A lot of research has been carried out on tunnel fireproof coatings both domestically and internationally. Domestic scholars have proposed a tunnel fireproof coating with silicate as the main binder, aluminum hydroxide, expanded vermiculite, magnesium trisilicate and other fillers, and sodium tetraborate as the fireproof additive; A water-based tunnel fireproof coating, mainly composed of inorganic cementitious materials, has been developed to resist high temperatures in tunnel masonry. This coating can be applied to both steel structures and concrete for fire protection in humid environments; A new type of physical expansion flame retardant has been developed, mainly based on expandable graphite, to produce a halogen-free, environmentally friendly, and excellent fire-resistant physical expansion fireproof coating.

Foreign scholars have developed inorganic fireproof coatings for building surfaces, which are composed of hydraulic white cement, water glass, vermiculite, expanded perlite, inorganic glass fibers, etc; A fireproof coating mainly composed of sepiolite, calcium silicate, reinforced fibers, high alumina cement, and amorphous silica has been launched. The coating has good insulation and explosion resistance, and can be applied to building exterior walls, tunnels, etc; A fireproof coating that can be used on metal and concrete surfaces, composed of bentonite, aluminum silicate, wollastonite, magnesium silicate, glass microspheres, and some porous fillers. The binder is one or more of water glass, Portland cement, gypsum, phosphate, etc.

The manufacturing of tunnel fireproof coatings reported above is based on inorganic materials such as water glass, cement, white cement, high alumina cement, phosphate, etc. as binders, perlite, expanded vermiculite, micro porous calcium silicate, diatomaceous earth, fly ash glass microspheres, sepiolite powder, talc powder, etc. as filling aggregates, glass fiber, steel fiber, polypropylene fiber, etc. as reinforcing materials, and aluminum, magnesium, boron, zinc oxides containing crystalline water as flame retardants. The components of the above products are mainly composed of inorganic materials. From the literature and patents of various fire-resistant coatings at home and abroad, it can be seen that coatings used to protect non combustible building structures include two types: organic expansion thick paste coatings and lightweight inorganic fire-resistant coatings.

At the fire temperature, the carbon foam layer of the organic expansion coating is easy to gradually disappear and reduce the fire and thermal insulation effect. Even the best coating, when the coating is increased to 4mm, the fire resistance limit is only 1h. The inorganic fire retardant coating, due to its light density, small thermal conductivity, and good fire resistance, can meet the fire resistance requirements of 1~2h or even longer depending on the thickness of the coating. However, fire-resistant coatings made entirely of inorganic materials are prone to adverse conditions such as hardness, brittleness, cracking, and detachment. Therefore, in the research of tunnel fireproof coatings, the research technology route of non expanding and pollution-free water-based organic-inorganic composite coatings should generally be adopted.

During the use of fireproof coatings, some fireproof coatings can achieve the expected effect, while others do not achieve the expected effect during the use of fireproof coatings in buildings, and some even affect the changes of the building that was originally attached to it. So what are the reasons that affect the performance of fireproof coatings? Let's take a look together below.

Tunnel fireproof coating is developed based on decorative fireproof coating combined with its own requirements, so the research and selection of raw materials can refer to decorative fireproof coating. As a special coating, tunnel fireproof coating should not only have the decorative function of ordinary coatings and provide physical protection for cable substrates, but also have the special function of flame retardancy and fire resistance, which requires them to foam and form a fireproof insulation layer at a certain temperature. Therefore, there is a special requirement for the base material. The base material is required to be compatible with the entire coating system, so that the coating has good mechanical and chemical functions, and can form a good foam insulation layer when exposed to fire. In order to achieve a certain flame retardant and fire-resistant time, the foam layer is required to not fall off at high temperatures. In addition, cable rubber materials are highly elastic, and cables need to be frequently inspected for movement, which requires the coating to have sufficient resistance to expansion and contraction changes. Fire retardant coatings are also required to have no erosion function on rubber cable materials, good adhesion, good room temperature curing, and good coating decoration properties.

Tunnel fireproof coatings are mainly suitable for fire prevention in highway tunnels and railway tunnels, as well as for fire prevention needs in petrochemical engineering, high-rise buildings, steel structures, and underground parking garages.