Acid formation in the anode/concrete interface of activated titanium cathodic protection systems for reinforced concrete and the implications for service life
conference paper
Cathodic protection has proven to be a reliable and economic method to stop corrosion in reinforced concrete structures. Many systems with activated titanium mesh anode embedded in cementitious mortar have functioned for more than 10 years. The service life depends on the anode/overlay system, which may be determined mainly by acid production due to current exchange. In order to assess this, samples of activated titanium/overlay specimens from laboratory tests were studied by light microscopy of thin sections and element mapping. The paper reports details on the amount of acid formation near the anode or in the mortarconcrete interface, related to the applied current densities. It appears that less acid is produced than calculated, even when hydroxide migration is taken into account. Diffusion of NaOH and KOH may explain this. In the interface between the mortar containing the anode and the carbonated concrete, Ca(OH)2 crystals dissolve. The diffusion of hydroxides is beneficial for the service life of CP systems based on activated titanium. The dissolution of Ca(OH)2 crystals in the interface between mortar and carbonated concrete may affect adhesion.
TNO Identifier
330334
Source title
15th International Corrosion Congress, ICC, Granada, Spain, 22-27 September 2002
Collation
8 p.
Files
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