Crystallizing waterproofing is not only but typically applied in cases of a negative side water pressure. A typical case of negative side waterproofing is when water comes through the walls of a basement and the waterproofing is carried out from the inside. In general, negative side waterproofing means that the waterproofing layer is applied to the side of the construction member which is opposite to the side with direct contact to the water. Negative side waterproofing is more difficult than positive side waterproofing because the water penetrates through the construction member behind the waterproofing material and tries “to push it off” the substrate.
The picture shows: Basements often cannot be accessed from the outside. Thus they can only be waterproofed from the inside (negative side).
Water that has penetrated through a construction member and has contact to the negative side of the waterproofing layer will always try to delaminate the waterproofing material from the substrate. Water pressure or salt crystals form growing capillaries and voids between the waterproofing material and the substrate. Therefore, especially an elastic coating is likely to delaminate and fail after some time. KÖSTER NB 1 has been developed to waterproof mineral substrates, like masonry and concrete, even from the negative side. The product contains agents which react with moisture and components of the substrate to form crystals which penetrate into the pores and capillaries of the substrate. KÖSTER NB 1 penetrates into the substrate, becomes an integral part of it and makes it waterproof but open to vapour diffusion. It has an expected life time just like the structure itself. KÖSTER NB 1 cannot delaminate and keeps the substrate permanently waterproof.
The picture shows a REM scan: The white areas are latent hydraulic compounds which penetrated into the pore structure of the substrate – and reacted to form a pore sealing solid body.
Drinking water is the most heavily regulated consumer good in Germany. KÖSTER NB 1 Grey is officially approved for waterproofing drinking water tanks by the Hygiene for Institute in Gelsenkirchen, Germany and the NSF International (USA).