The refurbished Absa Tower features an innovative facade that is self-washing, air-purifying and resistant to the formation of microorganisms.
The new facade of the imposing Absa Tower in the Pretoria central business district (CBD) not only washes itself when exposed to rain, but it also purifies the surrounding air day by day, making it a vertical urban forest, thanks to Agrob Buchtal’s revolutionary HT (Hydrophilic Tiles) coating.
The company supplied 31 000m² of its KeraTwin K20 ceramic facade panels which was treated with the HT coating, together with the necessary accessories for the refurbishment of the 140m high Absa Tower facade, which was completed last year.
The HT coating makes tile surfaces hydrophilic, which means that instead of water being repelled, it is spread to form a thin film on the tile’s surface. In this way, dirt is washed down, supporting an aesthetic impression.
“In contrast to conventional hydrophobic solutions such as the Lotus effect, the HT-coating is so robust that both wall and floor tiles can be coated with it,” adds Roger Skudder, the South African representative for Agrob Buchtal.
Thanks to the facade’s self-washing ability, it requires minimum maintenance and care, thereby lowering cleaning costs.
Based on the principle of photo catalysis, the HT coating also eliminates unpleasant and harmful odours. When light activates the oxygen molecules, odours such as formaldehyde, ammonia and industrial and car exhaust gases are removed, achieving a lasting improvement of air quality.
The coating itself is environmentally friendly, non-toxic and free of irritating substances.
Another advantage, also enabled by the photo-catalytic principle, is the HT coating’s ability to decompose moss, bacteria, fungi, algae and mould, and impede the formation of new microorganisms protecting the façade from greening and reducing cleaning efforts. This process is continuously renewed as the HT-coated façade is exposed to light.
The HT coating’s innovative properties further help to preserve the original characteristics of the surface it is applied to, such as resistance to abrasion and chemicals. It is available for a varied range of Agrob Buchtal tiles and carries a long-term guarantee.
Absa Tower installation
Looking to preserve the original shape, form and look of the building, originally completed in 1978, the new overclad façade was installed as close as possible to the original. The new rain screen, comprising of mechanically fixed, glazed ceramic tile also mimics the colour of the original glazed ceramic mosaics that were installed over all structural and services expressed on the façade.
The KeraTwin K20 20mm thick extruded ceramic stoneware facade panels were hung in a vertical system rail with holding grooves on the reverse side. The position of the panels was secured either by means of a joint profile adjusted to the joint width or by means of spacers.
To prevent clattering, a compression spring and removal protection were integrated into the system rail and constrain forces in the case of alternating wind loads. It also enables the easy removal of panels in the event of replacement being necessary.
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