PSI - Issue 78

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

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Fig. 2. Preparation procedure for lime-based mortar samples CNT mix.

All fresh mortars were cast into oiled 160 x 40 x 40 mm steel molds and compacted. Copper meshes were embedded along the length of each specimen during casting, as illustrated in Fig. 3. The samples were then sealed in polyethylene bags for 7 days to prevent moisture loss. Demolding was performed after 14 days, once the specimens had developed sufficient strength.

Fig. 3. Dimension of the sample and position of the electrodes.

2.2. Experimental procedure A universal testing machine (Instron 68TM-50) was used to assess the electromechanical behavior of the samples under a displacement-controlled regime. Loading was applied up to a maximum displacement of 1.5 mm, enabling the identification and tracking of crack initiation and propagation for damage-sensing analysis. Electrical characterization was also conducted, simultaneously using a NI PXIe-1071 data acquisition card. A ±10 V square waveform at 1 Hz was generated by a RIGOL DG-1022 function generator and applied to the specimens through a four-electrode configuration. Voltage drops across both the shunt resistor and the specimen were monitored via two channels of the NI PXIe-4313 module, as in Downey, D’Alessandro, Baquera, et al. (2017); Downey, D’Alessandro, Ubertini, et al. (2017). Electrical current ( I ) was derived from the voltage drop ( ) across the shunt resistor ( ) using Ohm’s Law (Eq. 1), enabling calculation of the specimen’s electrical resistance ( R ) from the voltage ( ( ) ) measured between the