Using Suitable Materials

The fire resisting material has the following characters:

1.   It should not expand under heat so as to introduce unnecessary stresses in the building
2.   It should not disintegrate under the effect of heat
3.   When subjected to fire it should not lose its strength.
4.   The material should not easily catch fire

Commonly used Fire resisting characters of some of building materials are given below:

1. Stone: It is a poor conductor of heat. Sand stones with fire grains may moderately resist fire. Granite disintegrates under fire. Lime stone easily crumbles. During cooling period Most of the stones disintegrate after heated by fire.
2. Brick: Bricks may resist heat up to 1200°C. If good quality mortar is used at the time of construction, fire resistance is good extremely.
3. Timber: Any structure made of timbers is destroyed in fire rapidly. Timber enhances the intensity of fire. In buildings use of heavy sections of timber is not desirable. The surface of timber is coated to make timber more fire resistant with chemicals like phosphate, ammonium and sulphate, borax and boric acid. Sometimes in the building fire resistant paint is applied to timber used.
4. Concrete: Concrete has obtained very good fire resistance. In case of fire the real behaviour of concrete depends upon the quality of cement and aggregates used. Concrete and prestressed concrete in case of reinforced, it also based on the position of steel. Larger the concrete cover better the fire resistance of the member. When it is heated up to 250°C There is no loss in strength in concrete. If the temperature goes beyond 250°C the reduction in strength begins. Reinforced normally concrete structures may resist fire for about one hour at a temperature of 1000°C. Therefore cement concrete is used ideally fire resistant material.
5. Steel: Steel is a good conductor of heat. Steel bars lose tensile strength. Steel yields at 600°C. It melts at 1400°C. During fire Steel columns become unsafe. Steel reinforcement weakens the reinforced concrete structures. Therefore usually steel columns are protected with brick works or by encasing in concrete. In concrete Reinforcement is protected by concrete cover. With fire resistant paints Steel grills and beams are applied.
6. Glass: It is a bad conductor of heat. During heating it expands little. When it cools after heating, cracks are formed in glass. Reinforced glass having steel wire is more resistant to fire and during cooling procedure, fractured glasses are in their original position, even if it breaks.
7. Aluminium: It is good conductor of heat. It got higher resistance to fire.
8. Asbestos Cement: It is non-combustible material. It possesses high fire resistance.