“…This kind of potentiometric sensors have been studied in aqueous solutions (Labrador 2009), in solutions simulating the pore water of concrete (Alves et al, 2006), (Vera, 2010) and in hardened concretes and mortars (Duffó y Farina, 2009), (Dong et al, 2011), (Alves et al, 2006, (Climent-Llorca et al, 1996), (Terol et al, 2013). The Expansion-Ring-System, formed by an expansion-ring-anode and a cathode that are drilled into the concrete, was developed under these principles.…”