| Summary: | 碩士 === 國立嘉義大學 === 土木與水資源工程學系研究所 === 96 === The purpose of this paper is to explore the characteristics of fresh concrete with high flowability whether the fresh concrete is able to mix mortar evenly with different grain size of aggregates and weight and to ensure the new mixture being free of segregation and bleeding. Moreover, to understand the effect to the mixture if the aggregate grains’ sizes are different.
The experiment shows that the aggregate grain size of paste does directly affect super-plasticizers and mixed water content. When the grain size is getting smaller without bleeding, the water/paste ratio is getting higher that produces the new mixture flowability directly without adding any super-plasticizers. The quantity of (SP/B) should be limited if the super-plasticizers is added to increase the workability of concrete. If not, even there is no bleeding to the mixture there will be settlement, consolidating and/or segregation to the mixture. In addition, the grain size of the paste is getting bigger or the diversity of size is getting wider, the reducing quantity of super-plasticizers is required more accordingly.
For coarse aggregate distribution, the experiment shows that the fresh concrete becomes uneven distribution when 1/2" grain size of aggregate limited above 50±4cm slump flow. The aggregate distribution is better when 3/8" grain size of aggregate limited below 50±4cm slump flow. The new mixture can be batched uniformly for #4 grain size of aggregate. General experiment, by visual checking the slump-body and consistency of concrete, however, cannot precisely determine the aggregate separation.
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