A fireproof structure for bridge cables

Abstract

This invention discloses a fireproof structure for bridge cables, comprising, from the inside out, a flexible fire-resistant insulation material layer, a fire-resistant winding covering layer, a mass transfer barrier layer, and an intumescent fireproof sealant layer. The fire-resistant winding covering layer and the mass transfer barrier layer designed in this invention form a dense layer composed of inorganic fillers and a silica skeleton at high temperatures, preventing further mass transfer of hot air to the flexible fire-resistant insulation material layer. This fireproof structure, composed of the flexible fire-resistant insulation material layer, the fire-resistant winding covering layer, the mass transfer barrier layer, and the intumescent fireproof sealant layer, exhibits excellent fireproof and heat-insulating effects. The epoxy ester, the intumescent fireproof sealant, and the entire fireproof structure are simple in design and convenient in preparation, offering significant economic and social benefits.

Description

Technical Field

[0001] This invention relates to the field of protection technology for bridge cables, and more specifically to a fireproof structure for bridge cables. Background Technology

[0002] Steel structure bridges have seen rapid development and widespread application in recent years, becoming the leading direction for future bridge construction and development due to their advantages such as rapid manufacturing, modular processing, flexible assembly, convenient construction, and environmental friendliness. With increasing traffic volume, the number of tank trucks carrying hazardous chemicals (flammable, gaseous, explosive, and chemical) is increasing. If these tank trucks catch fire, they release enormous energy and reach extremely high temperatures in a short period, directly damaging bridge structures and causing huge economic losses. Research indicates that the temperature change path of the flame field in a tank truck fire is very similar to that of a hydrocarbon fire, with rapid heating followed by a high-temperature peak combustion period, and the entire combustion process exhibiting an exponential distribution.

[0003] Currently, there are many fireproofing technologies for bridge cables. Patent CN202110492575.X discloses a fireproof coating structure for bridge main cables, a bridge main cable, and a method for manufacturing the bridge main cable. The fireproof coating structure for the bridge main cable is applied to the surface of the cable. The fireproof layer adopts a composite structure of 5-20mm aerogel felt, high-temperature resistant silicone sealant, and aluminum foil tape. Experiments have shown that aerogel felt, high-temperature resistant silicone sealant, and aluminum foil all lose mechanical strength and heat insulation performance in a fire environment of 1100℃, and fail to achieve the effect of fireproofing and heat insulation.

[0004] Patent CN202211191635.5 discloses a bridge cable with an intumescent sealing fireproof composite structure. It uses flexible fire-resistant material and an intumescent flame-retardant sealing strip as the main fireproof layer. The intumescent flame-retardant sealing strip, made by layering high-strength fire-resistant flexible fiber material with intumescent flame-retardant sealant and fire-resistant fiber cloth, forms a synergistic fire-resistant structure. The intumescent flame-retardant fireproof sealing strip is composed of non-combustible high-strength fiber cloth and intumescent flame-retardant sealant. However, while the intumescent flame-retardant fireproof sealing strip can achieve fireproof and heat-insulating requirements, its structure is complex and its cost is high.

[0005] Existing fireproof sealant products are fireproof sealing materials, suitable for fireproof sealing materials or fireproof sealing components used in various through holes and structural joints in buildings, structures and various facilities. However, when applied to bridge cables, they show insufficient adhesion, poor bonding with non-combustible fiber cloth, and are easy to peel off.

[0006] Therefore, how to provide a fireproof structure for bridge cables that is simple in structure, easy to prepare, has good fireproof effect, and is firmly bonded with fireproof sealant is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0007] In view of this, the present invention provides a fireproof structure for bridge cables, aiming to solve the above-mentioned technical problems.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A fireproof structure for bridge cables includes, in sequence from the inside out, a flexible fire-resistant and heat-insulating material layer, a fire-resistant wrapping cloth layer, a mass transfer barrier layer, and an intumescent fireproof sealant layer.

[0010] Preferably, the flexible fire-resistant and heat-insulating material layer is aerogel felt or aluminum silicate cotton; the thickness of the flexible fire-resistant and heat-insulating material layer is 5mm to 30mm.

[0011] Preferably, the refractory wrapping fabric layer is basalt fiber cloth, high silica fiber cloth, or carbon fiber cloth.

