| Summary: | 碩士 === 國立臺灣科技大學 === 營建工程系 === 104 === This study explores the adsorption behavior of the superplasticizer on the major phases of the hydrating cement pastes and their rheological behaviors during the early hydration. During the study, the major phases of the Portland cement, C3S, C2S and C4AF, are synthesized and prepared for the rheological and superplasticizer adsorption measurements. Results showed that the viscosities of the cement pastes during the early hydration were highly associated with the hydration of the major phases in cement. The viscosity of the phases mixed with water increased rapidly during the very early hydration. Such increases were also related with the segregation in the presence of superplasticizer. Both hydration and segregation may be responsible for the uncertain relationship between the paste viscosity and the superplasticizer dosage. Results also showed that the superplasticizer adsorbed the most on C4AF and the least on C3S, estimated by the amount of adsorption per unit surface area. During the early hydration, C4AF had the fastest viscosity increases among the three phases. In the presence of superplasticizer, the viscostity decreased with the increase of adsorption. Nevertheless, such relationship was not consistent in all the mixtures. There are some influencing factors, such as the compositions, hydration rate and segregation. These factors induced the incomplete adsorption of superplasticizer, which in turn affected the viscosity and adsorption capacity.
|
|---|
