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Study on the possibilities of separation of chlorides from by-pass dust
Havelka, Jaroslav ; Šoukal, František (referee) ; Opravil, Tomáš (advisor)
The thesis deals with the study and the characterization of bypass dusts from the cement plants. The aim of the thesis is to search for the possibilities of the usage of that secondary product by means of the cement production. The thesis focuses mainly on the determination of the amount of soluble substances in the dusts, the dependence of dissolution of the soluble share on water – dust ratio, the dependence of dissolution time on the yield of the soluble share and the influence of the temperature on the yield. The physical and chemical properties of the investigated samples taken from several cement plants in the Czech Republic and Slovakia were found out by using the following methods: by TG/DTA analysis, particles size by laser diffraction, phase composition of raw materials, treated raw materials and evaporation residues by X-ray diffraction. It was further investigated whether there was a link between finesse of the particles and the content of soluble substances (chlorides). This was accomplished by classification of the bypass dusts as fine and coarse fraction on the air cassifier with the target parameter X50 1 m. The aim of the classification was to find out whether some of the fractions carry majority share of some of components.
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Supersulphates cements
Mohelská, Lucie ; Wirthová, Michaela (referee) ; Opravil, Tomáš (advisor)
The work is studying posibilities of use secondary materials produced by energetical industry. In fact it studies posibilities of preparing supersulphates cements with secondary raw materials. Its main system for simulation was used milled portland clinker. To clinker were added diferent secondary raw materials from energetical industry with sulphate. On prepared samples were watched mechanical properties in time. Tested were different samples of secondary raw materials.
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The possibilities of using of foundry filter ash
Solik, Jaroslav ; Šoukal, František (referee) ; Opravil, Tomáš (advisor)
This thesis explores the posibility of using of foundry filter ash for production of inorganic composite materials, that could be used primary in the construction industry. The thesis is divided into theoretical and experimental section, where theoretical section contain literature review of used materials and the experimental section summarizes the results of laboratory tests performed on tested mixture based on portland and alumina cement with various content of foundry filter ash. For comparison was also used another foundry waste - foundry sand. Prepared test bodies with dimension of 40 x 40x 160 mm was subjected to mechanical strength tests and the influence of amount of foundry waste on the strenght of the prepared mixtures was monitored. Next the thesis deals with possibilities of alkaline activation of foundry waste, where sodium water glass, sodium hydroxide and commercially supplied baucis L 160 component B were used as alkaline activator. These test mixtures were also subjected to mechanical strenght tests and the influence of amount of foundry waste on the strenght was observed too. The analysis of input materials were performed by XRF, TG – DTA – EGA and XRD powder diffraction methods. All strength tests were tested by testing equipment desttest 4310.
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Sol-gel synthesis of a LAS glass ceramics and influence of additives on a phase transformation and crystallization.
Kramerová, Nina ; Opravil, Tomáš (referee) ; Ptáček, Petr (advisor)
This work is focused on Li ceramics and glass-ceramics with low thermal expansion. Composition of these material is based on mineralogical composition of ?-spodumene – Li2O•Al2O3•4SiO2. Sol-gel route of preparation was used for preparation of the material. Sol-gel route is profitable because of production of high purity and controlled grain size powder. Lower sintering temperature, higher degree of homogeneity and shorter time of heat treatment in comparison with traditional approach belong among other advantages of sol-gel route of preparation. Influence of Li+ substitution for K+, which has similar atomic radius, is assessed in this work. These ions are localized in the interstitial position of spodumene structure and are able to maintain the charge balance. Li+ ions were substituted with K+ in the amount of 0; 0,5; 1; 2; 5 and 10 wt. % in view of Li+ weight. In the next step influence of adding mineralizer was specified in the material modified this way. The effect of adding mineralizer on phase transformation and heat treatment tendency was considered. K+ were added to the mixture in the form of potash. Due to this addition forming of orthoclase phase next to spodumene, eucryptit and SiO2 (ss) was detected. Decrease in melting temperature and ability of melt to crystallize were consequence of orthoclase forming. No crystallization appears, when more than 1 wt.% of K+ was added.
