PURPOSES : Recently, air pollution caused by particulate matter has been worsening. Among the substances generating particulate matter, NOx is the main precursor of particulate matter and is widely distributed in areas with a high volume of traffic. TiO2 has been used as a material for removing NOx through a chemical reaction as a photocatalyst. In this context, the reduction of NOx through TiO2 concrete is proposed. However, the research on the surface deterioration on the performance of TiO2 concrete is not documented yet. Therefore, the objective of this study was to evaluate the long-term durability and NOx removal efficiency of TiO2 concrete by considering the concrete surface deterioration.
METHODS : Freezing–thawing resistance test (KS F 2456) and scaling test (ASTM C 672) were performed to investigate the variation in the TiO2 penetration distribution and NOx removal efficiency of TiO2 concrete corresponding to surface deterioration. The long-term durability of TiO2 concrete was evaluated through an environmental resistance test and changes in TiO2 penetration depth and distribution characteristics. In addition, the NOx removal efficiency of TiO2 concrete was evaluated as surface deterioration occurs. RESULTS : As a result of the freeze–thawing resistance test, a relative dynamic elastic modulus of more than 80 % was detected. In addition, a TiO2 penetration depth of 0.3 mm, NOx removal efficiency of 11.2 %, and a 30 % of TiO2 surface prediction mass ratio were achieved after 300 cycles. As a result of visual observation of the scaling test, “0, no scaling” was secured. After 50 cycles of scaling test, the TiO2 penetration depth, NOx removal efficiency, and TiO2 surface prediction mass ratio were 0.3 mm, 36.3 %, and 63 %, respectively. Through the results of the environmental resistance test, the excellent long-term durability and NOx removal efficiency of TiO2 concrete were confirmed.
CONCLUSIONS : As a result of the experiment, long-term durability and NOx removal efficiency of TiO2 concrete were secured. The application of TiO2 concrete can be a good alternative with long-term performance and durability.

ABSTRACT
1. 서론
2. TiO2 콘크리트의 특성
    2.1. TiO2의 질소산화물(NOx) 제거 원리
    2.2. 이론적 배경
3. TiO2 콘크리트의 장기 공용성 및 내구성 검토방안
    3.1. 실험개요
    3.2. TiO2 콘크리트 내구성 검토방안
    3.3. TiO2 콘크리트 장기 내구성 변화에 따른 질소산화물(NOx) 제거효율 검토방안
4. 노면열화에 따른 TiO2 콘크리트의 장기 내구성및 질소산화물(NOx) 제거효율 검토
    4.1. 동결융해 저항성 시험에 따른 질소산화물(NOx)제거효율 변화
    4.2. 표면박리 저항성 시험에 따른 질소산화물(NOx)제거효율 변화
5. 결론
REFERENCES

• 안희락(강릉원주대학교 토목공학과 박사과정) | Ahn Hui Rak
• 김영규(강릉원주대학교 방재연구소 연구교수 · 공학박사) | Kim Young Kyu
• 이승우(강릉원주대학교 토목공학과 교수 · 공학박사) | Lee Seung Woo Corresponding author