Tunnel fire retardant coating is developed on the basis of the decorative fire retardant coating combined with its own requirements, so the research and selection of raw materials can refer to the decorative fire retardant coating. As a special coating, in addition to having the decorative effect of ordinary coatings and providing physical protection for the cable substrate, it also needs to have the special function of flame retardancy and fire resistance, which requires them to foam to form a fire insulation layer at a certain temperature. Therefore, there is a special requirement for its base material, which requires that the base material can be concordant with the entire coating system, so that the coating has good mechanical and physical and chemical function, and can form a better foam insulation layer when it is subjected to fire. In order to achieve a certain flame retardant time, the foam layer is required not to fall off at high temperatures. In addition, the cable rubber material is highly elastic, and the cable needs to be often tested and moved, which requires that the coating should have enough resistance to expansion and change, and requires that the fireproof coating has no erosion function on the rubber cable material, good adhesion, good room temperature curing, and good coating decoration.
Scope of application
It is mainly applied to the fire prevention of highway tunnels and railway tunnels, and also applies to the fire prevention needs of petrochemical engineering, high-rise buildings, steel structures and underground garages.
Highway tunnels are generally in mountainous areas, and the tunnels are cool, damp and poorly ventilated. The inner wall of concrete is prone to moisture mildew, alkali return and falling off. The long tunnel is far away from the city, there is no reliable fire water source, the traffic flow in the tunnel is unbalanced, the vehicle items are uncertain, and the fire load is uncertain, which determines the unpredictability of the long tunnel fire. Therefore, the highway tunnel painting project should consider not only its good decoration, but also its excellent waterproof performance, anti-mildew performance and fire performance.
peculiarity
1. Tunnel fire retardant coating does not contain asbestos and harmful substances, and the coating after production, use and construction has no irritating odor. No toxic gas is released during the fire, and the smoke toxicity reaches AQ-1 level, which meets the requirements of environmental protection.
2, prepared by the factory, single component packaging, construction site mixing and stirring construction, easy to operate.
3, direct spraying and coating construction, drying and curing fast.
4. Light coating, strong bond, high strength, excellent aging resistance and waterproof performance.
Performance index
Main performance indicators (according to GB 28375-2012 standard)
|
entry
|
Technical indicators
|
|
State in container
|
Gray-white mixture of particles and powders
|
|
Drying time: table dry ≤
|
24h
|
|
Dry density (kg/㎡) ≤
|
650
|
|
Bond strength (Mpa) ≥
|
0.15
|
|
Water resistance
|
After 720h test, the coating does not crack, layer up, fall off, allowing slight expansion and discoloration
|
|
Alkali resistance
|
After 360h test, the coating does not crack, layer up, fall off, allowing slight expansion and discoloration
|
|
Acid resistance
|
After 360h test, the coating does not crack, layer up, fall off, allowing slight expansion and discoloration
|
|
Freeze-thaw cycle test
|
After 15 tests, the coating did not crack, layer up, fall off or change color
|
|
Fire resistance
|
The coating thickness is 12-16mm±2mm, and the fire resistance time is 2 hours
|
Description of different fire resistance limits
|
Fire resistance /h
|
1.5
|
2.0
|
2.5
|
3.0
|
3.5
|
|
Coating thickness /mm
|
10
|
18
|
23
|
27
|
30
|
Fire prevention mechanism
The fire prevention mechanism of tunnel fire retardant coating can be roughly summarized as the following five points:
(1) It is inflammable or incombustible, so that the protected substrate is not directly in contact with the air, delaying the object's fire and reducing the speed of combustion.
(2) In addition to the tunnel fire retardant coating itself is flame resistant or non-combustible, it also has a low thermal conductivity, which can delay the transmission of the flame temperature to the protected substrate.
(3) The tunnel fire retardant coating is decomposed by heat into non-flammable inert gas, diluting the flammable gas that is decomposed by heat of the protected object, so that it is not easy to burn or slow down the burning speed.
(4) The nitrogen-containing tunnel fire retardant coating is heated to decompose NO, NH3 and other groups, and combine with organic free groups to interrupt the chain reaction and reduce the temperature.
(5) The expansive tunnel fire retardant coating is heated and expanded to form a carbon foam insulation layer to close the protected object, delay the transfer of heat and the substrate, and prevent the object from burning or the strength of the decrease caused by the increase in temperature. Tunnel special fireproof coating classification: tunnel special fireproof coating; Fireproof paint for wood tunnel; Fireproof paint for steel structure tunnel.
