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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Once the effective pressure of the element was verified, the leakage test was carried out by applying soapy water on the walls and on the singular points of the mock-up, the formation of bubbles and the visual verification of any imperfections provides a clear indication of the presence of losses and therefore possibly the failure of the coating system. A check made in this way allows to identify the exact leak points so as to be able to exclude those due to the support from those due to the coating. 4.1. Specimen A - Polyurea The polyurea coating did not show any gas leaks. During the test there was a point swelling illustrated in fig. 17 due to imperfections of the support on which the product was applied. However, the swelling remained limited in the area of the imperfection and as the over-pressure decreased it completely returned. The material used in the coating was able to absorb the deformation while remaining in the elastic range and without suffering damage and loss. The deformability that distinguishes it makes it suitable for absorbing any movements present in structural joints. Furthermore, the formation of bulges in the coating can be a useful indication of the areas that need repairs of the support (Fig. 17, Fig. 18). In fact, by removing the waterproofing material, working on the support and reapplying the waterproofing material again, the problem of localized leaks can be eliminated.

(a) (b) Fig. 15. Details of the Leakage tests of specimen A. No local leaks have been detected.

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Fig. 16. Details of the coating bulges.

4.2. Specimen B – Mineral coating Specimen B protected by mineral coating showed no widespread leakage during the test. The leaks occurred both in the areas of lesser thickness of the walls of the support, and on the sealing of the lid. The material used in the coating was not able to retain the gas blown into the support, therefore it was deemed unsuitable to perform this function.