Non-intumescent fireproof coating for fiber reinforced composites, and preparation method and application thereof

Abstract

The application belongs to the technical field of fireproof materials, and particularly relates to a non-expanding fireproof coating for fiber reinforced composite materials and a preparation method and application thereof. In the preparation raw materials of the non-expanding fireproof coating, the binder comprises metakaolin, fly ash, CA80 high-aluminum cement and an activator, or comprises metakaolin, fly ash, CA80 high-aluminum cement, an activator and an organic binder, the organic binder comprises redispersible emulsion powder and / or polyvinyl alcohol powder, the heat-insulating filler comprises expanded vermiculite, hydrophobically modified expanded perlite, sepiolite and hollow glass microspheres, the flame retardant comprises aluminum hydroxide and magnesium hydroxide, the fiber comprises glass fiber, and the additives comprise a foaming agent, a thickening agent, a foam stabilizer and an acrylic emulsion. The formed coating has the advantages of low carbon, low cost, excellent heat-insulating performance and high-temperature strength, can be applied as a fireproof coating for fiber reinforced composite materials (FRP), and can effectively protect the FRP reinforcement system.

Description

Technical Field

[0001] This invention belongs to the field of fireproof materials technology, specifically relating to a non-intumescent fireproof coating for fiber-reinforced composite materials, its preparation method, and its application. Background Technology

[0002] In recent years, fiber-reinforced polymer (FRP) composites have become a popular material in reinforcement projects due to their light weight, high strength, good durability, and convenient construction. Despite the many advantages of FRP reinforcement, a major drawback is its poor high-temperature resistance. Currently, most adhesives used to bond FRP materials are epoxy resin polymers. However, studies have shown that the mechanical properties of these adhesives significantly decrease above 120°C, resulting in insufficient fire resistance of untreated FRP-reinforced concrete components in a fire, failing to meet relevant fire resistance standards and posing a fire safety hazard to the structure.

[0003] To improve the fire resistance of FRP-reinforced structures, fire-retardant boards or coatings are typically used, with non-intumescent fire-retardant coatings being the most widely applied. While these coatings effectively extend the fire resistance limit of reinforced concrete structures to meet code requirements, their protective effect on the FRP binder remains unsatisfactory. In high-temperature environments, the temperature at the FRP interface rapidly exceeds 120°C, causing a significant decrease in the mechanical properties of the epoxy resin, resulting in a loss of its load-bearing capacity. This indicates that while fire-retardant coatings delay the degradation of reinforced concrete, their protective effect on the FRP-reinforced system is limited, failing to fully consider the specific needs of FRP materials.

[0004] Currently, FRP materials have been widely used in the field of building reinforcement, but research on fire-retardant coatings that match them is significantly lagging behind. There is an urgent need to conduct more in-depth research on the fire protection of FRP materials in order to improve the overall fire resistance of FRP-reinforced structures. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a non-intumescent fire-retardant coating for fiber-reinforced composite materials, its preparation method and application. The coating formed by the non-intumescent fire-retardant coating provided by the present invention has excellent thermal insulation performance and high-temperature strength, and can be used as a fire-retardant coating for fiber-reinforced composite materials (FRP).

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] This invention provides a non-intumescent fire-retardant coating for fiber-reinforced composite materials. The raw materials for preparation, by mass percentage, include 50-58% binder, 20-24% heat-insulating filler, 5-10% flame retardant, 0.3-0.5% fiber, 0.3-0.6% additives, and 12-15% water.

[0008] The binder includes metakaolin, fly ash, CA80 high-alumina cement and an activator, or includes metakaolin, fly ash, CA80 high-alumina cement, an activator and an organic binder;

[0009] The organic binder includes redispersible latex powder and / or polyvinyl alcohol powder;

[0010] The thermal insulation filler includes expanded vermiculite, hydrophobically modified expanded perlite, sepiolite, and hollow glass microspheres;

[0011] The flame retardant includes aluminum hydroxide and magnesium hydroxide;

[0012] The fiber includes glass fiber;

[0013] The additives include foaming agents, thickeners, foam stabilizers, and acrylic emulsions.

[0014] Preferably, the hydrophobic modified expanded perlite has a particle size of 1-2 mm; the hydrophobic modified expanded perlite is isobutyltriethoxysilane modified expanded perlite.

[0015] Preferably, the hollow glass microspheres include two types of hollow glass microspheres with a D50 particle size of 65 μm and a D50 particle size of 40 μm; the volume ratio of the two types of hollow glass microspheres with a D50 particle size of 65 μm and a D50 particle size of 40 μm is 5-7:3-5.

[0016] Preferably, the foaming agent comprises sodium α-olefin sulfonate; the foam stabilizer comprises calcium stearate and / or a lightweight wallboard foam stabilizer; and the thickener comprises cellulose ether.

[0017] Preferably, the mass ratio of the foaming agent to the thickener is 0.1–0.3:0.07; the mass ratio of the foaming agent to the foam stabilizer is 0.1–0.3:0.5; the mass ratio of the foaming agent to the acrylic emulsion is 0.1–0.3:1; and the solid content of the acrylic emulsion is 40–60%.

[0018] Preferably, the mass ratio of metakaolin to redispersible latex powder is 70:0 to 5; and the mass ratio of metakaolin to polyvinyl alcohol powder is 70:0 to 1.5.

[0019] Preferably, the mass ratio of metakaolin, fly ash and CA80 cement is 50-70:20-48:2-3; and the mass ratio of metakaolin and activator is 70:123-135.

[0020] This invention also provides a method for preparing the non-intumescent fire-retardant coating for fiber-reinforced composite materials described in the above technical solution, comprising the following steps:

[0021] The binder (excluding the activator), the heat-insulating filler (excluding hollow glass microspheres), and the flame retardant are first mixed to obtain the base material;

[0022] The base material, foaming agent, thickener, and foam stabilizer are mixed a second time to obtain a dry material;

[0023] The dry material is mixed with hollow glass microspheres in a third mixing process, and then an activator, acrylic emulsion and water are added for a fourth mixing process to obtain a mixture.

[0024] The mixture and fibers are mixed and dispersed to obtain a non-intumescent fire-retardant coating for fiber-reinforced composite materials.

[0025] The present invention also provides the application of the non-intumescent fire-retardant coating for fiber-reinforced composite materials described in the above technical solution or the non-intumescent fire-retardant coating for fiber-reinforced composite materials prepared by the preparation method described in the above technical solution in the fire protection of fiber-reinforced composite materials.

[0026] The present invention also provides a method for preparing a non-intumescent fire-retardant coating, comprising the following steps: applying a non-intumescent fire-retardant coating for fiber-reinforced composite materials to the surface of a concrete structure reinforced with fiber-reinforced composite materials, and then curing it to obtain a non-intumescent fire-retardant coating.

