The building where we spent our life should be strong enough to handle natural disaster like flood, earthquake and fire etc. Fire prevention can be done by using the guidelines given below.
Characteristics of Fire Fighting/Resistant Materials
- The material used in building should be of such nature that it does not disintegrate under the effect of heat produced during fire.
- The material should not expand due to heat also and should ensure stability of structure.
- The nature of material used in building should have minimum contraction due to sudden cooling with water after the material is heated at high temperature.
- The nature of material used in the building should be such that it does not catch fire easily.
Fire Resistant Properties of Building
It is a bad conductor of heat. Sand stone with fine grains can moderate fire successfully without having serious cracks. Granite is disintegrated when it receives heat from fire. Lime stone is easily crumbled by ordinary fire. Most of stones are disintegrated into small pieces when heated during fire and cooled afterwards.
Bricks are bad conductor of heat. They have no serious effect of heat until the temperature during fire rises above 1200 degrees to 1300 degrees. At the time of construction if good quality mortar is used and brick work constructed by skilled mason, brick masonry offers good resistance to fire.
This material is rarely used in building construction. Cast iron breaks into pieces when gets a normal temperature after getting heat during the fire. Care should be taken while using cast iron in the building that it should be covered either by brick work, cement concrete or any other fire resistant material.
It is good conductor of heat and it is heated quickly during fire. Steel bars looses its tensile strength, yields stress if it is heated above 600 degree centigrade during fire. Steel bars completely melt at a temperature of 1400 degree centigrade. During fire unprotected steel columns, beams etc. become unsafe due to high temperature and structure may fail. The paint on the surface of the steel items catches fire easily, keeping in the above problem fire resistant paint should be done on steel members.
Concrete is a bad conductor of heat and an effective material for fire resistant construction. It offers higher resistance to fire than any other material. The actual behavior of concrete in case of fire depends on quality of cement and type of aggregate which form concrete. In case of reinforced and pre-stressed structures, it also depends on the position of steel in concrete.
There is no loss of strength in concrete when it is heated up to 250 degrees centigrade. The reduction of strength starts when the temperature of fire increases beyond 250 degrees centigrade. Normally re-enforced concrete structure can resist fire for about one hour at the temperature of 1000 degrees centigrade without any serious damage. Hence cement concrete is widely used in fire resistant construction.
It is a poor conductor of heat and expends little during heating. Cracks are formed in glass when it is cooled after heating. Re-enforced glass with steel wire is more resistant to fire than ordinary glass. Re-enforced glass can resist sudden variation in temperature without forming cracks. Wired glass even if it breaks, keeps fractured glass in its original position.
Any structure made from timbers rapidly destroys in case of fire. Timber also enhances intensity of fire. As timber is bad conductor of heat if heavy section is used it may attain a high degree of fire resistance. To make timber more fire resistant, the surface of timber is coated with chemicals such as ammonium phosphate and soleplate, borax and boric acid. After doing treatment, the timber becomes more resistant to heat. Sometimes fire resistant paint is also applied on surface of the timber to protect it from heat. ;
Cracks can happen due to foundation movements and settlements of building, thermal movements, chemical reactions, elastic deformations and shrinkage etc. in buildings. They can damage plaster of walls, ceilings and destroy the beauty of the structure also. Let’s know their reasons in detail and get preventive measures.