A flame-retardant concrete and its preparation method

Abstract

This application relates to the field of concrete, and specifically discloses a flame-retardant concrete and its preparation method. A flame-retardant concrete is made from the following raw materials in parts by weight: cement, fly ash, silica fume, crushed stone, sand, water, water reducer, filling fiber, and flame-retardant filler; the flame-retardant filler consists of aluminum hydroxide, antimony trioxide, and coated ammonium polyphosphate; its preparation method is as follows: The cement is mixed evenly with aluminum hydroxide and antimony trioxide, and 1 / 12 - 1 / 10 of the total amount of water is sprayed to obtain a cement mixture; the fly ash and silica fume are mixed evenly to obtain a powder; the crushed stone and sand are mixed evenly to obtain an aggregate; the filling fiber and coated ammonium polyphosphate are mixed evenly to obtain a filler; the cement mixture and the powder are mixed evenly, the aggregate and the filler are mixed evenly, and then the remaining water and water reducer are added and mixed evenly to obtain a mixture; the mixture is poured and cured to obtain a finished product; reducing the impact of fire high temperature on the strength of concrete and prolonging the safe evacuation time of high-rise residents.

Description

Technical Field

[0001] This application relates to the field of concrete, and more specifically, it relates to a flame-retardant concrete and a preparation method thereof. Background Art

[0002] Concrete can be used not only for building houses and buildings, but also for building bridges and so on.

[0003] In places such as residential buildings and commercial buildings, fires often occur due to the use of electrical circuits and household appliances. Once a fire breaks out, the fire will gradually spread to the middle and upper floors, and the residents on the middle and upper floors are easily trapped on their floors. As the temperature of the fire rises continuously, the building concrete gradually loses water and cracks appear, resulting in a gradual decrease in strength. While the pressure on the building from the high-rise residents still exists when they have not been evacuated, and the reduction of the concrete strength leads to the easy collapse of high-rise buildings, which not only threatens the lives and property safety of high-rise residents, but also has a threatening impact on the adjacent floors.

[0004] Therefore, how to prepare a flame-retardant concrete for application in high-rise residential buildings and commercial buildings, which has good flame retardancy, can reduce the impact of fire high temperature on the concrete strength after a fire, and extend the safe evacuation time of high-rise residents. Summary of the Invention

[0005] In order to prepare a flame-retardant concrete for application in high-rise residential buildings and commercial buildings, which has good flame retardancy, can reduce the impact of fire high temperature on the concrete strength after a fire, and extend the safe evacuation time of high-rise residents, this application provides a flame-retardant concrete and a preparation method thereof.

[0006] In the first aspect, this application provides a flame-retardant concrete, adopting the following technical solution:

[0007] A flame-retardant concrete is made from the following raw materials in parts by weight: 200-250 parts of cement, 40-60 parts of fly ash, 35-55 parts of silica fume, 850-1000 parts of crushed stone, 700-900 parts of sand, 150-160 parts of water, 4.5-6.0 parts of water reducer, 10-18 parts of filling fiber, 24-40 parts of flame-retardant filler; the flame-retardant filler is composed of aluminum hydroxide, antimony trioxide and coated ammonium polyphosphate with a weight ratio of 1:1-2:1-2.

[0008] By adopting the above technical solution, the flame-retardant filler and the filling fiber cooperate. On the one hand, by improving the density of the concrete structure, the strength of the concrete is improved, thereby reducing the impact of fire high temperature on the concrete strength and extending the safe evacuation time of high-rise personnel; on the other hand, through the flame-retardant effect of the cooperation of aluminum hydroxide, antimony trioxide and coated ammonium polyphosphate, the flame-retardant effect of the concrete is further improved, the impact of fire high temperature on the concrete strength is reduced, and the safe evacuation time of high-rise residents is extended.

[0009] Aluminum hydroxide, antimony trioxide and coated ammonium polyphosphate are combined. Aluminum hydroxide uses its endothermic effect to cooperate with the crystal water released at high temperature to provide flame retardancy. At the same time, the crystal water can also prevent the concrete from losing water and causing cracks, affecting the strength of the concrete. Antimony trioxide can form a glass layer to cover and achieve an insulating and flame retardant effect. After covering, the coated cementitious material in the concrete is not easy to lose water and crack. In addition, the coated ammonium polyphosphate does not react with the water in the mixing material during the mixing process. As the temperature rises during the fire, the film layer gradually melts and decomposes, and the ammonium polyphosphate is released. The ammonium polyphosphate is easy to expand after being heated, and the expansion The expanded volume can fill the cracks caused by water loss in the cementitious material, maintain the mechanical strength of the concrete for a certain period of time, and ensure the evacuation of high-rise residents. In addition, the non-volatile phosphorus oxides and polyphosphoric acid cover the surface of the substrate, and achieve the purpose of flame retardancy by isolating the air. At the same time, ammonium polyphosphate can promote the dehydration and carbonization of organic matter, further playing a flame retardant role. As it decomposes under heat, it releases nitrogen and ammonia, which dilutes the oxygen and cuts off the oxygen supply, thereby improving the flame retardant effect. Therefore, by reducing the impact of fire on concrete strength and combining with a good flame retardant effect, the safe evacuation time of high-rise residents can be extended.

