|
| |
|
|
The Influence of different Types of Fiber-reinforcement on the Behavior of Concrete Slabs
Wünsche, Dominik ; Žítt, Petr (referee) ; Kocáb, Dalibor (advisor)
The bachelor‘s thesis deals with the issue of concrete, specifically self-compacting concrete, fiber concrete and other types of concrete used. The work consists of two parts, the theoretical one, which will deal with the properties of the concrete. It describes the individual test methods used in the practical part. The test methods are the ultrasonic pulse method, the resonance method, the static modulus of elasticity, the compressive strength, and especially flexural strength. The second part is a practical part, which is processed by an experiment. In the experimental part, it will be mainly about carrying out tests of self-compacting concrete slabs and concrete with the addition of steel fibers. Subsequently, selected characteristics of concrete are determined and the whole experiment is evaluated.
|
|
|
Initiation of stable crack propagation of selected building composites
Majtánová, Romana Viktória ; Veselý, Václav (referee) ; Keršner, Zbyněk (advisor)
The purpose of my bachelor’s thesis is study of the effects of fibres in normal-weight concrete and light-weight concrete. Specimens were prepared from concrete with polypropylene fibres FORTA FERRO of three different lengths – 19, 38 and 54 mm – and also reference concrete (without fibres) was prepared. This thesis contains gradual evaluation of fracture tests on specimens from mentioned materials. The used fracture test was a three–point bending fracture test on beams with a central notch. From the measured load–deflection in the middle of span and load–crack mouth opening displacement diagrams were determined values of modulus of elasticity, unstable fracture toughness, initiation part of fracture toughness and also load level for beginning of stable crack propagation composites. For determination was used „double–K“ fracture model. For illustration is described evaluation using the effective crack model.
|
|
|
Study of properties of cement composites with addition of polymer fibers
Dokoupil, Tomáš ; Hela, Rudolf (referee) ; Bodnárová, Lenka (advisor)
The bachelor thesis deals with the use of polymer fibers in cement matrix. It describes the distribution and production of the most commonly used polymer fibers as well as the requirements for their properties. A comparison of the properties of different types of polymer fibers is given. The work presents the individual components of the fiber concrete matrix, its production, testing of fresh and hardened fiber concrete and specific examples of its use in practice. Using professional research, the influence of PP, PE and PVA fibers on the properties of fresh and hardened concrete is described in detail. New trends in the use of polymer fibers are also presented. At the end of the work, a procedure of experimental verification of the properties of fiber-reinforced concrete in comparison with a reference sample of plain concrete is proposed.
|
|
|
Study of the properties of concrete with reinforcement, intended for the production of concrete egg-shaped tubes
Šťastný, Antonín ; Hela,, Vlastimil (referee) ; Hubáček, Adam (advisor)
This diploma thesis examines the properties of concrete with reinforcement, designed for the production of a concrete egg-shaped tubes . The stress is put on using various types of fiber reinforcements. Theoretical part is divided into 4 subsections. The topic of the first subsection is a concrete in general. Second subsection deals with various technology of production of concrete pipes. The third subsection is focused on description and summary of basic properties of concrete and reinforced concrete tubes. The last subsection deals with standardized procedures for testing concrete. Experimental part of this thesis is divided into two subsection. First subsection deals with design of a reference sample. Six different samples of a concrete were designed and their rheological properties were tested. Second subsection deals with the additi-on of various types of fiber reinforcement to the reference sample. Eight different admixtures of a concrete were added to the reference sample. Properties of these admixtures were tested in fresh and hardened state.
|
|
|
Development glass-concrete of with high mechanical properties
Plochý, Ondřej ; Lederer, Peter (referee) ; Hela, Rudolf (advisor)
This master thesis summarizes the current knowledge regarding the design and properties of glass fiber reinforced concrete products. It also deals with the design of a new concrete recipe for Dako spol. s.r.o company. There is verified effect of changes in input materials in real conditions the company to increase tensile bending strength above 20 MPa.In particular, verification of the use of building chemistry like superplasticizing additives, polymer-cement matrix or a change type or dose of glass fiber.
|
|
|
Usability of basal fibres in cement composites
Kolková, Kristína ; Hela, Rudolf (referee) ; Bodnárová, Lenka (advisor)
The bachelor thesis deals with issues of using basalt fibers in cement composites and it consists of a theoretical research and an experimental part. In the theoretical research is a description of properties of basalt fibers, production technology and behavior of fresh and hard concrete with addition of basalt fibers. There is mentioned an example of application in practice of basalt fibers for a reconstruction of a bridge construction. The theoretical research also deals with more possibilities of use of products made from melted basalt. In the experimental part was verified behavior of fresh and hard concrete with the addition 3, 10 and 20 kg.m-3 of short basalt fibers. These mixtures were compared with the reference mixture from plain concrete. There was determined the consistency in fresh condition by the slump test, the density and the air content. The flexure strength, compressive strength and tensile strength were determined on hard concrete samples in age of 28 days. The presence of basalt fibers was detected by an electron scanning microscope.
|
|
|
Influence of the type of dispersed reinforcement on selected properties of concrete
Gajdušková, Patricie ; Křížová, Klára (referee) ; Sedlmajer, Martin (advisor)
This thesis is focused on the usage of fibers in concrete. The fibers are dispersed reinforcement which may have different behaviour based on the material characteristics or the geometric shape of the fibers. Due to this, we may predict the appropriate application of fibers and possibly improve mechanical properties of concrete. At the same time, the influence of used fibers on the behaviour of the concrete when exposed to high temperatures, thus the fire resistance of material, is observed. The purpose of this thesis is to compare the properties of the individual fiber types in concrete, which are suitable for specific application of fibre reinforced concrete.
|
|
|
Verification of the effect of fine fibers and absorbent additives on the process of self-healing concrete
Dokoupil, Tomáš ; Ťažký, Tomáš (referee) ; Hela, Rudolf (advisor)
The diploma thesis deals with self-healing of concrete composite. In the theoretical part, it represents the effect of polymer microfibers on reducing the development of cracks and on improving self-healing properties. It also describes the most commonly used types of bacteria used to enhance the self-healing process and their effect both alone and in interaction with fibers, calcium sources and absorbent additives. It also represents auxiliary additives in the form of superabsorbent polymers. In the practical part, it verifies the influence of the above elements and describes how much the self-healing of concrete has been enhanced by the use of combinations of fibers, absorbent polymers and a source of calcium in the form of calcium lactate. It also indicates whether the self-healing properties used were not improved at the expense of deteriorating the mechanical properties of the composite.
|
|
|
Experimental Investigation of the Influence of the Type of Fibres on the Behaviour of Fibre Concrete
Hanuš, Petr ; Vymazal, Tomáš (referee) ; Kocáb, Dalibor (advisor)
This diploma thesis deals with the comparison of different properties of fibre-reinforced concrete according to the type of fibres. The main monitored property is flexural strength, tested on prisms with a cross section of 150x150 mm and a length of 600 mm. Four concretes of natural aggregate and four concrete of lightweight aggregate were prepared for the experiment. There were 2 reference concrete and 6 fibre-reinforced concrete. Three types of fibres were used: steel, polypropylene and glass. More than 2500 kg of concrete was produced. The aim of the thesis is to assess the influence of fibres on the flexural strength and other characteristics of fibre-reinforced concrete.
|
guest ::
