Abstract
Chemical activity of rice husk ash is greatly controlled by the burning condition for rice husks. In this report a burning principle that is named “Two Step Burning Method” and two examples of furnace based on the principle were shown. The rice husk ash produced from these furnaces was very active, and it was confirmed by compressive strength test for concrete specimens. Furthermore, some physical properties for secondary agglomeration of ground rice husk ash were studied. The agglomeration causes to block the dispersion of ground rice husk ash when concrete is mixed. A grinding aid (di-ethylene glycol) was used to prevent that. It was also shown that theuse of the grinding aid was so effective to prevent the agglomeration. Highly active rice husk ash was also very effective to prevent bleeding of fresh concrete even in the case of water binder ratioof 70%. No bleeding was observed, and concrete which had ractical strength for concrete structure was obtained.