[0012] Preferably, the mass transfer barrier layer is a high-temperature resistant sealant layer, a fireproof sealant layer, or a flame-retardant sealant layer; the thickness of the mass transfer barrier layer is 1mm to 3mm.

[0013] Preferably, the thickness of the intumescent fireproof sealant layer is 2mm to 8mm; the intumescent fireproof sealant layer includes a fire-resistant wrapping cloth and an intumescent fireproof sealant coated on the outer surface of the fire-resistant wrapping cloth.

[0014] Preferably, the intumescent fireproof sealant is composed of the following raw materials by weight: 100 parts of acrylate elastic emulsion, 5-8 parts of epoxy ester, 0.1-0.15 parts of initiator, 4 parts of ethylene glycol, 3 parts of emulsifier, 8-10 parts of phosphate ester flame retardant, 54-58 parts of ammonium polyphosphate APP-II, 24-28 parts of melamine, 18-22 parts of pentaerythritol, 15-30 parts of aluminum hydroxide, 3-5 parts of titanate coupling agent, 3-4 parts of iron oxide red, 8-10 parts of expanded graphite, and 5-8 parts of basalt fiber.

[0015] Preferably, the solid content of the acrylate elastic emulsion is 50%.

[0016] This invention provides a method for preparing the intumescent fire-retardant sealant, comprising the following steps:

[0017] S1. Add acrylic elastic emulsion, ethylene glycol, phosphate flame retardant and emulsifier to the reaction vessel according to the ratio, and slowly heat to 60-80℃ with stirring, and keep at this temperature for 30 minutes; then slowly add epoxy ester and initiator, and keep the temperature at 80℃-85℃. After the addition is complete, keep at this temperature for 1 hour; cool and adjust the pH value to 8-9 to obtain epoxy modified acrylic emulsion;

[0018] S2. Add ammonium polyphosphate, melamine, pentaerythritol, aluminum hydroxide, expanded graphite, iron oxide red and basalt fiber to a high-speed mixer. Add titanate coupling agent to the mixer in the form of spray while stirring at high speed. After adding titanate coupling agent, continue stirring at high speed for 5 minutes and then stop to obtain coupling agent coated mixed powder.

[0019] S3. Add the epoxy-modified acrylic emulsion obtained in step S1 to a double planetary vacuum mixer. Gradually add the coupling agent prepared in step S2 to coat the mixed powder under stirring conditions. Then, evacuate and maintain the vacuum degree in the mixer at -0.08 to -0.09 MPa. Continue stirring until the colloid is uniform to obtain the intumescent fireproof sealant.

[0020] Preferably, the epoxy ester is composed of the following raw materials by weight: 50 parts of E-44 epoxy resin, 16 parts of acrylic acid, and 1 part of tetrabutylammonium bromide.

[0021] Preferably, the epoxy ester is prepared by placing epoxy resin and tetrabutylammonium bromide into a reaction vessel equipped with a condenser, a stirrer and a thermometer, stirring and heating to 105℃~110℃, adding acrylic acid dropwise after the solid is completely dissolved, completing the addition within 1 hour, keeping the temperature for 1.5h~2h after the addition is completed, and discharging the material when the acid value is less than 1mgKOH / g to obtain the epoxy ester.

[0022] As can be seen from the above technical solution, compared with the prior art, the present invention discloses a fireproof structure for bridge cables, which has the following beneficial effects:

[0023] The epoxy ester prepared by this invention contains a large number of hydroxyl groups, which significantly improves the bonding force between the fire-retardant sealant and the fire-resistant winding wrapping cloth. This ensures that after the fire-resistant structure of this invention is exposed to fire, a stable and reliable bond is formed between the intumescent fire-retardant sealant layer and the fire-resistant winding wrapping cloth. During fire exposure, no large cracks or even detachment will occur. This ensures that the uniform and dense intumescent layer formed effectively resists and blocks the heat transfer of high-temperature flames. The intumescent fire-retardant sealant prepared by this invention, with its preferred materials and proportions, forms a uniform and dense intumescent layer after being exposed to fire, with reliable expansion and outstanding fire resistance, fire insulation, and heat insulation capabilities.

