PSI - Issue 67

Oscar Aurelio Mendoza Reales et al. / Procedia Structural Integrity 67 (2025) 8–16 Mendoza Reales et. al./ Structural Integrity Procedia 00 (2024) 000 – 000

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section. Additionally, since the measurements were performed in transient regime, the Seebeck effect may also play a role in the observed behavior, Wen and Chung (1999), Sun et al. (1998).

(a) Temperature versus strain

(b) Temperature versus FCR Fig. 4. Relation between temperature, deformation, and electrical conductivity of the SSCC.

3.2. Effect of temperature in steady regime over the piezo-resistivity of SSCC After determining the effect of temperature in transient regime, without mechanical load application on the SSCC, samples were heated to a target temperature and compressed up to 2.0 MPa. The change in FCR due to compressive load application was measured using the copper electrodes. The stress versus strain and FCR versus strain curves obtained at 25°C, 50 °C and 75 °C are presented in Fig. 5. For each testing condition, the elastic modulus (E) was obtained from the slope of the strain versus stress curves, and the gage factor (GF) was obtained from the slope of strain versus FCR curves. Results are presented in Table 2. Regarding the mechanical behavior of the SSCC, it was found that SSCC2 reached higher deformation values than SSCC1 for the same applied stress, yielding a lower elastic modulus. This change can be related to differences in sand content between both SSCC. Temperature increases were found to decrease the elastic modulus of the 50°C and 75°C samples up to 20% when compared to the 25°C samples. It was found that in a stationary temperature regime, regardless of the differences in the overall electrical resistivity induced by temperature, the FCR of both SSCC was not affected by temperature up to 75 °C, indicating a good applicability for the SSCC in different scenarios where concrete structures are submitted to heating.

Table 2. Modulus of elasticity (E) and gage factor (GF) for both SSCC measured in different operation temperatures. E (GPa) GF Temperature 25°C 50°C 75 °C 25°C 50°C 75 °C SSCC1 7.11 ± 0.13 6.35 ± 0.13 5.57 ± 0.38 1070 ± 148 1093 ± 85 1398 ± 85 SSCC2 3.87 ± 0.25 3.83 ± 0.23 3.63 ± 0.19 419 ± 25 356 ± 4 531 ± 61