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Improvement of modern building materials by carbon nanotubes
Recently CNT (carbon nanotubes) were incorporated to normal concretes, high and ultra-high performance concretes as well as into model systems leading to improved mechanical properties. The influence of CNTs on the hydration of binders and the composite's macro- and microscopic mechanical properties were examined. In situ x-ray powder diffraction, isothermal calorimetric measurements and the nanoindentation technique were used to get information about how the nanostructures influence the hydration. The paper shows specialties in the application of the carbon-based nanostructures and their influence on the composite. For the experiments two types of samples were prepared. The reference samples were made of(3CaO)(SiO2), superplasticizer and water. The MWNTs (Multi-walled carbon nanotubes) samples also contained 1.0 mass-% nanotubes referred to the binder. To reduce the amount of pores pressure-compacted (3CaO)(SiO2)-prisms of the different mixtures were prepared. The system which contains the MWNTs show smaller phase contents of crystalline portlandite after 24 h hydration time. The first appearance of the portlandite's (001)-reflection is shifted from 4.5h in the case of the (3CaO)(SiO2)-reference system to 16.5 h when the MWNTs are used. The qualitative analysis of the data points to fewer and smaller crystals of Ca(OH)2. The smaller intensities could also come from retardation effect in the systems containing the MWNTs. Contrary to the results achieved by the diffraction measurements the incorporation led to an acceleration of the hydration measured by Isothermal calorimetry. The reaction maximum shifted from 35 h to 29 h.
Improvement of modern building materials by carbon nanotubes
Recently CNT (carbon nanotubes) were incorporated to normal concretes, high and ultra-high performance concretes as well as into model systems leading to improved mechanical properties. The influence of CNTs on the hydration of binders and the composite's macro- and microscopic mechanical properties were examined. In situ x-ray powder diffraction, isothermal calorimetric measurements and the nanoindentation technique were used to get information about how the nanostructures influence the hydration. The paper shows specialties in the application of the carbon-based nanostructures and their influence on the composite. For the experiments two types of samples were prepared. The reference samples were made of(3CaO)(SiO2), superplasticizer and water. The MWNTs (Multi-walled carbon nanotubes) samples also contained 1.0 mass-% nanotubes referred to the binder. To reduce the amount of pores pressure-compacted (3CaO)(SiO2)-prisms of the different mixtures were prepared. The system which contains the MWNTs show smaller phase contents of crystalline portlandite after 24 h hydration time. The first appearance of the portlandite's (001)-reflection is shifted from 4.5h in the case of the (3CaO)(SiO2)-reference system to 16.5 h when the MWNTs are used. The qualitative analysis of the data points to fewer and smaller crystals of Ca(OH)2. The smaller intensities could also come from retardation effect in the systems containing the MWNTs. Contrary to the results achieved by the diffraction measurements the incorporation led to an acceleration of the hydration measured by Isothermal calorimetry. The reaction maximum shifted from 35 h to 29 h.
Improvement of modern building materials by carbon nanotubes
Verbesserung moderner Baustoffe durch Zusatz von Kohlenstoffnanoröhrchen
Kowald, Torsten (author) / Trettin, Reinhard (author)
2008
6 Seiten, 11 Bilder, 2 Tabellen, 12 Quellen
Conference paper
English
Kohlenstoffnanoröhrchen , mehrwandiges Kohlenstoffnanoröhrchen , Tricalciumsilicat , Beton , mechanische Eigenschaft , Calciumsilicathydrat , Hydratationsdauer , Wasserabbinden von Zement , Hydratisieren , Kalorimetrie , Röntgenbeugung , Nanoeindringprüfung , Superplastifizierer , Zementpaste , mineralogische Zusammensetzung
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