The 4th Asian Concrete Federation Symposium on Emerging Technologies for Structural Longevity (ACF2023- ETSL)

Ground-penetrating radar (GPR), as an efficient nondestructive testing method, has been applied to the detection of rebar corrosion in concrete in recent years. However, the traditional ground-penetrating radar system can only measure co-polarized radar signal in a single channel. In this paper, a polarimetric GPR method is proposed for non-destructive detection of early-stage corrosion of reinforcing steel. A hybrid polarized GPR system is built up in laboratory to monitor the variation of radar reflection signals in different polarization during an electricity-accelerated corrosion process. The results show that the radar signal variation in the polarization channel perpendicular to the direction of the reinforcement is more sensitive to the reinforcement corrosion compared with the commonly used co-polarization radar. The scattering mechanism of radar wave signal during the corrosion process is further analyzed by H-Alpha decomposition. The results show that the scattering signal of rebar changes from low entropy dipole scattering to low entropy surface scattering with the development of rebar corrosion. The reason may be that the surface roughness of ribbed rebar wrapped by modifier decreases in the corrosion process. It is concluded that polarimetric GPR has a great potential be an effective means for nondestructive detection of early corrosion of reinforcing bars in concrete structures.