Drying limestone through electro-osmosis

Abstract

The issue of rising damp is synonymous with the built heritage of Malta which is mainly built in Lower Globigerina Limestone. At a time when modern damp proofing materials did not exist, the use of Coralline Limestone in the lower courses of the more important buildings helped, but generally other buildings relied on ventilated basements, or air-bricks. These attempts to mitigate rising damp were not always effective, with the result that rising damp issues are prevalent in this building stock. Electro-osmosis has been proposed as a technology which could reverse rising damp. The literature, however contains attestations of both success and failure of this technique. This dissertation explores the phenomenon of electro-osmosis and reviews the literature about the application of this phenomenon to control dampness in buildings. An experimental set-up, based on a prototype described in the literature, was constructed, and used to assess whether the description of the phenomena that controls moisture movement in clay and in concrete would occur in limestone, as is widespread in the local heritage building stock. The results suggest that, although electro-osmosis managed to control moisture movement in the limestone samples, further detailed studies of the different parameters which could affect the phenomenon are required.