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Effect of selected activators on the properties of alkali-activated composites reinforced with basalt fibers
Švardala, Daniel ; Hrubý, Petr (referee) ; Kalina, Lukáš (advisor)
This paper deals with the alkali activated materials (AAM) applicable as a construction material, thanks to low cost, environmental friendliness and good mechanical properties. The goal of this thesis is to search for suitable alkaline activator with respect to the final properties of alkali activated composite reinforced with basalt fibers. This thesis is focused on the determination the effect of basalt fibers addition on the mechanical properties. The influence of alkaline activator to basalt reinforcement was determined by simply strength tests, like the compressive and flexural strength measurements. The matrix fiber interaction, as one of the main parameters indicating the quality of the material reinforcement, was measured by electron scanning microscope equipped with an X ray energy dispersing analyzer (SEM EDS). It was found out that the most significant effect on the improvement of the mechanical properties of alkali activated material was in the case of the samples activated by sodium and lithium waterglass. The mechanical strength of these reinforced materials was considerably higher compared to non reinforced samples. AAM activated by potassium waterglass with and without the basalt reinforcement indicates the same or very similar mechanical strength. The comparison of composites with different alkaline activator leads to the conclusion that the mechanical properties depend on the type of used waterglass. AAM activated by sodium waterglass achieve the highest strengths compared to potassium and lithium waterglass activated materials and therefore seems to be the most appropriate for basalt fiber composites preparation.
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Setting control of alkali-activated systems
Komosná, Kateřina ; Novotný, Radoslav (referee) ; Kalina, Lukáš (advisor)
This thesis is focused on the possibilities of setting control of alkali-activated systems based on blast furnace slag. The aim of this work is finding the suitable retarder that most extends the time of setting and also preserves the mechanical properties of alkali-activated material. In experimental section were prepared samples of blast furnace slag, water glass, water and additives in various weight addition. Testing samples have undergone of flexural and compressive strength tests. Then the setting time was determined using the Vicat device. The samples were measured calorimetrically because of monitoring the setting process. Finally the mixtures were observed using scanning electron microscope for a closer view on the structure of samples and distribution of setting retarder.
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Effect of flexural loading on electrical properties of alkali-activated slag composites
Šimko, Lukáš ; Kusák, Ivo (referee) ; Rovnaník, Pavel (advisor)
Ordinary concrete is the most commonly used building material, but nowadays the requirements for low energy consumption, durability of structures together with their easy diagnostics as well as ecological production raises. This thesis deals with cement and aluminosilicate composites with content of conductive fillers, which allows to monitor the change in electrical properties, most commonly electrical resistance in dependence on mechanical stress. In the experimental part of the thesis, test beams were produced based on alkali-activated slag with content of carbon nanotubes, graphite powder, carbon black and carbon fibre. The beams were subjected to flexural loading in a three-point bending configuration and the shift in electrical resistance was monitored.
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Optimization of the concrete composition with the use of recycled concrete aggregates
Skriňáková, Eva ; Holák, Michal (referee) ; Hela, Rudolf (advisor)
Concrete as a building material is subject to continuous innovation and thanks to advanced technology and quantum of research, its properties are still improved. It is logical that the more concrete we produce, the more waste it arises. The volume of this waste can not be stored in landfills endlessly, nowadays most of the waste economies in the world are trying to recycle concrete rubble. The recycling is not such a problem, the technology has been long verified but the quality of the recycled concrete aggregate is unquestionably one of the primary assumption which leads to accomplish required properties of concrete. In fact, the recycling process is „crushing“ the concrete into particles with an effort to eliminate the cement paste on the surface of the aggregate. An ideal solution would be create a resistant and firm coating that would adhere perfectly to the cement matrix. This diploma thesis is focused on the properties of recycled concrete aggregate and methods of improvement and optimization of the concrete mix composition.