Construction method
The construction of tunnel fire retardant coatings generally adopts stratified interval construction technology, divided into basic (fire protection layer) and surface (color layer) construction. During the construction period and within 24 hours after the construction, the ambient temperature shall not be lower than 4 ° C to prevent freezing damage. In extremely dry and hot conditions, the necessary maintenance conditions should be created to prevent the coating from losing water too quickly.
Construction equipment
Mortar mixer, special spraying equipment (extruded mortar pump, air compressor), special iron plate for plastering mortar, cleaning tools, transportation tools, etc.
Preparation for construction
(1) Clean the floating dust and oil on the surface of the tunnel concrete, and wet it with water;
(2) Repair the uneven places to ensure the smooth surface of the tunnel concrete; At the same time, where the concrete surface is particularly smooth, it is required to use mortar.
(3) The leaking place must be filled with water.
Base construction
(1) The water and the paint are mixed in the ratio of (0.70 ~ 0.75) : 1, and stirred with a mixer for 20min (be sure to ensure the mixing time, and the paint should be mixed with it) to form a thick paste;
(2) Use a small amount of slurry to make a horizontal thickness mark with a spacing of 2.5m as a reference for spraying construction;
(3) Spray with the spray machine from the waist of the tunnel to the top (from the bottom to the top), each spray thickness of 3 ~ 8 ㎜;
(4) After the first spray is basically dry, continue to spray the second time, so the cycle, until the spray to the design thickness;
(5) Because the spraying surface is not smooth enough, after the last spraying, it is necessary to immediately use the slurry to manually fill and trim, so that the coating surface is smooth and smooth, and ensure that the coating reaches the design thickness;
(6) After the completion of the base, the coating surface is required to be smooth, smooth and clean.
Surface construction
After the basic dry molding of the base (about 3d), the surface construction can be carried out (for projects with higher requirements, such as municipal engineering, etc., it is best to scrape a layer of putty on the surface of the base before the surface construction). The surface can be constructed with spray gun, wool brush, roller and other machines, and the spray is required to be uniform, smooth and colorless. The dividing lines of different colors should be straight and clear.
Construction precautions
(1) When mixing the slurry is too dry, the water-cement ratio can be appropriately increased, depending on the appropriate construction;
(2) In the process of mixing, spraying and applying, the scattered and rebounded slurry can be recovered in time; Contaminated and more than 2 hours can not be reused;
(3) Once the coating bag is opened, it should be used immediately, and the coating that is wet and caked should not be used;
(4) The construction process can be adjusted appropriately according to the design thickness of the coating and construction conditions.
Packing and storage
1. This product is packed in woven bag lined with plastic bag, each bag is 25kg.
2, this product should be stored in a cool, dry warehouse, effective storage period of half a year.
3, this product is non-combustible, non-explosive, non-toxic, non-corrosive safety products. During storage and transportation, pay attention to sealing to prevent moisture and rain immersion, and the material will fail if it is damp.
Development report
With the rapid development of national economy, the acceleration of urban construction and the rapid increase of floating population, the construction and improvement of traffic is particularly important. The tunnel is favored by the planners because of its characteristics of the shortest distance to achieve the target, the least area, the least damage to the natural environment and the landscape, and the low cost. However, the tunnel structure is generally made of stone and reinforced concrete. When the temperature rises to 60 ° C, the strength loss of concrete is more than 50%, and the yield stress of steel is reduced to less than 1/3 of the yield force at normal temperature. When a fire occurs in the tunnel, the temperature is generally above 100 ° C, the tunnel masonry is difficult to withstand such high temperature, and the serious part is easy to burn down, coupled with the tunnel environment is relatively closed, the crowd density is large, once a fire occurs, the evacuation and rescue is very difficult, easy to cause heavy casualties and property losses, so the tunnel fire treatment is very important.
According to the Statistical Bulletin on the Development of China's Highway and Waterway Transportation Industry in 2005, by the end of 2005, 2 889 road tunnels had been built nationwide, with a total of 1.527 million meters. Among them, flame retardant design accounts for about 1/10, so there is a large market space for fire modification of existing tunnels. At the same time, according to the news released at the third Annual meeting of the railway tunnel, China will build 3 million m long railway tunnels in the next 6 years, and with the establishment of the Beijing to Shanghai high-speed rail project, it will drive the demand for tunnel-related products, especially the demand for tunnel fire retardant coatings.
Make up
Tunnel fire retardant coating is mainly composed of binder, refractory filler, foaming material and auxiliaries.
