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Utilization possibilities of industry gypsum and secondary materials containing for preparation of composites
Weiglová, Jana ; Šoukal, František (referee) ; Opravil, Tomáš (advisor)
The work studies the possibilities of the utilization of secondary raw materials produced by power industry. It addresses mainly the gypsum by-products and fluidized coal combustion ash. As for the secondary raw materials the content of sulphites is observed and the dependences of their transformation to sulphides via natural oxidation by air oxygen or by addition of adequate oxidant are studied. The work follows with describing the effect of sulphides contained in raw materials on the mechanical properties of composites prepared from several various matrices such as alumina or portland cement, lime or portland clinker. As for pure portland clinker the ability to retard the setting is also observed. The amount of contained sulphites is measured volumetrically via indirect titration of iodine surplus by sodium thiosulphate with the starch size as the indicator.
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Phosphate binders
Kalina, Lukáš ; Ptáček, Petr (referee) ; Šoukal, František (advisor)
The work deals with the preparation and study of polyphosphate composites. Aluminum phosphates provide some unusual properties like high-heat resistance in terms of inorganic binders. The addition of chromium in the form of Cr2O3 or directly the bond with the aluminum-chromium-phosphate can improve the properties of this binder. Highly viscous Al2Cr(H2PO4)9 and Al3Cr(H2PO4)12 binders were prepared by dissolving Al(OH)3 and CrO3 in 85% phosphoric acid, and mixed with Al2O3 and Cr2O3 fillers. The composites were cured in the furnace at 150 °C for 24 h under pressure of 10 MPa. During the annealing at temperatures up to 1 500 °C changes in chemical structure of the cured composites were observed, leading to the understanding of the creation of crystalline phases and their eventual changes. The characterization of binders was mainly based on FT-IR, EDAX, TG-DTA and optical microscopy analyses.
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Actual trends in manufacturing of ceramic shell moulds
Jankůj, Luděk ; Soukupová, Lucie (referee) ; Horáček, Milan (advisor)
Final thesis deals with the properties and production of ceramic shell moulds for investment casting method. Literature search focuses on the core of the production this mould used for ceramic and refractory slurry spreading. Attention is also paid to the technology of its production, testing ceramic shell mould and defects caused by improper manufacturing process forms. Another part of the work is focused on current trends in the production of ceramic shell moulds. The last part describes the production of ceramic shell mould in the company Česká zbrojovka. The conclusion summarizes information of production and the recommended choice of materials and manufacturing processes for ceramic shell moulds for the issue.
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Influence of type of base sand on strength of geopolymer sand mixture
Kudr, Martin ; Šupálek, Milan (referee) ; Cupák, Petr (advisor)
The goal of this research is to find out the effect of different types of opening material on bending strength geopolymer’s moulding mixture. Four different silical opening material were used along with two types of binder. To solve the selected problem I have used the test of bending strength. At first I have prepared the moulding mixture and after its induration, I have tested the bending strength. The times were always the same 60, 120 and 1440 minutes. The highest level of bending strength was achieved at opening material SH-34 when using binder Geopol 618. The value of bending strength level was 0,881MPa. The results of this research could help the foundries during implementing technology of geopolymer moulding mixture, which would help particulary when looking for a proper opening material.
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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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Design of asphalt concrete mixture and determinantion of the resistance against permanent deformation
Němec, Jan ; Matoušek, David (referee) ; Varaus, Michal (advisor)
This bachelor thesis deals with the problem regarding asphalt concrete mixtures, concretely ACO 11+. This type of mixture has low resistance to permanent deformation (rutting) while high temperatures are present. The binder and aggregate tests regarding physical and mechanical properties were carried out. Subsequently the new mixture was designed on the basis of stricter requirement for grading envelope and air void content. The design mixture was tested for resistance to permanent deformation. From the obtained results the change in the national annex of the standard ČSN EN 13108-1 is considered in terms of change in testing temperature for some kinds of binders. The same tests were conducted in others asphalt laboratories in the Czech Republic to ensure the maximum comparability.
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Phosphate bond of foam filters and its influence on the technical properties
Langer, Jan ; Lang, Karel (referee) ; Sokolář, Radomír (advisor)
The theses deals with the preparation of phosphate binder. This binder provides not only high strength, but also high-heat resistance. The bond is made of acid phosphate and alumina. There should be substitute of alumina (Cr2O3) or the adition of its. The slurry was prepared according to the applicable procedures of Pyrotek. After this, the slurry was applied to the polyurethane foam, dried and kilned. The result is foam filter for aluminium casting.
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Design and evaluation of asphalt rubber mixture
Hotař, Petr ; Dašek, Ondřej (referee) ; Kudrna, Jan (advisor)
The aim of bachelor thesis is to design the asphalt concrete for very thin layers using asphalt rubber and to perform laboratory tests according to ČSN EN 13108-2 and TP 148. The work is based on the literature review and respects properties of asphalt rubber. The expected properties of asphalt concretes for very thin layers are summarized and evaluated.
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