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Utilization of waste glass in cement composites
Gottwaldová, Aneta ; Dufka, Amos (referee) ; Bodnárová, Lenka (advisor)
Bachelor thesis deals with the processing of waste glass in cement composites. Bachelor thesis includes a search theoretical and experimental part. Specifically, it was verified by fluorescent waste glass and glass screen at a dose of 5, 10, 15 and 20 weight % of a batch of cement. Properties of composites were examined after 7, 28, 56 and 90 days. We monitored TG analysis and XRD analysis of cement composites with waste glass.
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Study of properties of bent FRP reinforcement
Lipoldová, Marie ; Prokeš,, Jan (referee) ; Bodnárová, Lenka (advisor)
The diploma thesis deals with the study of bent FRP reinforcements with the main focus on the methods of production of bent FRP reinforcement, examples of their application in structures. The work also mentions the effects of aggressive environments on the durability of FRP. In the practical part, a search of the possibilities of testing the properties of bent FRP reinforcement. Subsequently, an experiment is designed and performed to monitor changes in the properties of straight and bent FRP reinforcement exposed to the alkaline environment and water at 20 °C and 40 °C. Finally, the evaluation of changes in mechanical properties and observation of reinforcements using optical and scanning electron microscopy is performed.
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Use of FRP Composites as Reinforcing Material for Concrete
Kratochvílová, Denisa ; Prokeš,, Jan (referee) ; Bodnárová, Lenka (advisor)
Because FRP composites have high fiber strength and good durability, they are increasingly used for repairs, modernisation and reconstruction of concrete structures. In practice, however there is a risk of premature separation of FRP reinforcement from concrete. This can be avoided by appropriate selecting the fibers and the matrix and the appropriate shape of the reinforcement. The actual materials and consistency of FRP reinforcement with concrete are also covered by this diploma thesis.
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ELIMINATION OF NEGATIVE PROPERTIES OF CONCRETE INDUCED BY THE USE OF RECYCLED AGGREGATES USING BASALT FIBERS
Fittl, David ; Nováková, Iveta (referee) ; Bodnárová, Lenka (advisor)
The thesis summarises information about recycled aggregates and basalt fibres, their interaction in composite material such as concrete. It focuses on the potential deficiencies and properties of concrete due to the use of recycled aggregates and on the possibilities of their subsequent elimination of their negative impact by the use of basalt fibres. It characterizes individual raw materials and their interaction in concrete. It includes verification of the properties of the individual sub-components and the resulting concrete itself. An assessment is made of the impact of the use of recycled aggregates on the properties of concrete (compresive strength, static modulus of elasticity, residual flexure tensile strength and others). The thesis discusses the question of whether the same or similar mechanical properties of concrete can be achieved with natural and recycled aggregates using basalt reinforcing fibres. The work provides for the possibility of settlement the values of these concrete parameters by using basalt fibres as a dispersed reinforcement in concrete. The recycled aggregates come from concrete company JARO AS in the north of Norway, where this work was conducted with the financial support from Erasmus+ at The Arctic University of Norway - campus Narvik.
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Monitoring the influence of concrete composition on abrasion resistance
Černá, Hana ; Novosad, Petr (referee) ; Bodnárová, Lenka (advisor)
This diploma thesis focuses on the resistance of concrete to abrasion with regard to the raw materials used for their production. In the theoretical part of the thesis are described admixtures, different types of aggregate and aggregate composition which influence the resistance of concrete to abrasion. In the experimental part, 15 different C30 / 37, S4 concrete formulations were proposed. Different types of aggregates - fecal gravel (Žabčice), biotic granodiorite (Olbramovice) and amphibolite (Želešice) have always been used in the recipes. Fine ground limestone, micro-silica, high-temperature fly ash and finely ground slag were ingredients that were added to the proposed recipes. Consistency was determined by the method of cone seating and the density of fresh concrete. In the hardened state, concrete density, compressive strength, bending tensile strength, tensile strength, watertightness, concrete absorption, and abrasion resistance were determined using the Böhm method and wide wheel method. The test specimens were tested after 7, 28, and 90 days of maturation.
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The study of the influence of the composition of the lightweight fiber concrete physical and mechanical properties
Šindelek, David ; Bodnárová, Lenka (referee) ; Hela, Rudolf (advisor)
This bachelor thesis deals with a study of light construction concrete with an addition of steel fibre which monitors its impact of the physical mechanical properties. The work is divided into two parts, theoretical and practical. The theoretical part is focused on characteristics and a design of light concrete within the class 35MPa and over with the density within the class of D1,8. Furthermore, it focuses on the increase of toughness of cementitious composites with the form of application of steel fibre in different doses and lengths. In the practical part, formulas of two strength classes 35/38 D 1,8 and 45/50 D1,8 were designed with the help of the steel fibre Krampeharex in doses of 25 and30 kg/m3, and where there were both its impact of the working diagram as well as the compressive strength monitored for the duration of twenty-eight days
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RESEARCH AND DEVELOPMENT COMPOSITE MATERIAL WITH A HIGHER RESISTANCE TO HIGH TEMPERATURES
Válek, Jaroslav ; Durica,, Tibor (referee) ; Kolář,, Karel (referee) ; Sitek,, Libor (referee) ; Bodnárová, Lenka (advisor)
Concrete has many advantageous properties as regards resistance to fire. It is non-flammable and it has a low thermal conductivity. However, concrete structures, which are not designed for resistance against fire, show significant damage after heating. In particular, the explosive flaking with the consequence of weakening the reinforced concrete cross-section and exposing the steel reinforcement to the temperatures higher than critical temperature of reinforcement. There are only a few possible measures of preventing or mitigating the effects temperature load used. Ways of protection can be divided into two systems: active and passive. Active systems are designed to ensure the greatest possible reduction of temperatures the concrete is exposed to. Passive systems directly resist to high temperatures and fire. Design of composition of concrete with the aim of higher resistance to exposition to high temperatures belongs among the passive systems. A part of the work focuses on summary searches of the problems of concrete and reinforced concrete structures exposed to high temperatures and fire. The goal of the work is defining requirements for cement matrix based composite material and its design ensuring the highest possible resistance to high temperatures or direct fire.
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Study of inorganic matrix composites for FRP
Svora, Petr ; Rovnaník, Pavel (referee) ; Puliš,, Pavel (referee) ; Šubrt,, Jan (referee) ; Bodnárová, Lenka (advisor)
During a whole period of time which fibre-reinforced polymers have been used in the building industry, in dominating bonding agent has been the organic resins. There is no doubt about their advantages, but at the same time, they have two weaknesses: they are not fire resistant and they have no resistance to high temperature. Those are the reasons why the research on alternative materials which could replace organic matrix has been undertaken. The goal of the work is to maintain mechanical properties of fibre-reinforced polymer with organic matrix. Of course, an emphasis is placed to fulfilling ecological standards which are required from ecological material. An aluminosilicate inorganic matrix can meet them all. It is non-flammable, does not produce any toxic matter in contact with fire and the energy consumption during production process is lower than in case of the organic matrix. This work includes study and analysis of selected raw materials as well as their influence and impact on final reaction products which are created in inorganic matrix. A part of this work is also a design of the inorganic matrix recipe.
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