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Title |
A Defect Index-Based Condition Assessment Framework and Chloride Resistance Evaluation for Advanced Maintenance of Highway Underground Structures
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Authors |
오상혁(Sang-Hyuk Oh) ; 김현중(Hyun-Joong Kim) ; 도종남(Jong-Nam Do) ; 이지영(Ji-Young Rhee) |
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DOI |
https://doi.org/10.11112/jksmi.2026.30.3.19 |
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Keywords |
고속도로 지중구조물; 상태평가; 염해; 방수공법; KDS 설계기준 Underground highway structures; Condition assessment; Chloride; Waterproofing methods; Design standards |
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Abstract |
Underground expressway structures (culverts) in Korea account for approximately 44% of all road facilities, making them a major infrastructure asset. However, because they are excluded from the statutory management framework under the Facility Safety Act, they remain in a maintenance blind spot. In particular, 51.2% of these structures have been in service for more than 20 years, and there has been an increasing number of cases in which structural defects caused by long-term ground behavior and deterioration directly lead to damage in the overlying expressway pavement and related safety incidents. To address this issue, this study was conducted in two stages. First, a five-level condition assessment and inspection manual was developed for expressway underground structures, with particular emphasis on construction joints and leakage conditions in consideration of their unique characteristics. Second, full-scale concrete specimens were fabricated and subjected to a one-year exposure test in a 3% NaCl solution to quantitatively evaluate the resistance of different waterproofing methods to chloride attack. The experimental results showed that the single-layer asphalt coating system specified in the current KDS design standard achieved only about a 15% reduction in chloride ingress relative to the unwaterproofed control. In contrast, inorganic penetrating waterproofing and sheet-type composite waterproofing systems exhibited excellent chloride-blocking performance. These findings are expected to provide an engineering basis for establishing a proactive maintenance framework for underground structures and for revising the KDS 44 90 00 design standard based on durability performance.
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