Fire resistant material

Different types of fire resistant materials used in buildings

1. FIRE RESISTANT BUILDING MATERIALS Architectural building services | sem vi b.Arch v.p.p.m.p.c.o.a . Text by- sejal khandare Date: 02/04/2021

2. INTRODUCTION The fire hazards associated with materials, products, and assemblies used in buildings and other structures have long been a subject of concern and regulation. The hazards of flammable gases and flammable and combustible liquids are widely recognized and regulated with respect to their production, transportation, and utilization. Historically, combustible materials used as part of a building’s construction have been regulated more so than the furnishings and contents brought into buildings, but in recent years the fire hazards and risks associated with furnishings and contents have come under increased scrutiny as the contribution of these products to fires becomes more widely recognized. Evaluation of the fire hazards of materials is complicated, because so many variables can influence the process. These variables include material properties and configurations, environmental conditions, and enclosure effects. Consequently, the fire hazards associated with different materials depend not only on their chemical and physical properties, but also on their applications. -Uncontrolled fires present hazards to life and property due to release of smoke, toxic and corrosive compounds, and release of heat in all fire stages (pre-ignition, ignition, fire growth and flame spread, steady state, and decay). The non-thermal and thermal hazards are created primarily due to the use of products made of combustible materials (both natural and synthetic). These products are used in a variety of ways in residential, private, government, industrial, transportation, and manufacturing applications. Consequently, numerous fire scenarios need to be considered for testing of products MATERIALS CHARACTERISTICS Various products are constructed from natural and synthetic materials containing carbon, hydrogen, oxygen, nitrogen, sulphur, and halogen atoms that are attached to each other by a variety of chemical bonds in the structure. The fire resistance of the materials and products is identified in terms of the ease or difficulty with which materials or products undergo a transformation through the following processes when exposed to heat: • softening and melting • decomposition, vaporization, and charring • ignition • flame spread and fire growth • release of heat • release of smoke, toxic, and corrosive compounds

3. Fire-Resistant Building Materials According to ‘National Building Code of India’ (Part 4 Fire and Life Safety-2005) fire resistance is a property of either an element or material of building construction and is the measure of its ability to satisfy for a stated period of some or all of the following criteria : (a)  Resistance to collapse (b)  Resistance to penetration of flame and hot gases (c)  Resistance to temperature rise on the unexposed face up to a maximum of 180 degree Celsius and/or average temperature of 150 degree Celsius. Building materials used in constructing a house can be of two types: 01.  Non-combustible Materials 02.  Combustible Materials Non-Combustible Materials These materials do not contribute to the growth of fire but may get damaged when the temperature is reached to a very high level where decomposition of fusion occurs, resulting in the loss of strength of the building. If such materials are used in the structure, it may maintain the integrity of structure for longer duration but may eventually collapse. Examples of such materials are metal, stone, glass, concrete, clay products, gypsum products and asbestos products. Combustible Materials Combustible materials will combine exothermically with oxygen, give rise to flame and spread the fire. Such materials whether form part of the structure or contents of the building, burn themselves and increase the intensity and growth of fire i.e. it acts as a fuel for the fire. Examples of such materials are wood and all wooden products, manufactured products such as fibre board, straw board, etc . It can be said that non-combustible materials are safe up to certain level to use in building / house for the simple facts it cannot become the fuel for fire . Nowadays there is a fast-growing awareness amongst the architects and engineers to plan, design and construct the buildings, keeping the safety of the occupants as the focus in the event of outbreak of fire. Once the fire starts, it has a tendency to ignite all the combustible materials of the surrounding area and if not checked in time, it may spread to other parts of the buildings and ultimately lead to the collapse of the building. Most of the countries have described fire resistance in terms of duration of resistance to fire i.e. 1 hour, 2 hours of fire resistance etc.  There are also norms and regulations that should be kept in mind by architects & engineers to design buildings.

