Durability of a realkalisation treatment using impressed current or galvanic anodes for the rehabilitation of reinforced concrete structures
Résumé
Carbonation induced corrosion is a major cause of decay of reinforced concrete structures. Electrochemical realkalisation treatment is described as an interesting technique to rehabilitate such structures. In this paper, the results of tests on both efficiency and durability of two realkalisation treatments (impressed current and galvanic anodes), in accordance with the CEN/TS 14038-1 specification (threshold current density of 200 A.h/m²) are presented. The efficiency of both treatments is demonstrated qualitatively with acid/base indicators such as phenolphthalein and thymolphthalein and quantitatively by pH determinations. Non destructive electrochemical characterizations such as rest potential, linear polarization resistance and corrosion currents indicate a slight decrease of the corrosion activity after treatment although the passive state of the reinforcement encountered in uncarbonated concrete is not recovered. These results are confirmed by micro-Raman spectroscopy. Concerning the cement matrix, none evolution is detected by SEM, but alkaline content evaluation shows a noticeable enrichment in potassium (impressed current) or sodium ions (galvanic anodes) in the concrete cover.