GNGTS 2022 - Atti del 40° Convegno Nazionale

416 GNGTS 2022 Sessione 3.2 MULTISENSOR GEOPHYSICAL APPROACH FOR REBAR MONITORING G. Fornasari 1,2 , L. Capozzoli 2 , G. De Martino 2 , V. Giampaolo 2 , E. Rizzo 1,2 1 University of Ferrara, Dipartimento di Fisica e Scienze della Terra, Ferrara, Italy 2 CNR – IMAA, Laboratorio Hydrogeosite, Marsico Nuovo, Italy Introduction. This work describes a laboratory test on rebar corrosion monitoring by a multisensor geophysical methods: GPR and electrical methods. Rebar corrosion is one of the main causes of deterioration of engineering reinforced structure. This degradation reduces the service life and durability of the structures. Such degradation can result in the collapse of engineering structures. Non-destructive testing and evaluation of the rebar corrosion is a major issue for predicting the service life of reinforced concrete structures. The experiments were performed at Geophysical laboratory of University of Ferrara, where a concrete sample of about 500mm x 300mm with one steel rebar of 10 mm diameter and 40cm long was used. The experiment defined an accelerating rebar corrosion with direct current (DC) power supply along the rebar and a partial immersion of the sample in a 5% sodium chloride (NaCl) solution inducing the corrosion phenomena. The 2GHz GPR antenna by IDS and Self-Potential with unpolarized referenced electrode acquired by Keithley multivoltmeter at high impedance were used for rebar corrosion monitoring. The collected data were used for an integration observation to define the evolution of the phenomenon of corrosion on the reinforcement bar. Methods. Laboratory sample was built with fast concrete based on special binders, quartz and synthetic additives and develops high mechanical strength in a very short time. The sample was built with one improved grip steel rebar of 10 mm diameter and a length of 350 mm (fig.1). The exposed length of the rebars is 2.5 cm per side. The concrete thickness was 30 mm in the upper part and 40 mm in the lower part. For each survey with the georadar 60 radargrams of 500 mm length are acquired; the trace increment set is 1.379mm and the sampling is 512. After each georadar survey, Self-Potential (SP) acquisition was carried out on the sample. The SP signals is based on the electrical and electrolytic continuity between rebar in concrete, reference electrode on the sample surface and a high-impedance voltmeter. The Fig. 1 - Laboratory sample and acquisition with the GPR C-TRUE antenna.