La diga dell’Isola di San Bernardino necessita di un intervento per allentare le tensioni nel cemento, che si è gonfiato leggermente. È quanto emerso dalle ultime misurazioni effettuate dall’Azienda elettrica comunale di Mesocco, controllata della Axpo Holding.
Il rigonfiamento del calcestruzzo è un fenomeno noto in tutto il mondo e deriva da una reazione chimica, nel caso della diga Isola scatenata dalle sostanze della regione che contengono solfati utilizzate proprio nella produzione del cemento.
Dalla sua costruzione (1957-1963), il muro si è deformato sotto la pressione interna di circa 60 millimetri "in modo continuo e irreversibile verso il lato dell'acqua". Durante il prossimo inverno Axpo prevede quindi di rimuovere uno strato di circa 30 millimetri, allentando la tensione e permettendo l’espansione del calcestruzzo.
La procedura si basa su una tecnica collaudata e il completamento dei lavori, che costeranno circa 2,5 milioni di franchi, è previsto per la prossima primavera.
La diga di San Bernardino si "gonifa"
Il Quotidiano 22.08.2019, 21:30
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