Title: Mixture Properties of Self-Compacting, High-Performance Concrete
Author(s): Naoki Nagamoto and Kazumasa Ozawa
Publication: Symposium Paper
Appears on pages(s): 623-636
Keywords: box form test; funnel speed; quantity of coarse aggregate; Self-compacting
concrete; self-compactability; slump flow; coarse aggregates; deformation; slump tests; superplasticizers; tests
The self-compacting concrete, which was developed in 1988 in Japan, can be filled in a formwork without using any vibrators. It is an effective means of ensuring consistent quality in concrete structures, as the human factor in consolidation can be eliminated. This type of concrete has markedly increased deformability without segregation; high deformability is achieved mainly through the use of superplasticizers, while segregation resistance is achieved mainly through viscosity of the mortar or paste components of the concrete. The focus of this study is on experimental assessment of the effects of each component of concrete mixture in self-compacting concrete on the fresh state. The main findings are as follows: (1) There are certain combinations of slump flow and funnel speed that gave optimum self-compactability, with self-compactability falling off as one moves away from these combinations. This agrees with the results of the previous studies. (2) Increasin g the coarse aggregate content above the range G/Glim = 0.50 results in loss of compaction. The decrease in compaction is in a non-linear relationship with the increase in coarse aggregate, showing a rapid falling-off in self-compactability over G/Glim = 0.50. (3) If the quantity of coarse aggregate is varied while the quantity of fine aggregate remains fixed, no clear change can be seen in the water-powder volume ratio required to achieve self-compacting concrete, but the quantity of super-plasticizer required increases.