PSI - Issue 33

Fabrizio Pittau et al. / Procedia Structural Integrity 33 (2021) 630–645 Author name / Structural Integrity Procedia 00 (2019) 000–000

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4.3. Specimen C - Epoxy-primer The epoxy primer coating did not show any leaks, maintaining the internal pressure of the gas. At the same time, the rubberized bands with their joints and glues were found to be adequate to resist to the pressures applied inside the concrete box. It has been noted that the strip tends to swell as shown in Fig. 19 and Fig. 20 as the applied pressures increase. The phenomenon could lead to microfractures along which the gas would disperse. As for the sealing through the use of epoxy adhesive of the passing metal parts, an inability of the material to retain gas was found. Therefore, this treatment turns out to be effective only for a diffused coating on continuous walls, but the performance was poor in case of through hole.

(a) (b) Fig. 17. Details of the Leakage tests: (a) wall (b) through hole.

(a) (b) Fig. 18. Particolare della bandella, (a) e (b) Rigonfiamento durante il test.

4.4. Specimen D - Epoxy-cementitious The coating with epoxy-cementitious primer has not proved suitable to ensure gas tightness in the walls, specifically a series of leaks have been detected in the thinnest wall area and in the points of difficult application such as tapering areas. The sealing of the edges of the lid and the hatch with the chemical fixer has shown a positive result: The small leaks recorded in Fig. 21, due to the difficulty of spreading on the support, can be healed through a second layer of the same product. Finally, the sealing of the bolts and threaded rods carried out with the epoxy primer showed no signs of leaks.