[0010] Preferably, the flame retardant concrete also includes 2-8 parts of coated macroporous silica particles.

[0011] By adopting the above technical scheme, coated macroporous silica gel particles, flame retardant fillers and filling fibers are matched, and the coating effect of the coated macroporous silica gel particles and coated ammonium polyphosphate is utilized to prevent the macroporous silica gel particles and ammonium polyphosphate from reacting with water in the mixture, and the filling effect of the filler and the network connection effect of the fiber are coordinated to ensure that the concrete has high mechanical strength after hydration; when a fire occurs, the coating on the surface of the coated macroporous silica gel particles and ammonium polyphosphate gradually melts and decomposes, and when the firefighters spray water with water guns, the water absorption of the macroporous silica gel particles and the hydrophilicity of ammonium polyphosphate can be utilized to quickly absorb water and cool down, thereby achieving a flame retardant effect, and trying to avoid the fire causing rapid water loss of concrete cementitious materials to affect the strength of the concrete structure, thereby extending the safe evacuation time of high-rise residents.

[0012] Preferably, the coated macroporous silica gel particles are prepared by coating macroporous silica gel particles with a polyurethane resin melt and then bonding them with aramid fiber chopped strands.

[0013] By adopting the above technical solution, the macroporous silica gel particles, polyurethane resin, and short aramid fiber filaments are combined. In building concrete, by utilizing the water-blocking effect of the polyurethane resin film, it is possible to prevent the macroporous silica gel particles from absorbing the water in the concrete mixture, ensuring that the concrete has high mechanical strength after hydration; and by utilizing the bonding effect of the molten polyurethane resin, the short aramid fiber filaments can be bonded to the surface of the macroporous silica gel particles. By utilizing the high mechanical strength of the short aramid fiber filaments, the strength of the coated silica gel particles can be increased. When used as a filler material in concrete, it can improve the mechanical strength of the concrete; at the same time, the amino groups in the polyurethane resin are convenient for attracting and bonding with the cementitious materials in the concrete, thereby further improving the density of the internal structure of the concrete, making the concrete have high mechanical strength in construction.

[0014] The macroporous silica gel particles, polyurethane resin, and short aramid fiber filaments are combined. When a fire occurs, the melting point of the polyurethane resin is about 180°C. First, the polyurethane resin film melts, and its bonding effect can bond the internal structure of the concrete, ensuring the bonding stability of the internal structure of the concrete, thereby ensuring the mechanical strength of the concrete; as the fire temperature rises, the polyurethane resin and the short aramid fiber filaments carbonize, achieving a flame-retardant effect; and when firefighters spray water to extinguish the fire, the macroporous silica gel particles utilize their good water absorption to easily adsorb water and cool down, thereby further improving the flame-retardant effect of the concrete.

[0015] Utilizing the high mechanical strength of the concrete after pouring can provide space for reducing the fire intensity, enabling the concrete to still have a good supporting effect even when its strength decreases, providing support for the residents on the middle and top floors; and the raw materials in the concrete have a flame-retardant effect, which can prevent the fire while ensuring the strength of the concrete, thereby ensuring that the residents on the middle and top floors are not easily affected by the collapse of the concrete due to the fire and endangering their lives.

[0016] Preferably, the coated ammonium polyphosphate is prepared by coating ammonium polyphosphate particles with polyurethane resin.

[0017] By adopting the above technical solution, by utilizing the water-blocking property of the molten polyurethane resin film after film formation, it is ensured that the ammonium polyphosphate does not react with the water in the mixture, but plays a flame-retardant role after a fire occurs.

[0018] Preferably, the filler fiber is composed of basalt fiber and hydrophobic seaweed fiber with a weight ratio of 1:0.5 - 1.

[0019] By adopting the above technical solution, basalt fiber and hydrophobic seaweed fiber are combined. The rigidity of basalt fiber is combined with the flexibility of hydrophobic seaweed fiber, which is convenient for forming a network connection structure, improving the density of the internal structure of concrete and at the same time enhancing the mechanical strength of concrete; after a fire occurs, the hydrophobic seaweed fiber can be carbonized, and the carbon layer adheres to the surface of the basalt fiber and the cementitious material in contact with the filler fiber, ensuring the bonding effect between the basalt fiber and the cementitious material, thereby ensuring the mechanical strength of the concrete.

