PSI - Issue 64

5

Tom Argyle et al. / Procedia Structural Integrity 64 (2024) 1376–1385 Argyle et al./ Structural Integrity Procedia 00 (2019) 000 – 000

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Fig. 5. ECI Trials of groove cutting (centre) and installation of CFRP rods (left and right)

These trials were able to verify quality of installation through destructive means, by cutting through the strengthened slab, and verify the bond between the proposed waterproofing system and top of epoxy resin through pull off tests.

Fig. 6. Slice through off-site slab strengthening trial, showing cohesive CFRP rod installation.

There is no established practice for confirming the quality of installation of near surface mounted CFRP rod installations through non-destructive methods. Whilst CFRP plates can be hammer tapped to detect voiding within the epoxy resin material, a similar approach does not reliably work for CFRP rods. Several non-destructive scanning techniques, including Ground Penetrating Radar and ultrasonic techniques were trialled on an off-site CFRP rod installation, with known and intentional voids in the resin. However, no approach was successful. The small size of the voids being searched for and proximity of them the surface were not suited to the wave size used in standard Ground Penetrating Radar (GPR) and ultrasonic equipment. As such, quality control for the on-site implementation was achieved by using known competent installers (as demonstrated by site trials in Figure 7) with highly detailed and prescriptive method statements and recording.

Fig. 7. Ultrasonic techniques used on trial slab to detect known voids in CFRP rod installation – ultimately unsuccessful.