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Preparation of Tobermorite
Dlabajová, Lucie ; Palou, Martin (referee) ; Martinec, Petr (referee) ; Ptáček, Petr (advisor)
This doctoral thesis is focused on the study of reactions in the CaO–SiO2–H2O complex system, primarily to the synthesis of crystalline tobermorite. Hydrothermal conditions are necessary for the formation of crystalline tobermorite, whereas the course of the reaction is influenced by several factors. The main studied factor was the choice of the silica sources differing in means of solubility, crystallinity, particle size distribution, specific surface area, and purity. The water-to-solid ratio turned to be also an important factor as the length of the hydrothermal reaction. The influence of the mechanochemical pretreatment of starting materials to the final phase composition of samples was studied as well. The obtained results show that the crystallinity of the silica source is the main factor influencing the reaction rate and the purity of the synthesized tobermorite. While using the crystalline silica source the shorter silicate chains are formed and the formation of tobermorite structure is easier. Using the amorphous silica sources and the mechanochemical pretreatement of starting materials prolong the hydrothermal reaction. The prepared samples are always the mixture of crystalline or semicrystalline calcium hydrosilicates instead of the phase pure tobermorite.
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Comparison of microstructure of standard and modified fly ash autoclaved aerated concrete
Fleischhacker, Ján ; Kulísek, Karel (referee) ; Drochytka, Rostislav (advisor)
Nowadays, the amount of produced fly ash and fluidized ash is huge, so it is important to find ways of its proper use.Significant influence in field of fly ash consumption is production of autoclaved aerated concrete. Most important factor in production is properties of raw materials such as mineralogical and chemical composition. The study of raw materials is important to understand the mechanism of hydratation, tobermorite formation and mineralogy of final product. In present study, we investigate influence of raw materials to mineralogy of autoclaved aerated concrete, significantly to influence of fluidized ash on quality of autoclaved aerated concrete. Closure of study is design of the methodology, specialized in field of bachelor’s thesis study.
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The effect of fly ash aerated concrete production technology to formation of tobermoritic phases
Fleischhacker, Ján ; Kulísek, Karel (referee) ; Drochytka, Rostislav (advisor)
Autoclaved aerated concrete is long-time ecological building material with usefull properties. There needs to be done research of its mineralogical compound for reengineering the production. The main mineral compound of AAC is tobermorite, it increases its mechanical properties. In the presence study, we examine the usage of nature and artificial silicious materials. Also, we investigate the influence of sulfate and alumina admixtures, as well as fluidized bed combustion ash, which can be used as the lime and gypsum replacement. Closure of the study is design of the optimal raw material composition, also hydrothermal treatment of autoclaved aerated concrete. In relation to its mechanical properties, mineralogical composition and cost.
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The technology of aerated concrete
Koutný, Ondřej ; Repka, Martin (referee) ; Opravil, Tomáš (advisor)
Civil engineering is integral part of industry in each developed country. Naturally the construction point does not play the main role here, but also the material of building segments. In last fifty years the new possibility has been discovered against classic brick in form of autoclaved aerated concrete. This material gathers its customers not only due to low weight and easy application with sufficient strength, but particularly due to excellent heat-insulation properties. Contemporary trend in research of aerated concrete points to application of alternative raws, as for example metakaoline, to improve final properties of product by preserving of current technology and price.
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Study of usabiliti of sands for preparation of aeroconcrete in hydrotermal condition
Straka, Radek ; Ptáček, Petr (referee) ; Opravil, Tomáš (advisor)
A building industry is expanding branch all the time and it intervenes in the life of everyone. Aeroconcrete is very attractive and actual subject nowadays because economy is important point of view of production. This material finds a wide-spread use thanks to its specific properties. The good manipulation and great thermal insulating properties are secured by its porous structure. Furthermore, proper material selection provides a saving of power of house for every customer demands. Due to aeroconcrete's sufficient compressive strength it is useful for both constructions and internal walls. Fundamental and very important for final material properties is raw material composition of aeroconcrete. A relationship between composition of filler (quartz sand) and resultant properties of aeroconcrete is an objective of the thesis.
