Is cement fire-resistant?

This blog post will answer the question, “Is cement fire-resistant” and cover topics like fire-resistant properties of cement and frequently asked questions related to the topic.

Is cement fire-resistant?

Yes, cement is fire-resistant. Concrete has been classified as one of the most fire-resistant materials for three reasons: 

  • It is non-combustible, 
  • Non-toxic,
  • Low thermal conductivity. 

This implies it has a difficult time transferring heat energy and reacting with other chemicals. As a result, concrete is one of the safest and most effective structural fire prevention materials available.

What factors influence the fire resistance of concrete?

The exact fire resistance of a given kind of concrete is determined by several variables. The following are the most important:

  • Type of aggregate
  • Moisture level
  • Density
  • Thickness

I will now elaborate on the guidance given above.

Type of aggregate

The kind of aggregate used in concrete may have an impact on how well it resists fire. Carbonate and lightweight aggregates are the most common forms of aggregate used in the manufacturing of concrete. While all kinds of aggregates are useful against fire, research has revealed that carbonate aggregates are the most effective; in tests, dolomite (a calcium carbonate) gave the maximum compressive and tensile strength when exposed to high temperatures.

Moisture level

Concrete’s moisture content has an impact on how it reacts in a fire.

Spalling may develop on the surface of concrete that has not cured properly or has a very low water-cement ratio, according to research.


The higher the density of concrete, the more fire resistant it is.

The flame resistance of ultra-lightweight concrete with a density of 400 kgm3 was found to be more than 3 times that of other concrete samples with a density of 150 kgm3 in a research conducted by the University of Auckland in New Zealand.


When exposed to fire, thicker concrete often performs better.

The American Society of Civil Engineers has established the minimum thickness of various types of concrete for varying levels of fire resistance; for example, a siliceous aggregate with a thickness of 7.0 inches can withstand fire for up to four hours, while a lightweight aggregate with a thickness of only 5.1 inches can withstand fire for the same amount of time.

Enhancing concrete’s fire-resistance

Despite being one of the most flame-resistant materials, concrete may nevertheless be made more effective in a fire by:

  • Using an intumescent paint to coat a heat source.
  • Applying a thin coating of lightweight mortar to concrete surfaces that have been exposed.
  • Using board systems to protect concrete surfaces.

Is it possible for concrete to be fireproof?

Concrete is fire-resistant for a variety of reasons. Because concrete does not burn like wood or other organic materials, a fire will spread considerably more slowly through a concrete building than it would through a timber one.

In the event of a fire, the concrete walls are also more resistant. They are better than other materials in preventing fires from passing through from one side of the wall to the other.

Of course, just because your house is built of concrete doesn’t mean it’s fire-resistant. Other elements of your house, including as furniture, wooden fixtures, and other items, may not be fireproof.

Concrete does not burn or melt like wood or steel; it remains robust until it is subjected to flames significantly hotter than a typical home fire.

Is concrete tested for fire resistance?

Before they can be labeled as fireproof or fire resistant, all concrete and masonry materials must be evaluated. These studies have shown that cement is the most fire-resistant construction material over many years.

Concrete is practically incombustible due to the chemical inertness of the constituents. Concrete’s intrinsic chemical makeup is its biggest advantage in terms of fire resistance. Because of the slow passage of heat through concrete, it is more resistant to flames (another non-fire benefit is that your house will be better insulated with heat and air conditioning, since it will lose less warmth or a/c to the outside).

You may assist avoid the rapid spread of fire across rooms and make your house safer from flames by constructing your home with cement walls rather than wooden ones.

What is it about concrete that makes it so fire-resistant?

Concrete’s fire resistance is due to the components used in its construction. Chemically, cement, sand, crushed stone, and gravel are all inert materials. Chemical inertia refers to the lack of chemical reactivity of a substance, making it non-combustible.

Because of its sluggish rate of heat transmission, concrete is very fire resistant. That is to say, the walls serve as a fire barrier between adjoining rooms. The building’s structural integrity is also preserved due to the delayed heat transmission.

Another advantage of concrete is that when fire gets close to it, it does not emit harmful aromas, produce smoke, or drop melted particles due to its qualities.

Are all concretes the same when it comes to fire resistance?

The aggregate materials used in the production of concrete will determine how flame retardant your cement will be. Carbonate and lightweight aggregates are the best aggregates to utilize. Calcium and magnesium are examples of carbonate aggregates. Clay, slate, and shale are examples of lightweight aggregates.

Another aspect that determines how flame retardant your concrete is is moisture. Concrete that has not been properly cured or dried will degrade more quickly. Concrete with a low water-to-cement ratio will burn more quickly.

Another component that affects fire resistance is permeability. The sooner concrete breaks down, the more porous it is.

