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Study possibilities of nanotechnology in cement composites
Kardošová, Romana ; Bodnárová, Lenka (referee) ; Hela, Rudolf (advisor)
The aim of this paper is to summarize and assess the possibility of using nanoparticles as additives in concrete. These particles have the ability to improve the mechanical and physical properties of cement composites or even gave them brand new ones. Industrial use is hampered by effective incorporation of nanoparticles into the matrix, the health and environmental risks and, last but not least, the financial costs. The experimental part of the thesis deals with the dispersing nanosilica and nanometakaolin particles in aqueous solution and their subsequent integration into the structure of cement mortar.
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Studying the properties of high strength concrete using micro and nano admixtures
Gabko, Miroslav ; Bodnárová, Lenka (referee) ; Hela, Rudolf (advisor)
The objective of this bachelor thesis is to examine the properties of high strength concretes with the main focus on application of mikro or nano admixtures. In theoretical part their production, the properties and the influence on fresh and hardened properties of cement composites are described. In addition, it explores the influence of plasticizer type, some properties of aggregate and cement types. The practical part focuses on testing cement mortars in which fine cements were added. The compressive and flexural strengths were examined after 7 and 28 days of curing, moreover, rheological properties and heat hydration of cements were also observed. Furthermore, the influence of high speed mixing on cement mortars properties was studied.
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Interlaminar fracture toughness of fiber reinforced plastics
Vodička, Vít ; Mališ, Michal (referee) ; Klement, Josef (advisor)
Cílem této diplomové práce je lépe porozumět konceptu únavového poškození damage tolerance zmapováním všech možných vlivů na lomovou houževnatost vláknového kompozitu s polymerní matricí. Toho je dosaženo provedením zkoušek za různých podmínek (např. změna parametrů měření, mód zatížení, pořadí vrstev a materiál) a monitorováním odlišností v šíření trhliny. Na základě dat získaných během těchto testů je určena lomová houževnatost. Potenciální rozdíly jsou zkonzultovány a porovnány s ostatními vzorky.
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Spray-coated working electrodes of electrochemical sensors
Lechner, Filip ; Majzlíková, Petra (referee) ; Prášek, Jan (advisor)
This thesis is about the selection of the better type of thick film working electrode for the detection of substances in aqueous solutions, modified by spray coated carbon nanotubes. The theoretical part of this thesis describes the technology of thick film, properties and production of carbon nanotubes, introduction to electrochemistry and electroanalytical methods for the detection of substances in aqueous solutions. The practical part is aimed to realization of the working electrodes by thick film technology and their modification by spray-coated layer consist of carbon nanotubes. Electrodes are characterized using voltammetric methods, electrochemical impedance spectroscopy and electron microscopy. In conclusions is selected the most suitable type of working electrodes for reproducible electrochemical analysis.
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Design of the fluorescence microscope for carbon nanotubes spectroscopy
Borovský, Ján ; Novotný,, Karel (referee) ; Novotný, Jan (advisor)
This diploma thesis deals with design, implementation and testing of fluorescence microscope intended for carbon nanotubes spectroscopy. Theory of fluorescence resulting from solid state physics and atomic structure of nanotubes is briefly discussed. The basic idea, optical scheme and optical elements used in the fluorescence microscope are described based on requirements resulting from the theory. The thesis mentions the sample preparation procedure and measurements of its optical activity as well. Realized microscope is usable for fluorescence measurements within the supposed range of wavelengths as was proved by testing.
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High-grade concrete using nanoparticles
Labaj, Martin ; Bodnárová, Lenka (referee) ; Hela, Rudolf (advisor)
The aim of this paper is to summarize and assess the possibility of using nanoparticles as additives in high performance concrete. These particles have the ability to improve the mechanical and physical properties of cement composites or even gave them brand new ones. Industrial use, however, is hampered by several obstacles. In particular, it is the task of effective incorporation of nanoparticles into the matrix, the health and environmental risks and, last but not least, the financial costs. The experimental part of the work deals with the first-mentioned problem, namely with dispersing carbon nanotubes in aqueous solution and their subsequent integration into the structure of cement mortar.
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Use of nanotechnologies, especially CNT, in silicate composites
Jarolím, Tomáš ; Bodnárová, Lenka (referee) ; Martinec,, Petr (referee) ; Kalina,, Michal (referee) ; Hela, Rudolf (advisor)
Thesis theme were nanomaterials and its implementation to cementitious materials. Theoretical part has deal with description of carbon nanotubes types, their properties, production, ways of dispergation, nanotoxicity and CNT’s influence on silicate composites characteristics. Experimental part was divided to 5 stages. The first stages were focused on choosing appropriate carbon nanotubes and surfactants. In the next stage settings of US homogenizator were determinate (amplitude, US energy dosage, time). The part of US homogenizator setting process was observing influence of liquid environment characteristics (especially pH) on surface tension and particle distribution and influence of US energy on CNT walls damages through TEM. After dispergation parameters optimalization cement pastes were prepared and hydration temperature, hydration heat and viscosity were observed. Then testing specimens from cement mortar were prepared and tested form strength characteristics. Last stage was concrete production and their examination: compressive strength, flexural strength, static modulus of elasticity, dynamic modulus of elasticity, tensile splitting strength, depth of penetration of water under pressure, resistance of cement concrete surface to water and defrosting chemicals and determination of frost resistance of concrete. Samples with CNT addition had better strength characteristics and better resistance of penetration of water under pressure, water and defrosting chemicals resistance and frost resistance. Result of thesis is comprehensive study of CNT dispersion production and implementation CNT dispersion to concrete including testing specific concrete characteristics.
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Nanoparticle treatment technology to improve their dispersibility for use in cemt composites
Závacký, Jakub ; Sťahel,, Pavel (referee) ; Hela, Rudolf (advisor)
The diploma thesis deals with the possibility of using the addition of nanoparticles to improve the properties of cement composites. The theoretical part summarizes the findings of research in this area with a focus on methods of dispersion of nanoparticles and their treatment for use in cement composites. The experimental part focuses on the comparison of methods of dispersion and plasma treatment of reduced graphene oxide (rGO) nanoparticle solutions from the point of view of the agglomeration process. During this work, a method of systematic optical/visual monitoring of sedimentation/agglomeration was developed to complement sophisticated methods such as spectrophotometry (UV/Vis) and electron microscopy (SEM). Furthermore, the effect of the addition of rGO on the properties of cement mortar, in the form of aqueous solutions prepared by the dispersion methods determined in the previous section, was investigated.
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