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Special reports - 23 February 2015

Tunnel fires: Preventing explosive spalling of concrete

When fire breaks out in a tunnel the ensuing heat has little possibility of escaping. The heat that develops causes the concrete to spall explosively, weakening the structural integrity of the tunnel. This can be prevented by adding polypropylene fibres to the concrete. But what exactly happens inside the concrete? Engineers at the Technische Universit√§t M√ľnchen (TUM) have found a way to measure this.