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Alkali Activated Systems
Bílek, Vlastimil ; Rovnaník, Pavel (referee) ; Vlček, Jozef (referee) ; Ptáček, Petr (advisor)
This doctoral thesis is focused on the possibilities of alkali-activated slag (AAS) shrinkage reduction, which would together with the use of waste sludge from waterglass production contribute to wider practical utilization of this interesting material. Besides the influence on AAS dimensional changes also effect of various factors on workability, setting time and mechanical properties was investigated. Obtained results were supported by the application of instrumental techniques like izotermal calorimetry, mercury intrusion porosimetry, scanning electron microscopy and X-ray diffraction. The results show the possibilities of reduction of AAS drying shrinkage related to its cracking tendency through the combination of increased dose of waterglass and reduced water to slag ratio (w/b), partial replacement of slag by pulverized fly ash or cement by-pass dust and application of organic admixtures, where significant effect on AAS hydration was observed. On the basis of the obtained results concrete mixtures, where the whole activator was replaced by the waste sludge form waterglass production, were designed and optimized in terms of shrinkage, mechanical properties and price. Selected concretes were also tested in semi-operating conditions.
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Alkali Activated Systems
Bílek, Vlastimil ; Rovnaník, Pavel (referee) ; Vlček, Jozef (referee) ; Ptáček, Petr (advisor)
This doctoral thesis is focused on the possibilities of alkali-activated slag (AAS) shrinkage reduction, which would together with the use of waste sludge from waterglass production contribute to wider practical utilization of this interesting material. Besides the influence on AAS dimensional changes also effect of various factors on workability, setting time and mechanical properties was investigated. Obtained results were supported by the application of instrumental techniques like izotermal calorimetry, mercury intrusion porosimetry, scanning electron microscopy and X-ray diffraction. The results show the possibilities of reduction of AAS drying shrinkage related to its cracking tendency through the combination of increased dose of waterglass and reduced water to slag ratio (w/b), partial replacement of slag by pulverized fly ash or cement by-pass dust and application of organic admixtures, where significant effect on AAS hydration was observed. On the basis of the obtained results concrete mixtures, where the whole activator was replaced by the waste sludge form waterglass production, were designed and optimized in terms of shrinkage, mechanical properties and price. Selected concretes were also tested in semi-operating conditions.
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