A laboratory investigation was executed of electrochemical chloride removal (desalination) from cores taken from the splash zone of an eight year old reinforced concrete quay wall on the North Sea coast. The concrete was made with Blast Furnace Slag Cement according to Rijkswaterstaat specifications. The concrete had a high density, high electrical resistivity and relatively high strength. It contained penetrated chloride up to a depth of c. 20 mm. The reinforcement in eight cores was cathodically polarised with saturated lime or sodium carbonate electrolyte and activated titanium mesh anodes at current densities of 0.6 to 4 A/square meter of steel surface for 3 to 6 weeks. During the treatment the treatment the electrical resistance was measured. The total chloride content of the treated cores, the composition of the pore solution and the chloride content of the electrolyte were determined. The results show that significant but different amounts of chloride had been removed from the cores, depending on the electrolyte type and the total amount of charge that was passed. Using saturated lime more chloride was passed. Using saturated lime more chloride was extracted than using sodium carbonate. The electrical resistance was found to decrease strongly when sodium carbonate was used as electrolyte. Major pore solution composition changes due to the electrolysis were found. (A)
Samenvatting