[0020] Preferably, the hydrophobic seaweed fiber is prepared by soaking seaweed fiber in a silane coupling agent KH-570, then uniformly spraying a molten polyurethane resin solution on the surface and then uniformly spraying carbon nitride particles. The weight ratio of seaweed fiber, molten polyurethane resin solution, and carbon nitride particles is 1:0.1 - 0.3:0.1 - 0.4.

[0021] By adopting the above technical solution, seaweed fiber, silane coupling agent KH-570, molten polyurethane resin solution, and carbon nitride particles are combined. Utilizing the hydrophobicity of the silane coupling agent KH-570, the seaweed fiber has hydrophobicity and is not easy to absorb the moisture in the mixing material. Utilizing the viscosity of the molten polyurethane resin solution, the carbon nitride particles are bonded to the surface of the seaweed fiber. Utilizing the strength of the carbon nitride particles, the mechanical strength of the seaweed fiber can be improved, so that the concrete has a relatively high mechanical strength.

[0022] When a fire occurs, first, the polyurethane resin film softens and melts to absorb heat. As the temperature rises, the carbon nitride particles melt and absorb heat, and the polyurethane resin film decomposes and absorbs heat. Moreover, carbon nitride, polyurethane resin, and seaweed fiber can all achieve a flame retardant effect through their own carbonization; by virtue of their relatively high strength and good flame retardancy, the safe evacuation time of high-rise residents can be extended.

[0023] Preferably, the surfaces of aluminum hydroxide and antimony trioxide are modified by a sodium alginate solution.

[0024] By adopting the above technical solution, aluminum hydroxide and antimony trioxide are coated with a sodium alginate solution, so that the surfaces of aluminum hydroxide and antimony trioxide contain carboxyl groups in sodium alginate. Utilizing the carboxyl groups in sodium alginate to improve the bonding effect between aluminum hydroxide and antimony trioxide and the cementitious material, thereby improving the density of the internal structure of concrete, making the concrete have relatively high strength, and reducing the impact of fire on the strength of concrete.

[0025] In a second aspect, the present application provides a preparation method of flame-retardant concrete, adopting the following technical solution:

[0026] A preparation method of flame-retardant concrete includes the following steps:

[0027] S1. Weigh cement, aluminum hydroxide, and antimony trioxide, mix and stir them evenly, and then evenly spray 1 / 12 - 1 / 10 of the total amount of water to obtain a cement mixture.

[0028] S2. Weigh fly ash and silica fume, mix and stir them evenly to obtain a powder material.

[0029] S3. Weigh crushed stone and sand, mix and stir them evenly to obtain an aggregate.

[0030] S4. Weigh filling fibers and coated ammonium polyphosphate, mix and stir them evenly to obtain a filling material.

[0031] S5. Weigh the cement mixture and the powder material, mix and stir them evenly, and evenly mix the aggregate and the filling material. After mixing, add the remaining water and water reducing agent, and mix and stir evenly to obtain a mixing material.

[0032] S6. The mixing material is cast and cured to obtain a flame - retardant concrete.

[0033] By adopting the above - mentioned technical solution, after the cement, aluminum hydroxide, and antimony trioxide are mixed, it is convenient for the cement - formed cementitious material to bond with aluminum hydroxide and antimony trioxide. Cooperating with other filler substances, the compactness of the internal structure of the concrete is improved. And the filling fibers cooperate with the coated ammonium polyphosphate. Utilizing the connection effect of the filling fibers and the coated ammonium polyphosphate in the concrete, when the algal fibers and ammonium polyphosphate in the filling fibers are carbonized, the formed carbon layer is easily attached to the surfaces of basalt fibers, cementitious materials, crushed stones, sands and other raw materials, thereby utilizing their flame - retardant effects to prevent the internal structure of the concrete from generating cracks due to the high temperature of the fire as much as possible. After a fire occurs, the middle - and high - rise residents are not easily in danger of concrete collapse due to the loss of strength of the bottom floors, thus providing a longer rescue time for the middle - and high - rise residents.

[0034] Preferably, in S3, a sodium carboxymethylcellulose solution is evenly sprayed on the surface of the crushed stone, and the weight ratio of the crushed stone to the sodium carboxymethylcellulose solution is 100:0.2 - 1. Then, coated macroporous silica gel particles are added. After mixing evenly, it is dried and then mixed and stirred evenly with sand to obtain an aggregate.

[0035] By adopting the above - mentioned technical solution, after the crushed stone is treated with the sodium carboxymethylcellulose solution, sodium carboxymethylcellulose adheres to the surface of the crushed stone. Utilizing the carboxyl groups in the sodium carboxymethylcellulose to cooperate with the cementitious material, filling fibers, and flame - retardant fillers, the compactness of the internal structure of the concrete is further improved, thereby improving the mechanical strength of the concrete. When a fire occurs, the sodium carboxymethylcellulose solution not only absorbs moisture but also can be carbonized, thereby improving the flame - retardant effect of the concrete and extending the rescue time for the middle - and high - rise residents.

