Further developments of a poultice for electrochemical desalination of porous building materials: minimization of side effects

Salt induced deterioration of buildings is a frequently present problem and is in connection with traditional buildings a source for increased maintenance and costs. Especially in connection with Cultural Heritage (e.g. murals) even surface deterioration of original materials is unacceptable and should be avoided. Previously, an electrochemical method has been adapted and optimized for desalination of brick masonry and a high efficiency was obtained. Unfortunately, an accelerated weathering was seen among others in shape of crumbling of mortar below the cathode poultice and further developments were needed. The present paper reports further development of the cathode poultice from a single layer to a three layered poultice. The three layered poultice neutralized the produced hydroxides at the cathode and ensured precipitation of the buffering agent within the cathode poultice and still a high desalination was maintained. Possible side effects were examined with SEM-EDX, water saturation coefficient, saturation coefficient, open porosity, water and acid soluble calcium content, pH and electrical conductivity.