Attenuation of Ground Penetrating Radar Signal Amplitude in Monitoring Reinforced Steel Corrosion

In this study, the reduction of ground penetrating radar (GPR) signal amplitude magnitudes were measured to monitor the reinforcing steel corrosion in concrete slab. Geophysical Survey System Incorporation (GSSI) BridgeScan system which includes a SIR-3000 Windows, based on portable GPR data collection with 1.6 GHz ground-couple antenna has been used to generate electromagnetic waves and analysis of the signal on a slab sample. Four 16 mm diameter reinforcing steel were embedded in a 255 mm x 455 mm x 60 mm grade 40 concrete slab in the transverse direction and three in the longitudinal. The slab was immersed in concentrated sodium chloride solution (8 g/l) for three months to simulate the corrosive environment on the reinforced slab. The average signal amplitude decreases from 1139.75 dB (at day 7) to -404.25 dB (at day 61) and finally drop to -782.75 dB (at day 93) as the corrosion process progressing. The presence of corrosion activity on the reinforcing steel was confirmed based on the potential difference reading by Half Cell (HC) which shows that the reinforcing steel experienced probability of corrosion level by more than 90 % after 61 and 93 days. GPR method is found to be a promising approach as it possesses high sensitivity towards changes in amplitude at par with high potential changes in HC method in corrosion detection.