[0027] The non-intumescent fire-retardant coating for fiber-reinforced composite materials is the non-intumescent fire-retardant coating for fiber-reinforced composite materials described in the above technical solution or the non-intumescent fire-retardant coating for fiber-reinforced composite materials prepared by the preparation method described in the above technical solution.

[0028] This invention provides a non-intumescent fire-retardant coating for fiber-reinforced composite materials. The raw materials, by mass percentage, include 50-58% binder, 20-24% heat-insulating filler, 5-10% flame retardant, 0.3-0.5% fiber, 0.3-0.6% additives, and 12-15% water. The binder includes metakaolin, fly ash, CA80 high-alumina cement, and an activator, or includes metakaolin, fly ash, CA80 high-alumina cement, an activator, and an organic binder. The organic binder includes redispersible latex powder and / or polyvinyl alcohol powder. The heat-insulating filler includes expanded vermiculite, hydrophobically modified expanded perlite, sepiolite, and hollow glass microspheres. The flame retardant includes aluminum hydroxide and magnesium hydroxide. The fiber includes glass fiber. The additives include a foaming agent, a thickener, a foam stabilizer, and an acrylic emulsion.

[0029] The non-intumescent fire-retardant coating for fiber-reinforced composite materials provided by this invention contains pores of three sizes, which is beneficial to improving thermal insulation performance. Firstly, the geopolymer cementitious material generated by the reaction of metakaolin, fly ash, CA80 cement, and an activator possesses numerous nanoscale gel pores. Secondly, the addition of hollow glass microspheres introduces micron-sized pores into the coating, further improving its thermal insulation performance and also enhancing its fluidity. The addition of a foaming agent to the coating creates micron- or even millimeter-sized pores, which not only introduce air bubbles to improve thermal insulation but also reduce water consumption during preparation. The flame retardant decomposes upon heating, absorbing heat and reducing the temperature rise of building components, which also contributes to improving the coating's thermal insulation performance. Furthermore, the addition of hydrophobically modified expanded perlite significantly reduces water consumption and increases the strength of the geopolymer binder matrix skeleton. Therefore, under high temperature, the ability of the pore walls in the coating to resist the expansion stress caused by moisture evaporation and the stress caused by sintering shrinkage is improved, enhancing the coating structure's ability to resist thermal stress. This, in turn, improves the coating's strength at high temperatures (800℃), enabling it to better protect the FRP-reinforced concrete system. Moreover, it exhibits a significant temperature plateau period (100℃) when exposed to fire, with temperatures below 120℃ for nearly an hour. This is highly beneficial for the FRP-reinforced concrete system to continue to exert its mechanical function under fire, preventing it from being damaged in a short period after the fire starts, and effectively reducing the damage and loss caused by fire to the structure. Attached Figure Description

[0030] Figure 1 This is a diagram of a compression test.

[0031] Figure 2 This is a diagram of a flexural strength test.

[0032] Figure 3 This is a diagram of the bond strength test under direct tension.

[0033] Figure 4 This is a water resistance test diagram;

[0034] Figure 5 This is a schematic diagram of a fire resistance test.

[0035] Figure 6 The image shows a comparison of the fire resistance of the non-intumescent fire-retardant coatings for fiber-reinforced composite materials prepared in Examples 1-3 and the fire-retardant coating in Comparative Example 4. Detailed Implementation

[0036] This invention provides a non-intumescent fire-retardant coating for fiber-reinforced composite materials, which is prepared by weight percentage as follows: 50-58% binder, 20-24% heat-insulating filler, 5-10% flame retardant, 0.3-0.5% fiber, 0.3-0.6% additives, and 12-15% water.

[0037] The binder includes metakaolin, fly ash, CA80 high-alumina cement and an activator, or includes metakaolin, fly ash, CA80 high-alumina cement, an activator and an organic binder;

[0038] The organic binder includes redispersible latex powder and / or polyvinyl alcohol powder;

[0039] The thermal insulation filler includes expanded vermiculite, hydrophobically modified expanded perlite, sepiolite, and hollow glass microspheres;

[0040] The flame retardant includes aluminum hydroxide and magnesium hydroxide;

[0041] The fiber includes glass fiber;

[0042] The additives include foaming agents, thickeners, foam stabilizers, and acrylic emulsions.

[0043] Unless otherwise specified, the present invention does not have special requirements on the source of the raw materials used in the preparation, and commercially available products well known to those skilled in the art can be used.

[0044] The raw materials for preparing the non-intumescent fire-retardant coating for fiber-reinforced composite materials provided by the present invention include a binder with a mass percentage of 50-58%, preferably 54%. In the present invention, the binder includes metakaolin, fly ash, CA80 high-alumina cement and an activator, or includes metakaolin, fly ash, CA80 high-alumina cement, an activator and an organic binder.

[0045] In this invention, the particle size of the metakaolin is preferably 0.4–50 μm, more preferably D50 particle size = 14 μm; the particle size of the fly ash is preferably 0.32–57 μm, more preferably D50 particle size = 7.8 μm; the particle size of the CA80 high-alumina cement is preferably 1–50 μm, more preferably D50 particle size = 14.5 μm; the activator is preferably an alkali activator; the alkali activator is preferably a mixed solution of sodium silicate and sodium hydroxide; the mass ratio of sodium silicate to sodium hydroxide is 2:1; the modulus of the activator is preferably 1.5–2M, more preferably 1.6M.

[0046] In this invention, the preferred mass ratio of metakaolin, fly ash and CA80 cement is 50-70:20-48:2-3, more preferably 70:27.5:2.5; the preferred mass ratio of metakaolin and activator is 70:123-135, more preferably 70:135.

[0047] In this invention, the organic binder preferably comprises redispersible latex powder and / or polyvinyl alcohol powder, more preferably redispersible latex powder and polyvinyl alcohol powder; the particle size of the redispersible latex powder is preferably 1-7 μm, more preferably 3-5 μm; the particle size of the polyvinyl alcohol powder is preferably 120 mesh; the number average molecular weight of the polyvinyl alcohol powder is preferably 72600-81400, more preferably 80000; the mass ratio of metakaolin to redispersible latex powder is preferably 70:0-5, more preferably 70:2-5; the mass ratio of metakaolin to polyvinyl alcohol powder is preferably 70:0-1.5, more preferably 70:0.5-1.5.

