"Protecting the Runehamar Tunnel in Norway with Promatect®-T against multiple fires, as part of the uptun research programme."
By Donald van Olst & René van den Bosch, Promat BV, Tunnel fire protection
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 Introduction
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Promat belongs to the world-wide known Etex group, which mainly focuses on the production of building materials. Promat’s network consists of 36 subsidiaries all over the world enabling us to provide local support to all involved parties in a tunnel building (or refurbishing) process. Through the years Promat has supplied their PROMATECT materials to over 110 tunnels, on al continents. In preparation of the full-scale fire tests in the Runehamar tunnel, Promat has conducted several lab tests to judge if the intended system would meet the requirements. Normally fire protective materials in a fire test are only used once. For the Runehamer tests the construction should be able to withstand 4 tests. |
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| Why fire safety in tunnels ? |
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Safeguarding peoples lives
A tunnel fire is an immense disaster. Images of recent catastrophes will always remain in our minds. Safeguarding peoples lives means installing and maintaining escape possibilities.
Escape possibilities require:
 Smoke extraction and ventilation systems
- Escape signs and fire doors
- Fire and smoke resistant safe havens
- Construction integrity
- Compartmentation
- Integrity of technical installations so that light and communications remain available
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Preventing economical damage
Fire damage to a tunnel always has enormous financial consequences. Of course, the repair costs are huge, but the effects on the infrastructure and economy are even larger. Tunnels have been out of order for months or even years after a fire. Economical damage can be prevented by:
 Enhancing the fire resistance
of the structure
- Protection of the ventilation
ducts and systems
- Protecting power supplies and
signalling cables
- Detection systems
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The effect of fire on concrete
Although the massiveness and in-combustibility of a concrete construction seems immune to fire, graph 1 shows otherwise. After an increase of temperature of 500°C the strength of a concrete structure is halved! Starting at 200 C concrete will loose its strength. At 850°C the concrete strength is almost reduced to 0%.
One of the major influences on the strength loss is the spalling effect of concrete. Important factors causing spalling:
- Free & Chemically bound water combine to cause steam
pressure build-up
- Expansion Ratio of water-to-steam = 1 : 1700
- Temperature in excess of 500°C
- Concrete Grade dependant
Moisture content over 3% => spalling almost 100% within
30 minutes of exposure.
Note :- on recent tests carried out on tunnels in Netherlands, the average moisture content of the concrete 10 years after construction was approximately 6 – 7%
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High strength concrete structures
These types of concrete (50 – 80 Mpa) suffer from more spalling compared to the standard types (35 – 40 Mpa). This is mainly due to the additives used in the production process of such concrete mixes. To avoid spalling, the allowed surface temperature of standard concrete types is approximately 380 C (based on RWS requirements) whereas high strength concrete types can only take roughly 180 - 220 C on the concrete surface.
Spalling phenomenon on a concrete I-beam
 
Exposed to ISO-834 curve
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