[0024] The fire-resistant winding and wrapping fabric layer and mass transfer barrier layer designed in this invention form a dense layer composed of inorganic fillers and a silica skeleton at high temperatures, preventing further mass transfer of hot air to the flexible fire-resistant insulation material layer. Thus, the fireproof structure composed of the flexible fire-resistant insulation material layer, the fire-resistant winding and wrapping fabric layer, the mass transfer barrier layer, and the intumescent fireproof sealant layer has excellent fireproof and heat insulation effects. The use of epoxy ester to improve the intumescent fireproof sealant enhances its adhesion. The entire fireproof structure has a simple design and convenient preparation method, and has good economic and social benefits. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0026] Figure 1 The attached figure is a schematic diagram of the overall structure provided by the present invention;

[0027] in,

[0028] 1. Flexible fire-resistant and heat-insulating material layer; 2. Fire-resistant winding wrapping cloth layer; 3. Mass transfer barrier layer; 4. Intumescent fireproof sealant layer; 41. Fire-resistant winding wrapping cloth; 42. Intumescent fireproof sealant. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Example 1:

[0031] See Figure 1 This invention discloses a fireproof structure for bridge cables, comprising, from the inside out, a flexible fire-resistant and heat-insulating material layer 1, a fire-resistant winding and covering cloth layer 2, a mass transfer barrier layer 3, and an intumescent fireproof sealant layer 4.

[0032] After the bridge cable undergoes anti-corrosion and sealing treatment, a flexible fire-resistant and heat-insulating material layer 1 is first wrapped around the cable surface. The flexible fire-resistant and heat-insulating material layer 1 is made of aerogel felt with a thickness of 10mm. Then, a fire-resistant winding wrapping cloth layer 2 is wrapped around it. The fire-resistant winding wrapping cloth layer 2 is made of basalt fiber cloth. Next, a mass transfer barrier layer 3 is applied to the basalt fiber cloth. The mass transfer barrier layer 3 is made of high-temperature resistant silicone sealant with a thickness of 2mm. After the silicone sealant has cured, a fire-resistant winding wrapping cloth 41 is wrapped around it. The fire-resistant winding wrapping cloth 41 is also made of basalt fiber cloth. Then, an intumescent fireproof sealant 42 is applied as an intumescent fireproof sealant layer 4 with a thickness of 2mm. After the intumescent fireproof sealant dries, the outer protective layer is coated.

[0033] The raw material components of the intumescent fireproof sealant 42 are as follows by weight: 100 parts of acrylic ester elastic emulsion, 5 parts of epoxy ester, 0.1 parts of ammonium persulfate initiator, 4 parts of ethylene glycol, 3 parts of emulsifier, 54 parts of ammonium polyphosphate APP-II, 24 parts of melamine, 18 parts of pentaerythritol, 30 parts of aluminum hydroxide, 8 parts of phosphate ester flame retardant, 3 parts of titanate coupling agent, 3 parts of iron oxide red, 10 parts of expanded graphite, and 5 parts of basalt fiber.

[0034] The preparation steps for intumescent fire-retardant sealant are as follows:

[0035] S1. Add the acrylic elastic emulsion, ethylene glycol, phosphate flame retardant and emulsifier to the reactor according to the weight ratio of the formula, and slowly heat to 60-80℃ with stirring, and keep at this temperature for 30 minutes; then slowly add the epoxy ester and initiator, and keep the temperature at 80℃-85℃. After the addition is complete, keep at this temperature for 1 hour; cool and adjust the pH value to 8-9 to obtain the epoxy modified acrylic emulsion;

[0036] S2. Add ammonium polyphosphate, melamine, pentaerythritol, aluminum hydroxide, expanded graphite, iron oxide red and basalt fiber to a high-speed mixer. Add titanate coupling agent to the mixer in the form of spray while stirring at high speed. After adding titanate coupling agent, continue stirring at high speed for 5 minutes and then stop to obtain coupling agent coated mixed powder.

[0037] S3. Add the epoxy-modified acrylic emulsion obtained in step S1 to a double planetary vacuum mixer. Gradually add the coupling agent prepared in step S2 to coat the mixed powder under stirring conditions. Then, evacuate and maintain the vacuum degree in the mixer at -0.08 to -0.09 MPa. Continue stirring until the colloid is uniform to obtain the intumescent fireproof sealant.