[0048] In this invention, the geopolymer cementitious material formed by the reaction of metakaolin, fly ash, CA80 high-alumina cement, and activator possesses numerous nanoscale gel pores and adsorbs a certain amount of free water. Its evaporation and heat absorption at high temperatures are beneficial for thermal insulation. Higher metakaolin content generally results in better coating density and refractoriness because the geopolymer structure helps prevent heat conduction. However, excessive metakaolin content may affect the coating's flexibility and adhesion. Increasing fly ash content can improve the coating's fluidity and workability, reducing the risk of shrinkage cracks. However, fly ash has low reactivity, and excessive fly ash may reduce the coating's mechanical and refractoriness, especially affecting its stability under high-temperature conditions. Increasing the amount of CA80 high-alumina cement generally improves the coating's high-temperature resistance and mechanical strength. However, excessive cement may increase the coating's brittleness, affecting its adhesion and thermal expansion characteristics. Its content is usually controlled within a certain range (e.g., 1–5%) to achieve an optimal balance. The amount of activator directly affects the formation rate and strength of the geopolymer. If the activator dosage is too low, the geopolymerization reaction will be incomplete, resulting in poor coating hardening and strength. Conversely, if the activator dosage is too high, while it can improve reaction efficiency, it may increase the coating's brittleness and affect its refractory properties. Therefore, the activator dosage needs to be precisely adjusted based on the amounts of metakaolin and fly ash to obtain the appropriate hardening speed and strength.

[0049] Redispersible latex powder and polyvinyl alcohol can improve the bonding strength of coatings. Redispersible latex powder (RDP) is a polymer-modified material with excellent adhesion and flexibility. In fire-retardant coatings, it can enhance the coating's toughness, crack resistance, and adhesion, while improving its workability. Furthermore, RDP can form a waterproof film, helping to improve the coating's water resistance and preventing it from absorbing water and swelling or failing in humid environments. Although RDP can improve the overall performance of the coating, it is essentially an organic polymer with limited high-temperature resistance. At high temperatures, RDP will decompose or soften, potentially affecting the high-temperature stability of the fire-retardant coating. Therefore, the amount of RDP used must be controlled within a reasonable range to balance adhesion and fire resistance.

[0050] Polyvinyl alcohol (PVA) is a water-soluble polymer commonly used to enhance the adhesion and crack resistance of coatings. It can form a stable network structure with other inorganic materials, enhancing the mechanical strength of the coating. The introduction of PVA can improve the adhesion strength of the coating, especially in low-temperature or high-humidity environments, effectively preventing coating peeling. PVA increases the adhesion between the coating and the substrate by forming a thin film. PVA has good flexibility in coating systems, absorbing stress in the coating, reducing crack formation during the drying process, and improving the toughness and stability of the coating. As an organic material, although PVA can significantly improve mechanical properties and workability in the initial stages of coating application, its high-temperature resistance is limited. Above 200°C, PVA undergoes thermal decomposition or carbonization, which may cause the coating to fail under extreme high-temperature conditions. Therefore, the amount of PVA used is usually limited to 1-3% to avoid affecting fire resistance.

[0051] The raw materials for preparing the non-intumescent fire-retardant coating for fiber-reinforced composite materials provided by the present invention include 20-24% by mass of heat-insulating filler, preferably 21-23%, and more preferably 22.2%. In the present invention, the heat-insulating filler includes expanded vermiculite, hydrophobically modified expanded perlite, sepiolite, and hollow glass microspheres.

[0052] Expanded vermiculite is a natural mineral material that expands in volume after high-temperature treatment, exhibiting excellent thermal insulation, fire resistance, and a relatively low density. In fire-retardant coatings, its main function is to improve the coating's fire resistance and thermal insulation. Expanded vermiculite effectively expands at high temperatures, forming a porous structure that slows heat transfer to the substrate. Therefore, increasing the amount of expanded vermiculite can significantly improve the coating's fire resistance. However, because expanded vermiculite itself is relatively fragile, excessive dosage may lead to a decrease in the coating's mechanical strength, especially compressive strength and impact resistance. Therefore, the amount of expanded vermiculite used usually needs to be controlled to balance fire resistance and mechanical strength.

[0053] Hydrophobic modified expanded perlite is a lightweight, porous material that has undergone hydrophobic treatment, exhibiting excellent thermal insulation, fire resistance, and hydrophobic properties. The hydrophobic treatment enhances its stability in humid environments, making it less prone to water absorption and maintaining good structural properties. The introduction of hydrophobic modified expanded perlite can improve the water resistance of fire-retardant coatings, preventing the coating from absorbing water and swelling in humid environments, thus maintaining the integrity of the coating. The porous structure of expanded perlite is similar to that of expanded vermiculite, effectively blocking heat conduction and improving the thermal insulation effect of the coating. Appropriately increasing the perlite content helps improve the fire resistance of the coating. However, expanded perlite itself is relatively brittle; excessive content may lead to a decrease in the strength of the coating, especially its compressive strength and abrasion resistance.

[0054] Sepiolite is a fibrous mineral rich in hydrated magnesium silicate, possessing high heat resistance and good thermal insulation properties. Its fibrous structure helps enhance the adhesion and crack resistance of coatings. Sepiolite's high refractoriness and low thermal conductivity effectively reduce heat transfer in high-temperature environments while maintaining structural stability under fire conditions. The fibrous structure of sepiolite can form a network reinforcement system in the coating, improving its crack resistance and impact resistance, and reducing the risk of cracking and peeling at high temperatures. Sepiolite also has a certain degree of adsorption, which can improve the cohesion of the coating and enhance its stability. A dosage of 5%-10% generally has a positive impact on coating performance; excessive dosage may lead to poor workability or internal stress.

[0055] Hollow glass microspheres are tiny, hollow spherical particles with lightweight, low thermal conductivity, and high-temperature resistance. They are commonly used to improve the thermal insulation performance of coatings and reduce coating density. The low density of hollow glass microspheres can significantly reduce the overall weight of the coating, making them suitable for thick-coat or large-area fire-retardant coatings, reducing the additional load caused by weight. Due to their hollow structure, hollow glass microspheres can effectively reduce heat conduction, improve the thermal insulation performance of the coating, and prevent heat from being rapidly conducted to the substrate. Increasing the dosage of hollow glass microspheres can improve the thermal insulation and fire resistance of the coating; however, excessive dosage may affect the mechanical strength of the coating, especially its compressive and impact resistance.

[0056] In this invention, the particle size of the expanded vermiculite is preferably 68-564 μm, more preferably D50 particle size = 226.6 μm; the particle size of the hydrophobically modified expanded perlite is preferably 1-2 mm; the hydrophobically modified expanded perlite is isobutyltriethoxysilane modified expanded perlite; the preferred method for preparing the isobutyltriethoxysilane modified expanded perlite is to use isobutyltriethoxysilane to hydrophobically modify the expanded perlite; the concentration of isobutyltriethoxysilane is 5 wt%; the particle size of the sepiolite is preferably 300- The hollow glass microspheres preferably comprise two types: those with a D50 particle size of 65 μm and those with a D50 particle size of 40 μm. The volume ratio of the two types of hollow glass microspheres with a D50 particle size of 65 μm to 40 μm is preferably 5–7:3–5, more preferably 7:3. The wall thickness of the hollow glass microspheres is preferably 1–3 μm, more preferably 2 μm. The true density of the hollow glass microspheres with a D50 particle size of 40 μm is preferably 0.59–0.63 g / cm³. 3 More preferably 0.6 g / cm³ 3 The preferred bulk density is 0.33–0.36 g / cm³. 3 More preferably 0.35 g / cm³ 3The preferred true density of hollow glass microspheres with a D50 particle size of 65 μm is 0.19–0.23 g / cm³. 3 More preferably 0.2 g / cm³ 3 The preferred bulk density is 0.09–0.12 g / cm³. 3 More preferably 0.1 g / cm³ 3 .

