초록
The purpose of this study is to develop the precast concrete without steam curing. Generally, it is necessary that the precast concrete must cure in steam condition. If we make a precast concrete without steam curing, we could save the manufacturing energy and $CO_2$ emission. In this experiment, the high early strength cement containing massive $C_3S$ quantity was used to enhance the early strength of cement mortar using admixtures which can accelerate $C_3S$ hydration reaction in the condition of room temperature. The measuring items are zero flow, setting times, compressive strength and analysis of MIP & SEM. From the results of this experiment, hardening catalyst is very effective to increase the high early strength of cement mortar according to the early formation of C-S-H hydrate. The compressive strength of mortar is increased that it increases in the amount of consumption of hardening catalyst. The increasing cause of the compressive strength of mortar is decrease in a pore ratio and pore size of mortar due to the acceleration of $C_3S$ hydration with hardening catalyst. Also, the generation of C-S-H was confirmed by use of a hardening catalyst according to an SEM analysis. When the strength and workability of mortar are considered, the appropriate amount of hardening catalyst dosage is about 1.0%.
