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Thermodynamic Stability of Thaumasite
Pospíšilová, Klára ; Dvořák, Karel (referee) ; Fridrichová, Marcela (advisor)
This work deals with the resolution of the identification characteristics of the thaumasit, which falls into the same group of AFt phases as the mineral ettringit. Both of these stages have the same structural arrangement and the morphology. This work’s specific goal is the synthetic preparation of thaumasit in a variety of conditions and its evaluation.
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Monitoring of alkalis in Portland clinker
Siudová, Alena ; Šoukal, František (referee) ; Opravil, Tomáš (advisor)
This bachelor thesis focuses on the localization of alkali in Portland clinker and their properties, which can significantly affect the lifetime of the concrete produced from these cements. The bachelor thesis deals with the study of the phases of the alkali in Portland clinker and the compounds they represent. Further, the bachelor thesis deals with the study of the rate of transfer of alkali into solution when mixing Portland clinker with water. Several different Portland slinks are analyzed and compared. The aim of the thesis is to try to find a connection between measured experimental values, clinker composition and alkaline-silica reaction precursors.
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Possibilities of application of fluidized bed combustion solid residues from municipal waste
Melicher, Daniel ; Solný, Tomáš (referee) ; Opravil, Tomáš (advisor)
The bachelor thesis deals with the use of solid residues from incineration waste products, especially in the construction industry. The aim of the thesis is to test various modifications of solid residues from incineration waste. These secondary materials were tested in bonding systems based on hydratation of portland cement, gypsum made from chemogypsum, quicklime and alkali-activated systems. The aim was to verify whether solid residues from waste incineration could be used as a component of alternative materials for the construction industry.
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Development of phase composition in silicate systems by available methods and their optimalization
Opravilová, Lenka ; Palou, Martin (referee) ; Škvára, František (referee) ; Havlica, Jaromír (advisor)
One of the most prominent measurable parameters of the development of phases and phase transformations in inorganic systems are undoubtedly the volume changes of silicate matrix. The study of volume changes is crucial in the terms of usable durability of final product. They represent shrinkage or expansion of the material and may lead to significant decrease of technological and ecological parameters and often to complete destruction of these materials. Most often the volume changes can be observed when cement is used as a binder and in concretes, mortars, artificial aggregates and other similar materials. There are many methods to detect, define and determine the volume changes qualitatively or quantitatively. The development of phases was investigated as a part of the dissertation thesis and hence the volume changes were observed under the conditions closest to the real state in the construction industry. The raw materials and admixtures were selected which model the content of hazardous components present in conventional materials (both natural and secondary), used in construction and the relationship with volume changes was searched and demonstrated. The contacts for measuring the volume changes were attached to test surfaces of specimens and the physical - mechanical tests (volume changes, phase changes, strength, etc.), chemical analysis and ecotoxicity tests depending on the length of hydration were performed.
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Effect of pH of mixing water on hydration and mechanical properties of cement composites.
Bezděk, Ondřej ; Krátký, Josef (referee) ; Šiler, Pavel (advisor)
This master’s thesis is focused on the effect of mixing water pH value on hydration and mechanical properties of cement composites based on portland cement. Source material was CEM I 42,5 R. Hydration process was analyzed by isoperibolic calorimetry, X-ray diffraction analysis and differential thermal analysis. Compressive and flexural strength was examined as mechanical properties. The samples microstructure was observed by scanning electron microscopy. Influence of mixing water pH value on flexural and compressive strength, retardation of hydration and ratio of individual phases was shown.
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The influence of zinc oxide on the cement composite with silica fume.
Dobiáš, Jiří ; Koutný, Ondřej (referee) ; Šiler, Pavel (advisor)
The aim of this work was to investigate the influence of zinc oxide on the properties of blended Portland cement mixed with silica fume. On the pastes were monitored flow properties and by using of isoperibolic calorimetry process of the hydration. On the prepared samples were studied mechanical properties of obtaining values of compressive and flexural strength after 1, 7 and 28 days. By using of XRD were measured phase composition and microstructure development war observed by SEM. The elemental composition of cement leaches was measured by using of ICP-OES.
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The effect of boron and its compounds on setting time of portland cement
Kratochvíl, Jiří ; Švec, Jiří (referee) ; Opravil, Tomáš (advisor)
The aim of this work is to study the influence of boron and its compounds, boric acid and borax, on hydratation of portland cement. The first part describes chemical composition of portland cement and reactivity of its components. The second part deals with hydratation of portland cement. The teoretical part ends with description of retardation of portland cement using gypsum or other sulphate options. The experimental part describes preparation of samples – cement paste – modified by addition of boron, boric acid and borax in diferent concentrations. Results are obtained by evaluation of calorimetric curves, mechanical properties and phase composition. The goal is to describe kinetics of targeted slowed down process of hydratation and to find such addition which would suspend setting of boron modified system entirely. Comparison of effects of each boron-containing compound is based on its concentration and on its kind.
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