[0057] In this invention, the preferred mass ratio of expanded vermiculite to hollow glass microspheres is 43.8:17.4-21.6, more preferably 43.8:17.4; the preferred mass ratio of hydrophobically modified expanded perlite to hollow glass microspheres is 22.5:17.4-21.6, more preferably 22.5:17.4; and the preferred mass ratio of sepiolite to hollow glass microspheres is 15.4:17.4-21.6, more preferably 15.4:17.4.

[0058] In this invention, expanded vermiculite and hydrophobically modified expanded perlite have low densities, effectively reducing the density of the fire-retardant coating. Furthermore, expanded vermiculite has a hollow internal structure with micron-sized pores and a layered structure, providing excellent thermal insulation. Hydrophobically modified expanded perlite also has a porous microstructure and extremely low water absorption. The advantages of adding hydrophobically modified expanded perlite are mainly: 1. The modified expanded perlite has a relatively closed pore structure, reducing pore damage caused by thermal stress while insulating heat, thus improving the thermal insulation performance of the fire-retardant coating; 2. It significantly reduces water consumption. Reducing water consumption not only promotes the hydration of the geopolymer raw materials into a denser gel phase, improving the strength of the matrix, but also, the denser gel phase contains more small capillaries, which can absorb more water and slow down heat conduction in the coating; 3. Lower water consumption reduces excessive foaming of the foaming agent, preventing an excessive proportion of interconnected pores in the coating, which would hinder effective heat insulation and result in low coating strength, affecting daily use. Adding a low amount of CA80 cement is beneficial to promoting the geopolymerization reaction, and its hydration products can significantly improve the mechanical properties of the coating at high temperatures. Sepiolite contains a large amount of hydrated magnesium silicate with similar fibers and a large aspect ratio. At high temperatures, the water evaporates and absorbs heat, which helps to delay heat conduction. In addition, sepiolite also has a certain toughening effect.

[0059] In this invention, hollow glass microspheres have a low thermal conductivity. Adding hollow glass microspheres can introduce micron-sized pores into the coating, thereby improving the thermal insulation performance of the coating. In addition, it can also improve the working performance of the coating.

[0060] The raw materials for preparing the non-intumescent fire-retardant coating for fiber-reinforced composite materials provided by the present invention include a flame retardant with a mass percentage of 5-10%, more preferably 8-10%, and most preferably 9.4%. In the present invention, the flame retardant includes aluminum hydroxide and magnesium hydroxide; the mass ratio of aluminum hydroxide to magnesium hydroxide is preferably 1.5-2.5:1, more preferably 2:1.

[0061] In this invention, the flame retardant decomposes upon heating, absorbing heat and reducing the temperature rise of building components, which also helps improve the thermal insulation performance of the coating. Magnesium hydroxide has a relatively high decomposition temperature (350°C), making it suitable for use in higher-temperature fire-resistant environments, especially where the coating needs to maintain stability at high temperatures for extended periods. Aluminum hydroxide, on the other hand, has a lower decomposition temperature (200°C), making it suitable for applications requiring rapid flame retardancy in the early stages of a fire. While excessive amounts of either magnesium hydroxide or aluminum hydroxide can enhance the flame retardant effect, they may also lead to a decrease in the mechanical properties of the coating, such as increased brittleness or weakened adhesion. Therefore, the dosage needs to be carefully controlled to ensure good flame retardant properties while also considering the coating's workability and mechanical strength. The synergistic use of magnesium hydroxide and aluminum hydroxide allows aluminum hydroxide in the coating to provide an earlier flame retardant effect, while magnesium hydroxide continues to function at higher temperatures, thereby extending the flame retardant time and improving overall fire resistance.

[0062] The raw materials for preparing the non-intumescent fire-retardant coating for fiber-reinforced composite materials provided by the present invention include fibers with a mass percentage of 0.3-0.5%, preferably 0.4%. In the present invention, the fibers preferably include glass fibers; the length of the fibers is preferably 3-8 mm, more preferably 6 mm; the diameter of the fibers is preferably 5-20 μm, more preferably 10 μm.

[0063] Fiber length directly affects the reinforcing effect and crack resistance of coatings. Longer fibers can form a better reinforcing network in the coating, improving the overall strength and toughness of the coating. Longer fibers (e.g., 6–12 mm in length) can form a more stable three-dimensional reinforcing network, significantly improving the crack resistance and tensile strength of the coating. They can effectively disperse stress, reducing the risk of cracking during high temperatures or drying processes. While longer fibers contribute to the reinforcing effect, excessively long fibers may lead to poorer flowability and uniformity of the coating during application, increasing the difficulty of application. To ensure good workability, a moderate fiber length (e.g., 3–8 mm) is usually selected to strike a balance between reinforcing performance and ease of application.

[0064] Secondly, the fiber diameter affects its dispersibility, reinforcing effect, and overall density in the coating. Finer fibers disperse more easily, increasing the density and uniformity of the coating. Finer fibers (e.g., with a diameter of 10–20 μm) can be more evenly dispersed in the coating matrix, contributing to improved coating density and crack resistance. Simultaneously, the addition of fine fibers can reduce localized damage caused by stress concentration, improving the overall toughness of the coating. Coarser fibers (e.g., with a diameter greater than 50 μm), while providing stronger reinforcement, have poorer dispersibility and are prone to aggregation, affecting coating uniformity. Coarser fibers may also affect the coating's workability, increasing thickness and reducing smoothness. Therefore, smaller diameter fibers are commonly used in coatings requiring high workability and a smooth surface.

[0065] A reasonable fiber content can improve the crack resistance and tensile strength of coatings, but excessive content may lead to excessive coating density or application difficulties. With increasing fiber content, the crack resistance, tensile strength, and impact resistance of the coating are significantly improved. Fibers effectively prevent cracking of the coating during high temperatures or drying by dispersing stress and forming a reinforcing network. Furthermore, fibers enhance the impact resistance of the coating and improve its stability and durability at high temperatures. However, with increasing fiber content, the fluidity and workability of the coating decrease, and the coating may become more viscous and difficult to apply evenly.

