Nuclear magnetic relaxation and diffusion of gas in partially water saturated natural soil

Salt crystallization is one of the most important reasons for the decay of historical objects. A well known example is the historical city of Venice in which there is a lot salt decay. Reducing salt contamination is important for conservation of old historic buildings. Therefore often desalination treatments are done. The desalination of non-movable objects, like buildings, is usually made through application of so-called poultices. That is a moistened absorbent material is put on the surface of masonry. Water will than penetrate and desolve the soluble salt present. By subsequent drying the ions will be transport fror the substrate into the tpoultice. The removal of water-soluble salts sounds easy, but it can prove difficult in practice. To achieve a better poultice performance, knowledge about salt transport in the combination poultice/substrates is needed. We have studied the moisture and ion transport for various desalination systems by NMR. Based on these measurements one can categorize poultices according to their working principle of salt extraction and indicate the effectiveness for various desalination methods.