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Preparation of Tobermorite
Dlabajová, Lucie ; Palou, Martin (referee) ; Martinec, Petr (referee) ; Ptáček, Petr (advisor)
This doctoral thesis is focused on the study of reactions in the CaO–SiO2–H2O complex system, primarily to the synthesis of crystalline tobermorite. Hydrothermal conditions are necessary for the formation of crystalline tobermorite, whereas the course of the reaction is influenced by several factors. The main studied factor was the choice of the silica sources differing in means of solubility, crystallinity, particle size distribution, specific surface area, and purity. The water-to-solid ratio turned to be also an important factor as the length of the hydrothermal reaction. The influence of the mechanochemical pretreatment of starting materials to the final phase composition of samples was studied as well. The obtained results show that the crystallinity of the silica source is the main factor influencing the reaction rate and the purity of the synthesized tobermorite. While using the crystalline silica source the shorter silicate chains are formed and the formation of tobermorite structure is easier. Using the amorphous silica sources and the mechanochemical pretreatement of starting materials prolong the hydrothermal reaction. The prepared samples are always the mixture of crystalline or semicrystalline calcium hydrosilicates instead of the phase pure tobermorite.
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|
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The effect of fly ash aerated concrete production technology to formation of tobermoritic phases
Fleischhacker, Ján ; Kulísek, Karel (referee) ; Drochytka, Rostislav (advisor)
Autoclaved aerated concrete is long-time ecological building material with usefull properties. There needs to be done research of its mineralogical compound for reengineering the production. The main mineral compound of AAC is tobermorite, it increases its mechanical properties. In the presence study, we examine the usage of nature and artificial silicious materials. Also, we investigate the influence of sulfate and alumina admixtures, as well as fluidized bed combustion ash, which can be used as the lime and gypsum replacement. Closure of the study is design of the optimal raw material composition, also hydrothermal treatment of autoclaved aerated concrete. In relation to its mechanical properties, mineralogical composition and cost.
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Possibilities of using of energy by-products as raw materials for hydrothermal reaction
Galvánková, Lucie ; Koplík, Jan (referee) ; Opravil, Tomáš (advisor)
The aim of this master thesis is study of possibilities of processing energy by-products, especially coal fly ash and fluidized bed ash, by hydrothermal treatment. Thanks to hydrothermal conditions and proper alkali activation of ashes we can obtain zeolites. Zeolites are microporous crystalline aluminosilicates which are use in many industrial sectors as catalysts, adsorbents and very good ion exchangers. The results of hydrothermal synthesis are influenced by many variable factors. This thesis mainly focused on influence of chosen alkali activator and the concentration of the activator together with a temperature of hydrothermal process. Other factor that is studied is choice of starting materials and solution/ash ratio. Phase composition of prepared samples was characterized by XRD and scanning electron microscopy (SEM). Also cation exchange capacity of prepared samples was determined.
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Study of usabiliti of sands for preparation of aeroconcrete in hydrotermal condition
Straka, Radek ; Ptáček, Petr (referee) ; Opravil, Tomáš (advisor)
A building industry is expanding branch all the time and it intervenes in the life of everyone. Aeroconcrete is very attractive and actual subject nowadays because economy is important point of view of production. This material finds a wide-spread use thanks to its specific properties. The good manipulation and great thermal insulating properties are secured by its porous structure. Furthermore, proper material selection provides a saving of power of house for every customer demands. Due to aeroconcrete's sufficient compressive strength it is useful for both constructions and internal walls. Fundamental and very important for final material properties is raw material composition of aeroconcrete. A relationship between composition of filler (quartz sand) and resultant properties of aeroconcrete is an objective of the thesis.
|
|
|
The technology of aerated concrete
Koutný, Ondřej ; Repka, Martin (referee) ; Opravil, Tomáš (advisor)
Civil engineering is integral part of industry in each developed country. Naturally the construction point does not play the main role here, but also the material of building segments. In last fifty years the new possibility has been discovered against classic brick in form of autoclaved aerated concrete. This material gathers its customers not only due to low weight and easy application with sufficient strength, but particularly due to excellent heat-insulation properties. Contemporary trend in research of aerated concrete points to application of alternative raws, as for example metakaoline, to improve final properties of product by preserving of current technology and price.
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