[0066] The raw materials for preparing the non-intumescent fire-retardant coating for fiber-reinforced composite materials provided by the present invention include additives with a mass percentage of 0.3-0.6%, preferably 0.4-0.5%, and more preferably 0.45%. In the present invention, the additives include foaming agents, thickeners, foam stabilizers, and acrylic emulsions.

[0067] In this invention, the foaming agent preferably includes sodium α-olefin sulfonate.

[0068] The main function of foaming agents is to reduce the density of the coating and enhance its thermal insulation properties by forming a foam structure. In fire-retardant coatings, foaming agents help form a lightweight, porous coating structure, thereby improving the coating's thermal insulation performance. Foaming agents are mainly divided into chemical foaming agents, such as carbonates and bicarbonates, which produce gas through high-temperature decomposition; and physical foaming agents, such as surfactants, which promote foam formation by reducing surface tension. By forming bubbles, foaming agents create a porous structure within the coating, reducing its thermal conductivity and enhancing its thermal insulation effect. When using chemical foaming agents, it is necessary to control their reaction rate and bubble size to avoid producing excessively large or unstable bubbles, which can affect the uniformity of the coating. However, excessive foaming agent may lead to excessive foam, resulting in uneven pores within the coating and reducing its mechanical strength. Therefore, the amount of foaming agent used should be moderate.

[0069] In this invention, the thickener preferably comprises cellulose ether.

[0070] Thickeners are used to adjust the viscosity of coatings, enhancing their workability and flowability. They help prevent sagging or dripping during application, ensuring a uniform coating. Thickeners are mainly cellulose-based (HPMC, HEC) and acrylic polymer thickeners, widely used in water-based coatings. The use of thickeners improves coating flowability, increases workability during application, reduces uneven coating caused by sagging, and ensures uniform coverage. Adding an appropriate amount of thickener can improve the coating's anti-sagging properties and surface smoothness. However, excessive use may result in an overly viscous coating, affecting workability and the coating's flexibility.

[0071] In this invention, the foam stabilizer preferably includes calcium stearate and / or lightweight partition board foam stabilizer, more preferably calcium stearate and lightweight partition board foam stabilizer; the mass ratio of the calcium stearate and lightweight partition board foam stabilizer is preferably 1:2 to 0.5, more preferably 1:1.

[0072] The main function of foam stabilizers is to stabilize the foam structure generated by foaming agents, prevent bubbles from bursting too quickly, maintain the porous structure inside the coating, and ensure thermal insulation and fire resistance. Organic foam stabilizers mainly fall into the following categories: surfactants and polyvinyl alcohols, which help form a stable foam film. Adding foam stabilizers can significantly extend the lifespan of the foam, ensure the uniformity of the foam structure inside the coating, and thus improve the thermal insulation and fire resistance of the coating. Insufficient foam stabilizers can cause the foam to burst easily, affecting the thermal insulation effect of the coating; however, excessive foam stabilizers may lead to an overly viscous coating system, affecting workability. Foam stabilizers help maintain a uniform distribution of bubbles in the coating, ensuring the formation of a stable thermal insulation layer under high-temperature environments, thereby improving the fire resistance of the coating.

[0073] In this invention, the solid content of the acrylic emulsion is preferably 40-60%, more preferably 50%. In this invention, the manufacturer of the lightweight partition board foam stabilizer is Luoyang Tongrun Nanotechnology Co., Ltd.

[0074] Acrylic emulsions, as a base material, impart excellent adhesion, flexibility, and weather resistance to coatings. They also improve the water resistance, alkali resistance, and UV resistance of coatings, making them a crucial binder for fire-retardant coatings. Acrylic emulsions significantly enhance the adhesion of coatings, ensuring good bonding between the coating and the substrate. They also provide good flexibility, reducing cracking caused by temperature changes. Different emulsion types exhibit varying water resistance and weather resistance. Pure acrylic emulsions perform well in outdoor protection and are suitable for fire-retardant coating systems exposed to the elements for extended periods. Insufficient dosage can lead to decreased coating adhesion and water resistance, while excessive dosage may affect the coating's breathability and hardness.

[0075] In this invention, the mass ratio of the foaming agent to the thickener is preferably 0.1-0.3:0.07, more preferably 0.2:0.07; the mass ratio of the foaming agent to the foam stabilizer is preferably 0.1-0.3:0.5, more preferably 0.2:0.5; and the mass ratio of the foaming agent to the acrylic emulsion is preferably 0.1-0.3:1, more preferably 0.2:1.

[0076] The raw materials for preparing the non-intumescent fire-retardant coating for fiber-reinforced composite materials provided by the present invention include water with a mass percentage of 12-15%, preferably 13-14%, and more preferably 13.4-13.5%.

[0077] The non-intumescent fire-retardant coating for fiber-reinforced composite materials provided by this invention is based on a geopolymer cementitious material, in which various lightweight heat-insulating fillers and flame retardants are dispersed. The bonding strength is enhanced by adding redispersible latex powder and polyethylene, and the room temperature and high temperature strength are improved by adding hydrophobically modified expanded perlite. Furthermore, various additives are added to improve workability and durability.

[0078] The present invention also provides a method for preparing the non-intumescent fire-retardant coating for fiber-reinforced composite materials described in the above technical solution, comprising the following steps:

[0079] The binder (excluding the activator), the heat-insulating filler (excluding hollow glass microspheres), and the flame retardant are first mixed to obtain the base material;

[0080] The base material, foaming agent, thickener, and foam stabilizer are mixed a second time to obtain a dry material;

[0081] The dry material is mixed with hollow glass microspheres in a third mixing process, and then an activator, acrylic emulsion and water are added for a fourth mixing process to obtain a mixture.

[0082] The mixture and fibers are mixed and dispersed to obtain a non-intumescent fire-retardant coating for fiber-reinforced composite materials.

[0083] In this invention, the first mixing is preferably carried out under low-speed stirring; the speed of the low-speed stirring is preferably 130-150 rpm, more preferably 140 rpm; the time of the first mixing is preferably 3-5 min, more preferably 3 min.

[0084] In this invention, the second mixing is preferably carried out under low-speed stirring; the stirring speed is preferably 130-150 rpm, more preferably 140 rpm; the mixing time is preferably 1-3 min, more preferably 1 min; and the equipment used for the second mixing is preferably a mixing pot. During the second mixing process, this invention preferably uses a cover plate to shield the top of the mixing pot to prevent the added additives from splashing out.

[0085] In this invention, the third mixing is preferably performed by first manually stirring, followed by low-speed stirring; the low-speed stirring rate is preferably 130-150 rpm, more preferably 140 rpm; the low-speed stirring time is preferably 1 minute; and the equipment used for the third mixing is preferably a mixing pot. During the third mixing process, the top of the mixing pot is preferably covered with a lid. Because the hollow glass microspheres have extremely low density, they are first dispersed in the dry material by manual stirring, and then low-speed stirring is performed.

