Beobachtungen zum Stofftransport und zu einhergehenden Schädigungseffekten in porösen Baustoffen / Observations of mass transport and related deterioration mechanisms in porous building materials

It is reported about substance migration problems and their consequences, which have been investigated experimentally and which could be particularly relevant with regard to repair and restoration of historic buildings. One aim of the investigations was to find out, whether facades, treated with water repellent agents, showing non treated areas, can be affected in their long time behaviour. Such lacks can be due to non careful application of the repellent agent. In addition, investigations were made to find out. of coatings on salt containing mineral substrates, especially natural stones can reduce their life time. As a result of the experiments and the theoretical considerations, it follows, that a lack in water repellent treatment. could cause the risk of crust-development spallings in environment of non treated spots in the case that substrate is salt contaminated and moisture exchange takes place. All experiments with coatings, performed under the same conditions, show, that the coated surfaces have a more favourable behaviour than the same surfaces without coatings.