[0036] Preferably, the coated macroporous silica gel particles are prepared by the following method:

[0037] The polyurethane melt is evenly sprayed on the surface of the macroporous silica gel particles, and then the aramid fiber chopped strands are evenly sprayed. After drying, the macroporous silica gel particles are obtained; the polyurethane melt forms a polyurethane film with a thickness of 0.2-1mm, and the weight ratio of the macroporous silica gel particles to the aramid fiber chopped strands is 1:0.5-1.2.

[0038] By adopting the above technical scheme, the viscosity of the polyurethane melt can be used to bond the chopped aramid fibers to the surface of the macroporous silica gel particles, which can not only improve the strength of the macroporous silica gel particles, but also improve the flame retardant effect after a fire occurs by utilizing the heat and water absorption of the macroporous silica gel particles in combination with the carbonization effect of the polyurethane.

[0039] In summary, this application has the following beneficial effects:

[0040] 1. Aluminum hydroxide, antimony trioxide, coated ammonium polyphosphate and filling fiber are combined to improve the mechanical strength of concrete and reduce the impact of fire on the strength of concrete. Combined with the good flame retardancy of concrete, the impact of fire on the strength of concrete is further reduced, so that when residents in middle and high-rise buildings are trapped in middle and high-rise buildings, the concrete still has a good supporting effect and is not prone to collapse, thereby extending the safe evacuation time of high-rise residents.

[0041] 2. The combination of coated macroporous silica particles, flame retardant fillers and filling fibers gives the concrete a high mechanical strength. When a fire occurs, the coated macroporous silica particles and the coating on the surface of ammonium polyphosphate gradually melt and decompose. When the firefighters spray water with water guns, the water absorption of the macroporous silica particles and the hydrophilicity of ammonium polyphosphate can quickly absorb water and cool down, thereby achieving a flame retardant effect and avoiding the fire as much as possible to cause rapid water loss of concrete cementitious materials and affect the strength of the concrete structure, thereby extending the safe evacuation time of high-rise residents.

[0042] 3. Basalt fiber, seaweed fiber, silane coupling agent KH-570, polyurethane resin melt, and carbon nitride particles are combined. When a fire occurs, the polyurethane resin film softens and melts to absorb heat. As the temperature rises, the carbon nitride particles melt and absorb heat, and the polyurethane resin film decomposes and absorbs heat. In addition, carbon nitride, polyurethane resin, and seaweed fiber can achieve flame retardant effects through self-carbonization. The higher strength and better flame retardancy are used to extend the safe evacuation time of high-rise residents. DETAILED DESCRIPTION

[0043] The present application is further described in detail below in conjunction with embodiments.

[0044] Preparation Example of Aluminum Hydroxide

[0045] Preparation Example 1: Aluminum hydroxide is prepared by the following method:

[0046] Weigh commercially available aluminum hydroxide particles and disperse and stir them in a sodium alginate solution. Filter out the aluminum hydroxide particles and dry them to obtain the finished aluminum hydroxide. The particle size of the aluminum hydroxide particles is 18 mesh, and the sodium alginate solution is an aqueous sodium alginate solution with a concentration of 1%.

[0047] Preparation Example of Antimony Trioxide

[0048] Preparation Example 2: Antimony trioxide is prepared by the following method:

[0049] Weigh commercially available antimony trioxide particles and disperse and stir them in a sodium alginate solution. Filter out the antimony trioxide particles and dry them to obtain the finished antimony trioxide. The particle size of the antimony trioxide particles is 18 mesh, and the sodium alginate solution is an aqueous sodium alginate solution with a concentration of 1%.

[0050] Preparation Example of Coated Ammonium Polyphosphate

[0051] Preparation Example 3: Coated ammonium polyphosphate is prepared by the following method:

[0052] Heat the polyurethane resin until it is completely melted to obtain a molten polyurethane resin solution;

[0053] Spray the molten polyurethane resin solution evenly on the surface of ammonium polyphosphate, dry and disperse it to obtain coated ammonium polyphosphate. A polyurethane resin film is formed on the surface of ammonium polyphosphate. The thickness of the polyurethane resin film is 0.5 mm, and the particle size of the coated ammonium polyphosphate is 14 mesh.

[0054] Preparation Example of Coated Macroporous Silica Particles

[0055] Preparation Example 4: Coated macroporous silica particles are prepared by the following method:

[0056] Heat the polyurethane resin to 180 °C until it is completely melted to obtain a molten polyurethane solution;

[0057] Spray the molten polyurethane solution evenly on the surface of the macroporous silica particles, and then evenly spray short cut aramid fibers. After drying, coated macroporous silica particles are obtained. The particle size of the macroporous silica particles is 2 mm, the particle size of the short cut aramid fibers is 0.5 mm, the molten polyurethane solution forms a polyurethane film, the thickness of the polyurethane film is 0.5 mm, and the weight ratio of the macroporous silica particles to the short cut aramid fibers is 1:0.8.