[0038] A self-made liquefied gas furnace was used to simulate a hydrocarbon fire. The intumescent fireproof sealant layer expands when exposed to fire, and the expansion layer is uniform and dense with a height of 20mm.

[0039] The preparation method of epoxy ester is as follows: 50 parts of E-44 epoxy resin and 1 part of tetrabutylammonium bromide are put into a reaction vessel equipped with a condenser, stirrer and thermometer, and stirred and heated to 105℃~110℃. After the solid is completely dissolved, 16 parts of acrylic acid are added dropwise over 1 hour. After the addition is completed, the temperature is maintained for 1.5h~2h. The product is discharged when the acid value is less than 1mgKOH / g to obtain epoxy ester.

[0040] Using an electronic universal testing machine, the adhesion failure performance between the above-mentioned intumescent sealant layer and the mass transfer barrier layer was tested according to the method for testing the peel adhesion of building sealant. After the peel test, it was found that a large amount of intumescent fireproof sealant was clearly and firmly attached to the surface of basalt fiber, with a peel strength of 4.8 N / mm. In contrast, the fireproof structure prepared using commercially available fireproof sealing material and fireproof sealant showed more complete peeling between basalt fiber and fireproof sealant after the peel test, with very little sealant adhering to the basalt fiber cloth, and a peel strength of 0.9 N / mm.

[0041] A self-made liquefied gas furnace was used to simulate a hydrocarbon fire. The fire resistance test endpoint was set at 300°C for the surface temperature of the simulated cable wire bundle. The fire-resistant structure of this embodiment was tested. The results showed that the steel substrate reached 300°C in 62 minutes. The intumescent fireproof sealant layer expanded after being exposed to fire. The expansion layer was uniform and dense, and the height of the expansion layer was 20mm.

[0042] Example 2:

[0043] The fireproof structure of the bridge cable includes, from the inside out, a flexible fire-resistant and heat-insulating material layer 1, a fire-resistant winding and covering cloth layer 2, a mass transfer barrier layer 3, and an intumescent fireproof sealant layer 4.

[0044] After the bridge cable undergoes anti-corrosion and sealing treatment, a flexible fire-resistant and heat-insulating material layer 1 is first wrapped around the cable surface. The flexible fire-resistant and heat-insulating material layer 1 is made of aerogel felt with a thickness of 20mm. Then, two layers of basalt fiber cloth are wrapped around it as a fire-resistant winding wrapping cloth layer 2. Next, a mass transfer barrier layer 3 is applied to the basalt fiber cloth. The mass transfer barrier layer 3 is made of elastic fire-resistant sealant with a thickness of 3mm. After the elastic fire-resistant sealant has cured, a layer of fire-resistant winding wrapping cloth 41 is wrapped around it. The fire-resistant winding wrapping cloth 41 is made of high-silica fiber cloth. Then, an intumescent fire-resistant sealant 42 is applied as an intumescent fire-resistant sealant layer 4 with a thickness of 3mm. After the intumescent fire-resistant sealant dries, the outer protective layer is coated.

[0045] The raw material components of the intumescent fireproof sealant are as follows by weight: 100 parts of acrylic ester elastic emulsion, 8 parts of epoxy ester, 0.15 parts of ammonium persulfate initiator, 4 parts of ethylene glycol, 3 parts of emulsifier, 56 parts of ammonium polyphosphate APP-II, 26 parts of melamine, 20 parts of pentaerythritol, 20 parts of aluminum hydroxide, 7 parts of phosphate ester flame retardant, 4 parts of titanate coupling agent, 3 parts of iron oxide red, 9 parts of expanded graphite, and 7 parts of basalt fiber.

[0046] The preparation steps for the intumescent fire-retardant sealant are the same as in Example 1.

[0047] Using an electronic universal testing machine, the adhesion failure performance between the above-mentioned expanding sealant layer and the mass transfer barrier layer was tested according to the method for testing the peel adhesion of building sealant. After the peel test, it was found that a large amount of fireproof sealant was clearly and firmly attached to the surface of the basalt fiber, with a peel strength of 5.5 N / mm.

