New raw material composition for the multifunctional white waterproofing KÖSTER 21 - higher water vapor permeability guarantees more breathable building envelope.
The improved formulation of KÖSTER 21 has greatly increased the water vapor permeability so that moisture in the concrete can escape more easily in vapor form through the coating and the formation of bubbles in the coating is avoided.
KÖSTER 21 is a mineral based, flexible surface waterproofing and at the same time concrete protection and reflective coating. It is often used outdoors as the system can be exposed to freeze / thaw cycles. This alternating exposute means a high level of stress, since the water freezes in the building material pores during the freezing phases with a corresponding volume expansion.
The Materials Testing Institute for the Building Industry (MPA TU Braunschweig) has tested KÖSTER 21 in accordance with EN 1504-2 under frost/thaw exposure and additionally with a salt water solution, so that the so-called frost/de-icing salt test is available. The system is applied to concrete and frozen and thawed a total of 50 times. At the end of the test phase, the tested product is visually assessed and its adhesion to the building material is checked. The binder in the new material has been optimized to improve the tensile properties. The minimum criteria were already achieved with the previous formulation, but the tensile adhesive values are now even higher and an better than before.
Another significant improvement is the increased coverage with a consumption of approx. 2.2 - 2.6 kg/m² (previously: 2.5 - 3.0 kg/m²).
More about the product here: https://www.koester.eu/?productId=2269&p=95&c=de_en