Concrete may not be as aesthetically popular a choice for architectural materials, like wood, granite, glass, and aluminum, but it remains one of the strongest and most durable materials for construction of homes, offices, bridges and many other projects. Its resistant to fire makes it a material that is safe for homes.
Concrete is a combination of cement, aggregates, and water. Cement is made from limestone, clay, and gypsum, all of which are chemically inert and therefore are not combustible. Aggregates also have this property, thus adding to the fire resistance. Concrete also transfers heat very slowly, and thus concrete walls are a fire shield that prevents the spread of fire. Even so, when concrete is used in ovens, kilns, and fireplaces, it is important that this fire-resistant property is further enhanced, so that these structures are able to function in the manner they are required to.
Fireproof concrete is made by using cement that is called refractory cement. The fireproof concrete that is in wide use, commercially, is made from cement that has fly ash as one of its components. Fly ash is a by-product that comes from kilns used in the manufacturing of Portland cement. You can buy refractory cement, which will have fly ash, from any building material supplier. To make fireproof concrete you need to have concrete that has 3 parts of gravel or aggregate, 2 parts of sand, 2 parts of refractory cement and 0.5 part of hydrated lime. Portion out the aggregate and sand onto a mixing platform or into a concrete mixer, and add the hydrated lime and cement over it. If you are using a mixing platform, dry mix all the ingredients taking care to see that they are all well distributed in the dry mix. Create a depression in the mixed pile and add water. Mix the combination till the water is completely distributed and the concrete so obtained has no dry pockets. Add the water in small quantities at a time, and continue mixing until you have a mixture that can stand by itself and yet remain workable.
It is assumed you will have earlier prepared the necessary formwork for the structure you are planning to build. Transfer the mixed concrete to the forms in layers, and consolidate it a rod. Use a trowel to give the required top surface to the concrete. Your fireproof structure is now ready to go through the curing process. After the concrete has hardened it has obtained its initial set, and you can spray on some water to prevent loss of moisture that comes from the setting process that releases a lot of heat. Cover the concrete structure with a plastic sheet or hessian and make sure that it is never allowed to dry. Leave this cover on for two days, before you remove it. It will now dry out in the air. Continue to keep it moist for another three weeks before you start using the structure and subject it to heat.
You can also make fireproof concrete using a combination of ordinary Portland cement, perlite, sand, and fireclay.
