National Repository of Grey Literature 217 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Effect of pollutants and concrete quality on durability and service life of reinforced concrete structures
Mazán, Tomáš ; Láník, Jaromír (referee) ; Hrabová, Kristýna (advisor)
The thesis describes the effects of an aggressive environment on structures in infrastructure that are exposed to adverse influences. The theoretical part of the thesis deals with the classification of different aggressive environments and the chemistry by which they cause degradation of concrete and structures. A substantial part is devoted to the interaction of degradation mechanisms, i.e. the synergistic effect. The practical part describes the experimental procedure, the test methods used and the experiment by which the thesis verifies the theoretical ideas. Based on the theoretical background, the thesis develops a model that simulates the effect of the environment. The execution of the experiment consists in simulating aggressive environments and detecting their influence on the investigated properties. After obtaining the results from the tests in the practical part, the risks that may reduce the durability of the structure are subsequently evaluated with respect to the different phases of the life cycle of the structure. Furthermore, the risks that have a significant impact on durability are evaluated and once arranged, measures are proposed. Finally, the thesis discusses the achieved results of the whole experiment and evaluates how to achieve the reduction of the adverse effects in the different phases of the life cycle of the structure.
Factors affecting engine health as a function of pilot activity
Trtíková, Klára ; Vrána, Michal (referee) ; Červenka, Miroslav (advisor)
The thesis deals with the lifetime of piston engines depending on the pilot's activity. Especially the problems of overheating and undercooling, which can be mostly avoided by proper piloting. This thesis opens this topic with a description of the problems caused by engine overheating and undercooling, describes various situations where this phenomenon may occur and its consequences. Further chapters continue with evaluation of operator and pilot questionnaires, description of engine limits and recommendations from the manufacturers of four different engines, an analysis of specific cases of failures due to severe thermal shocks, and a finally summarizes recommendations for pilots. The final chapter recapitulates experience on this topic based on interviews with hands-on aircraft engineers and maintenance technicians.
Methodology for determining the durability of concrete and its resistance to frost and chemical deicing salts
Chaloupková, Kristýna ; Novosad, Petr (referee) ; Hubáček, Adam (advisor)
The bachelor's thesis explores the possibilities of improving testing procedures for determining the resistance of concrete to frost and chemical deicing salts. Currently used testing methods are notably problematic in terms of their repeatability and reproducibility. These tests are influenced by several factors, including the method of sample storage prior to testing, the preparation of the test surface, and the significant impact of edge effects. Additionally, the raw materials used in the test solution also affect the outcomes. During the test, water condensation occurs in the freezing chamber, altering the concentration and level of the test solution.
Verification of the Applicability of Mixed Cement Types for the Production of Concrete Pavements
Klobása, Jan ; Hela, Rudolf
Concrete is the most widely used building material today. Due to the increase in the utility value of buildings, more and more emphasis is placed on the durability of buildings, which especially applies to concrete products exposed to frost and chemical deicing agents. Cement concrete pavements have the ability to transmit the effects of traffic and withstand adverse weather conditions. Concrete pavements can withstand high traffic loads without permanent deformations and have a long service life. However, it must be said that in the case of damage to the CB pavements, repairs require longer closures due to more demanding production and laying technology. The expected lifespan of a concrete road type is at least 30 years with basic and minimal maintenance, while the life cycle of tarmac roads is much shorter. Currently, great importance is placed on reducing emissions arising from industrial production, especially cement production, where it is stated that the production of 1 ton of cement produces approximately 0.6 tons of CO2. Reducing emissions is possible thanks to secondary raw materials that are produced in large volumes in the Czech Republic, for which a suitable use is being sought.
Development of concrete with high fly ash content and verification of durability in various environments
Ambruz, Pavel ; Voves, Jiří (referee) ; Hela, Rudolf (advisor)
This thesis contains two main parts: theoretical and experimental. The theoretical part deals with summarization knowledge of high-volume fly ash (HVFA) concretes. Among others, there are mentioned processes of producing of fly ash, characteristic features and resistance to aggressive environments of HVFA concretes. The theoretical part ends with a suitable example of practical application. In the practical part were tested properties of nine different mixtures containing 40%, 50% and 60% replacement by weight of the cement by fly ash. They were compared with the reference mixtures without fly ash addition. The main endpoints were long-term compressive strength, resistance to aggressive environments, the influence of fly ash on consistency, hydratation temperatures, water absorption and volume changes.
Assessment of physico-mechanical properties and durability of binder concepts based on purposeful creation of ettringitu
Pupíková, Petra ; Štenko, Miroslav (referee) ; Žižková, Nikol (advisor)
Masters`s thesis deals with study of binder concept based on purposeful creation of ettringite, assessment of physic-mechanical properties and durability. The teoretical part is the mention of ettringite and his function in building materials, are described binder concepts based on purposeful creation of ettringite and self-levelling screed for which the controlled formation ettringite typical. In the practical part are did analysis of raw materials and the composition of the mixture, including types corrosive environment for the assessment of durability. In addition are checked properties of the proposed mixture and evaluated the appropriateness of use of each type of waste materials with regard to the resulting properties.
Possibilities of evaluation durability of the surface layer of concrete structures
Blažek, Michal ; Žalud, Oldřich (referee) ; Vymazal, Tomáš (advisor)
The thesis is focused on possibilities of durability evaluation of surface layer of concrete structures. The durability of concrete surface layer usually determines the durability of the structure as a unit. It has to be determined in what environment the structure is situated and what influences it has to face, to set the durability of the structure. There is a several normative prescription to set the resistance of the structure. There is formulated a summary of the most widely used and known prescriptions in the theoretical part of the thesis. It is a lot of effort to estimate the durability of the concrete by estimation of permeability of the concrete surface layer recently. Thus these methods are also formulated in the summary and there are compared the individual outputs of the tests. The permeability and pore structures of the concrete surface layer are crucial parameters for the durability of concrete structure. These parameters influence the construction properties of the concrete as well, thus the thesis is focused on relationship of the pore structure and the strength in press of the concrete.
Life cycle costs of residential building
Biolek, Vojtěch ; Marková, Leonora (referee) ; Nový, Martin (advisor)
The aim of this work is to introduce the topic "Life cycle costs for residential buildings" and a specific example to compare the real cost with the model, resulting in the operating phase of the life cycle of a building, using indicators BLCC. The paper also solved possible replacements for alternative materials selected functional components that can be positively or negatively affect other life cycle costs. These solutions can be used investor to invest in other phases of the life cycle of the building.
Testing of Vehicle Suspension Components
Šidla, František ; Blaťák, Ondřej (referee) ; Hejtmánek, Petr (advisor)
This bachelor thesis deals with issues related to testing car chassis components during development. Automobile transport is the most common type of long-distance transport. That's why vehicles are constantly evolving to provide the best possible performance. Increasing demands on consumers are being placed on vehicles because of the introduction of modern technologies. New technologies and concepts need to be thoroughly tested that they can be properly integrated into existing models. Test devices for determining the characteristics of the chassis are generally described here using specific examples of individual machines. Subsequently, the work clarifies the testing of the service life of individual parts of the chassis. The last part is devoted to the conceptual design of a simplified hydraulic device for testing coil springs. From the calculated characteristics, a hydraulic actuator and pump are selected from the relevant catalogues. In conclusion, the importance of car testing in development is summarized, individual types of testing are described and the readiness of test devices for the future is indicated.
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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