Metody badań odporności materiałów elewacyjnych na przyspieszone starzenia w funkcji zmiany barwy

Materiały elewacyjne ulegają starzeniu, czego widocznym objawem jest zmiana ich barwy, świadcząca o zmianach w strukturze materiału. W warunkach laboratoryjnych wyroby te są poddawane badaniom przyspieszonego starzenia w specjalnych aparatach (takich jak Xenotest lub UVCON). Parametry cyklu badawczego są określone w dokumenyach (normach, ZUAT) precyzujących wymagania dla danej grupy materiałów. Podczas postępującego starzenia wyrobów są obserwowane zmiany ich barwy. Zmiany te ocenia się za pomocą szarej skali lub spektrofotometru.

The facade materials are exposed to natural weathering. On this exposure they can show the signs of deterioration. Weathering of materials causes changes of their colours and change of colours means that also structure of material has changed. It is necessary to monitor the ageing process. In laboratory it is possible to conduct accelerated weathering with special equipment where radiation, moisture and temperature have an effect on materials which are tested. The type of weathering machine and the test cycle are specified depending on the type of facade material (according to standards or similar documents). Polish standards for facade materials require two types of weathering machines - Xenotest and UVCON. The radiation source in the Xenotest is xenon arc and water in the test procedure is simply sprayed onto the test panels. The Xenotest chambre is closed with sample holders mounted vertically. The modern version is more sophisticated, with controlling irradiance and black surface temperature, chamber temperature, relative humidity and "rain function". The UVCON employs fluorescent lamps mounted horizontally. The test panels are secured in racks such that their fronts are exposed to light and their bracks - to a flow of air saturated with water vapour. During the dark cycle condensation takes place on the surface of the panels. Change of colours is measured with grey scale. This method is not objective. The New Finishing Technics Department in Building Research Institute intends to introduce spectrophotometer for colour fastness tests.