[0048] A self-made liquefied gas furnace was used to simulate a hydrocarbon fire. The fire resistance test endpoint was set at 300°C for the simulated cable wire bundle. The fire-resistant structure of this embodiment was tested. The results showed that the steel substrate reached 300°C for more than 180 minutes. The fireproof sealant layer expanded after being exposed to fire. The expanded layer was uniform and dense, and the expansion height exceeded 36mm.

[0049] Example 3:

[0050] The fireproof structure of the bridge cable includes, from the inside out, a flexible fire-resistant and heat-insulating material layer 1, a fire-resistant winding and covering cloth layer 2, a mass transfer barrier layer 3, and an intumescent fireproof sealant layer 4.

[0051] After the bridge cable undergoes anti-corrosion and sealing treatment, the fireproof structure of this invention is constructed. First, a flexible fire-resistant and heat-insulating material layer 1 is wrapped around the cable surface. The flexible fire-resistant and heat-insulating material layer 1 is made of aluminum silicate cotton felt with a thickness of 30mm. Then, a fire-resistant winding wrapping cloth layer 2 is wrapped around it. The fire-resistant winding wrapping cloth layer 2 consists of two layers of basalt fiber cloth. Next, a mass transfer barrier layer 3 is applied to the basalt fiber cloth. The mass transfer barrier layer 3 is made of high-temperature resistant silicone sealant with a thickness of 2mm. After the silicone sealant has cured, a layer of fire-resistant winding wrapping cloth 41 is wrapped around it. The fire-resistant winding wrapping cloth 41 is also made of basalt fiber cloth. Then, an intumescent fireproof sealant 42 is applied as an intumescent fireproof sealant layer 4 with a thickness of 2mm. After the fireproof sealant dries, the outer protective layer is coated.

[0052] The raw material components of the intumescent fireproof sealant are as follows by weight: 100 parts of acrylic elastic emulsion, 6 parts of epoxy ester, 0.11 parts of ammonium persulfate initiator, 4 parts of ethylene glycol, 3 parts of emulsifier, 58 parts of ammonium polyphosphate APP-II, 28 parts of melamine, 22 parts of pentaerythritol, 15 parts of aluminum hydroxide, 10 parts of phosphate ester flame retardant, 5 parts of titanate coupling agent, 3 parts of iron oxide red, 8 parts of expanded graphite, and 8 parts of basalt fiber.

[0053] The preparation steps for the intumescent fire-retardant sealant are the same as in Example 1.

[0054] Using an electronic universal testing machine, the adhesion failure performance between the above-mentioned expanding sealant layer and the mass transfer barrier layer was tested according to the method for testing the peel adhesion of building sealant. After the peel test, it was found that a large amount of fireproof sealant was clearly and firmly attached to the surface of the basalt fiber, with a peel strength of 5.0 N / mm.

[0055] A self-made liquefied gas furnace was used to simulate a hydrocarbon fire. The fire resistance test endpoint was set at 300°C for the simulated cable wire bundle. The fire-resistant structure of this embodiment was tested. The results showed that the steel substrate reached 300°C in 174 minutes. The fireproof sealant layer expanded after being exposed to fire. The expanded layer was uniform and dense, with an expansion height of 22 mm.

[0056] Comparative Example 1:

[0057] After the bridge cables undergo anti-corrosion and sealing treatment, the existing fireproof structure is constructed. First, a 10mm thick aerogel felt is wrapped around the cable surface. Then, two layers of basalt fiber cloth are wrapped around it. Next, a 2mm thick intumescent fireproof sealant is applied to the basalt fiber cloth. After the fireproof sealant has cured and dried, another layer of basalt fiber cloth is wrapped around it. Then, another 2mm thick intumescent fireproof sealant is applied. After the fireproof sealant has cured and dried, another layer of basalt fiber cloth is wrapped around it. Then, another 2mm thick intumescent fireproof sealant is applied. The basalt cloth and fireproof sealant are overlapped to form a three-cloth, three-sealant configuration. After the fireproof sealant dries, the outer protective layer is coated.

[0058] Using an electronic universal testing machine, the adhesion failure performance between the above-mentioned intumescent sealant layer and the mass transfer barrier layer was tested according to the method for testing the peel adhesion of building sealant. After the peel test, it was found that a large amount of intumescent fireproof sealant was clearly and firmly attached to the surface of the basalt fiber, and the peel strength was 0.9 N / mm.

