PSI - Issue 64

Sareh Akbarpoor et al. / Procedia Structural Integrity 64 (2024) 822–832 Sareh Akbarpoor/ Structural Integrity Procedia 00 (2019) 000 – 000

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The results indicate comparability in terms of maximum bond stress between the developed cement-based adhesive and P-FS-CA. However, the compressive strength of the developed cement-based adhesive is 11% less than that of the P-FS-CA sample. Moreover, the findings highlight a more ductile behaviour in the post-peak performance of the NSM FRP system observed in this study, particularly evident in the higher fracture energy. Fracture energy, representing the area under the bond-slip curve and the energy required to cause debonding failure in the NSM FRP system, was detailed in Table 4. Specifically, Table 4 demonstrates that the fracture energy in the NSM FRP system using the developed cement-based adhesive is significantly higher than that observed in the comparisons.

Table 4. Comparison of different cement-based adhesives Sample

Bond Length (mm) Adhesive compressive strength (MPa)

FRP Surface treatment

Fracture Energy (N/mm)

P-FS-CA

125 120 120 100

78.6

YES YES YES YES

5.96 3.88 5.59

B-D-12-SG (3)

65

C10-R20-CM-12-0

67.6

CBA-S-100

70.28

23.06

Fig. 6. Comparison of the bond behaviour of different cement-based adhesives

3.2. Failure modes The failure modes observed in all three specimens of CBA-S-100 were consistent, as depicted in Fig. 7. Initially, cracks formed on the top surface of the adhesive within the bonded length area. These cracks gradually propagated throughout the bonded length area, along with the slip of the CFRP laminate from the cement-based adhesive, causing some cracked portions to separate from the top surface. As the CFRP slipped, some parts of the inside of the groove became visible. This demonstrates the ductile behaviour of this adhesive, which enabled the NSM FRP system to undergo different forms of failure, such as cracks and CFRP slippage, while still withstanding the applied load.