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Effect of ground limestone addition on properties of cement-slag binder systems
Bílek, Vlastimil ; Másilko, Jiří (referee) ; Opravil, Tomáš (advisor)
This thesis deals with the effect of ground limestone addition on properties of cement-slag binder system. The evolution of compressive and flexural strength of binary and ternary systems (pastes), where 25 % of cement was substituted by one or two admixtures in different ratio, were determined and mutually compared. Granulated blast furnace slag and three different limestones were these admixtures. Two of that limestones were natural and one was prepared by a precipitation. For comparison, mixtures, where ash was added insted of slag, were prepared. The mechanism, by which finely ground limestone participates in hydration process, was studied by conduductometric measurements of systems simulating conditions in fresh pastes, and by TG-DTA method, which was used to determination of added limestone amount which remains in its original form and the amount which participates in the formation of hydration products.
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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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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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Methods of using cement kiln by-pass dust in building materials technology
Sikorová, Věra ; Koplík, Jan (referee) ; Kalina, Lukáš (advisor)
This diploma thesis is focused on methods of using cement kiln by-pass dust in building materials technology. By-pass dust was treated to remove chlorides and could then be used as other constituent to various types of cements in the amount of 0–5 wt. % according to ČSN EN 197-1. The properties of dusts before and after chloride removal were examined and after incorporating modified by-pass dust into the cement, the properties of fresh and hardened cement pastes and mortars were studied. It was found that modified by-pass dust after incorporation into cement fulfill requirements of ČSN EN 197-1.
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Effect of activator type on rheology of alkali-activated slag
Markusík, David ; Smilek, Jiří (referee) ; Bílek, Vlastimil (advisor)
This work deals with rheology of alkali-activated slag pastes (AAP) because of importance of these properties in building connectors for processing and application. The effects of different concentrations of sodium and potassium hydroxides activation solutions on the rheological properties of prepared AAP are examined. For the basic characterization of activation solutions, rotational and rheological measurements of AAS were made, and were compared to measurements from the flow table. Dependences of setting time on the activator concentration and rheological and calorimetric monitoring of hydration progress were also investigated. The findings prove a major influence of concentration and activator type on any determinations made. In pastes activated by potassium hydroxide, fluidity increases with increasing concentration, which correlates with increases in values on the shake table. In case of sodium hydroxide, with the increasing concentration, fluidity increases up to 25 wt. %. The following sharp reduction in fluidity correlates to the values on the flow table as well as with the storage modulus courses from oscillation measurements. In the first minutes after mixing, there was evidence of a sharper increase in yield point for pastes with higher activator concentrations.
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Action of organic additives in various alkali-activated binders
Markusík, David ; Kalina, Lukáš (referee) ; Bílek, Vlastimil (advisor)
This thesis explores the influence of admixtures (lignosulfonate plasticizer, hexylene glycol) on the rheology of AAM. With the characterized precursors, the rheology of AAM without admixtures is examined based on the chosen activator. Then the influence of the additives was measured. Rheological measurements were complemented by the determination of LS admixture adsorption on chosen precursors in solutions of NaOH, NaVS, and Na2CO3, and the determination of zeta potential of chosen plastified AAP. For comparison, measurements of cement pastes with the same admixtures were made in parallel to the AAM. the ability of plasticizer to improve the workability of slag and fly ash-based AAM when activated by NaOH was observed. No plastifying effect was found in MK-based pastes in none of the studied environments. The rheological measurements are in accord with most of the measured adsorptions and determined zeta potentials. In the case of hexylene glycol, the rheology of pastes is primarily influenced by the combination of precursors and admixtures. With hexylene glycol admixture the NaVS activator is inapplicable because silicates and hexylene glycol interact and worsen the rheological properties of the AAP.
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Action of organic additives in various alkali-activated binders
Markusík, David ; Kalina, Lukáš (referee) ; Bílek, Vlastimil (advisor)
This thesis explores the influence of admixtures (lignosulfonate plasticizer, hexylene glycol) on the rheology of AAM. With the characterized precursors, the rheology of AAM without admixtures is examined based on the chosen activator. Then the influence of the additives was measured. Rheological measurements were complemented by the determination of LS admixture adsorption on chosen precursors in solutions of NaOH, NaVS, and Na2CO3, and the determination of zeta potential of chosen plastified AAP. For comparison, measurements of cement pastes with the same admixtures were made in parallel to the AAM. the ability of plasticizer to improve the workability of slag and fly ash-based AAM when activated by NaOH was observed. No plastifying effect was found in MK-based pastes in none of the studied environments. The rheological measurements are in accord with most of the measured adsorptions and determined zeta potentials. In the case of hexylene glycol, the rheology of pastes is primarily influenced by the combination of precursors and admixtures. With hexylene glycol admixture the NaVS activator is inapplicable because silicates and hexylene glycol interact and worsen the rheological properties of the AAP.
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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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Effect of activator type on rheology of alkali-activated slag
Markusík, David ; Smilek, Jiří (referee) ; Bílek, Vlastimil (advisor)
This work deals with rheology of alkali-activated slag pastes (AAP) because of importance of these properties in building connectors for processing and application. The effects of different concentrations of sodium and potassium hydroxides activation solutions on the rheological properties of prepared AAP are examined. For the basic characterization of activation solutions, rotational and rheological measurements of AAS were made, and were compared to measurements from the flow table. Dependences of setting time on the activator concentration and rheological and calorimetric monitoring of hydration progress were also investigated. The findings prove a major influence of concentration and activator type on any determinations made. In pastes activated by potassium hydroxide, fluidity increases with increasing concentration, which correlates with increases in values on the shake table. In case of sodium hydroxide, with the increasing concentration, fluidity increases up to 25 wt. %. The following sharp reduction in fluidity correlates to the values on the flow table as well as with the storage modulus courses from oscillation measurements. In the first minutes after mixing, there was evidence of a sharper increase in yield point for pastes with higher activator concentrations.
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Methods of using cement kiln by-pass dust in building materials technology
Sikorová, Věra ; Koplík, Jan (referee) ; Kalina, Lukáš (advisor)
This diploma thesis is focused on methods of using cement kiln by-pass dust in building materials technology. By-pass dust was treated to remove chlorides and could then be used as other constituent to various types of cements in the amount of 0–5 wt. % according to ČSN EN 197-1. The properties of dusts before and after chloride removal were examined and after incorporating modified by-pass dust into the cement, the properties of fresh and hardened cement pastes and mortars were studied. It was found that modified by-pass dust after incorporation into cement fulfill requirements of ČSN EN 197-1.
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