Binding agent
About 35% ~ 40% of the total volume of paint. Styrene propylene, vinegar propylene, EVA, 582 resin, water glass, refractory cement, phosphate, etc., are good binders. Due to the large amount of binder, the price of the material, the combustion performance and the smoke situation in the fire should be considered when selecting the binder.
Refractory packing
It is one of the skeleton components of tunnel fire retardant paint, accounting for about 35% to 38% of the total volume of paint, and its main function is high temperature insulation and reduce thermal conductivity. Sepiolite, expanded perlite, light calcium carbonate, glass hollow bleach beads, kaolin, slag wool, ultrafine aluminum silicate and so on are good inorganic light insulation fillers.
Swelling agent
It is another main component of tunnel fire retardant paint, accounting for about 8% to 10% of the total volume of paint. At high temperature, the composition of the coating changes and the expansion agent expands rapidly, thus forming a porous insulation layer to prevent the transfer of heat to the tunnel masonry. Expanded vermiculite and ammonium bichromate are inorganic foaming materials. Melamine, pentaerythritol and ammonium polyphosphate are mature organic foaming systems, which are mostly used in thin or ultra-thin fireproof coatings.
Flame retardant
Flame retardant for coatings, accounting for about 12% to 15% of the total volume of coatings. It absorbs heat and loses water when heated to assist expansion and insulation. Generally, borides, zinc compounds and aluminum hydroxide and magnesium hydroxide with more crystal water are selected.
Other additives
Mainly improve the workability and physical and chemical properties of the paint, accounting for about 3% to 5% of the total volume of the paint. Commonly used additives are redispersible latex, high efficiency water reducing agent and so on.
Design principle
At home and abroad, a lot of work has been carried out on the study of tunnel fire retardant coatings. For example, domestic scholars proposed a kind of tunnel fire retardant coating with silicate as the main binder, aluminum hydroxide, expanded vermiculite, magnesium trisilicate as the filling material, sodium tetraborate as the fire retardant agent; According to the characteristics of tunnel masonry not resistant to high temperature, a kind of hydraulic tunnel fire retardant coating based on inorganic cementing material was developed, which can be applied to the fire protection of steel structure and concrete at the same time. A new type of physical expansion flame retardant was developed, and a kind of halogen-free, environmentally friendly and physically expansion fire retardant coating with excellent fire performance was prepared.
Foreign scholars have developed inorganic fire retardant coatings on the surface of buildings, which are composed of hydraulic white cement, water glass, vermiculite, expanded perlite, inorganic glass fiber, etc. The fire retardant coating composed of sepiolite, calcium silica, reinforced fiber, high aluminum cement and amorphous silica is introduced. The coating has good heat insulation and anti-burst properties, and can be applied to the exterior walls of buildings and tunnels. It can be used as a fireproof coating on the surface of metal and concrete, which is composed of bentonite, aluminum silicate, wollastonite, magnesium silicate, glass beads and some porous fillers, and the binder is one or several kinds of water glass, Portland cement, gypsum, phosphate, etc.
The above-mentioned tunnel fire retardant coatings are made of sodium silicate, cement, white cement, high aluminum cement, phosphates and other inorganic substances as binder, perlite, expanded vermiculite, microvoid calcium silicate, diatomite, fly ash glass beads, sepiolite powder, talc powder and other filler aggregate, and glass fiber, steel fiber, polypropylene fiber and other reinforcement materials. With aluminum, magnesium, boron, zinc oxides containing crystal water as flame retardants, the components of the above products are mainly composed of inorganic materials. From the literature patents of various fireproof coatings at home and abroad, it can be seen that the coatings used to protect non-combustible building structures include organic expansive thick paste coatings and lightweight inorganic fireproof coatings. At the fire temperature, the carbonaceous foam layer of the organic expanded coating is easy to gradually disappear and reduce the fire insulation effect, even the best coating, when the coating is increased to 4 mm, the fire resistance limit is only 1h. Inorganic fireproof coatings, due to light density, small thermal conductivity, good fire resistance, with different coating thickness, can meet the fire resistance requirements of 1 ~ 2h or even longer. However, the fireproof coating composed of pure inorganic substances is easy to appear hard and brittle, crack and fall off. Therefore, in the research of tunnel fire retardant coatings, the research technical route of non-expansive and pollution-free water-based organic-inorganic composite coatings should be generally adopted.
<
<
<
<
Beauty paint online customer service
Customer Service 2