Ultrasonic guided waves for monitoring incipient corrosion in reinforced concrete with top-bar defect

Top-bar defects in reinforced concrete are voids that are observed below the reinforcing bars that are at an elevation of more than 300 mm. The authors have demonstrated a new ultrasonic guided wave technique to non-destructively detect top-bar defect (Wang, Mukherjee et al., 2021). It has been reported that bars with top-bar defect corrode is faster than other bars. The corrosion also manifests in a different manner in these bars. This paper proposes a guided ultrasonic wave-based non-destructive method for monitoring corrosion in reinforced concrete with top-bar defect. Concrete wall samples with bars of various extents of top-bar defect were subjected to accelerated corrosion. Simultaneously, the bars have been monitored with guided ultrasonics. The investigation revealed that top-bar defect has a significant influence on the corrosion process. The destructive tests performed at the end of corrosion exposure revealed that the top-bar specimens had a significant loss of strength than the bars with a good bond. The proposed non-destructive has been calibrated to assess the residual capacities of corroded bars in presence of top-bar defect.