Centimetric Accuracy in GPR Measurements of Column and Capital Connecting Rebars

In this paper we discuss the application of ground penetrating radar (GPR) method in exploring the metallic reinforcement elements in masonry structures, addressing the precision challenges inherent in structural assessments. Selecting the proper frequency of the antenna is critical to achieve the desired centimetric accuracy in such surveys. We present the results of structural assessment surveys on a historical column using a 3GHz antenna that emerges as an effective compromise between the precision and the penetration. We propose a three-step calibration procedure that improves analysis of the data and provides reasonable results. We applied the proposed strategy to estimate the diameter of the rebars connecting the studied column to its base as well as to the capitals. Moreover, we could determine the penetration lengths of rebars inside the column. Our study illustrates the precision of the GPR method for non-destructive evaluations of historical structures, emphasizing the importance of careful calibration for achieving reliable and accurate results.