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High-performance concretes based on the secondary raw materials
Sáček, Josef ; Brandštetr, Jiří (referee) ; Šoukal, František (advisor)
This work is devoted to study of physical-mechanical properties and structure of high performance concretes (HPC) based on portland cement. The attention is focused on possibility of substitution of economic high-cost components of concrete with utilization of secondary raw materials or cheaper components. Properties of raw materials and their influence on whole quality of concrete were tracked by various methods. Mechanical properties of prepared HPC samples were tested especially (compression and flexural strength) with further microscopic study of structure. Isoperibolic calorimetry and X-ray powder diffraction method were also used for concrete characterisation. These methods allowed to determine the influence of raw materials on prepared HPC and to carry out a certain optimization among price and quality of this material.
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Possibilities of using plasticizers and superplasticizers in alkali-activated systems
Langová, Markéta ; Švec, Jiří (referee) ; Kalina, Lukáš (advisor)
Bachelor thesis deals with the preparation and properties alkali activated blast furnace slag after addition of the different types of plasticizers and superplasticizers with the different weight percentage amount. The aim of this thesis is to find suitable plasticizers or superplasticizers which would improve both workability and mechanical properties of alkali activated blast furnace slag. The effect of these admixtures on compressive and flexural strength was determined. In conclusion the behaviour of plasticizing admixtures in alkaline environment through the infrared spectrometry is studied.
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Elemental composition analysis of inorganic materials
Szmek, Václav ; Richtera, Lukáš (referee) ; Zmrzlý, Martin (advisor)
This work deals with elemental analysis of inorganic materials, that are presented by blast furnace slag and geopolymeric material containing fly-ashes. In the theoretical part there are explained principles of elemental analysis of inorganic materials. Ways of dissolution of samples, optical emission spectroscopy and electron microscopy with energy dispersive x-ray analysis are commented. In experimental part the ICP analysis of oxide standards is described. The standards were used for estimation of EDS-correction factors. Then follow the preparation, proving and use of standards in analysis of blast furnace slag. The work is finished by exact analysis of concentration profiles of elements in interface of phases in geopolymeric material.
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The influence of different anions on fixation of Cu in alkali-activated blast furnace slag
Böhm, Petr ; Kotrla, Jan (referee) ; Koplík, Jan (advisor)
The work deals with the fixation of copper in alkali activated blast furnace slag and with the influence of anionts (sulphate, nitrate, chloride and oxide) to its immobilization. This is tested according to leaching tests ČSN EN – 12457 4. The concentration of copper in leachates was determined by inductively coupled plasma optical emission spectrometry. The aim of this work is to check the influence of addition (copper) to the resulting mechanical properties and also specify, how the heavy metal is bonded in the matrix. The structure was examined by scanning electron microscopy.
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Utilization of basalt fibers in alkali activated materials
Hrubý, Petr ; Šoukal, František (referee) ; Kalina, Lukáš (advisor)
Alkali activated materials (AAMs) represent construction materials with a huge potential especially because of environmental and economic aspects but sufficient mechanical properties as well. A fibre or fabric reinforcement of the AAMs could support more widespread application potential due to the mechanical properties, fracture toughness or composite durability improvement. Various alkaline activators were used for a blast furnace slag (BFS) activation to produce a suitable matrix for basalt fibres (BF) implementation in this thesis. The BFs represent applicable reinforcing material because of its favourable mechanical and thermal properties. Still, the utilization of BFs in the AAMs is quite limited due to the fibres low chemical stability under the alkaline conditions. Accelerated leaching tests with a determination of basalt fibres chemical composition same as tensile strength change using various analytical techniques (XRD, XPS, SEM-EDX, ICP-OES) have confirmed these assumptions. An influence of basalt fabric reinforcement in one or more layers on the mechanical properties was determined with the meaning of the compressive and flexural strengths. The fibre/matrix adhesion and transition zone properties were studied using SEM-EDX and pull-out tests as well because they are crucial parameters for the composite material reinforcement efficiency.
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