Influence of Quality of Powder on Rheology of High-Fluidity Concrete

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Title: Influence of Quality of Powder on Rheology of High-Fluidity Concrete

Author(s): T. Fumoto and M. Yamada

Publication: Special Publication

Volume: 221

Issue:

Appears on pages(s): 367-380

Keywords: blast-furnace slag powder; coarse aggregate; crushed stone powder; fly ash; high-fluidity concrete; limestone powder; mortar; mortar flow; pore volume; powder, recycled concrete powder; segregation; specific surface area

Date: 5/1/2004

Abstract:
High fluidity concrete needs appropriate amount of powder for preventing concrete segregation. But slump flow often decreases because of the properties of powder. It is important to investigate qualities of the powder influencing rheological properties of concrete. So, the purpose of this study is to investigate an evaluation index for segregation resistance and the qualities of powder relating to the index. Firstly, the evaluation indices for segregation resistance were examined. And the best proposed as the ratio between coarse aggregate weight in concrete contained in the lower part of cylindrical vessel and that in upper part after tamping by a steel rod. This index more accurately ex-pressed the segregation potential under construction. Plastic viscosity of mortar and volumetric percentage of coarse aggregate in concrete mainly influence the index. Next, we investigated the influence of fly ash, Blast-furnace slag powder, limestone powder, crushed stone powder and recycled concrete powder on properties of a mortar. If the surface of powder was rough, the mortar flow with the powder largely decreased with in-creasing plastic viscosity when quantity of the powder was increased.