This study analyzes the pore structure and durability of concrete according to four different ratios of steelmaking slag powder (SSP). Concrete containing SSP increased the formation of gel and capillary pores due to delayed hydration, and the largest cumulative pore volume was observed when the incorporation ratio was 20%. In terms of durability, the incorporation of SSP had decreased performance compared to concrete without SSP (NN), which was due to changes in the pore structure caused by incorporating SSP. In the case of the freezing and thawing resistance, concrete containing 10% SSP showed a remarkable relative dynamic elastic modulus of more than 80%, and a similar carbonation depth was predicted within 15% of SSP. In addition, the resistance performance of chloride ion migration in concrete with SSP was excellent. Accordingly, it can be utilized as a supplementary cementitious material if the freezing and thawing resistance of concrete containing 15% SSP is secured.

In this study, the compression and tensile sections of existing concrete were reinforced using carbon fiber sheet (CFS) and no-slump high-strength, ductility concrete (NSHSDC) to evaluate the structural response of the reinforced concrete. From the experimental test results, the CFS showed a low energy dissipation ability when reinforced at both the compression and tensile sections. However, the NSHSDC reinforcement exhibited high energy dissipation and the lowest deflection under maximum load at both the compression and tension sections. The NSHSDC without reinforcement in the compression section, and concrete reinforced with CFS, exhibited lower load resistance and concrete compression failure. Furthermore, a linear relationship between the compression reinforcement and structural performance was observed, which demonstrated the high load resistance and excellent structural performance of the member reinforced with NSHSDC at both the compressive and tensile sections.