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Study of the influence of fillers and external conditions on the resistivity of cement composites
Kejda, Dalibor ; Melichar, Jindřich (referee) ; Černý, Vít (advisor)
The progress of new materials is important for the construction industry. Modern materials include cement composites with reduced resistivity. This is achieved by adding suitable electrically conductive fillers. If there is enough of these fillers, the so-called percolation threshold occurs. Suitable fillers (Condufit C4 and Supragraphite C300) have been proposed. Recipes have been designed to be before and after the percolation threshold. The tests were performed on beams measuring 40x40x160 mm with built-in electrodes for measuring their resistivity. The aim of the work was the research of influencing external conditions on cement composites. The effect of temperature was verified. The lowest values of resistivity were evaluated at temperatures of 50 ° C and the resistivity increased with decreasing temperature. The effect of humidity on the resistivity was then verified. Reference samples and samples with a smaller proportion of graphite powder showed larger differences in resistivities with increasing humidity. The samples above the percolation threshold were not much affected by increasing humidity. Finally, the effect of loading on the resistivity of the samples was verified. Almost all samples with increasing compressive stress showed an increasing value of resistivity.
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Proposition of conductive silicate composite for heating
Surovcová, Jana ; Černý, Vít (referee) ; Drochytka, Rostislav (advisor)
The bachelor's thesis deals with the development of electrically conductive silicate composite with the self heating value designed for surfaces in the exterior, on which an ice layer can form during the winter. The developed silicate composite should replace the defrosting of surfaces with chemical defrosting substances, which could have an adverse impact on the environment and are usually applied with a delay when a sudden change of weather appears. The theoretical part of this thesis summarizes the theory of electric field and electric current conduction, approached the issue of silicate binders, various types of electrically conductive phases and presents the current state of knowledge in the field of research of self heated composites. The practical part contains an assessment of selected effects of the exposure environment, based on which the requirements for the developed composite are formulated. Furthermore, the practical part is devoted to the analysis of necessary materials for producing self heated composite, so the focus is on conductive fillers. Selected fillers with the low level of the impedance are then used in the proposed recipes and the production of test specimens for the comparison of real parameters and the required ones. The work succeeded in proving the ability of heating the silicate composite with a conductive filler by means of an electric current, while the required mechanical parameters were not achieved. The bachelor thesis serves as a suitable basis for further research linked to the issue of electrically conductive self heated silicate composites.
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Effective use of industrial waste in building materials
Szép, Melinda Klaudia Virág ; Mészárosová, Lenka (referee) ; Černý, Vít (advisor)
This bachelor´s thesis deals with one of current topics, namely to effective use of industrial waste in building materials. The theoretical part of this work presents changes in legislation of the Czech Republic in field of waste management system, explains the most important terms and defines each method of waste management. The main goal of this work was to formulate a methodological procedure for efficient use of industrial waste. The methodological procedure was compiled on the basis of elaborated base set of possible variants of waste utilization in the construction sector and a set of corresponding criteria of standards and legislative criteria. A table of elementary criteria has also been compiled for the better orientation in corresponding standards. The proposed methodological procedure was demonstrated on specific example, in fact on slag from municipal waste incineration. The slag was examined in two environments – one with standard laboratory condition and the second with controlled condition (8 % concentration of carbon dioxide and 80 % of relative humidity) – for better understanding of its behaviour. The expected acceleration of the aging process in the environment with controlled condition was confirmed based on the degree of carbonation. The expected reduction of volume changes of the sample exposed to the controlled condition was also confirmed.
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Development of industrial adhesive material for deposition of nonabsorbent components
Bergerová, Kamila ; Černý, Vít (referee) ; Drochytka, Rostislav (advisor)
The thesis deals with the development of industrial adhesive material for deposition of nonabsorbent components in environments exposed to aggressive chemicals and high temperatures. The theoretical part is mainly focused on summarizing knowledge about adhesive materials. The study also includes description of bonded components, describes theory of adhesion and introduces the used materials. The primary aim of this work is to present new design of material composition of a new adhesive of polymer and silicate base material. The work also investigates the possibility of using the industrial waste in the form of secondary raw material. The final part is dedicated to laboratory testing of new developed materials, summarization and discussion of the obtained results.
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Business Plan for Dancing-school Foundation
Žůrková, Lenka ; Černý, Vít (referee) ; Bayerová, Vladimíra (advisor)
Master’s thesis presents the prerequisites for producing a business plan for dancing-school foundation. It analyses problems, which are related to creation of business plan and of dancing-school foundation. It contains suggestions of organizational, marketing and financial plan that can be applied within creation and activity of this company. The work expresses how the project should be undertaken.
