|
|
: Development of special high strength concrete with low volume changes
Meruňka, Milan ; Hela,, Vlastimil (referee) ; Hela, Rudolf (advisor)
The bachelor thesis deals with problems of volume changes of concrete, especially shrinkage of concrete. Types of concrete changes, causes, occurrences, and ways to eliminate them are described. The experimental part is focused on monitoring the volume changes of concrete within 28 days of maturing using a different type and dose of shrinkage reducing additions, a summary of cement pastes within 24 hours of mixing, the development of temperatures of the hydration temperatures of concrete and cement pastes.
|
|
|
Studium a vývoj polymer-cementových kompozitů s důrazem na vysoký obsah druhotných surovin a kompenzaci objemových změn
Hermann, Radek ; Bydžovský, Jiří (referee) ; Reitermann, Pavel (referee) ; Kolísko, Jiří (referee) ; Drochytka, Rostislav (advisor)
Reducing of humanity's carbon footprint is currently one of the main directions of global research. Another significant problem is the disposal, recycling and secondary use of waste materials produced from a wide range of industries and municipal waste. This thesis deals with the problematics of polymer-cement composites, which are most often used for rehabilitation, reprofiling and structural repairs, especially of concrete structures. The thesis examines and verifies the possibilities of utilization of a large amount of secondary raw materials and waste as a substitute for cement as a primary binder. At the same time, the work deals with the full replacement of the primary filler with waste raw materials, for which there is currently no other use. The work also addresses and verifies the influence of several commonly available commercial polymer dispersions. The work deals with the use of liquid, but also powdered polymeric additives of various bases. The work also deals with the problematics of volume changes of the hydration process of polymer-cement composites and the effect of volume changes on the physical-mechanical properties of composites. The influence of volume changes that occur during the hydration of polymer-cement composites is a significant criterion in the selection and use of these composites. The volume changes of the material have a great influence especially on the maximum layer thickness and the maximum area that can be repaired with the material without the risk of cracks and the need to create a working joint. The results of this work are associated with a reduction in the economic and environmental impacts of production and use of polymer-cement building materials and increase the usability of these materials mainly due to the possibility of remediation of larger areas than previously possible.
|
|
|
Possibilities of reducing shrinkage of concrete and development of concrete recipes with limited shrinkage.
Stoklásek, Martin ; Louda,, Pavel (referee) ; Hela, Rudolf (advisor)
The bachelor thesis deals with the issue of volume changes of concrete and their causes. The theoretical part describes the various types of volume changes in concrete and the causes of their occurrence. Influence of concrete mix design and concreting conditions on volume changes. Methods for reducing volume changes are also addressed. The experimental part is focused on the development of recipes with limited volume changes. In which the development of shrinkage is monitored from an early age up to 60 days and at the same time the development of compressive strengths at 2, 7, 28 and 60 days is also monitored.
|
|
|
Study of the influence of composition and curing of self-leveling cement screeds on their properties in the early stage of maturation
Powetz, Dominik ; Štenko,, Miroslav (referee) ; Šťastník, Stanislav (advisor)
The diploma thesis deals with the study of the influence of composition and curing of self-leveling cement screeds on their properties in the early stage of maturation. Within this work, various concepts of ensuring the volume stability of cement self-leveling screeds were verified. An anti-shrink additive based on neopentyl glycol and an expansion additive based on hard-burnt lime were used as modifiers. The reduction of plastic and overall shrinkage using various types of liquid membrane-forming compounds was verified on the most volume-stable screed using the optical dilatometry method. The effectiveness of the individual solutions was monitored by continuous measurement of the intensity of evaporation from the screed surface. Subsequently, the effect of membrane-forming compounds on the residual moisture of the cured treated cement self-leveling screed was measured by the carbide method and also the effect of this curing on the adhesion of bonded ceramic tiles.
|
|
|
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.
|
|
|
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.
|
|
|
Study of possibilities of reduction of volume changes and development of hydration temperatures in concrete
Pikna, Ondřej ; Ťažký, Tomáš (referee) ; Hela, Rudolf (advisor)
Volume changes are one of the priority characteristics of concrete that plays an important role place mainly in the durability of structures as such. These low volume changes are required especially for structures as: industrial concrete floors, massive structures and waterproof structures. One of the possibilities in reducing these changes is the use of mineral admixtures with suitable grain curve of aggregate. Another possibility is the use of shrinkage reducing admixtures. There can occur problem with efficiency (long term age) with other components of the mixture. Therefore, the effort of this work is to use the avaible processes for maximum reduction of shrinkage and hydration temperatures.
|
|
|
: Development of special high strength concrete with low volume changes
Meruňka, Milan ; Hela,, Vlastimil (referee) ; Hela, Rudolf (advisor)
The bachelor thesis deals with problems of volume changes of concrete, especially shrinkage of concrete. Types of concrete changes, causes, occurrences, and ways to eliminate them are described. The experimental part is focused on monitoring the volume changes of concrete within 28 days of maturing using a different type and dose of shrinkage reducing additions, a summary of cement pastes within 24 hours of mixing, the development of temperatures of the hydration temperatures of concrete and cement pastes.
|
|
|
Analysis of selected silicate based composites volume changes
Kubeš, Pavel ; Šimonová, Hana (referee) ; Keršner, Zbyněk (advisor)
This diploma thesis deals with the analysis of volume changes of selected silicate based composites. The first part introduces the issue of volume changes of concrete, especially the shrinkage process, two selected models for shrinkage prediction, describes configuration and course of performed tests, as well as the processing of measured experimental data. The second part contains input data modified by the program GTDiPS and another calculated parameters. The result of the work is the evaluation of the influence of thermal dilation on the development of shrinkage of young concrete. Another output is the comparison of accuracy of the two selected prediction models to capture the course of measured shrinkage.
|
|
|
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.
|
guest ::
