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The effect of appication of fine organic fibers to cement composites
Kavka, Lukáš ; Hela, Rudolf (referee) ; Bodnárová, Lenka (advisor)
This bachelor thesis describes the effect of using fine organic fibers in cement composites. In the theoretical part of bachelor thesis a composite material was defined and his individual components were described. Then was created a research of information about organic fibers focused on natural fibers. The basic parameters of cellulosic fibers and polypropylene fibers, the effect on the properties of cement composites and their application in practice were described. In the practical part there were created a reference concrete and 3 types of concrete with the addition of various types of organic fibers. The influence of fiber addition on the properties of fresh and hardened concrete were investigated. Another task of practical part was monitored the resistance of cellulose fibers in acidic and alkaline media in which the tested fibers were deposited. The development of pH solutions was examined over time.
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Verification of the effect of fine fibers and absorbent additives on the process of self-healing concrete
Dokoupil, Tomáš ; Ťažký, Tomáš (referee) ; Hela, Rudolf (advisor)
The diploma thesis deals with self-healing of concrete composite. In the theoretical part, it represents the effect of polymer microfibers on reducing the development of cracks and on improving self-healing properties. It also describes the most commonly used types of bacteria used to enhance the self-healing process and their effect both alone and in interaction with fibers, calcium sources and absorbent additives. It also represents auxiliary additives in the form of superabsorbent polymers. In the practical part, it verifies the influence of the above elements and describes how much the self-healing of concrete has been enhanced by the use of combinations of fibers, absorbent polymers and a source of calcium in the form of calcium lactate. It also indicates whether the self-healing properties used were not improved at the expense of deteriorating the mechanical properties of the composite.
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Properties of concrete with cement matrix at high temperatures
Fiala, Jiří ; Dvořák, Karel (referee) ; Bodnárová, Lenka (advisor)
This bachelor´s thesis deals with the behaviour of the cement concrete at high temperatures depending on the aggregate and cement type. The theoretical part describes the processes in the concrete structure at high temperatures affecting the individual concrete components. The design of concrete structure with basalt aggregate and four types of cement in the experimental part was carried out. The proof of physical-mechanical properties after thermal load was reviewed, particularly change of density, compressive strength and tensile strength in bending. The X-ray diffraction analysis was carried out with prepared test samples.
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Durability of repair materials with higher fire resistance for concrete structures
Počekajlo, Václav ; Dohnálek,, Pavel (referee) ; Bydžovský, Jiří (advisor)
This dissertation deals with the study of durability and degradation repair mortars for reinforced concrete structures. In its theoretical part, there are the research findings on the behavior of repair mortars exposed to corrosive environments with different exposure time and selected high temperatures. Processes occurring in repair mortars during their loading at high temperatures or when exposed to chemically aggressive environments are described, We can find recipes designed for cementitious binder based with a specific replacement using slag or fly ash in its practical part. The object of the research was to determine the durability of the proposed repair mortars, and determine their suitability for use on concrete structures, which may be exposed to a synergistic effect of chemically aggressive environments with high temperatures simulating fire.
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Study the abrasion resistance of concrete
Kolková, Kristína ; Hela, Rudolf (referee) ; Bodnárová, Lenka (advisor)
The thesis deals with the issues of concrete abrasion resistance and it consists of a theoretical research part and an experimental part. The types of abrasion affecting concrete construction and abrasion effect of flowing water-borne sand are described in the theoretical research part. A substantial part is dedicated to the impact of concrete properties and to each material of the concrete mixture on the abrasion resistance. The impact of addition of various types of fibers is inquired. The mixtures with the addition of 2 kg.m-3 and 4 kg.m-3 of basalt fibers and the addition of 1 kg.m-3 and 2 kg.m-3 of polypropylene fibers are designed in the experimental part. The mixtures are compared to a reference mixture without fibers. Density and consistency of fresh concrete settling at 5 minutes are determined in fresh condition. Density, compressive strength, tensile strength, watertight, concrete absorption and bending tensile strength are determined on hard concrete. The impact of the addition of fibers to the concrete abrasion resistance is inquired using the Bohm abrasion method and wheel abrasion method. A water jet is used as another method for testing abrasion resistance and for comparing the suitability of the used methods.
