PURPOSES : In this study, a method for evaluating concrete bridge deck deterioration using three-dimensional (3D) ground penetrating radar (GPR) survey data and its in situ application are discussed. METHODS : Field surveys are conducted on two bridges in Yongsan-gu (Bridge A) and Seodaemun-gu (Bridge B) in Seoul using 3D GPR. The obtained survey data are used to calculate the dielectric constant map of each bridge using the extended common midpoint method. In addition, random points on both bridges are selected for the chloride content test in accordance with the KS F 2713 standard. The results from the dielectric constant map and chloride content test are compared. RESULTS : For Bridge A, it is discovered that the percentage of sections with a dielectric constant of 5.0 or less is 1.57%, whereas that above 5.0 is 98.43%; this indicates that the percentage of deteriorated sections for Bridge A is low. Meanwhile, for Bridge B, the dielectric constants calculated for the entire bridge exceed 5.0, which suggests no deterioration for Bridge B. Moreover, all the points selected for the chloride content test have less than 0.15% chloride content and have dielectric constants ranging from 5.0 to 7.0, which are favorable condition for the bridge deck. CONCLUSIONS : The analysis results of the dielectric constants of the concrete bridge deck obtained from the 3D GPR system are consistent with the actual chloride content results. Furthermore, additional verification of this method through field surveys on bridge sections with severe deterioration is highly recommended for future improvements.

ABSTRACT
1. 서론
2. 연구동향
3. 분석방법
    3.1. 상대유전율
    3.2. 공통중심법
4. 현장조사
5. 조사결과 분석 및 검토
    5.1. 상대유전율 분석
    5.2. 염화물 함량 분석
6. 결론
REFERENCES

• 마경훈((재)서울기술연구원 도시인프라연구실 전임연구원) | Ma, Gyeong Hoon
• 이진욱((재)서울기술연구원 연구기획실 수석연구원) | Lee, Jin Wook
• 오한진((재)서울기술연구원 도시인프라연구실 수석연구원) | Oh, Han Jin
• 이상염(인덕대학교 토목공학과 교수) | Lee, Sangyum
• 김기덕(㈜아이리스테크놀로지 도로사업부 차장) | Kim, Kideok Corresponding author