The influence of hydrophobic protection on building exterior claddings
Researchers recently investigated the hydrophobic protection of three substrates (stone, render and external thermal insulation composite system – ETICS) with the application of three hydrophobic products.
Silicon and titanium dioxides-based nanostructured dispersion (HNST); a silane/oligomeric siloxane (HSila/Silox); and a siloxane (HSilox) were used. To determine the effectiveness of the hydrophobic treatments, specimens of the untreated and treated wall coatings were characterised with different laboratory tests. The results showed that all products introduced significant improvements in the hydric properties of the substrates, leading to lower capillary water absorption (98 %), water permeability with Karsten pipes (99 %), drying index (39 %), and higher water repellency assessed through the contact angle (283 %).
Rendering mortar with best initial performance
The application of hydrophobic materials also had a negative effect, leading to up to a 227 % increase in resistance to water vapor diffusion. Among the assessed wall coatings, the rendering mortar appears to have the best initial performance after the application of all the types of hydrophobic materials tested. In general, the hydrophobic product HSilox was proved to be the most suitable for rendering mortars, while HNST was more appropriate for stone substrates.
The study is published in: Journal of Coatings Technology and Research, September 2019, Volume 16, Issue 5, pp 1379–1388.
