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Possibilities of application of basalt fibers in concrete
Zourek, Milan ; Hela, Rudolf (referee) ; Bodnárová, Lenka (advisor)
This diploma thesis deals with possibilities of application of basalt fibers in concrete and in cementitious composites. In the theoretical part there is a summary of fibers usually used for fiberconcretes. Manufacturing process of basalt fibers is described, and properties of basalt fibers are summarized. Next part deals with properties of basalt fiber reinforced concrete. Concretely fresh properties, physical-mechanical properties, shrinkage and cracking, microstructure and fire resistance. The last chapter deals with fire resistance of concrete in general. The experimental part of this diploma thesis is divided into two phases. There were two mixes of basalt fiber reinforced concrete made with basalt aggregate and one mix of concrete without basalt fibers in the first phase. Density, consistency by slump and air content were determined as fresh properties. As hardened properties density, compressive strength and flexural strength were determined. There was determined the effect of the temperatures 600 and 800 °C on density, compressive strength and outward of specimens. Also, deformation during the high temperature curing was recorded. In the second phase of the experimental part there were three mixes of cementitious composite made with basalt fibers and one cementitious composite without basalt fibers. Density was determined as a fresh property. Material was monitored during its mixing. As a hardened properties density, flexural strength and compressive strength were determined. There was determined the effect of the temperatures 600 and 800 °C on density, flexural strength, compressive strength and outward of specimens.
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Analýza vlastností vláknocementových kompozitních materiálů
Hoško, Marek ; Bydžovský, Jiří (referee) ; Reitermann, Pavel (referee) ; Pavlík,, Zbyšek (referee) ; Bodnárová, Lenka (advisor)
Thesis theme was the issue of sludge waste generated during the production of fiber cement and its reverse implementation into the matrix. The theoretical part of the work has deal with description of Hatschek's fiber cement production technology, technological water system, sludge management and its separation from the system. Experimental part was divided into 5 stages. The first stage was focused on monitoring the qualitative parameters of the sludge waste, which were monitored using selected qualitative tests. In the next stage, was compared the mineralogical and chemical composition of the sludge waste samples with the standard slurry used for production. In the third stage was proposed an alternative method of producing laboratory samples, on which the influence of the addition of sludge on the strength characteristics was verified. In the next step were summarized the results from the previous stages and recipes with waste sludge for production on the production machine were proposed. The fourth stage dealt with the sludge processing itself, its collection and dosing. During the wet production process were evaluated a number of important indicators of the efficiency of production of fiber cement products. Among the most important of them belong percolation and retention evaluation. In the last stage were compared the produced samples with sludge with the standard ones. The samples were subjected to a series of physical-mechanical and durability tests: longitudinal and transverse strength, density, watertightness, impact test, frost resistance, soak-dry, hidden defect method, dimensional stability and warping. The result of the thesis is a comprehensive study on the properties and implementation of sludge waste into fiber cement.
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3D printing technology of concrete structures
Roupec, Josef ; Bodnárová, Lenka (referee) ; Hela, Rudolf (advisor)
Subject of Bachelor thesis was the gathering of information about 3D printing using concrete for designing new possible technologies. List of problems connected with material and technological properties in accordance with 3D printing was developed. Based on these findings new modification of fastener was developed. This fastener works with reaction time of few minutes. Testing was conducted using calorimetric measurements. Findings confirmed the usability of fastener in a cement paste. These results led to design of technology able to use the fastener. This technology was designed for as fast printing as technologically and materially possible in controlled environment. Furthermore, two new technologies for printing of extremely lightweight constructions from UHPC using 3D printing. First uses extrusion technique with screw feeder. Second method is based on binder jetting technology.
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Study of resistance of selected aggregates to high temperatures
Holanec, Aleš ; Sitek,, Libor (referee) ; Bodnárová, Lenka (advisor)
The thesis deals with the monitoring of changes taking place in natural stones and aggregates under high temperatures. The theoretical part of the work provides information about basic groups of rocks, the technology of processing the natural stone and primarily about the study of behavior of natural stone and aggregates at high temperatures. Also some findings from different research works aimed at monitoring the behavior of rocks at high temperatures are presented. In the experimental part a selection of rocks with a higher expected resistance to high temperatures is made, including detailed information and description. Further in this section we provide the comparison of the properties of individual rocks. Later we describe the most important methods of testing, the procedure of preparation of rock samples and we design an experiment to use for evaluation of resistance of rocks and aggregates under high temperatures.
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Study the abrasion resistance of concrete
Kolková, Kristína ; Hela, Rudolf (referee) ; Bodnárová, Lenka (advisor)
The thesis deals with the issues of concrete abrasion resistance and it consists of a theoretical research part and an experimental part. The types of abrasion affecting concrete construction and abrasion effect of flowing water-borne sand are described in the theoretical research part. A substantial part is dedicated to the impact of concrete properties and to each material of the concrete mixture on the abrasion resistance. The impact of addition of various types of fibers is inquired. The mixtures with the addition of 2 kg.m-3 and 4 kg.m-3 of basalt fibers and the addition of 1 kg.m-3 and 2 kg.m-3 of polypropylene fibers are designed in the experimental part. The mixtures are compared to a reference mixture without fibers. Density and consistency of fresh concrete settling at 5 minutes are determined in fresh condition. Density, compressive strength, tensile strength, watertight, concrete absorption and bending tensile strength are determined on hard concrete. The impact of the addition of fibers to the concrete abrasion resistance is inquired using the Bohm abrasion method and wheel abrasion method. A water jet is used as another method for testing abrasion resistance and for comparing the suitability of the used methods.
