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Development of concrete with limited volume changes
Martanová, Jana ; Skopal, Ing Karel (referee) ; Hela, Rudolf (advisor)
The bachelor thesis deals with volume changes of concrete. Attention is paid to the shrinkage. They describe the different kinds of volume changes in cement concrete, the reason for their creation and the ways in which they can be eliminated. The practical part is focused on monitoring the volume changes of concrete for 28 days using different amount of plasticing additives.
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Numerical analysis of selected silicate based composites shrinkage
Drbušková, Magdaléna ; Vlk, Zbyněk (referee) ; Keršner, Zbyněk (advisor)
The thesis is divided into two main parts. In the first theoretical part is described the problems of shrinking including a comparison of Czech standard and Model Code 2010, Vol. 1. The second practical part of the master`s thesis is focused on the numerical analysis shrinkage primarily on the initial stage of this process. The experimentally obtained data are set approximations of the relative deformation using ShrCeC. Subsequently the numerical simulation of shrinkage of selected silicate specimens using a computer applications SpatiDist and FyDiK 2D. The real test specimens are modelled as two-component composite consisting of cement paste and aggregates. The result is a parametric study takes into account the influence of type and size of grain aggregate.
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Methods for Monitoring of Volume Changes of Cement and Polymer-modified Mortars
Vrablová, Simona ; Sedlmajer, Martin (referee) ; Žižková, Nikol (advisor)
Bachelor thesis is focused on monitoring of volume changes in polymer-modified mortars. Using Czech and foreign literature searches are processed, in which mortars in general and ongoing chemical and physical processes are described. Thesis is further concerned with description of polymer-modified mortars and with explanation of polymer-matrix forming mechanisms. The following are noticed volume changes and experimental methods of their investigation. Experiment is performed by monitoring the volume changes in polymer-modified mortars using two selected methods. For comparison volume changes in gypsum are also measured.
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The effect of the shrinkage reducing additives on rheological properties of high-strength concrete
Červenka, Jiří ; Kucharczyková, Barbara (referee) ; Daněk, Petr (advisor)
Master’s thesis examines the effect of the shrinkage reducing additives on rheological properties of high-strength concrete. The first part is focused on high-strength concrete in terms of their composition and properties. The second part contains a detailed analysis of the cementitious composites shrinkage problems. Total shrinkage is divided into individual elementary shrinkages. For each of them there is a detailed description of causes and factors that affect their sizes. The next part describes the basic additives used to reduce the shrinkage of cementitious composites. The experimental part is focused on verifying the effectiveness of the shrinkage reducing additives during preparation of high-strength concrete. Usage of shrinkage drains for relative strain measurement enables to determine the process of shrinkage immediately after placing the concrete in the form and to obtain the overall curve of the hight-strength concrete volume changes during its setting and hardening. At the end of the thesis, there are overall analysis and summary of the results of the performed experiments.
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Fibre reinforcement with plasma in cement composites
Žižková, Lucie ; Hela,, Rudofl (referee) ; Bodnárová, Lenka (advisor)
The usage of polymer fibres can be increased by the new progressive method of the plasma treatment. This thesis is focused on verification of the influence of the low-temperature treatment on polymer fibres´ surface used in concrete. The treatment of polypropylene fibres in low-temperature plasma is described in the theoretical part. The impact of the treatment on the volume differences of cement composites is also evaluated. The influence of the addition of commercially available fibres and plasma treated fibres on the volume differences of cement composites is also experimentally verified.
