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Reduction of efflorescence in the geopolymer systems
Suchý, Rostislav ; Šoukal, František (referee) ; Kalina, Lukáš (advisor)
Alkali metal cations are weakly bound in the structure of alkali activated materials. This fact causes the formation of undesirable efflorescence in humid environment. In this work, the effect of fluoride additives, which significantly reduce the efflorescence, was investigated. The chemical mechanism of selected additive in the modified binder was studied based on XRD, SEM EDX and ICP OES analysis. Also the effect of the added fluorides on the mechanical properties of the final product was monitored.
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Optimization of concrete mixture based on alkali activation of secondary materials
Šafář, Martin ; Šoukal, František (referee) ; Kalina, Lukáš (advisor)
This bachelor thesis deals with design, preparation and optimization of concrete mixture based on alkali activated secondary materials – blast furnace slag and fly ash. Sodium hydroxide partially replaced by bypass cement kiln dust was used as an activator. Mixture design was based on model made for Portland cement based concrete. Observed properties were workability of fresh mortar, price of mixtures and mechanical properties of concrete. Microstructure and composition of concrete was studied by SEM-EDX and XRD. Analysis of raw materials was based on XRF. The optimal mixture composition was chosen from obtained data.
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Reinstating of concrete floors on alkalic way
Straděj, Tomáš ; Šiler, Pavel (referee) ; Opravil, Tomáš (advisor)
The work deals with the reinstanting of concrete floors by alkali way. The section deals with concrete, its development, production, use, and substances from which it is made. The second part deals with connective systems based on portland cement concrete flooring applications and possibilities of their reinstanting through alkaline. The thesis proposal for the reinstanting of the floor and describes the laboratory experiment.The last part contains information of practical measurements and conclusions drawn regarding the suitability of repair methods and resources for concrete floors different alkali and their combinations.
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Mosaic geopolymeric thin-film plasters for decorative applications
Svidroňová, Barbora ; Šiler, Pavel (referee) ; Šoukal, František (advisor)
This bachelor thesis deals with preparation of mosaic geopolymeric plasters, used fillers and it observes their influence on the final properties of geopolymeric plaster. The aim of the study is the selection of proper raw materials for filler, the determination of optimal filler-to-sand ratio and the preparation of plaster with proper shade of colour. In experimental part, during the detection of adequate ratio of raw materials, there were prepared beams from several types of metakaoline, sand, water and water glass. The beams were tested for compressive strength and bending. The blasters themselves were watched for their applying, hardness, shades of colour and efflorescence.
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Thin-film geopolymeric plasters for exterior application
Ručková, Jana ; Opravil, Tomáš (referee) ; Šoukal, František (advisor)
This thesis is dealing with preparation of exterior thin-layer geopolymer plaster where the effect of supplement of various types of superplasticizers in their different amounts on the quality of geopolymer plaster is studied. The objective of this work is to determine suitable type of superplasticizer which would improve rheological quality of fresh plaster mix, its adhesion to the surface and last but not least would preserve good mechanical qualities of geopolymer binder. In the experimental part initially test subject were prepared from meta-kaolin, water, water-glass, sand and with supplement of various types of superplasticizers in various amounts. These test subjects were tested for compressive and flexural strength. Further workability and adhesion to the surface of these plaster pastes was observed. Geopolymer pastes were also subjected to calorimetric comparison of kinetic processes occurring during solidification and hardening. In order to identify the exact composition of superplasticizers used as rheological modifiers, the infra-red spectrometry of these substances was performed. There was a need to specify the water-glass in more detail as well, elemental analysis was performed on it on radiographic fluorescent spectrometry. To closer identify the structure and distribution of superplasticizer in geopolymer paste the pictures of the mix which was the most suitable for use for exterior thin-layer geopolymer plasters were made on scanning electron microscope. On the same mix radiographic diffraction on the powder samples was also performed which served for phase analysis.
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Preparation and characterization of concretes based on blended geopolymeric binder
Bulejko, Pavel ; Straka, Radek (referee) ; Šoukal, František (advisor)
This bachelor thesis focuses on preparation of concretes based on alkali activated binding systems (geopolymers). Finely ground blast-furnace slag was used as a basic aluminosilicate compound for preparation of an alkali activated binder. A mixture of sodium water glass and 50 % KOH solution, which was replaced by cement kiln dust in some cases, was used as an activator. The prepared testing samples (columns 40x40x160 mm) were mechanically tested for strength and the influence of the substitution of KOH solution by cement kiln dust on strength was observed. Then the work aims at structure analysis of binders prepared – the thermal analysis was carried out and the phase composition was explored with RTG diffraction.
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Solubility of power plant fly ashes in high-alkali environment
Kejík, Pavel ; Opravil, Tomáš (referee) ; Šoukal, František (advisor)
This work deals with study of alkali activated ashes from high-temperature and fluidized bed coal combustion in thirteen powerplants in Czech republic. A solution of 50% sodium hydroxide was used as an alkali activator in this case. Because the two main elements of these secondary raw materials are silica and aluminum, the main part of the work is study of their evolution to solution and dissolve time dependence. The second part is comparing of the phase composition of powerplant ashes before alkali activation and after that.
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Preparation of geopolymeric binders based on power plant fly ashes
Jevická, Lucie ; Opravil, Tomáš (referee) ; Šoukal, František (advisor)
This thesis deals with preparation of geopolymeric binders based on power plant fly ashes by alkali activation. It studies influence of different types ashes content in pastes on setting and final properties of geopolymeric binders. The aim of study is determination of optimal ratio of raw materials to reach the best possible characteristics of final binder. Ashes from high-temperature and fluidized bed coal combustion were used for experimental works. Mass content of ashes in tested mixtures and total ratio of oxides crucial for polycondensation and geopolymeric structure formation were chosen as major input parameters. Calorimetric measurements of tested mixtures fresh pastes were implemented to learn about setting process. Hardened binder specimens were tested for bending and compressive strength.
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