Abstract
Recently, the demand for precast concrete have been increased with the object for construction, productivity, quality control and the shortening of a construction period. In addition, the study for compressive strength of fly ash concrete under the steam curing has been investigated. However the effect of various condition such as, temperature history and curing condition（water curing or air curing）after steam curing on concrete performance has not been clarified. With regard to the Fly ash concrete cured in temperature history, the study of compressive strength under long term curing age has not been enough.
From the background, the relation between the phase composition and compressive strength of Fly ash concrete was investigated in this study. In order to clear the effect of the replacement of Fly ash for compressive strength under the period early age between long term ages, the phase composition of hardened Fly ash cement paste was measured. Furthermore, in order to evaluate the effect of the curing condition after the temperature history, the relation between phase composition and compressive strength cured at water curing or air curing were investigated by Gel/Space ratio.
From these experimental results, the compressive strength of Fly ash cement paste cured at water curing after the temperature history was increased until the age of 365 days. The reaction ratio of Fly ash in cement paste cured at water curing was increased until the age of 365 days. On the other hand, the reaction ratio of Fly ash in cement paste cured at air curing was slightly increased until the age of 365 days. A high correlation is observed between the phase composition and the compressive strength independent of the temperature history and type of binder. Therefore, the compressive strength of hardened cement paste cured at water curing and air curing was evaluated by the relation between phase composition and compressive strength. From these results, the compressive strength of cement paste cured at air curing after the temperature history was not increased until the age of 365 days.