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Thin-film geopolymeric plasters for exterior application
Ručková, Jana ; Opravil, Tomáš (referee) ; Šoukal, František (advisor)
This thesis is dealing with preparation of exterior thin-layer geopolymer plaster where the effect of supplement of various types of superplasticizers in their different amounts on the quality of geopolymer plaster is studied. The objective of this work is to determine suitable type of superplasticizer which would improve rheological quality of fresh plaster mix, its adhesion to the surface and last but not least would preserve good mechanical qualities of geopolymer binder. In the experimental part initially test subject were prepared from meta-kaolin, water, water-glass, sand and with supplement of various types of superplasticizers in various amounts. These test subjects were tested for compressive and flexural strength. Further workability and adhesion to the surface of these plaster pastes was observed. Geopolymer pastes were also subjected to calorimetric comparison of kinetic processes occurring during solidification and hardening. In order to identify the exact composition of superplasticizers used as rheological modifiers, the infra-red spectrometry of these substances was performed. There was a need to specify the water-glass in more detail as well, elemental analysis was performed on it on radiographic fluorescent spectrometry. To closer identify the structure and distribution of superplasticizer in geopolymer paste the pictures of the mix which was the most suitable for use for exterior thin-layer geopolymer plasters were made on scanning electron microscope. On the same mix radiographic diffraction on the powder samples was also performed which served for phase analysis.
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Possibilities of using laser spectroscopy for the analyses of inorganic binders and concrete
Kratochvilová, Lucie ; Hrdlička,, Aleš (referee) ; Opravil, Tomáš (advisor)
This master’s thesis is dealing with the possibility of using laser-induced breakdown spectroscopy for the detection of non-metallic elements (e. g. chlorine) in concrete. These elements cause degradation of concrete which leads to a shortening lifetime of reinforced concrete buildings. In the experimental part of thesis, a methodology for the determination of chlorides in concrete will be created and verified. A comparison of the single pulse and the double pulse configuration of the LIBS will be done on the samples containing only pure chemical substances with known concentrations of chlorine.
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Possibilities of utilization of solid residues from fluidized bed combustion for preparation of composite Portland cements
Beranová, Denisa ; Šiler, Pavel (referee) ; Opravil, Tomáš (advisor)
The bachelor thesis deals with possibilities of utilization of solid residues from fluidized bed combustion of coal, bed and filter ash, to be used in the production of composite Portland cements. 6 ash types were investigated, of which 3 were bed ash (finely ground) and 3 were filter ash colected from Ledvice, Tisová and Poříčí K8 power plants. The chemical composition of the ash collected was determined and the progress of a hydration reaction monitored, and then samples mixed with Portland clinker were prepared. Their respective compressive strength and flexural strength were then analysed and observations made on the hydration and composition of products of the hydration reaction. Finally the results of selected mixtures were verified with prepared standardized mortars.
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Vanadium corrosion of refractory materials
Florian, Ondřej ; Opravil, Tomáš (referee) ; Ptáček, Petr (advisor)
The bachelor thesis is focused on the influence of vanadium corrosion process on the corrosion and properties of high-alumina refractory products used in gasified on production of synthesis gas from a carbon feedstock, water on oxygen. The composition, properties of refractory product and mutual interaction of corrosion processes was investigated by method of thermal analysis, X-ray diffraction analysis and scanning electron microscopy.
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Possibilities of using waste foundry sand
Kopecký, Filip ; Koplík, Jan (referee) ; Opravil, Tomáš (advisor)
Considering increasing manufacture of metallic materials made in foundries increases also production of waste foundry sands. Foundry sands that remain after moulding and can not be reused in the prouction process anymore are usually not recycled nowadays and in the better cases they are clasified as a fill materials. These secondary raw materials are produced in relatively big amounts. Thats why is apropriate to search for their effective reuse. One of the possibilities is using of this materials in buliding industry. Thanks to their constitution and properties we can consider the possibilties of an alkaline activation, additional source to alkalit activated systems or like part of refractories.
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Polymer-cement composites of increased refractoriness
Ryšková, Martina ; Opravil, Tomáš (referee) ; Šoukal, František (advisor)
The subject of the diploma thesis is the preparation of macro-defect-free (MDF) composites based on calcium-aluminate cement and organic polymer polyvinylalcohol. Attention focused on the optimization of the dose, the degree of hydrolysis and molecular weight of the polymer with respect to the heat resistance of the material. Thermal degradation of polyvinyl alcohol leads to changes in the structure of MDF composite. The study was mainly focused on the characteristics of polyvinyl alcohol dosage associated with the resultant mechanical properties of the material. During the work were monitored for changes in the mechanical properties of samples were cured at 60 °C and subsequently fired at 180 °C, 600 °C, 1000 °C and 1400 °C. It was tested in flexural strength, heat microscopy, TGA-DTA-EGA and SEM analysis.
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