4. Fire-Resistant Materials 01. Stones Stones are used in a hilly area where stones are available easily. Depending upon their characteristics, different types of stones are used at different places. Polished granites are used as table tops, cladding for walls and columns. Stones are also used in backyard garden for planters, in entrance hallway in home and to build compound wall. Granite, sandstone and limestone are used to build walls. Slate stones are used in roofs and floors. Stone has a higher capacity to withstand fire up to 1300 C – 1500 C, beyond which it starts melting/breaking. The use of stone in a fire-resisting construction should be restricted to a minimum as this fire-resistant material cannot resist sudden cooling and breaks into pieces. 02. Bricks Bricks are the most common and favoured construction material throughout the world. Bricks are used for the construction of wall, lintel and arch, retaining wall, cavity wall and damp roof courses etc.First class bricks are practically fireproof as they can withstand the exposure of fire for a considerable length of time. Being poor conductors of heat, the bricks can withstand high temperatures up to 1300 C without causing serious effects. Fire bricks are best for use in fire-resisting construction. Fire bricks have melting point about 2800 C. 03 . Steel Steel is used to build high rise building, residential buildings . Steel is used in beam, column, lintel purlin , roof , ceiling, walls etc. It is also used in building as heating and cooling equipment and interior ducting. At about 600 C, its yield strength is reduced to only one-third of its value at normal temperatures. Steel melts at 1400 C . The term fireproof does not necessarily mean that an item cannot ever burn: It relates to measured performance under specific conditions of testing and evaluation. Fireproofing does not allow treated items to be entirely unaffected by any fire, as conventional materials are not immune to the effects of fire at a sufficient intensity and/or duration.

5. Fire-Resistant Materials 04. Wrought-Iron and Cast-Iron Wrought iron is used as a decorative purpose in outdoor stairs, railing, gates and fences. Cast-iron is rarely used for fire-resisting point of view in construction as on sudden cooling, it gets contracted and breaks into pieces or fragments. They melt at around 1100 C to 1500 C. For using cast iron in fire-resistive construction, it should also be protected by a suitable covering of bricks, concrete etc 05 . Aluminium Aluminium is used for window frames, for roofing, and curtain walling, as well as for cast door handles, catches for windows and staircases. In some advanced countries, the aluminium is being used for reinforcement purposes in multi-storied structures because of its light weight and anti-corrosion properties. Melting point of aluminium is about 660 C. 06. Concrete In general, it is a bad conductor of heat and is a good fire-resistant material. Concrete does not have melting point but there is loss o f strength after certain degree of temperature. There is no loss of strength in concrete up to 250 C .  The actual degree of fire-resistance of concrete depends upon the nature of aggregates used and its density. In case of RCC and pre-stressed construction, it depends upon the position of steel in concrete. RCC structure can resist fire up to 1000 C for one hour. Coarse aggregates, like foamed slag, blast furnace slag, crushed brick, crushed limestone, cinder etc. are best suited for concrete for fire resistance. Aggregates like flint, gravel, granite etc. possess poor fire-resisting characteristics . 07. Glass Because of its low thermal conductivity, glass is a very good fire-resistant material. Glass melts at approximately around 1400 C to 1600 C. Sudden and extreme changes in temperature, however, result in fracture or cracks. But when glass is reinforced with steel wire netting, e.g ., in wired glass, its fire resistance is considerably increased , and its tendency to fracture with sudden changes in temperature, gets minimized. Reinforced glass has a higher melting point and hence commonly used for making fire-resisting doors, skylight, windows etc. in construction work. Glass Ceramic can handle very high temperature and are suitable for fire-proof doors.

6. Fire-Resistant Materials 08. Asbestos Cement This fire-resistant material, which is formed by combining fibrous mineral with Portland cement, has a great fire-resistive value. Its melting point is about 871 C. Asbestos cement products are widely used for the construction of fire-resistive partitions and roofs among others. Being poor conductor of heat and incombustible material, the structural members blended with asbestos cement offer great resistance to cracking, swelling, or disintegration when subjected to fire . 09. Plaster or Mortar It is an incombustible fire-resistant material and hence used for protecting the walls and ceilings of building from fire-risks. Cement plaster is better than lime plaster as the latter is likely to be calcined . The fire resistance of the plaster to fire hazards can be increased by using it in thicker layer or reinforcing the plaster with metal lathes. 10. Gypsum Gypsum is another commonly used fire-resistant material used in construction world. Gypsum has melting point about 100 C–150 C . Many structural materials are attached underneath with gypsum sheeting to prevent any fire hazards and to achieve good fire-resistant ratings. 11 . Terra-Cotta It is also a clay product like brick but possesses better fire-resisting qualities than bricks. Being costlier, its use is restricted to fire-resisting floors only. 12. Stucco Stucco is a plaster that has been used for centuries for both structural purposes and artistic. Modern stucco is made of Portland cement, sand and lime, and it serves as an excellent and durable fire-resistant material for buildings. Stucco is often suggested as one of the best materials for boxing in hazardous eaves. Because of versitality in finishing techniques, stucco can come in various textures and colours. Gypsum plaster is also applied on steel columns and other steel members to increase their fire-resistive qualities. The use of fire-resistant materials like cement mortar with surkhi or pozzolana is preferred from the viewpoint of fire-resistance. Nowadays vermiculite plaster is also used as fire-resistant material. Vermiculite is used in building boards because of its low density and good insulation properties.