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Study the concrete abrasion process by water
Boucníková, Veronika ; Hela, Rudolf (referee) ; Bodnárová, Lenka (advisor)
The master thesis is focused on resistance of concrete against to effects of flowing water. In the theoretical part of the thesis mechanical and chemical effects of flowing water were described. The research of aspects that affects resistance of concrete against flowing water was done. Futhermore, the methods that evaluated resistance of concrete against flowing water were described. In the experimental part of the thesis the effect of concrete composition on resistance against mechanical and water abrasion was observed. Abrasive and plain high-speed water jet was used to simulate the effects of water abrasion. After interaction of concrete and water jet the relief and volume loss of material were observed.
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Study of the behavior of selected rocks at high temperatures
Holanec, Aleš ; Sitek,, Libor (referee) ; Bodnárová, Lenka (advisor)
The diploma thesis deals with the observation and diagnostics of transformations that take place in stone slabs of different mineralogical composition during heating to high temperatures. The theoretical part of the thesis deals with a summary of available information about selected types of rocks. Furthermore, it presents findings from the experimental thermal loading of a granite sample. The principles and instruments of laboratory experimental methods that are used to judge the resistance of rocks are described in detail. In the experimental part, the testing methodology is proposed, the procedure of production of rock test specimens is described and the way in which the thermal loading of stone slabs took place is explained. The results of the experiments are shown in the tables and graphs. A comparison of individual tests and properties of selected samples and evaluation of the obtained results is performed.
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ELIMINATION OF NEGATIVE PROPERTIES OF CONCRETE INDUCED BY THE USE OF RECYCLED AGGREGATES USING BASALT FIBERS
Fittl, David ; Nováková, Iveta (referee) ; Bodnárová, Lenka (advisor)
The thesis summarises information about recycled aggregates and basalt fibres, their interaction in composite material such as concrete. It focuses on the potential deficiencies and properties of concrete due to the use of recycled aggregates and on the possibilities of their subsequent elimination of their negative impact by the use of basalt fibres. It characterizes individual raw materials and their interaction in concrete. It includes verification of the properties of the individual sub-components and the resulting concrete itself. An assessment is made of the impact of the use of recycled aggregates on the properties of concrete (compresive strength, static modulus of elasticity, residual flexure tensile strength and others). The thesis discusses the question of whether the same or similar mechanical properties of concrete can be achieved with natural and recycled aggregates using basalt reinforcing fibres. The work provides for the possibility of settlement the values of these concrete parameters by using basalt fibres as a dispersed reinforcement in concrete. The recycled aggregates come from concrete company JARO AS in the north of Norway, where this work was conducted with the financial support from Erasmus+ at The Arctic University of Norway - campus Narvik.
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Study of FRP for concrete reinforcement
Blahová, Aneta ; Prokeš,, Jan (referee) ; Bodnárová, Lenka (advisor)
The diploma thesis aims to analyze bent FRP reinforcements. It describes the method of production of bent FRP reinforcement, examples of application of FRR reinforcement in structures and mentions aggressive influences influencing the durability of FRP reinforcement. Furthermore, an experiment is proposed to monitor changes in straight and bent FRP reinforcement stored in an aqueous environment at 20 °C and an alkaline environment at 20 °C and 40 °C. The output of the diploma thesis is the evaluation of changes in mechanical properties and durability. The condition of the FRP reinforcement is documented using optical and electron mocroscopy.
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BEHAVIOUR OF CEMENTITIOUS COMPOSITES EXPOSED TO HIGH TEMPERATURES
Nováková, Iveta ; Chobola, Zdeněk (referee) ; Sitek,, Libor (referee) ; Wallevik, Ólafur Haralds (referee) ; Pimienta, Pierre (referee) ; Bodnárová, Lenka (advisor)
Fire resistance is becoming increasingly important along with the development of new concrete types with high strength and dense structure with reduced porosity. Such concrete types are susceptible to fire spalling and extensive crack formation. At the moment, there are a limited number of methods for enhancement of fire resistance of existing structures, which could be applied in underground structures with restricted space and limited air exchange, such as tunnels, underground garages or nuclear powerplants. This work is focused on the development of two methods, and both are dealing with porous structure modification. The first method is intentional heat treatment (IHT) method, suitable for the enhancement of fire resistance of existing structures. The second method emphasized the design of air-entrained concrete (AeA-FiResCrete) with the use of “new generation” air-entraining agents suitable for enhancement of fire resistance of newly designed concrete. Testing of compressive strength, porous structure modification was completed by the analysis of “moisture clog,” which contributes to explosive spalling and extensive cracking. The efficiency of developing methods was verified during large-scale testing according to modified ISO834 (m-ISO) curve. No extensive crack formation or explosive spalling was observed during the exposure period during the large-scale testing of slabs with the applied IHT method. The total thickness of the IHT method with configuration IHT200/2, composed of IHT zone and IHT transition zone, penetrated to the depth of 25,5 to 43,0 mm depending upon various concrete types. Moisture clog in AeA-FiResCrete was more significant than in the case of slabs with applied IHT method, and it could be concluded that the IHT method enhances fire resistance of concrete exposed to elevated temperatures without influencing its compressive strength and durability. Results from AeA-FiResCrete testing showed only a slight improvement of its fire resistance.
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