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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The boxes were perforated to add a bushing for the injection of nitrogen gas. The jack is instrumented with a pressure gauge, capable to check the internal pressure (Fig. 4). A great care is devoted to the internal and external sealing of this singular point, by means of sealing rings and mastic. To prevent dangerous overpressure, the inferior face of the box is not sealed, leaving a surface permeable to gas discharge. The boxes are layered with four commercial products with the following materials: polyurea, mineral coatings, epoxy primer and epoxy cementitious.

(a)

(b) Fig. 1. Concrete box: (a) exploded view (b) overall view

(a) (b) Fig. 2. Details of the set up: (a) reduced thickness, (b) discontinuity and superficial defeats.