Steel is a non-combustible building material. Compared with concrete, steel has many advantages such as earthquake resistance and bending resistance. Therefore, in modern buildings, steel structures are widely used, not only can relatively increase the load capacity of buildings, but also meet the needs of aesthetic design of architectural designs, such as various single- or multi-storey factories, skyscrapers, warehouses, waiting rooms. , Terminal halls, etc. are generally designed with steel structures.
Although the steel does not burn, the steel will deform when exposed to high temperatures, causing the structure to collapse.
As a building material, steel has some unavoidable defects in fire prevention.
Generally, the fire resistance limit of unprotected steel structures is about 15 minutes. Usually, the bearing capacity will be lost at 450 ～ 650 ℃, and great deformation will occur, which will cause the steel columns and beams to bend and even the structure to collapse.
Around us, shocking fires often occur, causing huge loss of life and property.
2009.02.09 Beijing, CCTV North Annex Building Fire
2010.11.15 Shanghai, Jingan District apartment fire 2013.12.25 Guangzhou, Jianye Building fire ...
In 2013, there were 9,596 fires in Shanghai, killing 73 people and directly losing 122 million yuan ...
In the event of a fire, fire-resistant coatings can withstand high temperatures and prolong escape and rescue times.
Therefore, steel structures need fire protection coatings for protection. To resist high temperature in the event of a fire, protect the steel structure from deformation and collapse within a certain period of time, and extend the time for personnel escape and fire rescue.
Fire-resistant coatings are divided into two categories according to the state after fire: intumescent and non-intumescent
Intumescent fireproof coating
When exposed to fire, the intumescent fire-resistant coating forms a carbon foam insulation layer with a thickness of 50-80 times the original coating thickness, which protects the building structure through a series of chemical and physical changes to delay the transfer of heat and substrate.
Intumescent fireproof material?
Conventional fire rating: 0.5 hours, 1 hour, 1.5 hours, 2 hours
2. Non-intumescent fireproof coating
It is mainly composed of cement, vitrified beads, sepiolite and other inorganic materials. The basic fire protection principle is that the low thermal conductivity of medium or low density and high temperature resistant inorganic or hollow microsphere materials delays the progress of heat energy transmission to the steel structure substrate. It generates an endothermic reaction when exposed to fire, releasing non-combustible gases (such as water vapor, carbon dioxide, etc.), diluting the oxygen concentration on the surface of the steel structure, and forming a dense "enamel layer" to block the transmission of heat insulation like steel surface.
Beijing fireproof coating construction