[0086] In this invention, the acrylic emulsion and water are preferably used in the form of a mixture of acrylic emulsion and water; the method for preparing the mixture of acrylic emulsion and water is preferably to mix and stir the acrylic emulsion and water evenly; the stirring speed is preferably 30 to 50 rpm, more preferably 30 rpm.

[0087] In this invention, the fourth mixing is preferably performed by first stirring at low speed and then stirring at high speed; the speed of the low-speed stirring is preferably 130-150 rpm, more preferably 140 rpm; the time of the low-speed stirring is preferably 1-2 min, more preferably 1 min; the speed of the high-speed stirring is preferably 270-300 rpm, more preferably 290 rpm; the time of the high-speed stirring is preferably 2-3 min, more preferably 2 min; the equipment used for the fourth mixing is preferably a mixing pot; after the high-speed stirring, this invention preferably uses a spatula to scrape the unevenly mixed material on the pot wall and blades into the already evenly mixed material in the mixing pot. In the fourth mixing process, the first low-speed stirring ensures sufficient contact between the dry material and the liquid, and also prevents the material from splashing out during high-speed stirring.

[0088] In this invention, the preferred method for dispersing the mixture and fibers is as follows: the fibers are gradually added to the mixture under low-speed stirring, followed by high-speed stirring for dispersion; the gradual addition is preferably done in small amounts multiple times; the low-speed stirring rate is preferably 130-150 rpm, more preferably 140 rpm; the high-speed stirring rate is preferably 270-300 rpm, more preferably 290 rpm; the high-speed stirring time is preferably 3-5 min, more preferably 5 min; this invention preferably involves manually dispersing any clumps of fibers before adding them to the mixture to prevent fiber clumping.

[0089] The present invention also provides the application of the non-intumescent fire-retardant coating for fiber-reinforced composite materials described in the above technical solution or the non-intumescent fire-retardant coating for fiber-reinforced composite materials prepared by the preparation method described in the above technical solution in the fire protection of fiber-reinforced composite materials.

[0090] The present invention also provides a non-intumescent fireproof coating, comprising the following steps: applying a non-intumescent fireproof coating for fiber-reinforced composite materials to the surface of a concrete structure reinforced with fiber-reinforced composite materials, and then curing it to obtain a non-intumescent fireproof coating.

[0091] The non-intumescent fire-retardant coating for fiber-reinforced composite materials is the non-intumescent fire-retardant coating for fiber-reinforced composite materials described in the above technical solution or the non-intumescent fire-retardant coating for fiber-reinforced composite materials prepared by the preparation method described in the above technical solution.

[0092] In this invention, the coating method is preferably manual application or spraying, more preferably manual application; the curing temperature is preferably 25–35°C, more preferably 25–30°C; the curing humidity is preferably 70–85%, more preferably 70–80%; and the curing time is preferably 14–28 days, more preferably 28 days. This invention does not impose a specific limitation on the thickness of the non-intumescent fire-retardant coating; it can be determined according to the requirements of the application scenario. In an example application of this invention, the thickness of the non-intumescent fire-retardant coating is 30 mm.

[0093] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, but they should not be construed as limiting the scope of protection of the present invention.

[0094] Example 1

[0095] The raw materials for preparing the non-intumescent fire-retardant coating for fiber-reinforced composite materials described in Example 1 are shown in Table 1:

[0096] Table 1 shows the raw materials for preparing the non-intumescent fire-retardant coating for fiber-reinforced composite materials described in Example 1.

[0097]

[0098] Among them, the D50 particle size of metakaolin is 9.1 μm; the D50 particle size of metafly ash is 5.2 μm; the particle size of CA80 high-alumina cement is 14.5 μm; the alkali activator is a mixed solution of sodium silicate and sodium hydroxide, and the modulus of the alkali activator is 1.6M. The specific preparation process is as follows: taking the preparation of 1L of alkali activator as an example, firstly, weigh 64g of sodium hydroxide, dissolve it in an appropriate amount of water, then add 128g of water glass with a mass ratio of 2:1, stir evenly, and finally add water to adjust the total volume to 1L; the particle size of redispersible latex powder is 5 μm; the particle size of polyvinyl alcohol powder is 120 mesh, and the number average molecular weight of polyvinyl alcohol powder is 80,000; the D50 particle size of expanded vermiculite is 226.6 μm; the hydrophobic modified expanded perlite... The expanded perlite with a particle size of 1-2 mm was prepared by hydrophobic modification of expanded perlite with 5 wt% isobutyltriethoxysilane. The preparation process is as follows: Taking 1000g of expanded perlite as an example, firstly, 62.5g of 40wt% isobutyltriethoxysilane solution and 437.5g of water were mixed to obtain 5wt% isobutyltriethoxysilane solution. Then, the solution was allowed to stand for 1 hour to allow the hydrophobic agent to fully hydrolyze. Then, 1000g of expanded perlite and 500g of 5wt% isobutyltriethoxysilane solution were thoroughly mixed in a dish container and soaked at room temperature for 24 hours to allow the hydrophobic agent to fully react with the hydroxyl groups on the surface of the expanded perlite. Finally, the liquid was filtered off, and the modified perlite was placed in a 100℃ forced-air drying oven and dried to constant weight to obtain hydrophobic modified expanded perlite.

[0099] The sepiolite has a particle size of 350–400 μm; the hollow glass microspheres are composed of two types of hollow glass microspheres with a D50 particle size of 65 μm and 40 μm, with a volume ratio of 7:3. The wall thickness of the hollow glass microspheres is 2 μm, and the actual density of the hollow glass microspheres with a D50 particle size of 40 μm is 0.6 g / cm³. 3 The bulk density is 0.35 g / cm³. 3 The true density of hollow glass microspheres with a D50 particle size of 65 μm is 0.2 g / cm³. 3 The bulk density is 0.1 g / cm³. 3 The glass fiber has a length of 6 mm and a diameter of 15 μm; the foaming agent is sodium α-olefin sulfonate; the foam stabilizer is calcium stearate and lightweight partition board foam stabilizer in a mass ratio of 1:1 (Luoyang Tongrun Nanotechnology Co., Ltd.); the thickener is cellulose ether; the solid content of the acrylic emulsion is 50%.

[0100] The preparation method of the non-intumescent fire-retardant coating for fiber-reinforced composite materials is as follows:

[0101] Step 1: First, add the binder (excluding water glass activator), the heat insulation filler (excluding hollow glass microspheres), and the flame retardant to the mixing pot for dry mixing. Stir at a low speed of 140 rpm for 3 minutes to obtain the base material.

[0102] Step 2: Add foaming agent, thickener and foam stabilizer to the base material, and continue to stir at a low speed of 140 rpm for 1 minute. The top of the mixing pot should be covered with a cover plate to prevent the added additives from splashing out, and dry material is obtained.

