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Survey and Diagnostics of Building Construction
Haloun, Jan ; Cikrle, Petr (referee) ; Anton, Ondřej (advisor)
The topic of the first part of this bachelor thesis covers the methods of diagnostics of reinforced concrete constructions and their practical application. In the theoretical part are described the methods currently used with diagnostics of reinforced concrete constructions with focus on methods used in practical part. The practical part covers the survey of reinforced concrete constructions and its evaluation. The main objects of the practical part were the detection of the strength class of concrete and real reinforcement of certain elements.
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Assessing the state of a prefabricated bridge construction
Válková, Michaela ; Stehlík, Michal (referee) ; Cikrle, Petr (advisor)
This thesis deals with assessing the state of prefabricated bridge construction on the motorway D46 near the village Drysice. The thesis is divided into theoretical and practical part. The theoretical part is focused on kinds of prefabricated bridge girders and their defects. Additionally an overview of methods for exploration of these girders. The goals of the practical part are visual inspection, documentation of the state of construction. Execution of laboratory tests of concrete girders in the number of 12 bores. Evaluation of results of laboratory testing and classification of the state of bridge construction.
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Investigation of portlandite carbonation using the in-situ X-ray diffraction analysis
Růžička, Lukáš ; Koplík, Jan (referee) ; Másilko, Jiří (advisor)
Thesis deals with carbonation of portlandite using in-situ X-ray diffraction analysis. The carbonation of portlandite progress in concrete structures and it is already quite widely discussed. It is responsible for corrosion and degradation of reinforced concrete elements, and thus its influence is perceived very negatively. The main goal of this work is to determine the ideal conditions for the progress of carbonation of portlandite. In this work the progress of carbonation depending on the relative humidity and temperature was observated. The amount of carbonated portlandite was evaluated by means of thermal analyzes (TG / DTA) and X-ray analysis.
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Study of carbonatation in alkali activated systems
Suchý, Rostislav ; Koplík, Jan (referee) ; Kalina, Lukáš (advisor)
The carbonation of the building materials based on the ordinary Portland cement is relatively well-known and extensively studied phenomenon. Conversely mechanism, reaction products and factors affecting the carbonation of the alkali activated materials are still not sufficiently clarified. In this work, the progression of the carbonation of the alkali activated materials under different conditions was investigated. The reaction products and the microstructural changes were determined by XRD respectively SEM-EDX analysis. The corrosive conditions due to the decreasing of the pH of the binders by the carbonation were observed by XPS analysis of the steel fibers. The carbonation of the alkali activated samples was compared with the reference samples based on the Portland composite cement. Besides these analyzes, the mechanical properties of the binders were monitored.
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Investigation and Modelling of Concrete Carbonation
Rovnaníková, Markéta ; Keršner, Zbyněk (referee) ; Bajza, Adolf (referee) ; Havlica, Jaromír (advisor)
The corrosion of steel reinforcement is probably the most frequent type of degradation of reinforced concrete structures. Reinforcing bars are protected from corrosion by a thin iron oxide layer which is formed on their surface due to a high alkalinity of the surrounding concrete. Corrosion may start when this layer is destroyed (i) either by chloride ion penetration (when the concentration of dissolved chloride at the depth of the reinforcing steel exceeds a critical value) or (ii) by a reduction in the pH value of pore solution to values below 9.5. Such a reduction in alkalinity is the result of carbonation of the Ca(OH)2 in the concrete mass, i.e. of its reaction with the atmospheric CO2. The main aim of this work is an experimental investigation and modelling of carbonation process. The effect of relative humidity, curing period and replacement of Portland cement by supplementary cementing materials (SCM - fly ash, blast furnace slag and metakaolin) on carbonation process has been studied. Calcium hydroxide content in the presence of SCM and their pozzolanic activities have been also determined. Furthermore, lots of parametric studies and comparison of carbonation models have been provided. The software tools based on the introduced models and considering the input data to be statistically independent random variables have been described and used for other parametric studies.
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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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Diagnostic properties of concrete exposed to high temperatures
Hudský, Petr ; Sitek,, Libor (referee) ; Bodnárová, Lenka (advisor)
This master’s thesis studies the problems of high temperatures on cement concretes, their following diagnostics from pre-treatment to rehabilitation, the emphasis was on the use of high-speed water jet. In the experimental part of the design of a concrete composition with basalt aggregate. Were reviewed the physico-mechanical properties after thermal loading. The influence of pressure water jet on the thermal load on concrete, pull-off test, the volume of the removed concrete with a strength evaluation and comparison.
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Influence of changes in concrerte pore structure on actually durability of reinforced and pre-stressed structures.
Kovalčíková, Hana ; Adámek, Jiří (advisor)
This master thesis deals with a durability of concrete, which has become the centre of the interests of international scientific insitutes during the last years. The resistence of reinforced concrete depends on the covercrete which the aggresive liquids and gases penetrate through from the environment to reinforcement. According to the ability of the covercrete to penetrate degradative species is possible to tell the durability of concrete constructions. In experimental part we look for the actual state of covercrete, ordinary and high strength, by combination of various experiments. We can find here the test´s results of water and gas permeability and absorbability and sorption of concrete which complete the permeability tests. In final part the impact of different concrete types on durability of reinforced concrete is discussed.
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Nonlinear analysis of load-bearing capacity of reinforced concrete bridge
Sadílková Šomodíková, Martina ; Novák,, Drahomír (referee) ; Lehký, David (advisor)
The subject of master’s thesis is determination of bridge load-bearing capacity and fully probabilistic approach to reliability assessment. It includes a nonlinear analysis of the specific bridge load-bearing capacity in compliance with co-existing Standards and its stochastic and sensitivity analysis. In connection with durability limit states of reinforced concrete structures, the influence of carbonation and the corrosion of reinforcement on the structure’s reliability is also mentioned.
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