Influence of ageing process on porosity changes of the external plasters

In recent time more and more attention has been paid to the durability problems of building materials and components. The key issue in this area is to define the service life. Therefore, useful methods for durability valuation are of prime importance. In the paper we present a method to define an acceleration ageing coefficient involving naturally and simulate degradation of external mineral plasters. To reach the above objective, elements of the kinetics process theory used in chemistry and power engineering have been adopted for the description of changes in pore-capillary materials. The emphasis has been placed on open capillary porosity, which was examined over time by mercury porosimetry method. Plasters were exposed to ageing processes in the natural and an artificial environments. Basing on that, the porosity changes in plasters in both environments and their mutual relation were studied. An acceleration coefficient of ageing process has been established, which can be used for durability assessment on the grounds of a short laboratory test.