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Phosphate binders
Kalina, Lukáš ; Ptáček, Petr (referee) ; Šoukal, František (advisor)
The work deals with the preparation and study of polyphosphate composites. Aluminum phosphates provide some unusual properties like high-heat resistance in terms of inorganic binders. The addition of chromium in the form of Cr2O3 or directly the bond with the aluminum-chromium-phosphate can improve the properties of this binder. Highly viscous Al2Cr(H2PO4)9 and Al3Cr(H2PO4)12 binders were prepared by dissolving Al(OH)3 and CrO3 in 85% phosphoric acid, and mixed with Al2O3 and Cr2O3 fillers. The composites were cured in the furnace at 150 °C for 24 h under pressure of 10 MPa. During the annealing at temperatures up to 1 500 °C changes in chemical structure of the cured composites were observed, leading to the understanding of the creation of crystalline phases and their eventual changes. The characterization of binders was mainly based on FT-IR, EDAX, TG-DTA and optical microscopy analyses.
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Mosaic geopolymeric thin-film plasters for decorative applications
Svidroňová, Barbora ; Šiler, Pavel (referee) ; Šoukal, František (advisor)
This bachelor thesis deals with preparation of mosaic geopolymeric plasters, used fillers and it observes their influence on the final properties of geopolymeric plaster. The aim of the study is the selection of proper raw materials for filler, the determination of optimal filler-to-sand ratio and the preparation of plaster with proper shade of colour. In experimental part, during the detection of adequate ratio of raw materials, there were prepared beams from several types of metakaoline, sand, water and water glass. The beams were tested for compressive strength and bending. The blasters themselves were watched for their applying, hardness, shades of colour and efflorescence.
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Preparation and characterization of concretes based on blended geopolymeric binder
Bulejko, Pavel ; Straka, Radek (referee) ; Šoukal, František (advisor)
This bachelor thesis focuses on preparation of concretes based on alkali activated binding systems (geopolymers). Finely ground blast-furnace slag was used as a basic aluminosilicate compound for preparation of an alkali activated binder. A mixture of sodium water glass and 50 % KOH solution, which was replaced by cement kiln dust in some cases, was used as an activator. The prepared testing samples (columns 40x40x160 mm) were mechanically tested for strength and the influence of the substitution of KOH solution by cement kiln dust on strength was observed. Then the work aims at structure analysis of binders prepared – the thermal analysis was carried out and the phase composition was explored with RTG diffraction.
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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.
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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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Magnetic classification of fly ashes and application of products
Červený, Ľuboš ; Švec, Jiří (referee) ; Šoukal, František (advisor)
Submitted bachelor thesis is dealing with problematics of magnetic separation of fly ash and utilization of the products of the separation in production of refractory ceramic materials. High temperature fly ash from power station Mělník was used in this thesis.Thesis evaluates results of magnetic separation at different setting of magnetic separator. It proves, that fraction of particles rich in iron as well as fraction depleted by this iron can be obtained by magnetic separation. In this thesis are presented results of volumetric weight, mineralogic element composition, measurments by heating microscope and results of particle size distribution of unseparated fly ash, but also its both separates. The thesis is focusing on possibilities of utilization as additive in refractory ceramic materials and comparison of their refractory properties. It evaluates results of characterisation of the products using XRD analysis and scanning electron microscopy.
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Optimization of concrete mixture based on alkali activation of secondary materials
Šafář, Martin ; Šoukal, František (referee) ; Kalina, Lukáš (advisor)
This bachelor thesis deals with design, preparation and optimization of concrete mixture based on alkali activated secondary materials – blast furnace slag and fly ash. Sodium hydroxide partially replaced by bypass cement kiln dust was used as an activator. Mixture design was based on model made for Portland cement based concrete. Observed properties were workability of fresh mortar, price of mixtures and mechanical properties of concrete. Microstructure and composition of concrete was studied by SEM-EDX and XRD. Analysis of raw materials was based on XRF. The optimal mixture composition was chosen from obtained data.
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Mapping the potential of secondary products from the production of titanium white
Nehéz, Samuel Emil ; Šoukal, František (referee) ; Opravil, Tomáš (advisor)
This bachelor’s thesis deals with the use of secondary products from the production of titanium white and its subsequent use during cement production. Secondary products from the production of TiO2 could be regarded as several kinds of sulphate waters, where by their successive neutralization gypsum by-products are prepared. The aim of the bachelor’s thesis was to experiment whether it is possible to use some of these gypsum by-products as solidification retarder in Portland cement. Cement pastes were prepared and subjected to mechanical and analytical examinations. During the mechanical examinations, strength in pressure during bending and strength in pulling for the duration of 60 days were monitored. The material from tested bodies of pastes was reviewed by x-ray difraction analysis after 7 and 28 days. Just as was determined the optimum W/C, initial and final setting time. The prepared samples with the gypsum by-product as their content had some features comparable with commercially used cement.
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