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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Vliv typu aktivátoru na reologii a povrchovou chemii alkalicky aktivované strusky / Effect of activator nature on rheology and surface chemistry of alkali-activated slag

Russkykh, Kostyantyn January 2021 (has links)
V této závěrečné práci bylo popsáno časné reologické chování alkalicky aktivované strusky, anorganického materiálu, který vzniká aktivací mleté granulované vysokopecní strusky alkalickým roztokem. Vliv typu aktivačního roztoku (hydroxidů, křemičitanů a uhličitanů) a jeho koncentrace na časné reologické parametry byl zkoumán pomocí amplitudových oscilačních měření. Bylo pozorováno, že typ aktivátoru je hlavním faktorem ovlivňujícím reologické chování alkalicky aktivované strusky. Dále bylo pozorováno, že aktivátory na bázi draslíku vedou ke slabší struktuře (nižší mez kluzu, mez toku a nižší hodnoty viskoelastických modulů) oproti použití aktivátorů na bázi sodíku. To lze vysvětlit rozdíly ve velikosti alkalických iontů. Na rozdíl od ostatních aktivátorů křemičitany způsobovaly zvýšení ztrátového faktoru, přičemž vykazovaly spíše kapalné chování. Z výsledků vyplynulo, že většina aktivátorů má tzv. kritickou hodnotu koncentrace, po jejímž dosažení mají reologické vlastnosti vzorků tendenci se měnit s rostoucí koncentrací. Získané výsledky korelovaly s výstupy zeta potenciálu.
2

Vliv alkalického aktivátoru na imobilizaci kovů v alkalicky aktivované strusce / The influence of alkali activator on immobilization of metals in alkali activated blast furnace slag

Bystrianska, Emília January 2019 (has links)
In this work the influence of alkaline activator on immobilization of lead and copper in alkali-activated blast furnace slag was investigated. A total of five activators were used; sodium water glass, potassium water glass, sodium hydroxide, potassium hydroxide and sodium carbonate. The leaching test according to ČSN EN 12457-4 was used to evaluate the level of immobilization of heavy metals, the leached solutions were analyzed by ICP-OES. For a better understanding of immobilization, the selected samples were characterized by analytical methods (FTIR, XRD, SEM, XPS). It was found that the degree of immobilization Pb2+ and Cu2+ in AAS was very high, regardless of the type of alkaline activator used.
3

Funkce superplastifikátorů ve směsích alkalicky aktivovaných aluminosilikátů / Role of superplastisizers in alkali activated aluminate silicate mixtures

Habrdová, Eva January 2008 (has links)
Preparation of geopolymers with main components of slug and metakaolin. After being alcali activated the raw materials are complemented by superplasticizers of different kind and concentracion.
4

Vláknové kompozity s alkalicky aktivovanou struskovou matricí / Fibre coposites with alkali -activated slag matrix

Pluskalová, Barbora January 2015 (has links)
This master thesis is concerns the preparation of Alkali Activated Materials, specifically Alkali Activated Slag (AAS), with the addition of fiber reinforcement. Alkali Activated Materials have great potential for use in construction practice. However, their use is limited by certain undesirable properties, which can be diminished by adding fiber reinforcement. This thesis deals with the influence of carbon fibers (2 % by weight of the binder) and carbon nanotubes (0,2 % by weigh of the binder) on the mechanical properties, microstructure and shrinkage of AAS. The results of the experiments which were carried out correspond with the literary research. Conclusions of this thesis agree with research published in original scientific papers.
5

Studium karbonatace alkalicky aktivovaných systémů / Study of carbonatation in alkali activated systems

Suchý, Rostislav January 2016 (has links)
The carbonation of the building materials based on the ordinary Portland cement is relatively well-known and extensively studied phenomenon. Conversely mechanism, reaction products and factors affecting the carbonation of the alkali activated materials are still not sufficiently clarified. In this work, the progression of the carbonation of the alkali activated materials under different conditions was investigated. The reaction products and the microstructural changes were determined by XRD respectively SEM-EDX analysis. The corrosive conditions due to the decreasing of the pH of the binders by the carbonation were observed by XPS analysis of the steel fibers. The carbonation of the alkali activated samples was compared with the reference samples based on the Portland composite cement. Besides these analyzes, the mechanical properties of the binders were monitored.
6

