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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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The optimization of the wood polymer composite composition regarding its utilization in building structures
Benešová, Anna ; Pospíšil,, Ladislav (referee) ; Ďurica,, Tibor (referee) ; Bodnárová, Lenka (referee) ; Vaněrek, Jan (advisor)
Wood-polymer composite is a relatively new type of material that combines shattered wood mass and a thermoplastic polymer. This material is utilized especially as an alternative to hard wood in the area of non-bearing exterior elements, as it reaches better properties in terms of the basic durability and low maintenance. Raw material composition and processing of the composite enable to provide a significant modification with further matters leading to an improvement of the end-product properties. Research and development in this field focuses predominantly on the utilization of such modifying additives that either enhance the resistance to weathering or are of the recycled nature, as a significant part of the raw material mixture comprises the constituent obtained from non-renewable resources. The aim of the thesis is the evaluation of the influence of the wood-polymer composite modification separately at two levels. First of them is the modification to matrix by using a recycled polymer, the second one comprises the modification of the wood flour with a secondary spherical filler. Both types of modified composites have been assessed in terms pf the prime characteristics and the resistance to adverse ambient.
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Usability of basal fibres in cement composites
Kolková, Kristína ; Hela, Rudolf (referee) ; Bodnárová, Lenka (advisor)
The bachelor thesis deals with issues of using basalt fibers in cement composites and it consists of a theoretical research and an experimental part. In the theoretical research is a description of properties of basalt fibers, production technology and behavior of fresh and hard concrete with addition of basalt fibers. There is mentioned an example of application in practice of basalt fibers for a reconstruction of a bridge construction. The theoretical research also deals with more possibilities of use of products made from melted basalt. In the experimental part was verified behavior of fresh and hard concrete with the addition 3, 10 and 20 kg.m-3 of short basalt fibers. These mixtures were compared with the reference mixture from plain concrete. There was determined the consistency in fresh condition by the slump test, the density and the air content. The flexure strength, compressive strength and tensile strength were determined on hard concrete samples in age of 28 days. The presence of basalt fibers was detected by an electron scanning microscope.
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Usability of hig speed water jet in civil engineering
Boucníková, Veronika ; Sitek,, Libor (referee) ; Bodnárová, Lenka (advisor)
The bachelor thesis deals with possibilities of using high-speed water jet in construction industry. In the theoretical part, water jet technology was generally described and a research for use in the construction industry with an emphasis on the application of concrete structures redevelopment and the process of interaction of water jet with concrete was done. Furthermore, the safety risks during work with high-speed water jet and the possibilities of recycling of waste generated by the use of this technology were evaluated. In the experimental part were prepared concrete samples with dispersed concrete reinforcement. The characteristics of the concrete samples were determined and the depth and appearance of the cross-section after interaction with the high-speed water jet was evaluated.
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The use of nanotechnology for ultra-high strength concretes
Šindelek, David ; Bodnárová, Lenka (referee) ; Hela, Rudolf (advisor)
This diploma thesis deals with the concept of use of nanotechnology for cement composites and UHPC. In the theoretical part of this diploma thesis there are theoretical principles described for successful design of high performance concrete and characteristics of main feedstock and its production. Furthermore, there is a focus on nanoparticles, especially the ones with carbon base in the form of carbon nanotubes CNT, in addition to that, graphenes GN that are new on the market, moreover, graphene oxide GO and its application in cement composites to mechanical characteristics and its durability. The first part of the practical part devotes in trying to find out an optimal parameter for ultrasonic mix with a suitable surface active substance of three graphenes. The other two parts of the practical part are about influence of graphenes on mechanical characteristics, cement paste microstructure, and application in the mix of concrete C 35/45 and UHPC
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Verification of the properties of concrete with carbon nanotubes
Kutová, Lenka ; Hela, Rudolf (referee) ; Bodnárová, Lenka (advisor)
This diploma thesis deals with monitoring the properties of concrete with carbon nanoparticles. The theoretical part describes properties of nanoparticles, their dosing and dispersion. In the practical part of the diploma thesis the physico-mechanical properties of the concrete with the addition of carbon nanotubes were determined after 7 and 28 days of aging. The frost resistance test was then determined after 100 cycles. All results were compared with the reference samples.
