PSI - Issue 67

Gabriele Milone et al. / Procedia Structural Integrity 67 (2025) 90–106 G. Milone et al./ Structural Integrity Procedia 00 (2024) 000 – 000

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Figure 9. Visual depiction of three reinforced mortar beams with a cover depth of 4.8 mm; (a,c,d) before and (b,d,f) after the corrosion of the rebar: (a,b) sample #1; (c,d) sample #2; (e,f) sample #3.

The electrical output from sensors Y for each specimen is visually presented in Figure 10. Initially, all sensors exhibited an early negative response in the FCR (A.P. < 14 μm). This decline in resistance was attributed to oxide movements, which intensified compression in the region beneath the sensors (Andrade, Alonso, and Molina, 1993; Alonso et al. , 1996). Figure 11 confirms a significant oxide presence below the rebar, whose volumetric expansion caused preliminary tensile and compressive strains in the bottom and top surfaces, respectively. For higher attack penetrations (~33 μm), the decreasing FCR trend stopped and reached a stable negative value. This performance was related to oxide production on the top portion of the rebar, influencing the compressive strains of the above region. This initial step affected all three specimens and was consistent along the rebars direction (i.e., for sensors X, Y and Z). However, in more advanced corrosion settings, fracture propagation to the surface influenced the sensing response of the coatings.