LABORATORY AND IN-THE FIELD EXPERIENCES ON THE MEASUREMENT OF SPONTANEOUS POTENTIAL IN MASONRY AFFECTED BY RISING DAMP

Rising damp is a severe problem in historic masonry structures all over the world, as it jeopardises the indoor comfort and causes several deterioration processes in building materials, such as frost damage, salt crystallisation cycles, etc.. Among the technologies proposed for fighting rising damp, electro-osmosis has found several applications in real buildings, but its effectiveness can be considered still under investigation. In fact, although this method is based on electrokinetic principles that are already widely exploited in different fields, the electrokinetic processes taking place in historic masonry walls have not been fully elucidated yet. In this paper the results of the measurement of spontaneous electric potential in fired-clay brick walls affected by rising damp are reported, as a contribution towards a better knowledge of the electrokinetic process in masonry. The testing was performed firstly in small-scale masonry models built in the lab with different bricks and subjected to capillary rise of water and saline solutions. Then, some brick masonry walls of heritage building affected by rising damp were tested with the same methodology used in the lab, in order to detect the presence of spontaneous electric potentials also in real materials and conditions.