In previous studies of the durability of concrete containing slag exposed to the combined impact of de-icing chemicals and freeze-thaw cycles, the scaling resistance of concrete was improved by using slag replacement amounts ranging from 25 to 35% of the total cement content. However, the resistance decreased rapidly when the amount of slag replacement increased beyond 40% of the cement content. Furthermore, in these studies, only normally cured concrete products were used rather than steam-cured concretes. Thus, the research on the scaling resistance of steam-cured concrete products with slag replacement has not been studied enough. In this study, the durability characteristics of steam-cured concrete containing slag exposed to the impact of concrete de-icing chemicals and freeze-thaw cycles were investigated with the aim of improving the quality of precast concrete products. Scaling, chloride ion penetration, pull-off strength and the relative dynamic modulus of elasticity were evaluated for both the pouring and bottom surfaces of the specimens. This was done because it was expected that the concrete pouring surface would suffer more degradation than the bottom surface owing to weakened concrete strength caused by bleeding effects.

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In the previous study, the analysis method based on the bond analysis was proposed to estimate cracking behavior due to drying shrinkage in RC wall, and the validity of the analysis method was verified from experimental study. However, because there is a shortcoming that calculation is complex, the simple estimation method is demanded. Accordingly, for the more simple estimation of the crack width and number of cracks of RC wall in the buildings, an improved and simple equation based on the bond analysis was proposed in this paper, and the calculation values were compared with the experimental values.

The thermal decomposition characteristics of the ZPP(Zirconium/Potassium perchlorate), widely used as a primary charge of initiators, were investigated by differential scanning calorimetry(DSC). The DSC results with different heating rates were elaborated with AKTS-Thermokinetics software for the determination of the kinetic parameters of the thermal decomposition of ZPP. There was good agreement between the experimental and the simulation curves, based on the determined kinetic parameters, which indicates the validity of the kinetic description of the thermal decomposition process of ZPP.