Diagnostics of pillars in St. Mary’s Church (Gdańsk, Poland) using the GPR method

ABSTRACT

The main goal of this study was non-destructive evaluation of pillars in the St. Mary’s Church (Gdańsk, Poland) using the ground penetrating radar (GPR) technique. The GPR inspection was conducted on four brick masonry pillars and five pillars strengthened by reinforced concrete jacketing. Data were acquired with a 2 GHz antenna along longitudinal and transverse profiles. The study involved the estimation of the electromagnetic wave velocity in both brick and concrete, the inspection of the internal structure of the pillars, and the precise identification of reinforcement bars. To determine the wave velocity in bricks, a novel mathematical model was developed. Finite-difference time-domain (FDTD) simulations were used to verify and assess the feasibility of the proposed model. Finally, GPR maps were processed using the hyperbolic summation method to visualize the reinforcement distribution in the concrete jacket.

KEYWORDS:

• Ground penetrating radar
• historical buildings
• masonry pillars
• non-destructive testing
• reinforced concrete jacketing
• strengthening
• velocity estimation