[0058] Preparation Example 5: The difference between this preparation example and Preparation Example 4 is that:

[0059] The particle size of the macroporous silica particles is 2 mm, the particle size of the short cut aramid fibers is 0.5 mm, the molten polyurethane solution forms a polyurethane film, the thickness of the polyurethane film is 0.2 mm, and the weight ratio of the macroporous silica particles to the short cut aramid fibers is 1:0.5.

[0060] Preparation Example 6: The difference between this preparation example and Preparation Example 4 is as follows:

[0061] The particle size of the macroporous silica particles is 2 mm, the particle size of the short cut aramid fibers is 0.5 mm, the polyurethane molten liquid forms a polyurethane film with a thickness of 1 mm, and the weight ratio of the macroporous silica particles to the short cut aramid fibers is 1:1.2.

[0062] Preparation Example of Hydrophobic Seaweed Fiber

[0063] Preparation Example 7: The hydrophobic seaweed fiber is prepared by the following method:

[0064] Ⅰ Weigh 1 kg of seaweed fiber, soak and disperse it in 5 kg of silane coupling agent KH-570, then take out the seaweed fiber and dry it to obtain modified seaweed fiber; the length of the seaweed fiber is 4 mm;

[0065] Ⅱ Uniformly spray 0.2 kg of polyurethane resin molten liquid on the surface of the modified seaweed fiber, and then uniformly spray 0.25 kg of carbon nitride particles, and dry it to obtain the finished hydrophobic seaweed fiber; the polyurethane resin molten liquid is obtained by heating polyurethane resin to 180 °C for hot melting; the particle size of the carbon nitride particles is 40 mesh.

[0066] Preparation Example 8: The difference between this preparation example and Preparation Example 7 is as follows:

[0067] Ⅱ Uniformly spray 0.1 kg of polyurethane resin molten liquid on the surface of 1 kg of modified seaweed fiber, and then uniformly spray 0.1 kg of carbon nitride particles, and dry it to obtain the finished hydrophobic seaweed fiber.

[0068] Preparation Example 9: The difference between this preparation example and Preparation Example 7 is as follows:

[0069] Ⅱ Uniformly spray 0.3 kg of polyurethane resin molten liquid on the surface of 1 kg of modified seaweed fiber, and then uniformly spray 0.4 kg of carbon nitride particles, and dry it to obtain the finished hydrophobic seaweed fiber.

[0070] Preparation Example of Filled Fiber

[0071] Preparation Example 10: The filled fiber is prepared by the following method:

[0072] Weigh 1 kg of basalt fiber and mix it with 0.7 kg of hydrophobic seaweed fiber and stir evenly to obtain the filled fiber; the length of the basalt fiber is 3 mm, and the hydrophobic seaweed fiber is the hydrophobic seaweed fiber prepared in Preparation Example 7.

[0073] Preparation Example 11: The filled fiber is prepared by the following method:

[0074] Weigh 1 kg of basalt fiber and 0.5 kg of hydrophobic seaweed fiber, mix and stir them evenly to obtain the filling fiber. The length of the basalt fiber is 3 mm, and the hydrophobic seaweed fiber is the hydrophobic seaweed fiber prepared in Preparation Example 8.

[0075] Preparation Example 12: The filling fiber is prepared by the following method:

[0076] Weigh 1 kg of basalt fiber and 1 kg of hydrophobic seaweed fiber, mix and stir them evenly to obtain the filling fiber. The length of the basalt fiber is 3 mm, and the hydrophobic seaweed fiber is the hydrophobic seaweed fiber prepared in Preparation Example 9.

[0077] Examples

[0078] Example 1: A flame-retardant concrete:

[0079] 235 kg of cement, 52 kg of fly ash, 46 kg of silica fume, 940 kg of crushed stone, 820 kg of sand, 155 kg of water, 5.2 kg of water reducer, 15 kg of filling fiber, 32 kg of flame-retardant filler; the cement is ordinary Portland cement of P.O42.5; the particle size of the crushed stone is 5 - 25 mm continuous grading, and the mud content < 1%; the sand is medium sand in Zone II, with an apparent density of 2660 kg / m 3 , with a fineness modulus of 2.5 and a mud content < 1.0%; the fly ash is Class II F fly ash, with a fineness (residue on 45μm square hole sieve) of 8%, a loss on ignition < 4.5%, a water demand ratio < 6%, and a water content < 0.2%; the silica fume is SF93, with a silica content in the silica fume ≥ 86%, an average particle size of 0.1 - 0.2μm, a moisture content < 3%, a loss on ignition < 5%, a pozzolanic activity index > 92%, and a specific surface area ≥ 15000 m 2 / kg, the water reducer is a polycarboxylate superplasticizer; the filling fiber is the filling fiber prepared in Preparation Example 10; the flame-retardant filler consists of 8 kg of aluminum hydroxide prepared in Preparation Example 1, 12 kg of antimony trioxide prepared in Preparation Example 2, and 12 kg of coated ammonium polyphosphate prepared in Preparation Example 3;

