding admixture regarding rheological properties of modified fresh cement pastes and their mechanical properties after 3 and 7 days from mixing.
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Reological properties of cement pastes modified by amorphous SiO2
Zimmermann, Štěpán ; Rovnaník, Pavel (referee) ; Vyšvařil, Martin (advisor)
The subject of this thesis are the rheological properties of cement paste with the addition of amorphous silicon dioxide. The basic rheological parameters are that describe the behavior of cement pastes in the fresh state. The work also included rheological tests including measurement principle and method of evaluation. Effect of mineral admixtures with high content of amorphous SiO2 is summarized the available scientific articles. In the experimental part, the effects of impurities with a high content of amorphous SiO2 on the rheological properties of fresh cement paste. It was tested by substitution of up to 10 % by weight of cement in the cement pastes mineral admixtures of different chemical composition, particle size and pozzolanic activity. Flow measurement was measured yield value, viscosity, and flow index. The stability of cement pastes was investigated oscillatory measurements. To complement the behavior pastes in the fresh state was determined by calorimetry. Test results were compared with those determined by reference samples and compared the effect of various ingredients.
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Study of durability of binders concept on purposeful creation of ettringite
Sokolt, Stanislav ; Štenko,, Miroslav (referee) ; Žižková, Nikol (advisor)
This master thesis is focused on the binary and ternary systems with connective purposeful ettringite formation for fast hardening adhesive for ceramic tiles. It deals with the durability of these materials after exposure to the corrosive environment. It examines the physical and mechanical properties and mineralogy changes after exposure to corrosive environments. Within processing of this paper provides basic information concerning the connective concept of purposeful formation of ettringite.
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