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Study of the properties of cement composites with polypropylene fiber modified low-temperature plasma
Žižková, Lucie ; Herka, Petr (referee) ; Bodnárová, Lenka (advisor)
Plasma treatment of polypropylene fibers presents a new progressive method, how to increase the utility properties of these fibers. The thesis is focused on verifying the effect of surface treatment of polypropylene fibers in concrete with low-temperature plasma discharge in the normal atmosphere. The paper describes the procedure for treatment of polypropylene fibers with low-temperature plasma and evaluate the impact of this adjustment on the volume changes of cement composites. It should also be emphasized that the thesis is focused on the initial volume changes, ie volume changes in the early stages of solidification and only for your own mixture, which is not considered an external load. Subsequently, the experimental verification of the effect of the addition made commercially available fibers and fibers treated plasma volume changes to a selected physico-mechanical properties of the test compounds.
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Development of phase composition in silicate systems by available methods and their optimalization
Opravilová, Lenka ; Palou, Martin (referee) ; Škvára, František (referee) ; Havlica, Jaromír (advisor)
One of the most prominent measurable parameters of the development of phases and phase transformations in inorganic systems are undoubtedly the volume changes of silicate matrix. The study of volume changes is crucial in the terms of usable durability of final product. They represent shrinkage or expansion of the material and may lead to significant decrease of technological and ecological parameters and often to complete destruction of these materials. Most often the volume changes can be observed when cement is used as a binder and in concretes, mortars, artificial aggregates and other similar materials. There are many methods to detect, define and determine the volume changes qualitatively or quantitatively. The development of phases was investigated as a part of the dissertation thesis and hence the volume changes were observed under the conditions closest to the real state in the construction industry. The raw materials and admixtures were selected which model the content of hazardous components present in conventional materials (both natural and secondary), used in construction and the relationship with volume changes was searched and demonstrated. The contacts for measuring the volume changes were attached to test surfaces of specimens and the physical - mechanical tests (volume changes, phase changes, strength, etc.), chemical analysis and ecotoxicity tests depending on the length of hydration were performed.
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Volume changes of concrete based on reactive powder components and possibilities of their regulation with chemical admixtures
Hlaváček, Jaroslav ; Kalinová, Helena (referee) ; Opravil, Tomáš (advisor)
Very high strength of RPC allows them to an unusual extreme possibilities of their applications. Volume change (shrinkage) negatively affects their relatively broad range of applications, particularly in applications which are used for filling tubes or other components. In today's advanced time with plenty of chemical ingredients and additives on the market (such as the expansion component) could be a side effect of this largely eliminated, or removed entirely. Only some components of the expansion will be appropriate for RPC cements. This reaserch investigates the expansion of ingredients on the basis of sulfates and monitors not only volume changes, but also the strength characteristics and tolerability of the tested anchors tested with a matrix component of the expansion.
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Experimental and Numerical Analysis of the Volume Changes of Fine-grained Concretes
Odstrčil, Štěpán ; Frantík, Petr (referee) ; Kucharczyková, Barbara (advisor)
This diploma thesis deals with the experimental and numerical analysis of volume changes of fine-grained concrete. Experiments were carried out, measuring both the length changes as well as the mass losses and the internal temperature of the test specimens made from fine-grained concrete. The measurements were divided into two parts (phases). The first phase took approx. 72 hours. The second phase was focused on the long-term measurements and will be completed after stabilization of the mass losses and length changes. In the diploma thesis, the first phase of measurement was elaborated in detail, both in terms of experimental and numerical analysis. In addition, a C # .NET program was created to facilitate the processing of raw measurement data from the data logger. Finally, a comparative calculation was performed according to the model B4, where the result of the calculation was compared with the results of the experiment.
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Development of the anchor expansion silicate based material with thermal resistance
Müller, Jiří ; Bydžovský, Jiří (referee) ; Drochytka, Rostislav (advisor)
The research conducted focused on studying the development of expansive, silicate based- anchor materials that were resistant to high temperatures. The results showed that shrinking is a critical property as volume can change (mainly cause shrinkage) the anchoring materials. This can ultimatly lead to a collapse of a loaded connection. The aim of the study was to summarizing products on the market, to develop the development of anchor matters alone and methodology for testing. Selected were directly related to expansion and thermal resistence.
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