|
|
Options of preparation of tobermorite
Dlabajová, Lucie ; Másilko, Jiří (referee) ; Opravil, Tomáš (advisor)
The bachelor thesis deals with options of preparation of tobermorite. Tobermorite is a mineral, which, thanks to its composition and properties, is an important phase in aerated concrete. On the field of science and research, an attention has been drawn on tobermorite as an ion ex-changer. Synthesis of a pure mineral can cause problems with testing and improving its properties. Tobermorite crystallizes together with other calcium silicate hydrates from system CaO-SiO2-H2O during a hydrothermal reaction. This thesis mainly focuses on influence of choosing starting materials and their treatment before the hydrothermal synthesis. Other influences which are studied are conditions of hydrothermal processes and their influence on final products of hydrothermal synthesis. Phase composition of prepared samples was characterized by XRD and TG-DTA. As an additional analyze was used scanning electron microscopy (SEM).
|
|
|
The admixtures which are influencing setting time of portland cement
Hlaváček, Jaroslav ; Kalina, Lukáš (referee) ; Opravil, Tomáš (advisor)
During the production of concrete is important the careful selection of raw materials. Nowadays, we are trying in the production to minimize the economic burden and to maximize the use of secondary raw materials. This work is focused on the use of secondary raw materials from the energy industry in construction for the preparation of hydraulic binders. As the main raw materials were used different power plant fly ash from fluidized combustion. The composition of these secondary materials is quite different from conventional high-temperature ash, due to mixing with water they solidify and harden. Experiments were performed with three lodge fly ash from electrostatic precipitators of the fluidized combustion and one high-temperature fly ash. This work is focused on the possibility of monitoring the use of these secondary materials in construction, especially when tests were evaluated characteristics of strength and speed of setting and hardening.
|
|
|
Possibilities of clay plasters shrinkage elimination
Melichar, Jindřich ; Koplík, Jan (referee) ; Opravil, Tomáš (advisor)
Earth plasters which are applicated in interiers don´t have just an estetic, but mainly heat storage function. To accomplish better storage properties the plaster has to be laid on the wall in sufficient thick ply. But this use to be accompained by creating of cracks during dehydration of the plaster. This bachelor work will be considering possibilities of elliminating this negative event by additing suitable components to suppress shrinkage and cracks by creating ettringite.
|
|
|
Composite materials based on alcali activated blast furnace slag with admixture of fly ash
Indra, Ivo ; Brandštetr, Jiří (referee) ; Opravil, Tomáš (advisor)
This thesis concerns on substitution of blast furnace slag or its part with fly ash in alkali-activated systems based on aluminosilikates. Classic, fluid bottom and fluid filter fly ashes will be tested. The goal is to prepare geopolymer with required mechanical properties, but with maximal admixture of alternative raw materials. In composites with substitutioned slag or its part the thesis focuses mainly on workabilityof fresh mixture, pressure and bending strenght. Use of secondary raw materials has advantages in the economic point of view and it´s friendly to enviroment, too.
|
|
|
Possibilities of alcali activation of steel slag
Frýbortová, Iva ; Rovnaník, Pavel (referee) ; Opravil, Tomáš (advisor)
The properties of alkali activated steel slag as a clinker-free binder system was studied in this thesis. The aim was to find the optimal composition of alkaline activator providing good properties of the prepared binder. Sodium and potassium hydroxides and alkaline silicates in the form of solutions and powders were used as the activators. Mixture of steel slag, fluidized bed coal combustion ash and water without any activating ingredient was another binder system studied in this work. Mechanical properties, such as compressive and flexural strength, of the mixtures were determined. Calorimetric measurements were used for the study of hydration process, scanning electron microscopy for the examination of microstructure.
|
|
|
Evaluation of properties of coal combustion solid residues
Cesnek, Ľuboš ; Bílek, Vlastimil (referee) ; Opravil, Tomáš (advisor)
The bachelor’s thesis focuses on condition monitoring of a stored high-temperature fly ash and its properties over time. The high-temperature fly ash comes from a dumping where it has been aggregated over several years. Samples of fly ash used for our analysis were taken from a bore-hole with a depth of 38 meters. Subsequently, detailed analyses of the fly ash from individual depth levels were performed. Furthermore, mechanical properties, volume stability and changes in weight of the prepared test beams were tested. The aim of the experiment was to evaluate suitability of using fly ash from a dumping site as a pozzolanic admixture in cement pastes.
|
|
|
Possibilities of utilization of boiler slag
Fialová, Gabriela ; Másilko, Jiří (referee) ; Opravil, Tomáš (advisor)
This bachelor thesis studies the boiler slag (slag) and its potential use in refractory materials industry. It concentrates its on chemical and mineral composition. Mullite parts and Fe2O3 probably lowers the melting point and heat resistance. During the work is proposed and experimentally validated a method for reducing the content of iron in the slag shares.Is observed the effect of the reduced number of iron units for the heat resistance of the material. The results are further processed and assessment. Thermal resistance was monitored using incandescent microscopy.
|
|
|
Study of particles of various cosmetic pigments
Cerevatova, Kristina ; Opravil, Tomáš (referee) ; Zemanová, Jana (advisor)
The main focus areas of this master thesis include the writing of a literature review, which contains an overview and segregation of pigments which are used in the preparation of cosmetic products. The thesis is focused on the properties and characterization of pigments for use in cosmetology. The following focus is on legislation, more specifically on pigments that the cosmetic industry allows, limits and does not allow. The main part of this thesis is an overview of methods for the characterization of pigments. The practical part deals with the characterization of particles of selected cosmetic pigments by applying methods for determination of color, elemental and phase composition, particle size and morphology. The thesis is concluded by evaluation of the achieved results.
|
|
|
Solubility of power plant fly ashes in high-alkali environment
Kejík, Pavel ; Opravil, Tomáš (referee) ; Šoukal, František (advisor)
This work deals with study of alkali activated ashes from high-temperature and fluidized bed coal combustion in thirteen powerplants in Czech republic. A solution of 50% sodium hydroxide was used as an alkali activator in this case. Because the two main elements of these secondary raw materials are silica and aluminum, the main part of the work is study of their evolution to solution and dissolve time dependence. The second part is comparing of the phase composition of powerplant ashes before alkali activation and after that.
|
|
|
Induced siphonage of air into the flowing fluid.
Matlák, Jiří ; Opravil, Tomáš (referee) ; Svěrák, Tomáš (advisor)
The aim of this diploma thesis is to deepen the knowledge in the field of drain liquid from vessel with free surface due to the effluent jet with defined profile. Formation of complete suction vortex is taken place gradually depending on the starting conditions. In the diploma thesis basic relations in liquids considering whirl are described and the types of vortex are divided on the bases of circulation intensity. In the experimental part of diploma thesis the possibilities of liquid level prediction are searched for, where the whirl is formed depending on the size of effluent jet.
|
guest ::
