| Summary: | 碩士 === 國立臺灣科技大學 === 營建工程系 === 101 === This study explored the rheological behaviors of the Portland cement pastes partly replaced by fly ash or limestone powders by volume in the presence of superplasticizers. Results showed that the fly ash reduced the viscosities of the cement pastes. Similar behaviors were found in the pastes with superplasticizers. Since the paste rheology is associated with the superplasticizer adsorption, this study also explored the changes in the superplasticizer adsorption and the ionic concentrations in pore solutions. Results further showed that the addition of fly ash increased the amount of adsorption on cement particles. The naphthalene-based superplasticizer reduced the potassium ion concentrations in pore solutions. However, the carboxylated superplasticizer did not alter the ion concentrations much. In the presence of fly ash, the potassium ion concentration was reduced. Finally, similar results were found when cement was replaced by 10% limestone powders. The viscosity and the superplasticizer adsorption of the pastes remained reduced by the addition of fly ash.
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