The fire resistance of concrete is well appreciable, whether it is in material form or in the structural form. Many issues due to fire risk can be reduced drastically by the application of concrete as a structural material.
This is due to the inherent properties inbuilt in concrete. This does not ask for an additional fire resistance for the concrete used.
Altogether the performance of concrete in fire is such a way that the structural integrity of the concrete is maintained, the fire resistance is not compromised and provide perfect shielding from the heat attack. This makes concrete a reliable material against fire.
Fire Resistance of Concrete MaterialWe cannot let the concrete set on fire or let it to get burned. This material does not have any reaction with fire to emit any dangerous or toxic fumes or gases. A higher degree of fire resistance is observed in concrete and it is a perfectly cost-effective fire resistant structural material that can be used in construction. The reason behind this amazing property of concrete is due to the presence of main ingredients cement and aggregate combination. The combination of these materials along with water bring a mass called the “concrete” which is found to be an inert material and most importantly inert for fire and safety structural design. In other words, the concrete material has a very lower value of thermal conductivity. This lower value makes the concrete to conduct heat very slowly behaving as a perfect shield to protect the adjacent space and the material itself from damage due to fire.
Fire Resistance of Concrete StructuresIf the concrete material performs good in fire, then the concrete structures too will possess the same property. The concrete structures have a greater fire resistance mainly due to the:
- Inherent properties of the construction material i.e. the concrete
- Quality based structural design of each structural members against fire attack
- Overall design to ensure robustness
Preparation of High Fire Resistance ConcreteAs mentioned before, one of the main reason behind the inherent property of fire resistance for the concrete is due to the constituent materials present in it. A well-designed use of concrete constituent materials can help to bring concrete with better fire resistance. One of the important factor concerning the concrete fire resistance is composition of aggregates. The use of special aggregates can help in increasing the fire resistance and strength of concrete. Another means is through the use of special plastic fibers (PP). The use of plastic fibers have brought considerable increase in the fire resistance of concrete. The resistance of the cement matrix can be increased by the use of special sands in concrete manufacture. The production of concrete for fire resistance does not have any kind of difference from the standard concrete production. If fibers are used in concrete, the mixing has to be carried out carefully and monitored throughout.
Methods to Improve Fire Resistance of ConcreteThe concrete constituent materials and their property have a greater influence in fire resistance. There were situations where the concrete temperature increased rapidly within minutes and resulted in spalling. There are various methods by which we can improve the concrete fire resistance.
- When concrete made of ordinary Portland cement is subjected to fire greater than 300 degrees Celsius, it will lose most of its important properties. This concrete will lose its structural performance for a temperature greater than 600 degrees Celsius.
- The depth of the weakened zone of the concrete will range from small thickness from millimeters to many centimeters as the temperature of the concrete increases with fire.
- The refractory linings above the temperature of 1600 degree Celsius can be protected with the help of high alumina cement. This is observed to have higher performance in fire. An excellent resistance to fire is shown for a temperature greater than 1000 degree Celsius.
- Using heat shields that is coated with intumescent paint
- Spray applied lightweight mortars
- The used of protective board systems