The Stetten salt mine is located 80 kilometers from Stuttgart in the far southwest of Baden-Württemberg, Germany. The almost-white salt vaults cover more than 10 km² underground.

When it was established 150 years ago, the mine initially produced table salt, then industrial salt. Most of the Stetten salt (sodium chloride) is supplied to WACKER’s Burghausen plant, where it is used to produce chlorine via electrolysis.

Chlorine is an essential building block in many chemical processes, including the production of silicones and hyperpure silicon.

Today, Stetten produces around 500,000 metric tons of rock salt annually, which is used not only in industry but also as road salt. To ensure the site’s continued existence, cavities created by mining activities are backfilled with suitable mineral material obtained elsewhere. For this purpose, an additional tunnel into the mine was needed.

An innovative, polymer-enhanced shotcrete developed by WACKER application engineers in Burghausen was used in this tunnel to seal off some 40 meters of wall against groundwater. Originally, the engineers had simply wanted to test the new, polymer-enhanced shotcrete in the tunnel, but it soon became clear that it was the perfect solution for sealing off the tunnel against water ingress – and thus making it safer.

ETONIS-enhanced shotcrete is a little thicker and softer than conventional concrete, and there is significantly less rebound. Only half as much product ended up as rebound on the tunnel floor. The enhanced shotcrete also adheres better to wet walls.

To make this high-quality construction material, ETONIS dispersion is added to the basic concrete formulation – a procedure which, as practice has shown, is easily performed at the construction site. The mobile concrete mixers frequently used in tunnel construction can switch to ETONIS-enhanced shotcrete within a few hours.