A high-resolution view at water repellents and consolidants: critical review and recent developments

The growth in the renovation and maintenance activities of old buildings has largely contributed to the success of water repellents and consolidants. The greatest difficulty however, is the selection of the most appropriate one out of this wide range of products. Although certain products can work splendidly on a certain stone type, they can be harmful to another, especially when they alter important petrophysical material characteristics. Therefore combined research is necessary on the properties of the conservation products in combination with the determination of some important technical and moisture transfer parameters of the stone material itself. Different traditional research techniques exist in order to determine these technical and moisture transfer properties. These traditional techniques, in combination with advanced 3D visualization techniques, like X-ray and high-speed neutron tomography, turn out to offer important additional information on both the stone material and on the transfer method of the conservation products inside the stone material. In this paper, results of traditional research in combination with data obtained from X-ray micro-CT and high-speed neutron tomography is given, as well as a comment on the recent developments in material research by means of tomography.