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Unbound and bound mixtures from recycled concrete of highway D1
Mikulíková, Petra ; Mondschein,, Petr (referee) ; Stehlík, Dušan (advisor)
The work is divided into two parts. The first part deals with the description of unbound and bound base layers and their comparison. Furthermore is presented the description of the recycled concrete, its properties, production, improvement and issues. International experiences with recycled concrete technology are described as well. The practical part is focused on laboratory testing of concrete recycled material taken from the highway D1. The aim of this part is to determine whether the concrete can be recycled back into unbound or bound base layers and concrete casing.
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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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Possibilities of the utilization of the waste sand from the water glass production in building industry
Bílek, Vlastimil ; Kalina, Lukáš (referee) ; Opravil, Tomáš (advisor)
Nowadays, the waste sands from the water glass production have no utilization and due to high alkali content are considered as a dangerous waste. So the aim of this thesis is to find and study some possibilities of their utilization in the building industry. First of all, some necessary analysis of these sands were performed and then some advantages and disadvantages of their application for production of materials based on portland cement and alkali activated materials were studied. Characteristics of fresh and hardened pastes, mortars and concretes containing these waste sands were determined. The most tested properties were their workability and their compressive and flexural strength. Close attention for the risks of alkali-silica reaction and for options of its suppressing by the mineral admixtures was paid.
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ASR potential of quartz in experimental mortar bar specimens
Kuchyňová, Markéta ; Kuchařová, Aneta (advisor) ; Vavro, Martin (referee)
The alkali-silica reaction is one of the most damaging chemical reactions taking place in concrete, which can cause fatal damage. ASR originates under following conditions: high moisture (> 80 %), sufficient amount of alkaline ions (Ca2+ , Na+ , K+ ) and use of reactive aggregates (low crystaline or deformed quartz, amorphous SiO2). Reactive aggretates react with high alkaline pore solution and produce hydrofile gels. These gels absorb water and swell. Dilatometric test methods are commonly used to evaluate the reactivity of aggregates. The principle of dilatometric test methods is simple. Mortar or concrete prisms are created in a laboratory, then they are stored in the special environment, which accelerates the inception of ASR. The creation and expansion of alkali-silica gels cause prism's length changes. The major goal of this diploma thesis was to evaluate the alkali-silica reactivity potential of quartz-rich rocks using microscopic (polarizing microscopy, scanning electron microscopy combined with SEM/BSE image analysis) and dilatometric (ASTM C1260, RILEM AAR-4.1) methods. Rocks were assessed as reactive, potentially reactive and non-reactive by the ASTM C1260 method. The reactivity of aggregates was connected with the amount of cryptocrystaline matrix, grain size, shape of grain boundaries,...
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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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ASR potential of quartz in experimental mortar bar specimens
Kuchyňová, Markéta ; Kuchařová, Aneta (advisor) ; Vavro, Martin (referee)
The alkali-silica reaction is one of the most damaging chemical reactions taking place in concrete, which can cause fatal damage. ASR originates under following conditions: high moisture (> 80 %), sufficient amount of alkaline ions (Ca2+ , Na+ , K+ ) and use of reactive aggregates (low crystaline or deformed quartz, amorphous SiO2). Reactive aggretates react with high alkaline pore solution and produce hydrofile gels. These gels absorb water and swell. Dilatometric test methods are commonly used to evaluate the reactivity of aggregates. The principle of dilatometric test methods is simple. Mortar or concrete prisms are created in a laboratory, then they are stored in the special environment, which accelerates the inception of ASR. The creation and expansion of alkali-silica gels cause prism's length changes. The major goal of this diploma thesis was to evaluate the alkali-silica reactivity potential of quartz-rich rocks using microscopic (polarizing microscopy, scanning electron microscopy combined with SEM/BSE image analysis) and dilatometric (ASTM C1260, RILEM AAR-4.1) methods. Rocks were assessed as reactive, potentially reactive and non-reactive by the ASTM C1260 method. The reactivity of aggregates was connected with the amount of cryptocrystaline matrix, grain size, shape of grain boundaries,...
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Relationship between macro- and microscopic sings of alkali-silica reactivity in concrete
Burdová, Anna ; Přikryl, Richard (advisor) ; Martinec, Petr (referee)
This thesis deals with deterioration observed in cement-concrete cover (CBK) for three selected road sections of highways in the Czech Republic. The main objective was to determine whether concrete failure arose due to alkali-silica reaction, or other mechanism. The deterioration of concrete failure was observed in the macroscopic and microscopic scale. The mostly macroscopically observed deterioration of the concrete were cracks breaking the surface and inner parts of concrete. In micro- scale the microcracks and alcali-silica gels were observed. The CBK deterioration was quantitatively determined by three main parameters: specific length of microcracks on the CBK surface, specific length of microcracks in the drill cores and volume of alcali-silica gels and microcracks in thin sections. According to these indicators it was possible to distinguish two different types of CBK deteriorations. (1) Degradation mainly associated by alkali-silica reaction (observed on highways D11 - Vrbová Lhota and D1) and (2) degradation connected with another mechanism (cycles of freezing and thawing, mechanical degradation) was observed on the highway D5.
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