The density and thickness of your concrete will also influence its fire resistance. Higher fire resistance is achieved by using thicker concrete with a higher density.

How Can Concrete Be Made More Fire Resistant?

Although concrete is incredibly fire resistant, it is not fireproof. Fortunately, there are certain things you can do to boost your concrete’s resilience.

  • One approach to assist increase the fire resistance of your cement is to use a heat shield intumescent paint. The material’s purpose is to function as an insulator, keeping hot temperatures out of the structure and protected apertures.
  • It’s also a good idea to use lightweight mortars on your concrete. This material functions as a thermal barrier, transferring heat away from critical structures.
  • In the event of a fire, a protective board system might also aid to safeguard your house. The mechanism is intended to support the weight of buildings for long enough for people to exit on time.

How to Create Fire-Resistant Concrete?

Fireproof concrete may be used in a variety of ways by both homeowners and businesses. Fireproof cement or other fireproof material known as refractory cement is used in many wood-fired ovens, furnaces, and fireplaces. Commercially, fireproof cement is created by combining fly ash, a by-product of the Portland cement manufacturing process. Materials from home improvement shops may be used to produce your own fireproof concrete. If you’re going to make blocks, you’ll need to have your forms ready ahead of time so you can pour the concrete mix immediately into the forms when it’s the perfect consistency.

Concrete Preparation

  • Place your plywood sheet on the work surface or in the wheelbarrow. When it’s time to clean up, you should be near a hose so that water can be conveniently poured and the area and tools can be washed.
  • Three parts gravel, two parts sand, two parts refractory cement, and 0.5 parts hydrated lime are proportioned as follows: 3 parts gravel, 2 parts sand, 2 parts refractory cement, and 0.5 parts hydrated lime. Regardless of the amount of fireproof concrete you’ll be building, stick to this ratio.
  • Fill the wheelbarrow with gravel and sand, or place it on the plywood.
  • Over the sand and gravel, pour the refractory concrete and hydrated lime.
  • With a shovel, combine all of the dry ingredients. Mix until all of the ingredients are spread equally. With the shovel, make a depression in the centre of the pile to accept the water.
  • Toss in some water to the mixture. Mix the dry ingredients and water until there are no dry pockets in the mixture. Do not over-water the mixture to the point that it gets soupy. Water should be slowly added to the mixture, approximately 1/2 to 1 gallon at a time, and then well mixed before adding more.
  • Add additional water or mix in the right proportions until the cement is workable. It’s the right consistency if you can compress a handful of concrete into a snowball and it doesn’t come apart.
  • With a shovel, fill in the forms. Scrape off any excess concrete and smooth the surface with the trowel.

The Curing of Concrete

  • Using the spray bottle, wet the borders and surface of the concrete. This will prevent moisture from evaporating too quickly as the concrete cures.
  • Cover the concrete with a plastic sheet after it has been wet for 48 hours.
  • After 48 hours, remove the plastic. Allow for at least 48 hours of air drying before attempting to remove the forms. Allow it to cure for up to three weeks if the weather isn’t sunny or the air temperature is chilly or cold.
Materials NeededTools Needed
Plastic sheetShovel
SandSpray bottle
Refractory cementPlywood sheet

Frequently Asked Questions(FAQs), “Is cement fire resistant?”

Is concrete a fire-resistant material?

Concrete has the highest fire resistance of any construction material. When exposed to fire, it does not burn, cannot be’set on fire’ like other construction materials, and does not produce hazardous gases, smoke, or drop molten particles.

What is the reaction of cement to fire?

Concrete can not burn — it cannot be ignited and does not produce poisonous vapors when exposed to fire. Concrete has been shown to have a high level of fire resistance and may be classified as nearly fireproof in the majority of situations.

In the event of a fire, will cement blocks explode?

In a fire pit, you don’t want to utilize a densely packed concrete block. It must be permeable enough to allow steam to escape when trapped water converts to steam within. If the blocks aren’t porous, steam might build up and cause them to explode.

Is it true that when concrete is heated, it explodes?

Concrete may really explode when heated to incredibly high temperatures. When a fire breaks out near a concrete building, such explosions may have serious effects, but experts aren’t sure how they happen. 

What is the maximum temperature that cement can reach?

Cement has a very high heat storage capability. It can warm to greater temperatures and release heat more slowly than most other materials. On a hot summer day, even shaded concrete may readily reach 70°F; but, concrete in full sunshine can easily reach 135°F.

Is it possible to build a fireplace out of concrete?

Pouring a concrete slab directly down onto the floor to create a hearth for your fireplace or wood stove is a simple option! With its gentle gray tone, we adore how rustic and simple ours came out, ideal for the country home style that we like.


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