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A unique long-term experiment

A unique long-term experiment
Vodoodpudivé nátěry zabraňují vsakování vody a jsou využívány k ochraně kamenných památek.

Water-repellent (hydrophobic) coatings are used to protect stone monuments because they prevent absorption of water which damages these monuments. The protective ability of the coatings can be further improved by addition of nanoparticles. Long-term monitoring of changes in the properties of hydrophobic coatings exposed to the weather under the open air is extremely important for practice but very time-consuming. Therefore, artificial aging in the laboratory is used more often, but it cannot fully replace experiments in real conditions. So far, only a few such long-term observations have been made in the world. With the exception of one experiment in oceanic climate with warm summers, all experiments dealing with hydrophobic coatings containing photoactive nanoparticles were performed in Mediterranean or subtropical climate with hot summers. The experiments were performed in areas with low air pollution and their duration did not exceed one year. The existing information on changes in the properties of hydrophobic coatings due to the weather thus came only from the behavior of the coatings in these climatic conditions.

Experts from the Nanotechnology Centre at VŠB-TUO, the Institute of Geonics of the CAS, and the Czech Hydrometeorological Institute have now carried out the first monitoring of hydrophobic coatings in humid continental climate with warm summers, i.e. in Central Europe, and in area with high levels of air pollution, specifically in Ostrava. The experiment lasted eighteen months and, in addition to changes in color and hydrophobicity, meteorological data (air humidity, precipitation, concentrations of particulate matter, etc.) were recorded daily throughout the experiment. In the field of experiments of this type, the complete set of meteorological data was obtained for the first time, and for the first time, dependencies between the meteorological data and the observed changes in properties of the coatings were also found.

This unique interdisciplinary research has been published in the prestigious international Journal of Building Engineering.



Sandstone blocks - pristine and covered with hydrophobic coatings - exposed to the weather during the long-term experiment.

Author of the photo: Jiří Ščučka

Created: 22. 3. 2022
Category:  News
Entered by:  Administrator
Department: 9360 - CNT - Nanotechnology Centre