Studium mechanismu působení přísad redukující smrštění v alkalicky aktivovaných materiálech / On the mechanisms of shrinkage reducing admixtures in alkali activated materials

Komosná, Kateřina January 2017 (has links)
This thesis is focused on the principles of behavior of shrinkage reducing agents (SRA) in alkali-activated materials based on blast furnace slag. The main focus of this work is selecting the most suitable admixture based on experiments, by which will be achieved through minimal shrinkage and will have negative effect on the properties of alkali-activated blast furnace slag at the same time. In experimental section of this work, the surface tension as individual additives as their mixtures with pore solution were measured primarily. Then the testing samples composed of blast furnace slag, water glass and addition of SRA were prepared. Of these samples was measured shrinkage and weight loss. Moreover, their mechanical properties such as flexural and compressive strength were monitored. Next, the beginning and the end of solidification was studied using the Vicat device and last but not least workability. The hydration process of alkali-activated materials with SRA was measured calorimetrically. Finally the microstructure in prepared samples was observed using scanning electron microscopy (SEM-EDS) and the total porosity was determined by mercury porosimeter.
7

Experimentální in situ transformace metalurgických odpadů v půdních systémech / Experimental in situ transformation of smelting wastes in soil systems

Jarošíková, Alice January 2018 (has links)
Metallurgical activities are one of the important sources of environmental pollution, especially due to inappropriate treatment of waste materials containing potentially harmful elements. Soils in the vicinity of smelting operations are the main target reservoirs for these emitted contaminants. The aim of this study was to depict reactivity of copper smelter flue dusts and slags in aqueous and soil environments using laboratory and field experiments. Slags exhibited high concentrations of As (up to 0.95 wt.%), Cu (up to 2.4 wt.%), Pb (up to 1.02 wt.%), Sb (up to 0.37 wt.%), and Zn (up to 2.45 wt.%). Copper and other metal(loid)s were predominantly bound in sulphides, especially bornite, digenite, chalcocite, and galena. Flue dusts were mainly composed of As2O3 phase (arsenolite and claudetite), with minor amounts of gypsum, galena, quartz and covellite. The main contaminants in the dust were As (53.3 wt.%), Pb (3.41 wt.%), Sb (1.26 wt.%), Zn (1.41 wt.%), Cu (1.07 wt.%) and Bi (0.80 hm.%). The leaching tests performed in the pH range of 3-12 indicated that the release of metal(loid)s from both types of metallurgical wastes was highly pH-dependent. During the leaching in deionised water, up to 42 mg/kg As was released from slags and up to 52.6 g/kg was leached from the flue dust; the latter highly...
8

Využití některých velkoobjemově produkovaných druhotných surovin k přípravě pojiv a kompozitů na bázi geopolymerů / Utilization of some massive produced byproducts for preparation of geopolymer based binders and composites

Eckl, Ondřej January 2009 (has links)
Preparation of geopolymer composites from industrial wastes of energy power stations and metalurgy.
9

Vývoj přísad redukující smrštění navržených pro alkalicky aktivované materiály / Development of shrinkage reducing admixtures designed for alkali activated materials

Šístková, Pavlína January 2018 (has links)
This thesis deals with development of shrinkage reducing admixtures designed for alkali activated materials based on blast furnace slag. The main task of this work is to select the most suitable shrinkage reducing admixture based on experiments, in which can be observed minimal shrinkage and at the same time it will not adversely affect the properties of alkali activated blast furnace slag. In the experimental part of the work, test beams containing shrinkage reducing admixtures were prepared, in which the shrinkage and loss of weight were measured. Moreover, the mechanical properties of individual beams, such as tensile strength and compressive strength, were measured. Next, the surface tension of individual shrinkage reducing admixtures was measured in a mixture with pore solution. The hydration process of alkali activated materials under the action of reducing shrinkage admixtures was monitored by calorimetric analysis. The microstructure of the prepared samples was observed by scanning electron microscopy.
10

Způsoby využití by-passových cementářských odprašků v technologii stavebních hmot / Methods of using cement kiln by-pass dust in building materials technology

Sikorová, Věra January 2019 (has links)
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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