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Development of new types of composites for concrete rehabilitation with increased protection reinforcement
Taranza, Luboš ; Durica,, Tibor (referee) ; Dohnálek,, Pavel (referee) ; Bydžovský, Jiří (referee) ; Drochytka, Rostislav (advisor)
Around the world there is a great number of reinforced concrete structures, who´s life cycle, for which they were designed, is significantly shortened due to action of various aggressive environments, or due to defects created during the construction process. (i.e. insufficient steel reinforcement cover depth). One of the most common causes of problems in reinforced concrete structures is corrosion of steel reinforcement. It is necessary to repair structures degraded in this fashion and return them to their original state. We made a unique polymercement concrete repair system was developed with value added. Corrosion inhibitors, including the newly developed, are implemented into its polymercement matrix, which significantly limit the corrosive processes in all new materials. The principle of proposed solution is application of repair system on a corrosion damaged structure, and then the active substances in the repair material will penetrate into substrate concrete and protect corroded steel reinforcement. Another value added is the application of recycled raw materials into the proposed materials, which has indisputable environmental effect and simultaneously allows for improvement of some properties of the repair materials. Further was developed a new method for detecting corrosion inhibitors in concrete.
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Enhancement of HSS tools cutting performance with PVD coatings
Medek, Martin ; Sliwková, Petra (referee) ; Píška, Miroslav (advisor)
Diploma work describes speed drill steels and its qualities before and after coating by methods PVD (Physical Vapour Deposition). The theoretic part is concerned with thermic processing of speed drill steels and their qualities with regard to individual alloying elements contained and its mechanical features. Second part of the theoretic part is concerned with particular methods of coating by the help of PVD technologies, kinds of coating with regard to additional elements and their qualities and surface treatments of coated material before and after its coating. The goal of the experimental part was the confrontation of cutting power features of cylindrical four-fluted face mills with straight shank, from speed drill steels non-coated and coated in two basic modes of milling – down-feed method and upfeed method. The results of measurements were interpreted by the help of four basic pictures (source values, power analysis, specific values). The result of all the experiment is that the application of PVD coatings enabled the increasing of cutting speed (with preservation of other cutting requirements) and led to decreasing of cutting force and cutting enforcements and extended durability of cutters.
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Specific cement composite based on secondary raw materials with emphasis on durability
Figala, Petr ; Dohnálek,, Pavel (referee) ; Drochytka, Rostislav (advisor)
Nowadays the attention to the utilization of secondary raw materials as a component of building materials is being paid to in the Czech Republic and in the world. This thesis deals with possibilities of using secondary raw materials as partial cement substitutes in industrial floors. The aim of this thesis is to verify the influence of cement substitution amount with secondary raw materials and their fineness of grinding on the properties of the floor surface in time and on its structure. On the basis of the acquired knowledge, the influence of the pre-treatment of the secondary raw material on the properties of the floor ceiling with an emphasis on the economic aspect was assessed. After evaluating the results, some substitution of cement in the floor screed with secondary raw materials is beneficial. The significant influence of more intensive milling of the floor screeds base on the parameters of the final floor screed was not confirmed. It seems, that it is possible to achieve very good results even when using secondary raw materials with a lower percentage of fine particles. This brings together the economic benefits of lowering the cost of a lower dose of expensive cement by using cheaper secondary raw materials, because pre-treatment of such materials does not require the use of a large amount of energy.
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The influence of the preparation and editing of test specimens for testing the durability of concrete and concrete products
Šťastný, Antonín ; Brožovský, Jiří (referee) ; Hubáček, Adam (advisor)
This bachelor’s thesis examines the influence of the preparation and editing of test specimens for testing the durability of concrete and concrete products. In particular it monitors the effect of surface treatment and storage of test samples on durability of concrete. The theoretical part describes the mechanism of damage to the samples exposed to salt scaling. It further describes the test methods, which identifies and describes the durability of concrete and concrete products according to the test standards in force in the Czech Republic. Three types of concerete was proposed and mixed in the experimental part of this work. They were using the same raw materials and were differed in degree of aeration. Samples were made from each types of concrete. Thay had different surface treatment, various degrese of saturation before the salt scaling test and the samples were compared with each other.
