Numerical moisture simulation of redeveloped structures using active materials based on cement composite

Abstract

Signs of moisture in the connecting joints of window constructions represent a typical feature of contemporary modern civil engineering. These problems occur both in new buildings and in reconstructed historical buildings. They manifest themselves as wet spots or black mould on window reveals, corners and edges.

This article describes a non-destructive solution of these problems using a concrete real case in an existing building with long-term signs of moisture in the window connecting joints. The elimination of this problem lies in the application of the developed calcium silicate material designed for moisture and thermal redevelopment of buildings. This article describes the properties of the newly developed material based on cement composite containing alumina silicate filler. The final material uses the same principles of moisture transport as the widely used autoclaved calcium silicate insulations. In comparison with these normally used materials, the developed material is unique by omitting hydrothermal curing in an autoclave. The new material, with a defined capillary structure, also utilizes waste heating plant fly ash, which improves the mixture rheology and decreases the amount of cement, thanks to its latent hydraulic properties. Materials with similar properties using waste raw material are used, for example, in the form of plasters [1–3]. The aim of this research was to develop a material belonging to the segment of the energy redevelopment of buildings, moisture redevelopment and interior insulation. Materials compliant with these segments must meet the requirements for a low value of diffusion resistance, high value of capillary activity and low value of thermal conductivity coefficient. The measured thermal and technical parameters of the developed material were transferred into the numerical Delphin software, where the moisture behaviour of the structural detail of the connecting joints of window construction was simulated. The developed recipes were further modified on the basis of these calculations, and boards with the best combination of thermal and technical variables were compared as well.