[0059] The self-made liquefied gas furnace was used to simulate a hydrocarbon fire. The fire resistance test endpoint was set at 300°C for the simulated cable wire bundle. The fire resistance time of the fire-resistant structure in Comparative Example 1 was tested. The results showed that the steel substrate reached 300°C in 54 minutes. The fireproof sealant layer expanded after being exposed to fire. The expansion layer was uniform and dense, with an expansion height of 22 mm. There was some peeling between the outer expansion layer and the underlying basalt cloth.

[0060] Comparative Example 2

[0061] After the bridge cables undergo anti-corrosion and sealing treatment, the existing fireproof structure is constructed. First, a 20mm thick aerogel felt is wrapped around the cable surface. Then, two layers of basalt fiber cloth are wrapped around it. Next, a 2mm thick intumescent fireproof sealant is applied to the basalt fiber cloth. After the fireproof sealant has cured and dried, another layer of basalt fiber cloth is wrapped around it. Then, another 2mm thick intumescent fireproof sealant is applied. After the intumescent fireproof sealant has cured and dried, another layer of basalt fiber cloth is wrapped around it. Then, another 2mm thick intumescent fireproof sealant is applied. The basalt cloth and fireproof sealant are overlapped to form a three-cloth, three-sealant configuration. After the fireproof sealant dries, the outer protective layer is coated.

[0062] Using an electronic universal testing machine, the adhesion failure performance between the above-mentioned intumescent sealant layer and the mass transfer barrier layer was tested according to the method for testing the peel adhesion of building sealant. After the peel test, it was found that a large amount of intumescent fireproof sealant was clearly and firmly attached to the surface of the basalt fiber, and the peel strength was 1.5 N / mm.

[0063] Using the self-made liquefied gas furnace to simulate a hydrocarbon fire, the fire resistance test endpoint was set at 300°C for the simulated cable wire bundle. The fire resistance time of the fire-resistant structure in Comparative Example 2 was tested. The results showed that the steel substrate reached 300°C in 166 minutes. The fireproof sealant layer expanded after exposure to fire, and the expanded layer was uniform and dense with an expansion height of 23 mm. There was some peeling between the outer expanded layer and its underlying basalt cloth.

[0064] Comparative Example 3

[0065] After the bridge cables undergo anti-corrosion and sealing treatment, the existing fireproof structure is constructed. First, aluminum silicate cotton felt with a thickness of 30mm is wrapped around the cable surface. Then, two layers of basalt fiber cloth are wrapped around it. Next, a 2mm thick intumescent fireproof sealant is applied to the basalt fiber cloth. After the fireproof sealant has cured and dried, a layer of basalt fiber cloth is wrapped around it, followed by another 2mm thick layer of intumescent fireproof sealant. After the fireproof sealant has cured and dried, a layer of basalt fiber cloth is wrapped around it, followed by another 2mm thick layer of intumescent fireproof sealant. The basalt cloth and fireproof sealant are overlapped to form a three-cloth, three-sealant configuration. After the fireproof sealant dries, the outer protective layer is coated.

[0066] Using an electronic universal testing machine, the adhesion failure performance between the above-mentioned intumescent sealant layer and the mass transfer barrier layer was tested according to the method for testing the peel adhesion of building sealant. After the peel test, it was found that a large amount of intumescent fireproof sealant was clearly and firmly attached to the surface of the basalt fiber, and the peel strength was 1.0 N / mm.

[0067] Using the self-made liquefied gas furnace to simulate a hydrocarbon fire, the fire resistance test endpoint was set at 300°C for the simulated cable wire bundle. The fire resistance time of the fire-resistant structure in Comparative Example 3 was tested. The results showed that the steel substrate reached 300°C in 169 minutes. The fireproof sealant layer expanded after exposure to fire, and the expanded layer was uniform and dense with an expansion height of 21 mm. There was some peeling between the outer expanded layer and its underlying basalt cloth.

[0068] The fire resistance properties of the examples and comparative examples are shown in Table 1.

