Ground penetrating radar for assessment of reinforced concrete wastewater treatment plant

During their long-term service, wastewater treatment plants deteriorate due to rebar corrosion in concrete structures. This paper presents a case study of ground penetrating radar (GPR) survey performed on a reinforced concrete (RC) structure in sieving unit of the wastewater treatment plant in the City of Fortaleza, Brazil. The RC structure was subjected to both the sulfuric acid attack from the oxidation of hydrogen sulfide present in the wastewater gas and the cyclic dry–wet salt-fog environment due to its proximity to the ocean. The survey results suggest that the amplitude of electromagnetic waves from a GPR scan and the determined dielectric permittivity values can be used to monitor steel rebar corrosion in a concrete structure by rapidly detecting any growth of inherent faults. The results indicate that the rebar condition can be assessed through slices at different times/depths obtained from a three-dimensional (3D) survey. Based on this study, it is recommended that the upper RC slabs in sieving unit of the plant be demolished and the lower slabs be preserved.