Salt transport and crystallization in plaster layers : a nuclear magnetic resonance study

The durability and performance of specially developed restoration plasters or renders, are not always as good as expected. Salt crystallization is one of the causes of the observed degradation processes. To understand these processes in more detail, we investigated whether transport in the plasters depends on the masonry material. The transport of salt and moisture during drying of some plaster/strate systems is followed with a Nuclear Magnetic Resonance technique. The observed differences in drying behaviour can be related to differences in pore structure between the plaster and substrate. For a good performance of the plaster a proper matching of its pore-size distribution with that of the masonry is required.