PSI - Issue 64

Reza M. Fioruz et al. / Procedia Structural Integrity 64 (2024) 1142–1151 Firouz R. M. et. al./ Structural Integrity Procedia 00 (2019) 000 – 000

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transferring of the heating front until reaching the CFRP strips. The recorded temperature at failure in CFRP (middle and top) was similar for both adhesives. However, in the case of the surface temperature at failure and the temperature of the controlling curve, GPA samples recorded a slightly higher temperature. This is also evident when comparing the average TUF for GPA and CBA samples, which are 36.7 min and 34.2 min, respectively. However, it should be considered that the average constant thermo-mechanical load was about 10% higher in the samples with CBA matrices, as each series of samples is evaluated based on its own performance at ambient temperature. Pull-out bond tests on NSM CFRP systems using epoxy adhesives were per-formed by Azevedo et al. (2020). Tests were done while the samples were in steady state condition, under different stages of high temperatures exposure. 70% and 25% of residual bond strength at 70°C and 170°C were reported respectively. The results are also presented graphically in Fig. 4. Despite the slight differences mentioned above, the GPA adoption showed a promising performance when used as an adhesive for NSM CFRP strengthening.

Table 2. Thermo-mechanical pullout tests results.

CFRP middle temperature [°C]

CFRP top temperature [°C]

Concrete surface temperature [°C]

Furnace temperature [°C]

Time until failure [mm:ss]

Sample label

TM-CBA-1 TM-CBA-2 TM-CBA-3 TM-CBA-4 TM-GPA-1 TM-GPA-2 TM-GPA-3 TM-GPA-4

151 167 153 130 133 130 155 171

192 211 166 155 169 183 162 219

593 651 601 606 717 660 641 669

792 800 792 796 860 829 837 834

33:15 36:09 33:23 34:00 38:36 34:37 37:24 36:12

0 10 20 30 40 50 60

0 100 200 300 400 500 600 700 800 900 1000

Cement-based adhesive

Geopolymer adhesive

Temperature [ ° C]

Time until failure [min]

T-CFRP-mid T-Furnace-Control

T-CFRP-top

T-Surface

TUF

Fig. 4. Comparison of thermo-mechanical pullout tests results, temperature (T) at failure in different locations.

5. Life cycle assessment To compare the environmental impacts of the discussed adhesive materials for NSM CFRP systems, an LCA analysis was performed. In this section, the adopted methodology is introduced, and the results are presented and discussed.