Can Concrete Catch Fire? | Basics Explained

Concrete is a non-flammable material that cannot catch fire by itself. Yes, its surface can be burned by hot items such as cigarettes and barbecues, but the fire won’t spread to the concrete itself.

This durability makes it an excellent material for buildings and other structures that are exposed to extreme temperatures or open flames. 

For instance, it will catch fire when you cover it with flammable material such as plastic, fuel, or varnish. However, bear in mind that concrete alone is not at all explosive, but at the same time, it doesn’t necessarily mean that’s entirely resistant to fire hazards.

While fire cannot burn concrete itself, it can leave behind charred material and soot residue that can discolor the surface.

can concrete catch fire

How Do Concrete Works to Fire?

Concrete wall offers protection against flames – and this is one of the many reasons why it is considered such a great building material.

In the event of a fire, the concrete will increase its temperature and be exposed to high temperatures, however, it won’t burn – making it an ideal choice for construction.

It also provides insulation from heat transfer, meaning that the flames will not spread as easily from one area of the building to another.

Its surface gets hot, this is mainly because of the free space that’s being filled up with air that transfers heat. As a result, the surface of the concrete will heat up and may crack. However, it is important to note that the fire would not have spread in this scenario.

Autoclaved aerated concrete is one of the most famous heat-resistant building materials. It has good thermal insulation due to the space inside it, and at the same time, it heats up slower in comparison to traditional solid reinforced Concrete.

How Do Concrete Walls Respond In Fire?

Experience says that concrete structures stand erect in a fire compared to structures of other materials. Concrete does not burn, unlike wood, and does not bend or get soft, unlike steel.

Fire cannot break down concrete walls until it has exposure to a thousand degrees Fahrenheit.

According to a study, it is confirmed that solid and ICF concrete walls can withstand continuous gas flames and temperatures up to 2000 degrees Fahrenheit for about four hours. But concrete or ICF walls do not fail structurally.

Do Cracks Occur Due To Fire?

The answer is yes, it may. Concrete cracks may occur when the fire is at its peak and the temperature rises above the point where concrete can sustain. Because concrete is susceptible to chipping as it’s reinforced with heat, it can also crack when exposed to extreme temperatures.

We all know that the metal heats up and expands when it gets pressure, leading to breakages. And when the mortar joints heat up, they can expand, leading to the formation of cracks. This phenomenon is seen in walls that are exposed to fire directly or indirectly.

Grungy Brick Wall

However, when concrete or masonry, or walls are exposed to fire for a longer time than 5 hours, the fire eats the flammable materials from the blocks surrounding it.

It burns them silently and blows to the side of the burning block. If no combustible material is left and the block has no solid top, the next block extinguishes the fire. 

Do Concrete Walls/Floors Stop Fire From Spreading?

In some situations, a concrete wall stops the fire from spreading. Though, it has to be thick enough, should have proper mortar joints, and should not be exposed to direct or indirect fire. The concrete wall should also be placed in such a way that the flames don’t reach it.

If these conditions are fulfilled, then the wall can stop the fire from spreading.

However, if you have a ceiling, doors, or floors made up of wood, the fire can cross it without entering solid concrete.

Concrete has a slow heat transfer rate, which means that walls made up of concrete act as a fire shield. It protects adjacent rooms from the fire and stops the spread of flames. In some cases, it also limits the damage caused by the fire.

House fire

Do ICF Foam Burn?

Most of the concrete walls comprise the forms that remain in place after pouring Concrete, and these sorts of forms are known as ICF (insulated Concrete Forms).

Concrete is a good insulator, but the addition of insulation rigid foam boards on both sides of concrete walls provides more insulation for the home. But can they catch fire?

Foams help build ICF forms where rigid insulation boards are made with flame-retardant additives. Thus, foam can melt down in the fire in place of catching fire.

It does not burn, but it is less flammable than wood. So, foams utilized in ICF or other concrete walls prevent foams from burning by themselves due to flame-retardant additives.

Can Concrete Catch Fire: Final Thoughts

Concrete catching fire is uncommon, but it is possible in extreme conditions. Concrete walls are considered one of the best fireproof materials, and they can easily withstand temperatures over 2000 degrees Fahrenheit.

They also have the capacity to resist a continuous flame for up to four hours or more.

The foam utilized for ICF forms is also made with flame-retardant additives, which prevent the foam from burning itself. So when it comes to fire protection, concrete and ICF walls are always on top of the list. They help protect other materials from getting damaged by fire.

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