[0069] Table 1

[0070]

[0071] As can be seen from the comparative expansion layers, the outer layer of fire-resistant sealant expands to a height of about 18mm, while the fire-resistant sealant expansion layer wrapped in basalt cloth is constrained by the basalt cloth and cannot expand fully, or even expand at all. When exposed to fire, the foaming gas generated can be released through the basalt cloth. As a result, the internal structure where the basalt cloth and fire-resistant sealant overlap cannot provide good heat insulation. It is also easy for heat to enter the internal aerogel felt layer through the porous sealant layer, reducing the fire resistance effect.

[0072] As can be seen from the peel strength performance changes in the examples and comparative examples, the peel strength between the epoxy ester modified intumescent fireproof sealant and the basalt fiber cloth is significantly improved compared with the prior art; in the case of the intumescent fireproof sealant without the present invention, there is peeling between the outermost layer and the bottom basalt cloth layer, which reduces the fireproof effect.

[0073] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0074] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A fireproof structure for bridge cables, characterized in that, It includes a flexible fire-resistant and heat-insulating material layer, a fire-resistant wrapping cloth layer, a mass transfer barrier layer, and an intumescent fireproof sealant layer, which are formed sequentially from the inside out. The intumescent fireproof sealant layer includes a fire-resistant wrapping cloth and an intumescent fireproof sealant coated on the outer surface of the fire-resistant wrapping cloth. The flexible fire-resistant and heat-insulating material layer is aerogel felt or aluminum silicate cotton; the thickness of the flexible fire-resistant and heat-insulating material layer is 5mm to 30mm. The fire-resistant winding and covering fabric layer is basalt fiber cloth, high silica fiber cloth or carbon fiber cloth. The mass transfer barrier layer is a high-temperature resistant sealant layer, a fireproof sealant layer, or a flame-retardant sealant layer; the thickness of the mass transfer barrier layer is 1mm to 3mm. The thickness of the intumescent fireproof sealant layer is 2mm to 8mm; The intumescent fireproof sealant is composed of the following raw materials by weight: 100 parts acrylate elastic emulsion, 5-8 parts epoxy ester, 0.1-0.15 parts initiator, 4 parts ethylene glycol, 3 parts emulsifier, 8-10 parts phosphate ester flame retardant, 54-58 parts ammonium polyphosphate APP-II, 24-28 parts melamine, 18-22 parts pentaerythritol, 15-30 parts aluminum hydroxide, 3-5 parts titanate coupling agent, 3-4 parts iron oxide red, 8-10 parts expanded graphite, and 5-8 parts basalt fiber. The preparation method of the intumescent fire-retardant sealant includes the following steps: S1. Add acrylic elastic emulsion, ethylene glycol, phosphate flame retardant and emulsifier to the reaction vessel according to the ratio, and slowly heat to 60-80℃ with stirring, and keep at this temperature for 30 minutes; then slowly add epoxy ester and initiator, and keep the temperature at 80℃-85℃. After the addition is complete, keep at this temperature for 1 hour; cool and adjust the pH value to 8-9 to obtain epoxy modified acrylic emulsion; S2. Add ammonium polyphosphate, melamine, pentaerythritol, aluminum hydroxide, expanded graphite, iron oxide red and basalt fiber to a high-speed mixer. Add titanate coupling agent to the mixer in the form of spray while stirring at high speed. After adding titanate coupling agent, continue stirring at high speed for 5 minutes and then stop to obtain coupling agent coated mixed powder. S3. Add the epoxy-modified acrylic emulsion obtained in step S1 to a double planetary vacuum mixer. Gradually add the coupling agent prepared in step S2 to coat the mixed powder under stirring conditions. Then, evacuate and maintain the vacuum degree in the mixer at -0.08 to -0.09 MPa. Continue stirring until the colloid is uniform to obtain the intumescent fireproof sealant. The solid content of the acrylate elastic emulsion is 50%; The epoxy ester is composed of the following raw materials by weight: 50 parts of E-44 epoxy resin, 16 parts of acrylic acid, and 1 part of tetrabutylammonium bromide. The epoxy ester is prepared by placing epoxy resin and tetrabutylammonium bromide into a reaction vessel equipped with a condenser, stirrer and thermometer, stirring and heating to 105℃~110℃, adding acrylic acid dropwise after the solid is completely dissolved, and keeping the temperature for 1.5h~2h after the addition is complete. The epoxy ester is then discharged when the acid value is less than 1mgKOH / g.

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