PSI - Issue 78

Israel Sousa et al. / Procedia Structural Integrity 78 (2026) 1815–1822

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electrodes embedded in the middle zone of the specimens (Eq. 2) . Resistivity measurements (ρ) under unloaded conditions were performed to assess long-term electrical behavior at 20, 53, and 74 days after casting. For each mortar type, two specimens were tested for static resistivity (Eq. 3). = , (1) = ( ) , (2) = , (3) where A is the cross-sectional area and L is the distance between the two centered electrodes. A Digital Image Correlation (DIC) system from DANTEC Dynamics was employed to monitor strain evolution during the electromechanical tests, enabling a comparison between the optical strain data and the mechanical response obtained from the Instron machine. The DIC setup consisted primarily of a high-resolution camera and a computer equipped with Istra 4D image processing software (Dantec Dynamics). The setup was configured to capture full-field strain evolution during the 3-point bending test (Figure 4).

Fig.4. Representation of electromechanical test coupled with the DIC system.

2.3. Electromechanical model To support the analysis of damage detection, a correlation was established between the electrical response and the damage of the prismatic specimens. An electrical parameter, expressed as 0 , was defined to quantify the normalized change in conductivity. The electrical conductivity under loading conditions (σ) was computed as shown in Eq. (4): = 1 , (4) and σ 0 corresponding to the conductivity measured in the final cycle before crack initiation. In parallel, a mechanical damage index, dt, was calculated for each loading cycle according to Eq. 5 (Meoni et al., 2025): =1 − 0 , (5) with E 0 corresponding to the initial elastic modulus immediately before crack appearance, and E being the modulus