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Effect of plasticizers on the behaviour and properties of alkali activated materials
Langová, Markéta ; Koplík, Jan (referee) ; Kalina, Lukáš (advisor)
Alkali activated materials could be suitable alternative to construction materials based on ordinary Portland cement (OPC). Therefore, it is advisable to pursue these binders further on. Aim of this thesis is to clarify the effect of lignosulfonate-based plasticizer and polycarboxylate-based superplasticizer on the behaviour and nature of alkali activated materials. For the purposes of studying the efficiency of plasticizing additives, the change of workability of alkali activated blast furnace slag in dependence on time, effect of additives on mechanical properties as well as, with usage of isothermal calorimetry, their impact on kinetics of solidification and hardening had been observed. The stability of the plasticizing admixtures in a high alkaline environment such as water glass and sodium hydroxide had been studied using infrared spectrometry. As a last step, X-ray photoelectron spectroscopy (XPS) had been used while clarifying the chemical changes in the structure of plasticizing additives after adsorption to blast furnace slag.
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Durability of alkali-activated systems
Šafář, Martin ; Šoukal, František (referee) ; Kalina, Lukáš (advisor)
Alkali activated binders have the potential to become an alternative construction material to ordinary portland cement binders. This thesis concentrates on durability testing of alkali activated blast furnace slag and fly ash based concrete. The chosen aspects of durability included sulfate resistance, acid resistance, carbonation, freeze-thaw resistance, frost-salt resistance and porosity. Microstructural changes and formation of new crystalline phases were observed using XRD and SEM-EDX analysis. Potential application of the tested material from the durability point of view was evaluated by comparison with a reference ordinary portland cement based concrete.
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Influence of inorganic admixtures on shrinkage reduction of alkali activated materials
Šístková, Pavlína ; Koplík, Jan (referee) ; Kalina, Lukáš (advisor)
This bachelor thesis is focused on the influence of inorganic admixtures on shrinkage reduction of alkali activated materials. In the theoretical part the issue of alkali activated materials is explained in detail focusing on the reduction of their shrinkage. Alkali activated system is constituted by alkali activated blast furnace slag. Firstly, the effect of inorganic dashes is monitored such as low calcium fly ash and finely ground limestone. Furthermore, the influence of inorganic additives for reducing shrinkage has been studied, namely magnesium oxide and calcium oxide. The aim of this work is to determinate the mechanical properties and shrinkage of individual alkali activated mixture and then discuss whether there was a reduction of shrinkage and what the effect of added dashes and inorganic admixtures was.
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Effect of the composition of alkaline activator on the properties of hybrid cements
Šimko, Lukáš ; Vyšvařil, Martin (referee) ; Rovnaník, Pavel (advisor)
Building industry, especially production of Portland cement is the most ecologically and energetically demanding sector. Therefore, there is an effort of using waste products of energy industry as a (partial) substitution of conventional building materials. This bachelor thesis deals with the possibility of using the power station fly ash as a major part of mixtures with Portland cement, and therefore as a hybrid cement. In the experimental part, the influence of silicate module on the characteristics of mortars, whose binder is composed of 20% of Portland cement and 80% of fly ash from Dětmarovice power station, is examined. It further deals with influence of composition of alkaline activator on its characteristics. Its properties are examined in terms of porosity, strength and microstructure. Size and distribution of pores are examined by means of mercury intrusion porosimetry and evaluation of microstructure is based on scanning electron microscopy.
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Possibilities of application of fluidized bed combustion solid residues from municipal waste
Melicher, Daniel ; Solný, Tomáš (referee) ; Opravil, Tomáš (advisor)
The bachelor thesis deals with the use of solid residues from incineration waste products, especially in the construction industry. The aim of the thesis is to test various modifications of solid residues from incineration waste. These secondary materials were tested in bonding systems based on hydratation of portland cement, gypsum made from chemogypsum, quicklime and alkali-activated systems. The aim was to verify whether solid residues from waste incineration could be used as a component of alternative materials for the construction industry.