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Electrically conductive composites based on secondary raw materials
Baránek, Šimon ; Šteffan,, Pavel (referee) ; Černý, Vít (advisor)
Electroconductive composites are modern materials that are commonly used in many industries such as the construction industry among others. For example these materials can be useful as sensors for monitoring changes in constructions. The aim of this thesis is the research of electrically conductive silicate composite based on secondary raw materials. The design of this composite is based on the development of its own mixtures and experimental verification of the effect of the structure. The introduction part consists of a detailed analysis of 15 materials. Samples of the 5 fine and 2 coarse electrically conductive fillers were tested. Composite with filler Condufit C4 was selected as representative for type of fine fillers. Composite with filler Supragraphite C300 was selected as representative for type of coarse fillers. The selection of the composites was based on the impedance of the fabricated composites with these fillers. Subsequently, the individual components of the primary mixture were substituted. The cement was replaced by high-temperature fly ash in the amount of 20, 30, and 40 %, the aggregate of a similar fraction was replaced by steel sawdust, and the primary electrically conductive fillers were replaced by secondary ones in the amount of 30 and 50 %. All proposed replacements reduced the impedance of the composite. The most effective replacement for impedance reduction was replacement with waste graphite (up to 92 % reduction), which also slightly improved the mechanical properties of the composite. The result of this thesis is an optimized electrically conductive composite based on secondary raw materials with a fine type of filler with 30 % replacement by waste graphite "odpad vysavač"which achieves an impedance of 5 ohms. The partial goal of this thesis is a verification of the influence of moisture on the impedance of composites. Results are significantly affected by moisture when using the coarse type of filler, when using the fine type are not.
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Production of shower tray
Černý, Vít ; Žák, Ladislav (referee) ; Císařová, Michaela (advisor)
The thesis deals with design of technology production of the shower tray made of austenitic steel 17 240. Based on the research of deep drawing and calculations, it was proposed to draw in the tool with upper blankholder and the lower ejector. The drawing tools uses standard components that ensure its functionality and clamping in the CYA 500 hydraulic press with nominal tensile force of 5000 kN. Drawing punch and die are made of 19 437.3 grade steel, heat treated according to the attached drawing documentation.
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The usability of secondary raw materials in the design of liquefied suspensions based on soil
Hrubý, Jakub ; Kulísek, Karel (referee) ; Černý, Vít (advisor)
The bachelor's thesis deals with the usability of secondary raw materials in the design of liquefied suspensions based on soils in the form of self-compacting grouts. The soil treated in this way can be used as a substitute for backfill material for excavations of engineering networks. The theoretical part deals with the classification and description of soils. Furthermore, the types of soil stabilization using lime, cement, including their liquefaction, are mentioned. A wide range of potentially suitable secondary raw materials and liquefaction mechanization is presented. In the practical part, the basic soil F6-Cl is selected on the basis of a set of available soils. The basic reference mixture consists of soil, lime, cement and liquefier. A proposal for the concept of experimental verification is presented. Part of the concept is the automated calculation of input raw materials. The effect of the action of the superabsorbent polymer and the accelerating additive is verified. Based on optimization selections, functional secondary raw materials are selected. The basic recipe with the optimal amount of accelerating ingredient achieves the best results. Recycled concrete and brick generally improve the resulting parameters. Bed ash achieves the highest strength with the lowest shrinkage.
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Effective use of industrial waste in building materials
Szép, Melinda Klaudia Virág ; Mészárosová, Lenka (referee) ; Černý, Vít (advisor)
This bachelor´s thesis deals with one of current topics, namely to effective use of industrial waste in building materials. The theoretical part of this work presents changes in legislation of the Czech Republic in field of waste management system, explains the most important terms and defines each method of waste management. The main goal of this work was to formulate a methodological procedure for efficient use of industrial waste. The methodological procedure was compiled on the basis of elaborated base set of possible variants of waste utilization in the construction sector and a set of corresponding criteria of standards and legislative criteria. A table of elementary criteria has also been compiled for the better orientation in corresponding standards. The proposed methodological procedure was demonstrated on specific example, in fact on slag from municipal waste incineration. The slag was examined in two environments – one with standard laboratory condition and the second with controlled condition (8 % concentration of carbon dioxide and 80 % of relative humidity) – for better understanding of its behaviour. The expected acceleration of the aging process in the environment with controlled condition was confirmed based on the degree of carbonation. The expected reduction of volume changes of the sample exposed to the controlled condition was also confirmed.
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