[0080] The preparation method is as follows:

[0081] S1. Weigh the cement and mix it evenly with aluminum hydroxide and antimony trioxide, and then evenly spray 1 / 10 of the total amount of water to obtain the cement mixture;

[0082] S2. Weigh the fly ash and silica fume and mix them evenly to obtain the powder;

[0083] S3. Weigh the crushed stone and sand and mix them evenly to obtain the aggregate;

[0084] S4. Weigh the filling fiber and coated ammonium polyphosphate and mix them evenly to obtain the filler;

[0085] S5. Weigh the cement mixture and powder materials, mix and stir them evenly, mix the aggregate and filler evenly, add the remaining water and water reducer after mixing, and mix and stir evenly to obtain the mixture.

[0086] S6. The mixture is cast and cured to obtain the flame-retardant concrete.

[0087] Example 2: The difference between this example and Example 1 is as follows:

[0088] Cement: 200 kg, fly ash: 40 kg, silica fume: 35 kg, crushed stone: 850 kg, sand: 700 kg, water: 150 kg, water reducer: 4.5 kg, filling fiber: 10 kg, flame-retardant filler: 24 kg; The filling fiber is the filling fiber prepared in Preparation Example 11; The flame-retardant filler consists of 8 kg of aluminum hydroxide prepared in Preparation Example 1, 8 kg of antimony trioxide prepared in Preparation Example 2, and 8 kg of coated ammonium polyphosphate prepared in Preparation Example 3.

[0089] During the preparation process:

[0090] S1. Weigh the cement, mix it evenly with aluminum hydroxide and antimony trioxide, and then evenly spray 1 / 12 of the total amount of water to obtain the cement mixture.

[0091] Example 3: The difference between this example and Example 1 is as follows:

[0092] Cement: 250 kg, fly ash: 60 kg, silica fume: 55 kg, crushed stone: 1000 kg, sand: 900 kg, water: 160 kg, water reducer: 6.0 kg, filling fiber: 18 kg, flame-retardant filler: 40 kg; The filling fiber is the filling fiber prepared in Preparation Example 12; The flame-retardant filler consists of 8 kg of aluminum hydroxide prepared in Preparation Example 1, 16 kg of antimony trioxide prepared in Preparation Example 2, and 16 kg of coated ammonium polyphosphate prepared in Preparation Example 3.

[0093] Example 4: The difference between this example and Example 1 is as follows:

[0094] Add 5 kg of coated macroporous silica gel particles to the raw materials, and the coated macroporous silica gel particles are the coated macroporous silica gel particles prepared in Preparation Example 4.

[0095] During the preparation process:

[0096] S3. Evenly spray 5 kg of sodium carboxymethylcellulose solution on the surface of the crushed stone. The sodium carboxymethylcellulose solution is an aqueous solution of sodium carboxymethylcellulose with a concentration of 1%. Then add the coated macroporous silica gel particles, mix evenly, dry, and then mix evenly with the sand to obtain the aggregate.

[0097] Example 5: The difference between this example and Example 4 is as follows:

[0098] Add 2 kg of coated macroporous silica gel particles to the raw materials. The coated macroporous silica gel particles are the ones prepared in Preparation Example 5.

[0099] During the preparation process:

[0100] S3. Uniformly spray 1.88 kg of sodium carboxymethyl cellulose solution on the surface of the crushed stones, then add the coated macroporous silica gel particles. After mixing evenly, dry, and then mix evenly with sand to obtain the aggregate.

[0101] Example 6: The difference between this example and Example 4 is that:

[0102] Add 8 kg of coated macroporous silica gel particles to the raw materials. The coated macroporous silica gel particles are the ones prepared in Preparation Example 6.

[0103] During the preparation process:

[0104] S3. Uniformly spray 9.4 kg of sodium carboxymethyl cellulose solution on the surface of the crushed stones, then add the coated macroporous silica gel particles. After mixing evenly, dry, and then mix evenly with sand to obtain the aggregate.

[0105] Example 7: The difference between this example and Example 1 is that:

[0106] Aluminum hydroxide and antimony trioxide in the flame retardant filler are not treated with sodium alginate solution.

[0107] Example 8: The difference between this example and Example 1 is that:

[0108] During the preparation of the coated ammonium polyphosphate in the flame retardant filler, replace the molten polyurethane resin with an equal mass of aqueous polyvinyl alcohol solution, and the concentration of the aqueous polyvinyl alcohol solution is 10%.

[0109] Example 9: The difference between this example and Example 1 is that:

[0110] Replace the hydrophobic seaweed fiber with an equal mass of seaweed fiber in the filling fiber raw material.

