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Showing 1 to 16 of 16 for “"Ca/Si"”.
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Characterization of calcium-silicate-hydrate and calcium-alumino-silicate-hydrate
The primary objectives of this thesis were to synthesize calcium silicate hydrate (C-S-H) and calcium aluminosilicate hydrate (C-A-S-H) and characterize their structures with varying Ca/Si ratios and aluminum content. As a secondary objective, carbonation behavior in synthesized C-S-H was studied. …
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Nano-ChemoMechanical assessment of Rice Husk Ash cement by wavelength dispersive spectroscopy and nanoindentation
… consumed structural mateial worldwide. This massively produced material comes with a heavy environmental footprint rendering the cement industry contributing about 5% to global CO₂ emission. Rice Husk Ash (RHA) among many other silicious materials, has the potential to partially replace cement …
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Spectroscopic abundances of solar-type dwarfs in open cluster M34 (Ngc 1039)
… and relative abundances of Fe, Ni, Ti, Cr, Ca, Si, Al, and Mg have been derived for nine M34 G and K dwarfs from high-resolution, modest S/N, Keck/HIRES spectra. Effective temperatures have been derived spectroscopically and fall in the range 4750 ≤ Teff ≤ 6130 K. Despite modest …
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Quantitative comparison of nanoleakage among five resin luting agents after aging
Potential problems of one-step adhesives have been identified, including water uptake and subsequent plasticization, water-and enzyme-induced nanoleakage, and the presence of voids due to phase-separation or osmosis. Clinically, adhesive failures due to marginal degradation present as retention …
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Morphological, biochemical and molecular characterization of desiccation-tolerance in cyanobacterium Nostoc commune var. Vauch
Filaments of the desiccation-tolerant cyanobacterium Nostoc commune are embedded within, and distributed throughout, a dense glycan sheath. Analysis of the glycan of field materials and of pure cultures of N. commune DRH1 through light and electron microscopy, immunogold-labelling and staining with …
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Trace element geochemistry of marine biogenic particulate matter
Plankton samples have been carefully collected from a variety of marine environments under the rigorous conditions necessary to prevent contamination for major and trace-chemical analysis. Immediately after collection, the samples were subjected to a series of physical and chemical …
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Influence of calcium-(alumino)-silicate-hydrate nanostructure on viscoelastic behavior
Viscoelasticity in concrete has been studied since the early 20th century with continuously advancing technology and methods. Currently, calcium-silicate-hydrate (C-S-H) is thought to be the phase responsible for viscoelasticity in concrete. Advances in small-scale mechanical testing in the past …
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Geochemistry of a pristine fynbos ecosystem in the Harold Porter National Botanical Gardens and Kogelberg Biosphere Reserve
… were taken from the Harold Porter National Botanical Gardens and the Kogelberg Biosphere Reserve in order to investigate interactions between the various nutrient pools in a pristine fynbos ecosystem. Physical variables (pH, EC, temperature, DO, alkalinity) were measured in the field, and water …
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Calcium-Silicate-Hydrate in cementitious systems : chemomechanical correlations, extreme temperature behavior, and kinetics and morphology of in-situ formation
… most used material on the planet, is a multi-scale heterogeneous material. A fundamental component known as Calcium-Silicate-Hydrate which forms from the reaction between cement and water is the binding phase in concrete. Curiously, this is the least understood component of concrete because of …
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Korrosionsempfindliche Dosimetermaterialien zur Überwachung der Umweltbedingungen an Kulturgütern
Das Ziel dieser Arbeit war es, ein neues Dosimetermaterial zu entwickeln, das schneller reagiert als der klassische Glassensor. Einen vielversprechenden Ansatz dafür bietet der Sol-Gel Prozeß, mit dem dünne Schichten hergestellt werden können. Erste Versuche mit transparenten Schichten einer …
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Examination of hydrated and accelerated carbonated cement-heavy metal mixtures
Cement -based solidification/stabilisation (s/s) has been applied to the disposal of heavy metal bearing contaminated soil and wastes for approximately 50 years. This work studies the interactions of cement and heavy metals and provides further insight into encapsulation of heavy metals in cement …
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Characterisation and properties of alkali activated pozzolanic materials.
… cement and concrete industry. This creates a massive waste-disposal problem. Disposal of unused fly ash in open tips and ponds, for example, creates pollution problems since the drainage of effluents from the ash in the deposit ponds threaten water supplies by polluting the ground water with …
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Investigating the influence of vehicular traffic on a major trunk road on rural air quality
… and up to 60% by 2031. This means vehicular emissions from road transport may account for higher proportion of total emissions of pollutants resulting in air pollution with its attendant consequences. Although poor air quality concerns has often been linked to urban areas, many rural areas …
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Performance of geopolymer concrete subjected to mineral acid corrosion and related to microbially-induced corrosion (MIC) of concrete in sewers
… results from this study show that high resistance under the static acid corrosion exposure condition cannot be extended to mean high resistance under the erosion-corrosion exposure condition for some concrete mixes. In this study, the static HCl test and the dynamic HCl test were used to …
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Investigation on the Mechanical, Microstructural, and Electrical Properties of Graphene Oxide-Cement Composite
… to 100 nanometers (nm) in a wide range of applications. Use of nanomaterials in cement composite to enhance the mechanical properties, fracture toughness and other functionalities has been studied for decades. In this regard, one of the carbon-based nanomaterials, Graphene Oxide (GO), has …
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Quantification of the bioccumulation potential of various chemical elements from coal fly ash using Brassia juncea and Spinacia oleracea L and its implication for phytoremediation of coal fly ash dumps
South Africa is highly dependent on coal for production of electricity. The combustion of coal for electricity generation produces waste by-products which include fine ash (fly ash) and coarse ash. Fly ash (FA) is produced in large amounts while its utilization is low due to its classification as a …