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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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The development of composites based on alkali-activated matrices resistant to extreme temperatures
Ševčík, Marek ; Šácha, Libor (referee) ; Dufka, Amos (advisor)
The diploma thesis is focused on the development of composites from alkali activated materials (AAM) and their resistance to extreme temperatures. The theoretical part describes alkaline activation and precursors for the production of AAM. Furthermore, the problem of the effect of extreme temperatures on these materials is described. In the experimental part, the optimal silicate modulus with respect to the properties of AAM was gradually determined, and the effect of extreme temperatures on the AAM matrix was verified. In the next stage, the effect of the filler with respect to the behavior at extreme temperatures was tested and then the final formulation was optimized.
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Influence of ionts on the efficiency of shrinkage reducing admixtures in alkali activated systems
Vašíčková, Kateřina ; Bílek, Vlastimil (referee) ; Kalina, Lukáš (advisor)
Alkali activated materials, especially when activated with waterglass, are subjected to substantial drying shrinkage that hinders their broader industrial application. The effect of shrinkage reducing admixtures (SRA), based on poly(propylene glycol), on drying shrinkage of alkali activated blast furnace slag (BFS) mortars was studied. The aim of this thesis is to determine the efficiency of SRA as well as the influence of different type of alkali activator with varying silicate modulus on drying shrinkage characteristics. It was observed that the high amount of alkalis positively influenced the effect of SRA. The higher the amount of alkalis, the lower the drying shrinkage was. It also caused more water to be incorporated in the alkali activated structure and prevent it from evaporation. Thus, the weight change of such mortars was the lowest. Reduced effect of SRA on mechanical strength properties was observed in mortars with low amount of alkalis which was connected with delayed hydration resulting in insufficient amount of created C-S-H gel. The presented thesis further discussed and underlines the role of different kinds of alkali ions as well as their amount on the properties of alkali activated BFS systems.
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On the efficiency of plasticizing admixtures in alkali-activated slag based system
Flídrová, Michaela ; Šoukal, František (referee) ; Kalina, Lukáš (advisor)
Alkali-activated materials (AAM) are construction materials with great potential, especially for their environmental friendliness, but also due to their mechanical properties. Therefore, it is appropriate to pay further attention to these binders. This diploma thesis deals with monitoring the effectiveness of plasticizers in connection with the surface chemistry of the alkali-activated slag system. Sodium hydroxide and sodium water glass were used as alkaline activators for the preparation of alkali-activated blast furnace slag-based systems. To study the effectiveness of the lignosulfonate plasticizer, yield stress, heat flow, adsorption and zeta potential were monitored depending on the amount and time that the plasticizer was added to the system. The results show that the type of activator used in the mixtures plays an important role. NaOH-activated samples revealed the best efficiency of lignosulfonate plasticizers. A key factor in studying the behavior of the studied mixtures was the measurement of the zeta potential, which provided insight into the surface charge of blast furnace slag particles related to the ability of lignosulfonate to adsorb on grains of alkali-activated slag.
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The development of composites based on inorganic binders designed for the extreme applications
Janoušek, Petr ; Šácha, Libor (referee) ; Dufka, Amos (advisor)
The topic of this master's thesis is the development of composite materials based on inorganic binders for use in extreme conditions. It means especially geopolymeric or alkali activated materials (AAM) based composites. The theoretical part of this thesis summarizes knowledges about the development and use of alkali-activated materials, their structure and mechanisms of their formation. It also deals with the applicable raw materials for AAM and their exciters, which are in particular water glass and sodium hydroxide. There also have been a summary of the effects of high temperatures and chemicals on the mechanical properties of AAM and the requirements of standard EN 1504-3 for repairing materials. The task of the practical part was to develop a repair mortar for concrete structures based on AAM so that its production was as simple as possible, ie one-component materials. Gradually six recipes have been develeoped. Test specimens made from these recipes have been putted to selected tests according to the requirements of ČSN EN 1504-3.
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