29/07/2009 

Podcast-Episode

Extremely long railway tunnels thanks to
construction chemicals

In the construction process of the Swiss Gotthard Base Tunnel, which
will be one of  the longest train tunnels in the world, concrete has to
fulfill conflicting requirements: On the one hand wet concrete must
not harden while being transported through the mountain for several
kilometers, on the other it has to harden in an instant, when being
sprayed onto the tunnel wall. Additives to concrete uses such as
accelerators and plasticizers make it possible. In addition, a sprayable
fire protection mortar prevents concrete from exploding when being
exposed to temperatures above 500 degrees Celsius.