Air-coupled 충격반향법을 활용한 철도 궤도 콘크리트 내부 박리평가

초록

Air-coupled Impact-echo (IE) tesing was used to evaluate delamiantion in track concrete layer (TCL) in urban railway concrete tracks. A simulated traffic concrete layer (TCL) specimen was prepared in the laboratory. The concrete specimen was designed to have dimensions of 1500 mm (length)x 1500 mm (width) x 300 mm (depth), which is large enough to simulate a full scale TCL in urban subway concrete tracks in Korea. Four delamination defects, with different depth d (50 mm and 250 mm) and widths w (150 mm and 300 mm), were simulated in the concrete slab by inserting double layered plastic film before casting concrete: DL1 (d = 50 mm, w = 300 mm), DL2 (d = 250 mm, W = 300 mm), DL3 (d = 50 mm, W = 150 mm) and DL4 (d = 250 mm, W = 150 mm). The concrete surface scanned by a air-coupled IE equipment developed in the laboratory. A peak frequency map was constructed to visualize the delamination based on the results measured by air-coupled IE testing.