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Influence of multiple cyclic loading on the selected parameters of lightweight concrete
Alexa, Martin ; Misák, Petr (referee) ; Kocáb, Dalibor (advisor)
The diploma thesis deals with the observation of the values of selected parameters (especially the static modulus of elasticity) of light-weight concrete in compression before and after multiple cyclic loading. The deformation of test specimens during multiple cyclic loading were measured with resistive strain gauges. Test specimens (cylinders with a diameter of 150 mm and height of a 300 mm) were cyclically loaded and up to 4 500 loading cycles were performed. The aim of this thesis is assessment changes in the values of static modulus of elasticity depending on the number of loading cycles.
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Testing early strength concrete by electronic tester
Holbová, Monika ; Kocáb, Dalibor (referee) ; Cikrle, Petr (advisor)
This project solves the creation of calibration relations for determining the compressive strength of early age concrete. It deals with news in the field of hardness methods. 36 samples were made for this experiment and tested by ultrasound and by impact hammer SilverSchmidt type L with Mushroom Plunger. The result is set of calibration relations for determining of compressive strength for different methods and their combinations.
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The comparison of testing methods using for determining the frost resistance of concrete
Kněbort, David ; Vymazal, Tomáš (referee) ; Kocáb, Dalibor (advisor)
The diploma thesis deals with the possibilities of evaluating the degradation of mechanical resistance of non-air-entrained concrete in the structure by frost cycles. The first part is focused on concrete, its resistance and test methods. This is followed by the definition of frost resistance, the effects of freeze-thaw on concrete at all stages of its service life and the possibilities of determining freeze-thaw resistance according to current standards. It describes in more detail selected test methods for determining frost resistance. In the practical part, it focuses on the determination of degradation resistance of test specimens made in molds and taken from the structure using reference and non-reference methods. In conclusion, it compares the different test methods and their suitability for the determination of freeze-thaw resistance.
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The Use of the Ultrasonic Pulse Velocity Method for the In-situ Estimation of the Quality of Concrete
Sopúch, Martin ; Cikrle, Petr (referee) ; Kocáb, Dalibor (advisor)
The primary focus of this bachelor thesis is examination of concrete properties, principally with non-destructive methods. The ultrasonic apparatus Pundit PL-200 made by Proceq Company was used for the most of non-destructive examinations of the concrete. This paper is mainly focusing on determination of a modulus of elasticity. Measuring of the properties took place in the laboratory with use of probationary entities of 100 x 100 x 400 mm and in site on concrete block situated at BUT FCE campus. The probationary entities including twists from measured block were after non-destructive examining tested in the wring to secure more accurate results. The target of the research paper, firstly, was to attest options for determination of dynamic value. Secondly, with use of decreasing coefficient determine static values of elasticity modulus on the concrete that was built-in in a construction and, consequently, test practical usage possibilities of the modern apparatus Pundit PL-200.
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Diagnostics and assessment of the structure of bridge
Lehocký, Peter ; Komárková, Tereza (referee) ; Kocáb, Dalibor (advisor)
This diploma thesis focuses on diagnostics of bridge structures. First part of this diploma thesis will focus on theoretical knowledge about bridge structures and common diagnostic techniques suited for examining material priperties of samples taken from structure. Second part of this thesis will focus on practical use of experiments used in diagnostic branch. I will be doing visual observation of concrete structure followed by experiments on core samples. End of thesis will be evaluating structure from global perspective and will deliver specific sugestions for renovation.
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Experimental determination of the relationship between NDT parameters and the compressive strength of concrete
Kozáček, Vojtěch ; Komárková, Tereza (referee) ; Kocáb, Dalibor (advisor)
The diploma thesis deals with non-destructive testing of concrete as well as with the relationship between determined parameters and the compressive strength of concrete. The thesis is mainly focused on the ultrasonic pulse velocity method and the rebound hammer test. The experimental part of the thesis describes non-destructive tests performed on concrete blocks. The compressive strength was tested on the drill cores taken from the concrete blocks. The aim of this thesis is to find regression models of the relationship between the compressive strength and non-destructive parameters, and the subsequent analysis of the results.
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The issue of determination of the static modulus of elasticity of concrete in structures
Halamová, Romana ; Misák, Petr (referee) ; Kocáb, Dalibor (advisor)
The thesis deals with the measurement of the elastic modulus of concrete in existing structures and possibilities of applicability of equations for the calculation of characteristic values of concrete compressive strength on the modulus of elasticity. The modulus of elasticity is determined by dynamic and static methods on specimens taken from the concrete blocks, whose composition varies by a water cement ratio and varying amounts of admixtures. In conclusion, the results of the measurements are compared and the characteristic values of the modulus of elasticity is determined.
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Survey and assessment of masonry building castle
Kopecký, Martin ; Kocáb, Dalibor (referee) ; Cikrle, Petr (advisor)
This diploma thesis deals with the diagnostics of masonry structures. In the theoretical part of this thesis it is described the system of assessment of existing structures and then the assessment of existing masonry structures. The next chapter states the methods of survey of masonry structures, including evaluation. The practical part of the thesis deals with the survey of the building of a small castle. This survey includes a brief history of the castle building, the preliminary inspection of the building and the research of the supporting structure. The result of the survey is to determine the material characteristics of masonry.
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The verification of the time development of the concrete elastic modulus and the compressive strength
Alexa, Martin ; Cikrle, Petr (referee) ; Kocáb, Dalibor (advisor)
Especially in the early days of curing concrete for structures sensitive on deformation. Same like bridges of prestressed concrete a substantial knowledge of the exact value of the modulus of elasticity that could prevent excessive deformation. In this work we validates the development of concrete modulus of elasticity (in the first 28 days), which is used for the construction of bridges on the highway D1 near Ružomberok. To understand this issue was made a literature review and conducted experiment, which follows the time development of the concrete compressive strength and modulus of elasticity of concrete. Except the determination of modulus of elasticity in the experiment was investigated a dynamic moduli by an ultrasonic pulse method and the resonance method and the experiment was also performed by rebound hammer. The results can serve to verify the development of the modulus of elasticity on the actual structure.
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