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Possibilities of application of basalt fibers in concrete
Zourek, Milan ; Hela, Rudolf (referee) ; Bodnárová, Lenka (advisor)
This diploma thesis deals with possibilities of application of basalt fibers in concrete and in cementitious composites. In the theoretical part there is a summary of fibers usually used for fiberconcretes. Manufacturing process of basalt fibers is described, and properties of basalt fibers are summarized. Next part deals with properties of basalt fiber reinforced concrete. Concretely fresh properties, physical-mechanical properties, shrinkage and cracking, microstructure and fire resistance. The last chapter deals with fire resistance of concrete in general. The experimental part of this diploma thesis is divided into two phases. There were two mixes of basalt fiber reinforced concrete made with basalt aggregate and one mix of concrete without basalt fibers in the first phase. Density, consistency by slump and air content were determined as fresh properties. As hardened properties density, compressive strength and flexural strength were determined. There was determined the effect of the temperatures 600 and 800 °C on density, compressive strength and outward of specimens. Also, deformation during the high temperature curing was recorded. In the second phase of the experimental part there were three mixes of cementitious composite made with basalt fibers and one cementitious composite without basalt fibers. Density was determined as a fresh property. Material was monitored during its mixing. As a hardened properties density, flexural strength and compressive strength were determined. There was determined the effect of the temperatures 600 and 800 °C on density, flexural strength, compressive strength and outward of specimens.
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Study of the effect of the addition of the cellulose fibers on the selected properties of concrete
Blaha, Lukáš ; Hela, Rudolf (referee) ; Bodnárová, Lenka (advisor)
This dissertation desribes the behavior of cellulose fiber reinforced concrete. In the theoretical section one can find basic information on cellulose fiber and its methods of production and usage in concrete structures. One can find the information about the effect of high temperature on the mechanical and physical attributes of cellulose fiber reinforced concrete, and also a comparison with other fibers used in concrete based on the research done using scientific literature. Furthermore the details about particular cellulose fibers are provided. In the experimental section the formulas for CHRYSO and GREENCEL concrete are designed. The influence of the addition of various types of cellulose fibers into both liquid and solid states of concrete was researched. Tests were also done on the effect of high temperatures (600 °C and 800 °C) on the firmness and densitiy of concrete, its deformations and visual changes. Furthermore, the resistance of cellulose fibers was monitored by monitoring the development of the pH environment (from pH 4 to pH 12) with long-term deposition of different types of cellulose fibers in these environments.
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Studying the properties of fiber cement composites
Cederová, Kristýna ; Hoško, Marek (referee) ; Bodnárová, Lenka (advisor)
This diploma thesis deals with fiber-cement composites. Input materials are investigated for the production of fiber cement, are examined, the production and parameters of the pulp were monitored. Further, Hatschek's production technology and requirements for corrugated fiber-cement roofing are described. In the practical part the individual input materials and parameters of ground pulp were verified. The problem with production of samples and difference in the fineness of pulp milling in fiber cement products has been solved.
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Application of high speed water jet technology for concrete repair
Bodnárová, L. ; Sitek, Libor ; Foldyna, Josef ; Jarolím, T.
This article brings selected knowledge from the long-term cooperation between\nthe Brno University of Technology, the Faculty of Civil Engineering, the Institute of\nTechnology of Building Materials and Components, and the Academy of Sciences of\nthe Czech Republic, v.v.i., Institute of Geonics, Ostrava – Poruba in the field of\nthe interaction of high-speed water jets and concrete, especially with regard to\nthe use of high-speed water jet technology for the removal of surface layers of\nconcrete during repair of concrete.
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