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Blended alkali-activated aluminosilicate binders
Mizerová, Cecílie ; Bayer, Patrik (referee) ; Rovnaník, Pavel (advisor)
The first part of the work presents a summary of the current knowledge of two-component blended alkali-activated binders based on blast furnace slag, fly ash, metakaolin and ground brick with emphasis on their workability, microstructure, mechanical properties and durability. In the experimental part the alkali-activated binders with different ratio of fly ash and metakaolin were made to compare their workability and mechanical properties. The binder structure was evaluated by means of scanning electron microscopy (SEM) and mercury intrusion porosimetry. From the literature review and my own achievements it can be concluded that the combination of single precursors has a positive effect on the majority of the assessed properties of the material.
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Effect of curing conditions on shrinkage of alkali activated systems
Pragerová, Barbora ; Kotrla, Jan (referee) ; Kalina, Lukáš (advisor)
This bachelor thesis deals with the determination of optimal curing conditions of alkali-activated systems in order to reduce shrinkage. Hardened alkali-activated blast-furnace slag pastes activated by sodium silicate were tested in the empirical part. Six varieties of curing conditions were compared. Immediately after demolding process, three sets of samples were stored in air, water and plastic film. Another three sets were first placed in water for 14 days, then removed and two of them impregnate with lithium silicate and acrylate-based coatings. The formation and the number of cracks were monitored by an optical method. The percentage of cracks was evaluated by the ImageJ program. The highest number of cracks was formed after 7 days of curing, given the samples placed in the open air. Some them were filled later. Samples placed in the open air after being submerged in water for 14 days showed a rapid increase of cracks as well, but the percentage of cracks was reduced to 50 %. Treating agents reduced the development of cracks but have not stopped their formation. After 36 days of curing, the results of these types of curing conditions were comparable. Only the samples wrapped in plastic foil showed a minimum number of cracks and no cracks were observed if the samples were submerged in water. The lowest levels of shrinkage were reached with the samples placed in water, and with the ones wrapped in plastic foil. Samples stored in water for the first 14 days showed the identical tendency of high-level shrinkage, as did the ones placed in the open air.
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Rehydration of alkali-activated slag after high temperature loading
Fialová, Barbora ; Bayer, Patrik (referee) ; Rovnaník, Pavel (advisor)
Ground granulated blast furnace slag is a by-product of the steel industry and is often used in combination with ordinary Portland cement as a binder in concrete. When concrete is exposed to high temperatures, physical and chemical transformations lead to significant loss of mechanical properties. This study aims to investigate the effect of high temperatures and rehydration on the mechanical properties, microstructure and phase composition of alkali activated slag. The results of the research could make an important contribution to decisions made concerning the reconstruction of structures affected by fire. In suitable cases it would be possible to regenerate parts of a structure instead of totally rebuilding it.
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Preparation of light composites on the basis of alkali activated fly ashes from high temperature combustion of coal
Weiglová, Jana ; Ptáček, Petr (referee) ; Havlica, Jaromír (advisor)
This thesis studies possibilities of preparation light composite materials based on solid residues from high-temperature burning. The main focus is put on potential alkaline activation by water glass and 50% sodium hydroxide solution. Further on, the thesis analyzes suitable additions which when added into alkaline environment with alkali release gas and thus enable to create light porous composites. The aim of this work is to suggest one or several recipes for preparation of light composites made from solid residues from high-temperature burning through alkaline activation. To method of XRD diffraction analysis has been used to identify the products of hydration and alkaline-siliceous reaction (phases) of alkaline activation.
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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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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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Alkali Activated Fly Ash Composites with Wooden Filler
Brýdl, David ; Bayer,, Patrik (referee) ; Rovnaník, Pavel (advisor)
This thesis examines the possibility of creating composite mainly from waste materials. The matrix of this composite was prepared from fly ash type F, which was activated by sodium water glass. Wood chips were used as a filler. This thesis includes theoretical and experimental parts. The theoretical part deals with the most important issues of wood composites with an inorganic matrix as well as basic components of investigated composite, ie alkaline activated fly ash and wood. In the experimental part, the fly ash pastes were prepared, from which the most suitable mixture was chosen for the composite preparation. Properties of wood composite with alkali activated fly ash matrix were investigated depending on the dose of wood chips.
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Utilization of lignosulfonate plasticizer in alkali-activated materials
Zetocha, Martin ; Hrubý, Petr (referee) ; Kalina, Lukáš (advisor)
Tato bakalářská práce se zabývá využitím plastifikátorů na bázi lignosulfonátu v alkalicky aktivovaných materiálech. Sledován byl vliv na směs pasty aktivované vysokopecní strusky za použití hydroxidu sodného, vodního skla o různých modulech a uhličitanu sodného. Pozorován byl vliv plastifikátoru na bázi lignosulfonátu při zamíchávání do různých směsí, na zpracovatelnost, mechanické vlastnosti a reologii směsi. Důležitým faktorem byly použité aktivátory ve směsích. Nejlépe reagující směs na lignosulfonát se ukázala být za použití NaOH jako aktivátoru. Při pokusech pochopit reologické vlastnosti sledovaných směsí, jako klíčového faktoru chování těchto směsí bylo měření zeta potenciálu. Hodnoty zeta potenciálu nám daly bližší náhled na povrchový náboj častic vysokopecní strusky. Ten se prokázal jako klíčový faktor při posuzovaní účinnosti plastifikátoru. Tato zjištění budou vzata v úvahu a dále diskutovány v této práci.
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Synthesis of Aluminosilicate Systems Based on Alkali Activation of Industrial By-Products
Kalina, Lukáš ; Rovnaníková, Pavla (referee) ; Škvára, František (referee) ; Havlica, Jaromír (advisor)
Portland cement-based products are the most commonly used building materials. However, it is well known that the production of OPC not only consumes a significant amount of natural resources and energy but also releases high quantity of carbon dioxide (CO2) to the atmosphere. Purpose of this work is to develop new cementitious material similar to Portland cement-based concrete, which is convenient in terms of energy and is environmental-friendly at once. This work presents preparation, composition and properties of inorganic aluminosilicate polymer, called geopolymer, synthesized from blast furnace slag and fly ash, activated by sodium hydroxide and cement kiln dust. Study of the microstructure was based on SEM-EDX-WDX, TG-DTA-EGA and XRD analysis.
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Effect of admixtures on the properties of metakaolin geopolymer
Halasová, Kristýna ; Vyšvařil, Martin (referee) ; Rovnaník, Pavel (advisor)
Geopolymers are amorphous to semi-crystalline aluminosilicate polymers which are formed from inorganic polycondensation reaction of a solid aluminosilicate precursor with an alkaline sodium hydroxide or silicate. The resulting materials exhibit high durability, resistance to aggressive environments, high temperature resistance and many other properties that make them have received much attention in recent years, not only in construction. This thesis describes the influence of additives commonly used in concrete and mortar (water reducing, superplasticizer, air-entraining, foamer and defoamer, anti-shrinkage, stabilization) on the behavior of metakaolin in geopolymer fresh and hardened state. It describes metakaolin geopolymer effect on rheological properties of fresh mixtures, compressive strength and flexural strength after 28 days and a density in the fresh and hardened state.
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