[0103] Step 3: Add hollow glass microspheres to the dry material. Due to their extremely low density, first use manual stirring to disperse them in the dry material, then stir at a low speed of 140 rpm for 1 minute. Again, it is necessary to cover the mixture with a cover plate to obtain the hollow glass microsphere mixture.

[0104] Step 4: Mix the acrylic emulsion with water at 30 rpm until homogeneous to obtain a mixture of acrylic emulsion and water;

[0105] Step 5: Add the mixture of water glass activator, acrylic emulsion and water to the hollow glass microsphere mixture in the mixing pot. First, stir at a low speed of 140 rpm for 1 minute to ensure that the dry material and liquid are in full contact, and at the same time to prevent the material from splashing out during high-speed stirring. Then, stir at a high speed of 290 rpm for 2 minutes. Use a spatula to scrape the unevenly mixed material on the pot wall and blades into the already evenly mixed material in the mixing pot to obtain the mixture.

[0106] Step 6: Add glass fibers to the mixture using a low-speed stirring mode of 140 rpm. Add the glass fibers gradually in small amounts, manually dispersing any clumps before adding more. Then, stir again at a high speed of 290 rpm for 5 minutes to ensure the fibers are fully dispersed in the slurry, resulting in a non-intumescent fire-retardant coating for fiber-reinforced composite materials.

[0107] Example 2

[0108] The difference from Example 1 is that 5 wt% flame retardant was used.

[0109] Example 3

[0110] The difference from Example 1 is that 2.5 parts by weight of CA80 high-alumina cement in Example 1 are replaced with 5 parts by weight.

[0111] Comparative Example 1

[0112] The difference from Example 1 is that hollow glass microspheres are not added.

[0113] Comparative Example 2

[0114] The difference from Example 1 is that hydrophobically modified expanded perlite is not added.

[0115] Comparative Example 3

[0116] The difference from Example 1 is that hydrophobically modified expanded perlite and hollow glass microspheres are not added.

[0117] Comparative Example 4

[0118] The difference from Example 1 is that the hydrophobic modified expanded perlite is replaced with expanded perlite.

[0119] Comparative Example 5

[0120] The difference from Example 1 is that half of the hydrophobically modified expanded perlite in Example 1 is replaced with expanded perlite that has not undergone hydrophobic modification.

[0121] Application Example 1

[0122] The non-intumescent fire-retardant coating for fiber-reinforced composite materials prepared in Example 1 was applied manually to the surface of a concrete structure reinforced with fiber-reinforced composite materials and cured at 25°C and 70% humidity for 28 days to obtain a 30mm thick non-intumescent fire-retardant coating.

[0123] Application Example 2

[0124] The difference from Application Example 1 is that the non-intumescent fire retardant coating for fiber-reinforced composite materials prepared in Example 1 is replaced with the non-intumescent fire retardant coating for fiber-reinforced composite materials prepared in Example 2, while the rest is the same as Application Example 1.

[0125] Application Example 3

[0126] The difference from Application Example 1 is that the non-intumescent fire retardant coating for fiber-reinforced composite materials prepared in Example 1 is replaced with the non-intumescent fire retardant coating for fiber-reinforced composite materials prepared in Example 3, while the rest is the same as Application Example 1.

[0127] Comparative Application Example 1

[0128] The difference from Application Example 1 is that the non-intumescent fire retardant coating for fiber-reinforced composite materials prepared in Example 1 is replaced with the non-intumescent fire retardant coating prepared in Comparative Example 1, while the rest is the same as Application Example 1.

[0129] Comparative Application Example 2

[0130] The difference from Application Example 1 is that the non-intumescent fire retardant coating for fiber-reinforced composite materials prepared in Example 1 is replaced with the non-intumescent fire retardant coating prepared in Comparative Example 2, while the rest is the same as Application Example 1.

[0131] Comparative Application Example 3

[0132] The difference from Application Example 1 is that the non-intumescent fire retardant coating for fiber-reinforced composite materials prepared in Example 1 is replaced with the non-intumescent fire retardant coating prepared in Comparative Example 3, while the rest is the same as Application Example 1.

[0133] Performance testing

[0134] (1) The density of the non-intumescent fire-retardant coating for fiber-reinforced composite materials prepared in Example 1 was tested. The specific test method was as follows: a 50mm×50mm×50mm cube was used to measure the dry density. After curing for 28 days, the specimen was placed in a drying oven at 105℃ and dried to constant weight. Then, the side length b was measured with vernier calipers, and the mass m was weighed. The density was calculated using the following formula:

[0135]

[0136] The density of the non-intumescent fire-retardant coating for fiber-reinforced composite materials prepared in Example 1 of this invention is 686.8 kg / m³. 3 .

[0137] (2) The compressive strength of the non-intumescent fire-retardant coating for fiber-reinforced composite materials prepared in Example 1 was tested. Specifically, the compressive strength test was conducted using a 50mm×50mm×50mm cube. After curing for 28 days, the cube was placed in a drying oven at 60℃ for 12 hours and then calcined at 800℃ for 1 hour. A 5t MTS testing machine was then used for the compressive strength test at a loading rate of 200 N / min. The compressive strength test results were as follows: Figure 1 As shown.

[0138] The non-intumescent fire-retardant coating for fiber-reinforced composite materials prepared by this invention has a room temperature compressive strength of 1.31 MPa and a compressive strength of 3.81 MPa after calcination at 800°C for one hour.

[0139] (3) The flexural strength of the non-intumescent fire-retardant coating for fiber-reinforced composite materials prepared in Example 1 was tested. Specifically, a 160mm×40mm×40mm specimen was used for the flexural strength test. After curing for 28 days, it was placed in a drying oven at 60℃ for 12 hours. Then, a standard compressive and flexural strength testing machine was used for the flexural strength test. The loading rate was 10mm / min. The flexural strength test results were as follows: Figure 2 As shown.

[0140] The non-intumescent fire-retardant coating for fiber-reinforced composite materials prepared according to the present invention has a flexural strength of 1.05 MPa.

[0141] (4) Bond strength: The bond strength in this invention refers to the bond strength between the non-intumescent fireproof coating prepared in Example 1 and the cement mortar substrate. A 70mm × 70mm × 20mm cement mortar specimen was used, with a 5mm thick coating applied to its surface. After curing for 28 days, a direct tensile test was conducted to determine the bond strength. The direct tensile test results are as follows: Figure 3 As shown.

[0142] The non-intumescent fire-retardant coating for fiber-reinforced composite materials prepared in this invention has an adhesive strength of 0.39 MPa.

