| Summary: | 碩士 === 國立臺灣科技大學 === 營建工程系 === 90 === Initially, we investigate the constituents of cement and motar. With the addition of superplasticizer, fly ash, and slag in trun, we research into the effect of admixture on the rheological behavior of paste. We research further into the effect of aggregate proportion and grain size on the Rheological behavior of motar, and then we compare with workability, rheometer, viscometer, and power analyzer mutually.
The theory of rheology was used assess the quality of workability. The experimental results from this study can be represented by a simple model with some physical parameters that are, in turn, used to determine the yield stress τ0 and the plastic viscosity μ of fresh paste and mortar, and their flowing quality can thus be evaluated
Test results show that the yield stress τ0 goes from 605.2Pa to 271.9Pa; the plastic viscosity μ goes from 0.7505Pas to 0.1391Pa s; the increase of water-of-cement ratio tend to reduce the yield stress τ0 and the plastic viscosity μ. The yield stress τ0 goes from 303.8 Pa to 190.6Pa; and the increase of dosage of the superplasticizer tend to reduce the yield stress τ0. The yield stress τ0 goes from 324.9 Pa to 247.6 Pa; the increasing amount of the replacement of cement with fly ash reduces the yield stress τ0; the plastic viscosity μ goes from 0.2993Pas to 0.4227Pa s; the increasing amount of the replacement of cement with fly ash increases the plastic viscosity μ, but the range of replacement has been limited. The yield stress τ0 goes from 252.4 Pa to 280.1 Pa; the increasing amount of the replacement of cement with slag tend to increase the yield stress; the plastic viscosity μ goes from 0.9922Pas to 0.7257Pa s; the increasing amount of the replacement of cement with slag tend to reduces the plastic viscosity μ; the increase of dosage of the superplasticizer helps slag to increase the capability of leaching water, and it makes the paste more flowable. The cement replacing by fly ash is better than by slag. The decreasing of maximum aggregate sizes increases yield stress τ0 .The increasing amount of fine aggregate in the mortar increases the yield stress τ0 and the plastic viscosity μ. The character of slag is not only more complicated than fly ash, but it is also hard to know well.
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