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Study of alkali-silica reaction in hybrid systems
Bradová, Lada ; Bílek, Vlastimil (referee) ; Kalina, Lukáš (advisor)
This study evaluates question of alkali–silica reaction (ASR) in hybrid system, which was designed in the bachelor's thesis, to meet the requirements of EN 197-1 and classified to the Blastfurnace CEM III/C cements. The durability of this system is a great unknown. For this reason, the same methods (ASTM C1260, ASTM C289 and ASTM C856) were used to observer the ASR effects as the ones used to observer the Portland cement based concrete. Supplementary methods include determination of compressive strengths according to EN 196-2 and scanning electron microscopy to observe the microstructure. Hybrid system results were compared to two different types of cements, CEM I and CEM III/B. From the results of the ASR evaluation assays, it was found that the hybrid system (CEM III/C-HB) and CEM III/B showed the lowest tendency to ASR. The results of the supplementary methods showed that CEM III/C-HB compressive strength increases after 14 days within NaOH by 43 % in comparison to 28 days strength. Based on those results, it is sure that the CEM III/C-HB shows little susceptibility to ASR.
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Hybrid systems based on alkali activated materials and Portland cement
Bradová, Lada ; Koplík, Jan (referee) ; Kalina, Lukáš (advisor)
The most promising route to improve the sustainability of cement is to produce the blended Portland cements with supplementary cementitious materials. Blast furnace slag (BFS) is one of the significant pozzolan source used worldwide in blended cements contributing to lowering of the environmental impact of cement industry. On the other hand, the replacement of the Portland clinker is connected with the undesirable effects such as reduction of early strength development. In order to overcome this disadvantage, the study deals with the development of hybrid cements in which the utilization of solid waste alkaline activator quickly awakens the pozzolanic properties of BFS. The new types of blended alkali activated cements were designed to meet the European standard EN 197 1 and classified to the Blastfurnace CEM III/C cements in accordance with the mechanical, physical, chemical and durability requirements. The effect of alkali activation caused an increase in early (2 days) compressive strength development in comparison with reference sample. The setting time was delayed two times which is also interesting from the point of view of concrete production. Moreover, this non traditional hybrid alkali activated Portland cement provides considerable ecologically and economically potential.
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Study of alkali-silica reaction in hybrid systems
Bradová, Lada ; Bílek, Vlastimil (referee) ; Kalina, Lukáš (advisor)
This study evaluates question of alkali–silica reaction (ASR) in hybrid system, which was designed in the bachelor's thesis, to meet the requirements of EN 197-1 and classified to the Blastfurnace CEM III/C cements. The durability of this system is a great unknown. For this reason, the same methods (ASTM C1260, ASTM C289 and ASTM C856) were used to observer the ASR effects as the ones used to observer the Portland cement based concrete. Supplementary methods include determination of compressive strengths according to EN 196-2 and scanning electron microscopy to observe the microstructure. Hybrid system results were compared to two different types of cements, CEM I and CEM III/B. From the results of the ASR evaluation assays, it was found that the hybrid system (CEM III/C-HB) and CEM III/B showed the lowest tendency to ASR. The results of the supplementary methods showed that CEM III/C-HB compressive strength increases after 14 days within NaOH by 43 % in comparison to 28 days strength. Based on those results, it is sure that the CEM III/C-HB shows little susceptibility to ASR.
|
|
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Hybrid systems based on alkali activated materials and Portland cement
Bradová, Lada ; Koplík, Jan (referee) ; Kalina, Lukáš (advisor)
The most promising route to improve the sustainability of cement is to produce the blended Portland cements with supplementary cementitious materials. Blast furnace slag (BFS) is one of the significant pozzolan source used worldwide in blended cements contributing to lowering of the environmental impact of cement industry. On the other hand, the replacement of the Portland clinker is connected with the undesirable effects such as reduction of early strength development. In order to overcome this disadvantage, the study deals with the development of hybrid cements in which the utilization of solid waste alkaline activator quickly awakens the pozzolanic properties of BFS. The new types of blended alkali activated cements were designed to meet the European standard EN 197 1 and classified to the Blastfurnace CEM III/C cements in accordance with the mechanical, physical, chemical and durability requirements. The effect of alkali activation caused an increase in early (2 days) compressive strength development in comparison with reference sample. The setting time was delayed two times which is also interesting from the point of view of concrete production. Moreover, this non traditional hybrid alkali activated Portland cement provides considerable ecologically and economically potential.
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