[0111] Example 10: The difference between this example and Example 1 is that:

[0112] Replace the hydrophobic seaweed fiber with an equal mass of basalt fiber in the filling fiber raw material.

[0113] Example 11: The difference between this example and Example 1 is that:

[0114] During the preparation of the hydrophobic seaweed fiber in the filling fiber, it is not treated with the molten polyurethane resin and carbon nitride particles.

[0115] Example 12: The difference between this example and Example 1 is that:

[0116] In the preparation process of hydrophobic seaweed fibers in the filling fibers, carbon nitride particles are replaced with the same mass of silica particles.

[0117] Example 13: The difference between this example and Example 1 is that:

[0118] In the preparation process of the flame retardant concrete:

[0119] S1. Weigh cement, fly ash, and silica fume, mix and stir them evenly to obtain a powder material;

[0120] S2. Weigh crushed stones and sand, mix and stir them evenly, then add the powder material, filling fibers, and flame retardant filler, mix and stir them evenly, and then add water and water reducing agent, mix and stir them evenly to obtain a mixture;

[0121] S3. The mixture is cast and cured to obtain the flame retardant concrete.

[0122] Example 14: The difference between this example and Example 4 is that:

[0123] The surface of the crushed stones is not sprayed with sodium carboxymethyl cellulose solution.

[0124] Example 15: The difference between this example and Example 4 is that:

[0125] In the preparation process of the coated macroporous silica particles, short cut aramid fibers are not added.

[0126] Example 16: The difference between this example and Example 4 is that:

[0127] In the preparation process of the coated macroporous silica particles, an aqueous solution of polyvinyl alcohol with the same mass is used to replace the molten polyurethane.

[0128] Comparative example

[0129] Comparative example 1: The difference between this comparative example and Example 1 is that:

[0130] Filling fibers and flame retardant fillers are not added to the raw materials.

[0131] Comparative example 2: The difference between this comparative example and Example 1 is that:

[0132] Flame retardant fillers are not added to the raw materials.

[0133] Comparative example 3: The difference between this comparative example and Example 1 is that:

[0134] In the raw materials of the flame retardant filler, aluminum hydroxide with the same mass is used to replace antimony trioxide and coated ammonium polyphosphate.

[0135] Comparative example 4: The difference between this comparative example and Example 1 is that:

[0136] In the raw materials of the flame retardant filler, ammonium polyphosphate is replaced with coated ammonium polyphosphate in the same mass.

[0137] Performance detection test

[0138] 1. Mechanical strength detection

[0139] The finished flame retardant concrete is prepared by using the preparation methods of Examples 1-16 and Comparative Examples 1-4 respectively. Referring to GB / T50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete", the compressive strength at 28d is detected and the data is recorded.

[0140] 2. Flame retardant performance detection

[0141] The finished flame retardant concrete is prepared by using the preparation methods of Examples 1-16 and Comparative Examples 1-4 respectively. After the building catches fire, the temperature reaches about 400°C in 15 minutes. The test blocks are treated at 500°C for 15 minutes and then heated to 800°C for 15 minutes to simulate a fire. After the test blocks are treated at high temperature, they are restored to room temperature. Again, referring to GB / T50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete", the compressive strength at 28d is detected; and the number of surface cracks of the flame retardant concrete in Examples 1-14 and Comparative Examples 1-4 is recorded. The specimen size is 100mm×100mm×100mm.

[0142] 2. Fire extinguishing performance detection

[0143] The finished flame retardant concrete is prepared by using the preparation methods of Examples 1-6 respectively. A concrete house model is built, which is 40 cm high, has windows and doors, and has 4 floors. It is simulated that one floor catches fire. The fire burns at 500°C for 15 minutes, then is heated to 800°C for 15 minutes, and then a water spray gun is used to simulate a fire fighting water spray gun to extinguish the fire, and the time taken for the flame to completely go out is recorded.

[0144] Table 1 Performance detection table

[0145]

[0146]

[0147] Combined with Examples 1-3 and Table 1, it can be seen that the flame retardant concrete prepared in this application has good flame retardancy and high mechanical strength. Even after being exposed to the high temperature of a large fire, it is not easy for the strength to quickly dissipate, and the good support effect can extend the safe evacuation time of the top-floor residents.

[0148] Combining Example 1 and Examples 4 - 6 and referring to Table 1, it can be seen that for the flame - retardant concrete prepared in Examples 4 - 6, both the strength before and after high - temperature treatment is greater than the corresponding strength in Example 1, the number of cracks is less than that in Example 1, and the fire - extinguishing time is shorter than that in Example 1. This shows that the addition of coated macroporous silica particles can not only improve the density of the concrete, increase the concrete strength, but also improve the flame - retardant effect. When water - spraying fire - extinguishing is carried out, the hygroscopicity of the silica particles is utilized to quickly extinguish the fire, ensuring the strength of the concrete for the evacuation of high - rise residents.

