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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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Machining of hardened parts
Heiserová, Sofia ; Sliwková, Petra (referee) ; Polzer, Aleš (advisor)
The usage of quenched materials in industrial production leads to the application of hard machining. Higher requirements for machines and cutting tools are needed during hard machining than during conventional machining. Quenched materials carry problem of volume and geometric changes after quenching and after machining as well. It is necessary to think about volumetric compensation in advance, before quenching of the workpiece. An experiment is suggested for optimalisation of longitudinal turning of steels 42CrMo4 and 50CrMo4. Hard turning has notable benefits such as flexibility of cutting tools and elimination of coolants, which provides ecological benefits. However, the disadvantages are higher tool wear and high prices of tools.
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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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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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The Use of Tensograf for Optimization of the Composition of Mortars
Hrbáček, Matěj ; Melichar, Tomáš (referee) ; Žižková, Nikol (advisor)
Bachelor thesis is focused on monitoring of volume changes in concrete composites. Using Czech and foreign literature searches are processed, in which mortars in general 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. The last part describes in detail the Tensograf TGF-02. Experiment is performed by monitoring the volume changes in polymermodified mortars using Tensograf TGF-02 and it is verified its suitability for the subject matter.
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Study of the influence of aggregate composition on volume changes and mechanical properties of High Performance Concrete
Vobinušková, Kristýna ; Hela, Rudolf (referee) ; Bodnárová, Lenka (advisor)
The master´s thesis deals with the volume changes of concrete during its concrete glow. These volume changes are generally more susceptible to high-strength concretes – HSC, which contain a bigger dose of binder. The theoretical section describes the possible reduction volume change especially in HSC, which are focused on the composition of concrete, especially on the type and particle size distribution of aggregate. Then attention is also paid to the different types of cements and their possible substitution. The part of the theoretical work describes the types of volume changes that may occur. In the experimental part are suggested the HSC by to secure informations. Different kinds of aggregates are used and a continuous or discontinuous grain curve and a different maximum grain size. Part of the sample was made only from CEM I 42,5 R and the second part of the sample from CEM I 42,5 R with the addition of very finely ground limestone. In terms of the part of the work were monitored volume changes of concrete with different composition and also their mechanical properties after 7, 28 and 90 days. Specifically, compressive strength, tensile strength, strength of the surface layers of concrete, water absorption and water-permeability test concrete. In conclusion, are listed all the results of tests.
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Quick Setting Road Cement
Coufal, Daniel ; Jiroušková, Kateřina (referee) ; Fridrichová, Marcela (advisor)
The thesis deals with the study of magnesium oxide burned by various burning regimes and his possibilities of its usage as potential expansion additive. The theoretical part of the thesis concerns mainly the volume changes and how they can be influenced. The practical part focuses on monitoring morphology, phase composition and the hydration process of magnesium oxide.
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