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Possibilities of roman cements preparation by modification of limestone sludges
Petr, Jiří ; Koplík, Jan (referee) ; Opravil, Tomáš (advisor)
It is obvious that binders based on the portland clinker will still play the most important role in the building materials industry. Their high quality, the existence of standards and the affordability are the main reasons. Together with this there is of course an appreciable need for decreasing of energy consumption, carbon dioxide emissions and utilization of secondary raw materials. The roman cement is the possible answer to all of these requests. This historically experienced hydraulic binder, relatively less demanding for the quality of the raw material, is fired by the temperature below the sintering point and even though it does not achieve as good mechanical properties as the portland cement does, in some applications it could be re-established. This would ultimately lead to considerable savings both in the energy and the carbon dioxide emissions.
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The influence of storage conditions on the quality of fly ashes
Kalousová, Hana ; Koplík, Jan (referee) ; Opravil, Tomáš (advisor)
This thesis deals with the issue of influence of storage conditions on the quality of conventional fly ashes which are produced by combustion of lignite. These ashes were stockpiled for long time. A borehole for sampling was made in the fly ash stock-pile. Total depth of the borehole was 20 m. Samples of fly ashes taken from every single meter were analyzed and next mechanical properties and the volume stability of materials containing these fly ashes were tested. The quality of fly ashes especially with respect to the possibility to use them as components of pastes, mortars and concretes as pozzolanic admixture or fine filler was evaluated.
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The influence of alkali activator on immobilization of metals in alkali activated blast furnace slag
Bystrianska, Emília ; Kalina, Lukáš (referee) ; Koplík, Jan (advisor)
In this work the influence of alkaline activator on immobilization of lead and copper in alkali-activated blast furnace slag was investigated. A total of five activators were used; sodium water glass, potassium water glass, sodium hydroxide, potassium hydroxide and sodium carbonate. The leaching test according to ČSN EN 12457-4 was used to evaluate the level of immobilization of heavy metals, the leached solutions were analyzed by ICP-OES. For a better understanding of immobilization, the selected samples were characterized by analytical methods (FTIR, XRD, SEM, XPS). It was found that the degree of immobilization Pb2+ and Cu2+ in AAS was very high, regardless of the type of alkaline activator used.
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Methods of using cement kiln by-pass dust in building materials technology
Sikorová, Věra ; Koplík, Jan (referee) ; Kalina, Lukáš (advisor)
This diploma thesis is focused on methods of using cement kiln by-pass dust in building materials technology. By-pass dust was treated to remove chlorides and could then be used as other constituent to various types of cements in the amount of 0–5 wt. % according to ČSN EN 197-1. The properties of dusts before and after chloride removal were examined and after incorporating modified by-pass dust into the cement, the properties of fresh and hardened cement pastes and mortars were studied. It was found that modified by-pass dust after incorporation into cement fulfill requirements of ČSN EN 197-1.
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Calcium aluminates - hydration under various initial conditions
Tomala, Libor ; Másilko, Jiří (referee) ; Koplík, Jan (advisor)
This thesis deals with the preparation of calcium aluminate phases, namely monocalcium aluminate (CA), monocalcium dialuminate (CA2) and dodecalcium heptaaluminate (C12A7) and their hydration at temperatures of 20, 30 and 60 ° C. Preparation was carried out by sintering aluminium oxide and calcium carbonate in the correct molar ratio at a temperature typical for each of the phase preparation (1450, 1600 respectively 1360 ° C) in superkanthal furnace. Firings were conducted repeatedly until reaching the sufficient purity, which was determined by X-ray diffraction analysis on the diffractometer Empyrean from the PANalytical company. The pure calcium aluminate phases were subsequently hydrated in the already mentioned temperatures and progress was monitored on TAM Air isothermal calorimeter made by TA Instruments. The resulting hydrated products were identified again by using XRD.
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Recycling of steel-works flue dusts from electric arc and inductive furnaces
Huczala, Vít ; Koplík, Jan (referee) ; Šoukal, František (advisor)
This bachelor thesis deals with an application of electric arc furnace dust from steel production as secondary raw material for production of zinc and industrially process able zinc products. In this thesis the dust was processed by methods based on various physical and chemical properties. The most experiments were performed during the treatment with leaching in sulphuric acid. For this leaching the optimal concentration of sulphuric acid and the optimal ratio acid:dust was determined. The final products were prepared by precipitation or by evaporation of filtrate obtained after leaching. There were also used hydrolysis of dust and oxidative precipitation of filtrate during the processing. These steps led to increase of the quality of the final products. The price balance was also performed for the prepared products.
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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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The optimization of melting as a decomposition process for material analysis.
Ptáček, Martin ; Koplík, Jan (referee) ; Šiler, Pavel (advisor)
Fusion is the process in which the sample particles are dissolved in the flux. This is used for the decomposition of substances which under normal conditions do not decompose in acid. For example, silicon, which is a substantial part of cement, is not degraded under standard conditions, so it is fused. Fusion may be in solution or in a pearl. Solution fusing is used for ICP-OES rather than XRF pearls. In addition to the pearl, XRF can also be measured in powder, but it is less accurate. This bachelor thesis deals with decomposition of standards and comparison of measured values with certified values. In the course of the work, samples of the standards were decomposed using several types of fluxes, measured at ICP-OES. The same standards were measured using XRF in the form of pearls. In addition to these two methods, elemental analysis of sulfur content was also performed. These methods were finally compared. From the measured data we can say that the best results are achieved with the ICP-OES method.
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Possibilities of hexavalent chromium reduction within portland cement hydration
Mončeková, Miroslava ; Koplík, Jan (referee) ; Šoukal, František (advisor)
The issue of Hexavalent chromium toxicity to Portland cement hydration is a very actual these days. It takes much effort to obtain a cement containing Cr(VI) less than 2 ppm. The primary objective of this diploma theses is to find appropriate reducing substances and specify their efficiency, as well as to make an attempt to optimize their dosage. As reducing substances there were plumbed sulphites and tin(II) salts. The influence of reducing substances applied to the hydration and cement properties were validated by strenght tests, the calorimetric measurement and the volume-variation measurement. And also the changes in hydration products microstructure of Portland clinker after the gypsum replacement by sulphite ions were plumbed. The study of microstructure is based on SEM and XRD methods.
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