Two-layer waterproofing membrane for waterproofing reinforced concrete components in contact with the ground, consisting of a bentonite seal and a PE seal.
The bentonite waterproofing is based on the natural clay mineral sodium bentonite, which is woven into a geotextile carrier fabric as granules or needled with it. Both layers, both the bentonite and the plastic layer, have an additive effect. Only when the outer plastic layer fails does the activation of the bentonite occur, which occurs when the granules come into contact with penetrating moisture. Due to the resulting swelling pressure in the bentonite, the waterproofing membrane seals towards the concrete with simultaneous contact pressure from the outside (e.g. due to soil, additional load). This state of hydration persists even when the waterproofing environment dries out.
Multi-layer waterproofing membranes thus offer additional safety compared to single-layer systems. They can be installed horizontally or vertically below the ground surface, usually without a fresh concrete composite. This makes the trams also suitable for renovation work. Bentonite seals were developed in particular for water loads from damming leachate and pressing groundwater. While this technology has been anchored in earthworks, landfills and civil engineering for decades, it has only been used in the field of ground-contact building waterproofing for a few years as a so-called brown tank.
The use of multi-layer bentonite waterproofing systems is also possible in flowing groundwater, as it is not possible to wash out the bentonite through the water-side plastic layer.
