Concrete has certain advantages over other building materials because of its inherent fire-resistive properties. However, it is still important to use a protective fire barrier on concrete to negate the effects of heat produced by a fire.
Concrete must still be able to withstand loads without collapse even though the rise in temperature causes a decrease in the strength and amount of elasticity for concrete and steel reinforcement. Fully developed fires cause expansion of structural components such as rebar.
Another risk is that the rise in temperature causes the free water in concrete to change from a liquid to highly pressurized steam. Essentially, the water trapped inside acts like millions of tiny kernels of popcorn that can explode with enormous energy. This change in state causes changes in the rate with which heat is transmitted from the surface into the interior of the concrete wall or concrete column. This can result in “spalling” or fractures in the material, triggering a collapse. In addition, the rate at which the strength decreases depends on the rate of increase in the temperature of the fire and the insulating properties of concrete.
This is why it is necessary to use Contego Firebarrier Intumescent Paint. By applying this protective barrier, Contego controls the rise in temperature, thus protecting the structure from the rapid shift in temperature, which causes spalling and possible collapse. In the event of a fire, concrete protected by Contego is much more likely to retain its structural integrity, thus saving the expense of having to demolish and start from scratch.