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On the increase of cutting performance of thread cutting taps with PVD coatings
Grygárek, David ; Fiala, Zdeněk (referee) ; Píška, Miroslav (advisor)
This diploma thesis deals with HSS cutting taps performance in combination with very hard and tribological PVD coating application and their contribution to increasing of cutting properties. Then is described the mechanisms and forms of cutting tool wear. The goal of the experimental part of the thesis was determine, compare and subsequently evaluate cutting properties of threading tools using taps with different types of PVD coatings. During realization of the experiment, constant cutting conditions have been ensured and the only variable were the different types of coating layers. The result of the experiment was measurement of cutting torques depending on time and rate of wear of cutting tools. Measured value are statistically processed and drawn conclusion.
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Study of FRP for concrete reinforcement
Blahová, Aneta ; Prokeš,, Jan (referee) ; Bodnárová, Lenka (advisor)
The diploma thesis aims to analyze bent FRP reinforcements. It describes the method of production of bent FRP reinforcement, examples of application of FRR reinforcement in structures and mentions aggressive influences influencing the durability of FRP reinforcement. Furthermore, an experiment is proposed to monitor changes in straight and bent FRP reinforcement stored in an aqueous environment at 20 °C and an alkaline environment at 20 °C and 40 °C. The output of the diploma thesis is the evaluation of changes in mechanical properties and durability. The condition of the FRP reinforcement is documented using optical and electron mocroscopy.
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Influence of material base of coating systems onto wood durability
Bednářová, Ilona ; Petránek, Vít (referee) ; Vaněrek, Jan (advisor)
The thesis deals with the influence of the base material of the coating systems for wood durability when we exposed them to external conditions. The theoretical part is devoted to wood durability and weather resistance with a detailed description of the tests the durability of coating systems. A substantial part of the theory is devoted to description binder component of the coating material. In the practical part was performed the experiment, which examined the influence of the thickness of the coating system, the type of coating material (paint or lasure) as well as the type of binder (water dispersion with an alkyd or acrylic resin, respectively solution coating system with the alkyd resin). All coating systems were exposed to natural and artificial durability tests. The criterions for evaluation were chosen differences of colours.
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OPTIMIZATION OF ANALYTICAL METHOD FOR CALCULATING THE WEAR OF BUILDINGS
Hlavinková, Vítězslava ; Matějka, Libor (referee) ; Abraham, Karel (referee) ; Bradáč, Albert (advisor)
The dissertation focuses on the problems associated with determining the amount of wear (finding the remaining technical values) that are being addressed. It deals with an overview of the different methods used. The basic premise of the thesis is a comprehensive overview of the calculation procedure and the methods used. This area of wear does not except the price regulation precisely defined procedure, nor are they addressed the circumstances in which that would be the method to be used. Various possible methods or inaccuracies may result in questioning the expert opinions as at trial. In conclusion of this dissertation is shown how the calculation procedure should wear for what purpose should be used and it is also proposed several alternatives.
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Development of structural concrete with power plant ash
Ťažký, Martin ; Sokol, Pavel (referee) ; Hela, Rudolf (advisor)
Worldwide production of concrete is increasing, what has a negative environmental load of cement production. That is due to effort in building construction, also concrete production, greater use of the secondary raw materials. Fly ash is the most commonly used secondary raw material. His used has a very good impact on the economy and ecology of production and positively affects on the properties of concrete in both the fresh and hardened state. The aim of this bachelor's thesis was to improve its use in concrete, using a minimum void fraction of dry mix cement-fly ash.
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SCC with secondary raw materials
Ťažká, Lucia ; Ťažký, Tomáš (referee) ; Hela, Rudolf (advisor)
Bachelor thesis is focused on the possibility of using secondary raw materials and their application to the production of SCC. Large part deals with impurities of type I and its application results mainly from abroad. Furthermore, this work examines the impact of different types of impurities on the resulting concrete durability in various aggressive environments. The practical part is focused on the use of chemically non-reactive additives of type I instead of the commonly used additives of type II which are used to replace part of cement and the resulting design and manufacture of low-strength SCC using appropriate additives.
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