STUDY ON APPLICATION OF THE IMPACT ELASTIC WAVE METHOD FOR DETECTING INTERNAL DETERIORATION IN STEEL FIBER REINFORCED CONCRETE OVERLAY SLABS

Abstract

 The slab strengthened by a steel fiber–reinforced concrete (SFRC) overlay has developed significant deterioration due to aging, the effects of fatigue caused by heavy vehicle traffic, and other severe service conditions. However, it is difficult to identify internal deterioration based solely on external appearance. This study examines whether the impact elastic-wave method can be applied to detect internal deterioration in reinforced concrete deck slabs of in-service expressway bridges.

 The results suggest that elastic waves can pass through the boundary between concrete and asphalt, which have different acoustic impedances. Verification using fabricated test specimens revealed that when asphalt pavement is placed directly on a reinforced concrete deck slab, elastic waves pass through the concrete–asphalt interface and are reflected at the asphalt surface.

 Furthermore, based on these findings, this paper also discusses the challenges and future developments in detecting internal defects using the impact elastic-wave method.