GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 3.2 ___ GNGTS 2023 Multisensor geophysical approach for steel rebar corrosion monitoring G. Fornasari 1,2 , F. Zanotto 3 , A. Balbo 3 , V. Grassi 3 and E. Rizzo 1,2 1 Dipartimento di Fisica e Scienze della Terra, University of Ferrara, Ferrara, Italy 2 CNR – IMAA, Laboratorio Hydrogeosite, Marsico Nuovo, Italy 3 A. Daccò Corrosion and Metallurgy Study Centre, Dipartimento di Ingegneria, University of Ferrara, Ferrara, Italy Introduction This paper describes laboratory tests performed with a multisensory geophysical methods: GPR and electrochemical methods in order to monitor the corrosion of a rebar embedded in concrete. Rebar corrosion is one of the main causes of deterioration of engineering reinforced structure. This degradation phenomena 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 experiment was set up in two phases. In the first phase of this study, we monitored the "natural" corrosion occurred on sample "B" due to the diffusion of chlorides towards the steel rebar comparing the obtained data with those of sample "A" exposed to distilled water. In the second phase of the study, accelerated corrosion was applied to sample "B" in order to induce a relevant corrosion phenomena. The collected data were used for an integration observation to define the evolution of the corrosion on the reinforcement steel rebar and to define a quantitative analysis of the phenomena by GPR data. Methods Laboratory sample was built with 32.5 R cement, hydraulic binder coming from the grinding of Portland clinker with added percentages of gypsum and natural limestone. It is characterized by a mechanical compressive strength, after 28 days, higher than 32.5 N/mm2. The sample was built with one improved grip steel rebar of 10 mm diameter and a length of 350 mm. 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. The stell rebar was painted with a waterproof epoxy resin leaving exposed a central part for a length of 8 cm. The samples were cured for 30 days in laboratory conditions, and finally extracted from the wooden formworks. GPR measurements were performed before samples exposure to tests solutions.