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The study of alkali-silica reaction in the cement-concrete shelters
Láznička, Josef ; Urbanec, Květoslav (referee) ; Hela, Rudolf (advisor)
Alkali – silica reaction is concrete durability problem resulting in significant maintenance and reconstruction costs to concrete infrastructures. This paper intends to summarize the current state of understanding this reaction with respect to reaction mechanisms. The experimental part of this paper deals with deterioration observed in cement – concrete cover for sections of highways in the Czech Republic. The objective was to determine wheter concrete failure arose due alkali – silica reaction or other mechanism.
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Monitoring of alkali-silica reaction
Doležal, Martin ; Kalina, Lukáš (referee) ; Opravil, Tomáš (advisor)
Due to the alkali-silica reaction (ASR), concrete structures are damaged, which can lead to the loss of their useful properties. For the reaction to take place, the presence of alkalis is required. During the work, the release of alkalis into the pore solution was monitored. During hydration pore solutions were taken, on the basis of calorimetric curves. In pore solutions the K+ a Na+ content was analyzed by ICP-OES. The result is graphs of the development of alkali content and their relationship to cement hydration. The danger of the alkali in tested samples for the course of the reaction is described here. The description of the alkali content and its development is important for understanding the course of ASR and proposing a viable solution to protect against this problem.
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The study of zinc influence on Portland cement hydration.
Ptáček, Martin ; Janča, Martin (referee) ; Šiler, Pavel (advisor)
The topic of this work is the monitoring of the effect of zinc on the hydration process in Portland mixed cement (specifically with the addition of finely ground granulated blast-furnace slag, high temperature fly ash and fluidized bed combustion filter ash). How much zinc and at what time it remains in the pore solution during hydration. Activation energy of a mixture of cement with zinc in the form of soluble salts (Zn(NO3)2.6H2O and ZnCl2) and insoluble oxide (ZnO) by isothermal calorimetry was also investigated. The XRF method has shown composition during hydration. The zinc retardation effect was investigated by isothermal calorimetry and activation energy was calculated using this method. The XRF and ICP-OES methods were used to measure the zinc content of the pore solution. And the amount of portlandite was monitored by the DTA and XRF method.
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Monitoring of alkali-silica reaction
Doležal, Martin ; Kalina, Lukáš (referee) ; Opravil, Tomáš (advisor)
Due to the alkali-silica reaction (ASR), concrete structures are damaged, which can lead to the loss of their useful properties. For the reaction to take place, the presence of alkalis is required. During the work, the release of alkalis into the pore solution was monitored. During hydration pore solutions were taken, on the basis of calorimetric curves. In pore solutions the K+ a Na+ content was analyzed by ICP-OES. The result is graphs of the development of alkali content and their relationship to cement hydration. The danger of the alkali in tested samples for the course of the reaction is described here. The description of the alkali content and its development is important for understanding the course of ASR and proposing a viable solution to protect against this problem.
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|
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The study of zinc influence on Portland cement hydration.
Ptáček, Martin ; Janča, Martin (referee) ; Šiler, Pavel (advisor)
The topic of this work is the monitoring of the effect of zinc on the hydration process in Portland mixed cement (specifically with the addition of finely ground granulated blast-furnace slag, high temperature fly ash and fluidized bed combustion filter ash). How much zinc and at what time it remains in the pore solution during hydration. Activation energy of a mixture of cement with zinc in the form of soluble salts (Zn(NO3)2.6H2O and ZnCl2) and insoluble oxide (ZnO) by isothermal calorimetry was also investigated. The XRF method has shown composition during hydration. The zinc retardation effect was investigated by isothermal calorimetry and activation energy was calculated using this method. The XRF and ICP-OES methods were used to measure the zinc content of the pore solution. And the amount of portlandite was monitored by the DTA and XRF method.
|
|
|
The study of alkali-silica reaction in the cement-concrete shelters
Láznička, Josef ; Urbanec, Květoslav (referee) ; Hela, Rudolf (advisor)
Alkali – silica reaction is concrete durability problem resulting in significant maintenance and reconstruction costs to concrete infrastructures. This paper intends to summarize the current state of understanding this reaction with respect to reaction mechanisms. The experimental part of this paper deals with deterioration observed in cement – concrete cover for sections of highways in the Czech Republic. The objective was to determine wheter concrete failure arose due alkali – silica reaction or other mechanism.
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