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Verification of the effect of fine fibers and absorbent additives on the process of self-healing concrete
Dokoupil, Tomáš ; Ťažký, Tomáš (referee) ; Hela, Rudolf (advisor)
The diploma thesis deals with self-healing of concrete composite. In the theoretical part, it represents the effect of polymer microfibers on reducing the development of cracks and on improving self-healing properties. It also describes the most commonly used types of bacteria used to enhance the self-healing process and their effect both alone and in interaction with fibers, calcium sources and absorbent additives. It also represents auxiliary additives in the form of superabsorbent polymers. In the practical part, it verifies the influence of the above elements and describes how much the self-healing of concrete has been enhanced by the use of combinations of fibers, absorbent polymers and a source of calcium in the form of calcium lactate. It also indicates whether the self-healing properties used were not improved at the expense of deteriorating the mechanical properties of the composite.
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Study of properties of cement composites with addition of polymer fibers
Dokoupil, Tomáš ; Hela, Rudolf (referee) ; Bodnárová, Lenka (advisor)
The bachelor thesis deals with the use of polymer fibers in cement matrix. It describes the distribution and production of the most commonly used polymer fibers as well as the requirements for their properties. A comparison of the properties of different types of polymer fibers is given. The work presents the individual components of the fiber concrete matrix, its production, testing of fresh and hardened fiber concrete and specific examples of its use in practice. Using professional research, the influence of PP, PE and PVA fibers on the properties of fresh and hardened concrete is described in detail. New trends in the use of polymer fibers are also presented. At the end of the work, a procedure of experimental verification of the properties of fiber-reinforced concrete in comparison with a reference sample of plain concrete is proposed.
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The effect of appication of fine organic fibers to cement composites
Kavka, Lukáš ; Hela, Rudolf (referee) ; Bodnárová, Lenka (advisor)
This bachelor thesis describes the effect of using fine organic fibers in cement composites. In the theoretical part of bachelor thesis a composite material was defined and his individual components were described. Then was created a research of information about organic fibers focused on natural fibers. The basic parameters of cellulosic fibers and polypropylene fibers, the effect on the properties of cement composites and their application in practice were described. In the practical part there were created a reference concrete and 3 types of concrete with the addition of various types of organic fibers. The influence of fiber addition on the properties of fresh and hardened concrete were investigated. Another task of practical part was monitored the resistance of cellulose fibers in acidic and alkaline media in which the tested fibers were deposited. The development of pH solutions was examined over time.
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The issue of concrete resistance to high temperatures
Krejčík, Jakub ; Hela, Rudolf (referee) ; Bodnárová, Lenka (advisor)
Bachelor´s thesis deals with resistance of cement concrete to high temperatures. Theoretical part of bachelor´s thesis describes changes that occures in concrete at thermal loading and behavior of each component of concrete. Next there were discribed ways to improve resistance of concrete to high temperatures, by choosing the right component or by adding fibre reinforcement. In experimental part composites with bassalt and polypropylen fibre and with bassalt aggregates were tested. In these composites changes of compressive strenght and changes of density were mesured according to the thermal loading. Next individual fibre reinforcement polypropylen, celulose and bassalt fibres were exposed to the thermal loading and their changes were observed.
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Studying the behavior of high strength concrete at high temperatures
Sovová, Kateřina ; Kirnbauer, tech Johannes (referee) ; Bodnárová, Lenka (advisor)
This master’s thesis is divided into two parts; practical and theoretical. The theoretical part of this study describes the influence of high temperature on concrete structure and chemical, mechanical and physical changes, which take place during the exposure to high temperatures. The thesis also evaluates spalling of concrete and the methods to prevent it, as well as the function of polypropylene and cellulose fibers in the concrete. The practical part deals with design, production and testing of the cement-based concrete with the use of different fibers (polypropylene fibers and cellulose fibers). The properties and the means of applications in high temperatures are also included. The practical part also assesses the influence of high temperature on strength, porosity, visual changes of specimens, changes of surface and degradation of testing specimens due to heat loads according to normative heat curve (ISO 834) and also according to hydrocarbon curve. For clearer arrangement, the experimental tests are divided into two parts and the measured values are evaluated at the end of each part. The conclusion resumes all data obtained by testing and evaluates what is the most suitable formulation. The approach for further research is also discussed.
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