PURPOSES: Nitrogen oxide (NOx) is a particulate matter precursor, which is a harmful gas contributing to air pollution and causes acid rain. The approaching methods for NOx removal from the air are the focus of numerous researchers worldwide. Titanium dioxide (TiO2) and activated carbon are particularly useful materials for NOx removal. The mechanism of NOx elimination by using TiO2 requires sunlight for a photocatalytic reaction, while activated carbon absorbs the NOx particle into the pore itself after contact with the atmosphere. The mixing method of these two materials with concrete, coating, and penetration methods on the surface is an alternative method for NOx removal. However, this mixing method is not as efficient as the coating and penetration methods because the TiO2 and the activated carbon inside the concrete cannot come in contact with sunlight and air, respectively. Hence, the coating and penetration methods may be effective solutions for directly exposing these materials to the environment. However, the coating method requires surface pretreatment, such as milling, prior to securing contact, and this may not satisfy economic considerations. Therefore, this study aims to apply TiO2 and activated carbon on the concrete surface by using the penetration method.
METHODS : Surface penetrants, namely silane siloxane and silicate, were used in this study. Photocatalyst TiO2 and adsorbent activated carbons were selected. TiO2 was formed by the crystal structures of anatase and rutile, while the activated carbons were plant- and coal-type materials. Each penetrant was mixed with each particulate matter reductant. The mixtures were sprayed on the concrete surface using concentration ratios of 8:2 and 9:1. A scanning electron microscopy with energy dispersive X-ray equipment was employed to measure the penetration depth of each specimen. The optimum concentration ratio was selected based on the penetration depth.
RESULTS: TiO2 and activated carbon were penetrated within 1 mm from the concrete surface. This TiO2 distribution was acceptable because TiO2 and activated carbon locate to where they can directly come in contact with sunlight and air pollutant, respectively. Infiltration to the concrete surface was easily achieved because the concrete voids were bigger than the nanosized TiO2 and microsized activated carbon. The amount of penetration for each particulate matter reductant was measured from the concrete surface to a certain depth.
CONCLUSIONS : The mass ratio on the surface can be predicted from the mass ratio of the particulate matter reductant measurement distributed through the penetration depth. The optimum mass ratio was also presented. Moreover, the mixtures of TiO2 with silane siloxane and activated carbon with silicate were recommended with an 8:2 concentration ratio.

ABSTRACT
1. 서론
2. 미세먼지 전구체 저감 소재의 특성
    2.1. TiO2의 미세먼지 제거원리 및 특성
    2.2. 활성탄 미세먼지 제거원리 및 특성
3. 미세먼지 전구체 저감 소재의 고정화를 위한 실험전략
    3.1. 미세먼지 전구체 저감 소재의 고정화 방안 선정
    3.2. 미세먼지 전구체 저감 소재의 고정화를 위한 기존 콘크리트 구조물 검토
    3.3 미세먼지 전구체 저감 소재 및 표면 침투제 검토 및 선정
    3.4. 시편 제작 및 미세먼지 전구체 저감 소재 적용
    3.5. SEM/EDAX를 이용한 미세먼지 전구체 저감 소재의 침투 깊이 평가
4. 미세먼지 전구체 저감 소재 침투 깊이 및 침투 질량비 분석
    4.1. 콘크리트 구조물의 탄소 성분 검토
    4.2. 콘크리트 포장 미세먼지 전구체 저감 소재 침투분포 측정
    4.3. L형 측구 미세먼지 전구체 저감 소재 침투분포 측정
    4.4. 인터록킹 블록 미세먼지 전구체 저감 소재침투분포 측정
    4.5. 투수 블록 미세먼지 전구체 저감 소재 침투분포 측정
    4.6. 분포 패턴 분석에 따른 표면의 미세먼지 전구체 저감 소재 예측 질량비 및 적용방안
5. 결론
REFERENCES

• 안희락(강릉원주대학교 토목공학과) | Ahn Hui Rak
• 김영규(강릉원주대학교 방재연구소) | Kim Young Kyu
• 이승우(강릉원주대학교 토목공학과) | Lee Seung Woo (Department of Civil Engineering, Gangneung-Wonju National University) 교신저자