Abstract
Non-destructive tests are strongly required in engineering applications for monitoring civil structures. The use of compared and integrated innovative approaches based on geophysical methodologies represents an effective tool for the characterization and monitoring of reinforced concrete (RC) structures. Therefore, the main aim of the work was to improve the knowledge on the potentiality and limitations of the Ground Penetrating Radar (GPR) and the Electrical Resistivity Tomography (ERT) with electrodes disposed both on the surface and in the boreholes. The work approach was adopted on an analog model of a reinforced concrete frame built ad hoc at the Hydrogeosite Laboratory (CNR-IMAA), where simulated experiments on full-size physical models are defined. Results show the ability of an accurate use of GPR to reconstruct the rebar dispositions and detect in detail possible constructive defects, both highlighting the lack of reinforcements into the nodes and providing useful information about the safety assessment of the realized structure. The results of the ERT method defined the necessity to develop ad-hoc electrical resistivity methods to support the characterization and monitoring of buried foundation structures for civil engineering applications. Finally, the paper introduces a new approach based on the use of cross-hole ERTs (CHERTs) for the engineering structure monitoring, able to reduce the uncertainties usually affecting the indirect results.
Highlights
Non-Destructive Techniques (NDT) are widely applied in the engineering field for investigating reinforced concrete (RC) elements belonging to civil structures and infrastructures
Despite the impossibility to use an automatic system of acquisition, 2000 MHz data permit to accurately reconstruct the disposition of the longitudinal and transverse reinforcements
The reflections due to the presence of the rebars are observable at depths ranging between 3 and 4 cm according to the design specifications
Summary
Non-Destructive Techniques (NDT) are widely applied in the engineering field for investigating RC elements belonging to civil structures and infrastructures. Thanks to their high resolution and repeatability, analyses based on the study of the physical property variations, it is possible to identify defects and fractures due to induced stresses, intrinsic inhomogeneities, or structural problems. Several indirect methods are used for ground surface investigation correlated to geotechnical engineering problems, such as Ground Penetrating. NDT focused on the detection and characterization of foundations and/or buried structures is a complex topic covering many different techniques designed to gain information about the integrity and quality of the material that makes up a foundation. To overcome some of the limitations of the surface testing techniques, a few researchers have focused on the possibilities of downhole NDT techniques [5,6]
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