Development of Electrode Units for Electrokinetic Desalination of Masonry and Pilot Scale Test at Three locations for Removal of Chlorides

Electrode units for electrokinetic desalination of masonry has been developed and tested in pilot scale at three different locations. The units are formed as casings with a metallic mesh electrode, and carbonate rich clay to buffer the acid produced at the anode. The case has an extra loose bottom which allows continuous pressure between clay and masonry so good electrical contact is remained. The electrode units were tested at three different locations, two on baked brick masonry (inside in a heated room and outside on a masonry with severe plaster peeling) and the third pilot scale experiment was conducted outside on a limestone masonry. The duration of the experiments was 4-8 month. Chloride concentrations were measured in drilling powder from the masonry before and after experiments. In all three masonries, the average concentrations decreased. The transport numbers for chloride was between 0.33 and 0.48 which shows that the major part of the charge transfer towards the anode was chloride transport, even in the masonry with lowest chloride concentration. The transport number increased in the same order as the initial concentration increased.