[0143] (5) Water resistance: A fiber-reinforced low-alkalinity cement slab with dimensions of 150mm × 70mm × 6mm was used as the base plate. A 5mm thick layer of the non-intumescent fire-retardant coating prepared in Example 1 for fiber-reinforced composite materials was applied to the surface of the base plate to form a coating. After curing for 28 days, the edges and back of the specimen were sealed with a mixture of paraffin and rosin (mass ratio 1:1). Then, 2 / 3 of the specimen was immersed in water. After soaking for 28 days, no cracks appeared on the surface. The water resistance test results were as follows. Figure 4 As shown.

[0144] (6) High and low temperature cycling: The specimens used for high and low temperature resistance test are the same as those used for water resistance test. The cycling process is as follows: store in an environment of -20℃±2℃ for 3 hours, and then store in an environment of 50℃±2℃ for 3 hours. Repeat the above process 20 times.

[0145] The non-intumescent fire-retardant coating prepared by this invention did not crack on the surface after 20 cycles.

[0146] (7) Fire resistance performance: A simplified fire resistance limit test was conducted. The test substrate was a 150mm×150mm×25mm concrete block. A 30mm thick layer of the non-intumescent fire-retardant coating prepared in Examples 1-3 for fiber-reinforced composite materials and the fire-retardant coating of Comparative Example 4 were applied to the surface, respectively. The surface was then smoothed and cured for 28 days. The test equipment was a multi-functional box furnace purchased from the laboratory, which can achieve a heating process close to that described by the ISO standard heating curve. During the test, the coating surface was placed facing the inside of the furnace, directly exposed to the high-temperature environment. The temperature change at the interface between the coating and the concrete substrate was recorded by thermocouples embedded in the specimen. The test schematic diagram is shown below. Figure 5 As shown, the results are as follows Figure 6 As shown. The furnace temperature refers to the temperature of the heated surface. The concrete slab simulates the thickness of the concrete protective layer; therefore, the temperature on the back of the concrete block is the temperature of the reinforcing material under fire conditions.

[0147] The temperature change on the exposed side of the coating was recorded during the fire resistance test. Figure 6As can be seen from the data, Examples 1-3 all exhibit a low-temperature segment with temperatures below 100°C for up to 60 minutes in the early stage of fire exposure, including a significant plateau segment of approximately 100°C lasting up to 20 minutes. This is highly beneficial for the FRP-reinforced concrete system to continue exerting its mechanical properties under fire, preventing it from collapsing shortly after the fire begins. This provides more time for personnel to escape and rescue during a fire, effectively reducing the harm and losses caused by the fire. In contrast, the fire-retardant coating of Comparative Example 4 only had a temperature below 100°C for 46 minutes and did not exhibit a significant plateau segment, indicating that the non-intumescent fire-retardant coating for fiber-reinforced composite materials prepared in this invention has better thermal insulation performance.

[0148] (8) The mechanical properties of the non-intumescent fire retardant coatings for fiber-reinforced composite materials prepared in Examples 1-3 and the fire retardant coating of Comparative Example 4 were tested, and the results are shown in Table 2.

[0149] Table 2 Mechanical Properties

[0150]

[0151] As shown in Table 2, compared with the fire-retardant coating of Comparative Example 4, the non-intumescent fire-retardant coating for fiber-reinforced composite materials prepared in this invention exhibits higher compressive strength, bond strength, and flexural strength. Furthermore, strength tests show that the strength of Example 1 nearly doubled after being subjected to a high temperature of 800°C for one hour, indicating that this coating can maintain its mechanical properties under fire conditions, significantly reducing the problem of decreased fire resistance caused by coating peeling.

[0152] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for preparing a non-intumescent fire-retardant coating, characterized in that, The process includes the following steps: applying a non-intumescent fire-retardant coating for fiber-reinforced composites to the surface of a concrete structure reinforced with fiber-reinforced composites, followed by curing, to obtain a non-intumescent fire-retardant coating. The non-intumescent fire-retardant coating for fiber-reinforced composite materials is prepared by means of the following raw materials, by mass percentage: 50-58% binder, 20-24% heat-insulating filler, 5-10% flame retardant, 0.3-0.5% fiber, 0.3-0.6% additives, and 12-15% water. The binder is composed of metakaolin, fly ash, CA80 high-alumina cement, activator and organic binder; the mass ratio of metakaolin, fly ash and CA80 cement is 50~70:20~48:2~3; the mass ratio of metakaolin and activator is 70:123~135; The organic binder is composed of redispersible latex powder and polyvinyl alcohol powder; The thermal insulation filler is composed of expanded vermiculite, hydrophobically modified expanded perlite, sepiolite, and hollow glass microspheres; The flame retardant is composed of aluminum hydroxide and magnesium hydroxide; The fiber is glass fiber; the fiber has a length of 3~8mm and a diameter of 5~20μm; The additives consist of a foaming agent, a thickener, a foam stabilizer, and an acrylic emulsion; The hydrophobic modified expanded perlite has a particle size of 1-2 mm; the hydrophobic modified expanded perlite is isobutyltriethoxysilane modified expanded perlite; The hollow glass microspheres include two types of hollow glass microspheres with a D50 particle size of 65 μm and a D50 particle size of 40 μm; the volume ratio of the two types of hollow glass microspheres with a D50 particle size of 65 μm and a D50 particle size of 40 μm is 5~7:3~5. The foaming agent is sodium α-olefin sulfonate; the foam stabilizer is calcium stearate; and the thickener is cellulose ether. The mass ratio of expanded vermiculite to hollow glass microspheres is 43.8:17.4~21.6; the mass ratio of hydrophobically modified expanded perlite to hollow glass microspheres is 22.5:17.4~21.6; and the mass ratio of sepiolite to hollow glass microspheres is 15.4:17.4~21.

6. The mass ratio of the foaming agent to the thickener is 0.1~0.3:0.07; the mass ratio of the foaming agent to the foam stabilizer is 0.1~0.3:0.

5.

2. The preparation method according to claim 1, characterized in that... The mass ratio of the foaming agent to the acrylic emulsion is 0.1 to 0.3:1, and the solid content of the acrylic emulsion is 40 to 60%.

3. The preparation method according to claim 1, characterized in that, The mass ratio of metakaolin to redispersible latex powder is 70:0~5; the mass ratio of metakaolin to polyvinyl alcohol powder is 70:0~1.5; and the amount of redispersible latex powder and polyvinyl alcohol powder is not 0.

4. The preparation method according to any one of claims 1 to 3, characterized in that, Includes the following steps: The binder (excluding the activator), the heat-insulating filler (excluding hollow glass microspheres), and the flame retardant are first mixed to obtain the base material; The base material, foaming agent, thickener, and foam stabilizer are mixed a second time to obtain a dry material; The dry material is mixed with hollow glass microspheres in a third mixing process, and then an activator, acrylic emulsion and water are added in a fourth mixing process to obtain a mixture. The mixture and fibers are mixed and dispersed to obtain a non-intumescent fire-retardant coating for fiber-reinforced composite materials.

Images