GNGTS 2022 - Atti del 40° Convegno Nazionale

GNGTS 2022 Sessione 3.2 417 SP was acquired by a fixed cable to the rebar and an unpolarizable electrode as reference (Petiau electrode). The measurements were carried out by covering the entire surface of the sample according to a predetermined mesh of 54 points. The unpolarizable electrode was connected to the Keithley multivoltmeter at high impedance, while the positive pole was connected to the armature bar. At each movement of the electrode, the measurement of the spontaneous potential in (mV) and the contact resistance (Ohm) was carried out. Once the accelerated corrosion test was started, geophysical investigations were carried out every 24 h. The power supply was turned off after 15 days from the start of the test. At the end of the corrosion of the concrete sample, and disconnected the power supply, we performed 5 investigations to define a final state of the phenomenon. Finally, the sample was taken out of the water and NaCl solution and once it had completely dried. The acquired radargrams were elaborated by Reflex software and Results and discussions. The acquired radargrams were elaborated with ReflexW (Sandmeier software) and the base elaboration was applied. Moreover, an envelope trace analysis was applied. The envelope data set of each radargrams was compared with the previous one and the trace corresponding to the steel rebar was studied on all radargrams. The envelope signal of the steel rebar shows an increase in the strength of signal as corrosion increases. A greater increase in the envelope signal was observed where we observed greater corrosion in the steel rebar inside the sample and near the edges of the concrete, where the bar had a large damage due to corrosion. The acquired SP signals ​and the contact resistances were depicted as a map distribution. The contour maps defined a strong variation in the potential data highlighting the dangerous corrosion phenomena where the GPR depicted large envelope signals. From the investigations conducted on the reinforced concrete sample using GPR and studying the envelope signal over time, we obtained a correlation with the spontaneous potential investigations in defining the areas where we had corrosion and the areas of the steel rebar most corroded. Moreover, extrapolating laboratory results performedwith a single rebar to a large structure with interconnected rebars thus remains challenging. Therefore, during the next experiments, special care must be taken regarding the design and preparation of the samples to obtain meaningful information for field application. References Ahmad Zaki, Megat Azmi Megat Johari, Wan Muhd Aminuddin Wan Hussin and Yessi Jusman (2018). International Journal of Corrosion Volume 2018, Article ID 5389829, 10 pages https://doi.org/10.1155/2018/5389829 Ramzi Adriman; Israr Bin M. Ibrahim; Syifaul Huzni; Syarizal Fonna; Ahmad Kamal Ariffin (2022). Improving half- cell potential survey through computational inverse analysis for quantitative corrosion profiling. Case Studies in Construction Materials, ISSN: 2214-5095, Vol: 16, Page: e00854 Romain Rodrigues, Stéphane Gaboreau, Julien Gance, Ioannis Ignatiadis, Stéphanie Betelu. Reinforced concrete structures: A review of corrosion mechanisms and advances in electrical methods for corrosion monitoring. Construction and Building Materials, Elsevier, 2020, pp.121240. f10.1016/j.conbuildmat.2020.121240ff. ffhal- 02979786ff