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 4. (a) Schematic and (b) graphical description of setup employed for applying constant current to an unconfined rebar embedded in a 40 mm × 40 mm × 160 mm mortar prism in order to accelerate its corrosion propagation.

The mortar samples were all connected to the galvanostat – as specified in Figure 4b – which, in turn, was linked in series with a 500 Ω resistor. This setup provided a constant corrosion current of 3016 μA which, assuming a cylindrical geometry for the rebar, resulted in I corr = 100 μA/cm² for all mortar beams. Such a value was chosen in agreement with the literature to ensure rapid corrosion progress within the mortar sample (Andrade, Alonso, and Molina, 1993; Caré and Raharinaivo, 2007). This resulted in a constant mass loss for the steel rebar with an attack penetration (A.P.) of ~4.74 μm/day, according to equation 2 (Rodriguez and Andrade, 1990). ϕ(t)=ϕ i -0.023·I corr ·t (2) This test was conducted for approximately 24 days until the extreme corrosion of all samples produced cracks with a width above ~500 μm. For partially confined rebars, the corroded section was smaller than its unconfined counterpart. Thus, a constant current of 2.3, 1.5, and 0.75 mA for samples with a rebar confinement of 4, 8, and 12 cm, respectively. These current values were determined by considering the exposed area of the rebar when applying the fixed corrosion current of 100 μA/cm².