Fire pits can be built from many materials. You should always use stones, at least for the border, to prevent the fire from spreading - for example by the surrounding grass igniting and causing a wildfire. However, not all stones are suitable for this project because many types are not sufficiently fireproof.
Can you build a fire pit out of concrete?
A concrete fire pit should be built with fireproof concrete or firebricks, as traditional concrete can crack or even explode due to moisture. Alternatively, fired stones such as clinker or brick can be used, which are fire-resistant and inexpensive.
Problematic concrete
Types of stone that are not sufficiently fireproof include conventional concrete. The stone itself can withstand heat well, but its ability to absorb water is problematic. Concrete outdoor fire pits are exposed to wind and weather and of course also rain. The moisture seeps into the concrete - only to evaporate or even fizzle out as soon as the fireplace is lit again at the next opportunity. The result is that the concrete bursts and, in the worst case, concrete blocks (as well as Ytong stones, but these because of the air they contain) can even explode. For the same reason, the foundation of a fireplace should not be concreted.
Concrete Fire Pit Ideas
If you still want to use concrete for your fireplace, the stone must be protected from rain and moisture. This can be done, for example, through a roof, but also through a cover with a waterproof material. If these requirements are met, you cannot necessarily line the fire pit itself with concrete blocks, but you can use them for the border. For example, used manhole rings of various sizes are very suitable for this purpose. If you use firebricks for your fireplace, you should be absolutely on the safe side, as they are absolutely fireproof. Firebricks are manufactured specifically for lining fireplaces and blast furnaces and must therefore be able to withstand high, direct heat.
Refractory concrete
There is also the option of using fireproof concrete instead of conventional concrete. So-called refractory concrete can withstand temperatures from 1,100 °C to 2,000 °C and is therefore perfect for concreting a fire pit. By the way, if you are planning a brick fire pit, we recommend using fireproof mortar - otherwise it could happen that the wall cannot withstand the great stress of the heat.
Tip
Instead of concrete, burned stones can be used excellently for building a fireplace, for example clinker or brick. These stones are also inexpensive and are naturally fire-resistant.
