Fireproofing
Taking the Heat off Cold Steel
The majority of multi-storied high-rises today have a steel skeleton because this type of construction is light-weight. In this regard, load-bearing steel structures are the key concern of building authorities. Although steel does not burn, it rapidly loses strength above a temperature of 500 °C. Without proper protection at these temperatures, steel supports can sometimes bend and collapse within five to ten minutes.
Skylines require not only construction workers with a head for heights, but also engineers familiar with time- and cost-effective steel skeleton construction methods.
Skylines require not only construction workers with a head for heights, but also engineers familiar with time- and cost-effective steel skeleton construction methods.
Yet steel beams may be protected from such a loss in stability by using a fireproofing coating. “Intumescent” (swelling) coatings provide the steel beams with greater fire resistance. “The layers, usually between 1 and 4 millimeters thick, expand 10 to 100 times their original thickness when exposed to fire,” says Dr. Wilfried Huster, head of application technology for dispersions at WACKER POLYMERS.
The firm foam encasing insulates the beams from intense heat for a predictable period of time. Due to the extremely low thermal conductivity of the insulating layer which forms in the event of a fire, the temperature within the substrate increases only slowly. The steel structures do not rapidly heat up to the critical temperature at which they would lose stability.
When formulating fireproof coatings, more and more manufacturers depend on VAE copolymer- and terpolymer-based VINNAPAS® EZ 3010 and VINNAPAS® EZ 3523 dispersions. Although these binders can burn, the residues are incorporated into the microporous foam layer, thereby providing it with optimal viscoelasticity and strength. This causes the protective layer to adhere firmly to the substrate, forming a heat barrier for a limited period of time.
Skyline of Doha, Qatar
Skyline of Doha, Qatar
This advantage could be a matter of life or death, for in an emergency, these extra minutes provide rescue teams with precious time. Without the binder, the foam layer would be too brittle and would have inadequate adhesion to the steel substrate, and thus would not be able to function as an insulating layer.
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