Issue 74

V. J. Kalyani et alii, Frattura ed Integrità Strutturale, 74 (2025) 89-114; DOI: 10.3221/IGF-ESIS.74.07

Fig. 14 presents typical microscopic views at the failure plane in different configurations of three-layer coupon specimens, prepared using Sikadur 30 LP and Sikadur 330. Fig. 14(a) shows that steel wires of the SSWM are clearly embedded and well anchored within the hardened adhesive. Good adhesive penetration around and between the wires is evident, with minimal visible voids. The surface shows no prominent cracks, though minor irregularities and surface texture variations are present. In contrast, Fig. 14(b) shows that steel wires of the SSWM are embedded in the adhesive, but the bonding appears less integrated compared to Sikadur 30 LP. There are visible voids or air pockets around several wires, and in some areas, the adhesive seems to have pulled away or not fully wetted the mesh. The failure of SSWM wires is found to be ductile in nature, as indicated by the characteristic cup and cone morphology.

(a) SSS using Sikadur 30 LP

(b) SSS using Sikadur 330

(c) SGS using Sikadur 30 LP

(d) SGS using Sikadur 330

(e) GSG using Sikadur 30 LP

(f) GSG using Sikadur 330

(g) GGG using Sikadur 30 LP (h) GGG using Sikadur 330 Figure 14: Microscopic views at the failure plane in three-layer coupon specimens.

Figs. 14(c) and 14(d) show the failure planes of SGS hybrid specimens bonded with Sikadur 30 LP and Sikadur 330, respectively. In Fig. 14(c), the low viscosity of Sikadur 30 LP appears to facilitate deeper penetration into the SSWM mesh, resulting in a well-formed composite structure. However, this bonding effectiveness does not extend to the GFRP layer, where dry, poorly bonded fibers are evident. Despite this, the residual presence of Sikadur 30 LP near the failure plane

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