Passive fire protection prevents concrete collapse

Passive fire protection plays an important role in tunnels. Promat is part of Etex Building Performance BV, belonging to the Etex Group. Promat has played an important role in the passive fire protection of tunnels for more than 60 years. Frank van der Wal, Tunnel Manager Netherlands and Scandinavia, tells us all about passive fire safety.

Since 1963

"Our company has been supplying fireproof board materials and mortar systems to make tunnels passively fireproof since 1963," Van der Wal opens the conversation. "To be precise, the first tunnel we tackled in this way was the Holmesdale Tunnel in the United Kingdom. Since then, development has not stood still and we have become the market leader in this specialized field."

Passive fire safety in the Gaasperdamer Tunnel, thanks to Promat.

What does passive fire protection do?

Van der Wal explains: "With fire-resistant sheet material, we cover the concrete in a tunnel. This ensures that the concrete does not collapse as a result of the heat generated by a tunnel fire. This ensures the structural safety of the concrete. If the concrete were not protected, the heat would cause steam to form in the concrete, the vapor pressure could lead to concrete splashing. Pressure is also created in the concrete due to expansion of the concrete when heated. The concrete literally splashes apart -it then rains concrete- and the integrity of the structure is compromised, in addition to the fact that the splashing parts pose a danger to fleeing road users and emergency services. A major advantage is that our materials are maintenance-free and always work; they also have no expiration date. Should calamities occur in a tunnel, the fire-resistant sheet material can easily be replaced afterwards."

Collaborative systems extend evacuation time

Van der Wal continues: "Ghent University included our products in CFD models in a study of smoke stratification. This showed that a good smoke heat extraction in combination with our passive fire-resistant materials resulted in a significantly longer escape time because the hot smoke gases are cooled less quickly by the clad ceiling. This is obviously more than desirable in the event of an emergency."

Under the name PROMATECT^® Promat markets three sheet materials. "The oldest is the -H RWS/HCM, followed by the type T and the youngest variant is the T-FX. We are talking about a cement-bonded plate that can be retrofitted with anchors, or already laid in the concrete formwork. The plates last as long as the tunnel itself." What about the mortar variant? "The fire-resistant mortar can be sprayed against the tunnel concrete afterwards. This is how we made the Westerschelde tunnel, among others, safer," Van der Wal concludes.