[0149] Combining Example 1 and Examples 7 - 13 and referring to Table 1, it can be seen that in Example 7, the aluminum hydroxide and antimony trioxide in the flame - retardant filler were not treated with sodium alginate solution. Compared with Example 1, for the flame - retardant concrete prepared in Example 7, both the initial strength and the strength after high - temperature treatment are less than the corresponding values in Example 1, and the number of cracks is greater than that in Example 1. This shows that after the aluminum hydroxide and antimony trioxide are treated with sodium alginate solution, the surface hydroxyl groups can be used to improve the bonding density between the filler and the cementitious material, thereby improving the mechanical strength of the concrete and enhancing the flame - retardant effect.

[0150] During the preparation of the coated ammonium polyphosphate in the flame - retardant filler of Example 8, an equal - mass aqueous solution of polyvinyl alcohol was used to replace the molten polyurethane resin. Compared with Example 1, for the flame - retardant concrete prepared in Example 8, both the initial strength and the strength after high - temperature treatment are less than the corresponding values in Example 1, and the number of cracks is greater than that in Example 1. This shows that polyvinyl alcohol is water - soluble and easily dissolves in the concrete mixture, causing the ammonium polyphosphate to come into contact with water, so that the ammonium polyphosphate cannot play a good flame - retardant effect during a fire.

[0151] In Example 9, hydrophobic seaweed fibers were replaced with an equal - mass of seaweed fibers as the filling fiber raw material. Compared with Example 1, for the flame - retardant concrete prepared in Example 9, both the initial strength and the strength after high - temperature treatment are less than the corresponding values in Example 1, and the number of cracks is greater than that in Example 1. This shows that the water absorption of seaweed fibers easily affects the amount of mixing water, resulting in the hydration of the concrete being affected, thus affecting the mechanical strength and flame - retardant effect of the concrete.

[0152] In Example 10, hydrophobic seaweed fibers were replaced with an equal - mass of basalt fibers as the filling fiber raw material. Compared with Example 1, for the flame - retardant concrete prepared in Example 10, both the initial strength and the strength after high - temperature treatment are less than the corresponding values in Example 1, and the number of cracks is greater than that in Example 1. This shows that although basalt fibers have relatively high strength, their flame - retardant effect is poor, while both seaweed fibers and carbon nitride in hydrophobic seaweed fibers have a certain degree of flame - retardant effect, thus protecting the mechanical strength of the concrete.

[0153] In Example 11, during the preparation of the hydrophobic seaweed fiber in the filled fiber, without treatment with the molten polyurethane resin and carbon nitride particles, compared with Example 1, the initial strength and the strength after high-temperature treatment of the flame-retardant concrete prepared in Example 11 are both less than the corresponding values of Example 1, and the number of cracks is greater than that of Example 1. This shows that the polyurethane resin and carbon nitride particles have a flame-retardant effect, can improve the flame-retardant effect of the flame-retardant concrete, and the polyurethane resin and carbon nitride particles can improve the density of the concrete structure and the mechanical strength of the concrete, and try to avoid the generation of cracks after high temperature.

[0154] In Example 12, during the preparation of the hydrophobic seaweed fiber in the filled fiber, carbon nitride particles are replaced with an equal mass of silica particles. Compared with Example 1, the initial strength and the strength after high-temperature treatment of the flame-retardant concrete prepared in Example 12 are both less than the corresponding values of Example 1, and the number of cracks is greater than that of Example 1. This shows that the silica particles do not have a flame-retardant effect, thus easily affecting the flame-retardant effect of the concrete.

[0155] In Example 13, the raw materials in the flame-retardant concrete are mixed at one time. Compared with Example 1, the initial strength and the strength after high-temperature treatment of the flame-retardant concrete prepared in Example 13 are both less than the corresponding values of Example 1, and the number of cracks is greater than that of Example 1. This shows that after the cement, aluminum hydroxide and antimony trioxide are mixed, the density of the internal structure of the concrete can be improved to increase the mechanical strength of the concrete, and by using the connection effect of the filled fiber and the coated ammonium polyphosphate in the concrete, when the seaweed fiber and ammonium polyphosphate in the filled fiber are carbonized, a carbon layer is formed, so as to use its flame-retardant effect to try to prevent the internal structure of the concrete from cracking due to the influence of high fire temperature, and provide a longer rescue time for the middle and high-rise residents after a fire occurs.

[0156] Combined with Example 4 and Examples 14 - 16 and Table 1, it can be seen that in Example 14, the surface of the crushed stone is not sprayed with sodium carboxymethylcellulose solution. Compared with Example 4, the initial strength and the strength after high-temperature treatment of the flame-retardant concrete prepared in Example 14 are both less than the corresponding values of Example 4, and the number of cracks is greater than that of Example 4. This shows that the carboxyl group in sodium carboxymethylcellulose cooperates with the gelling material, filled fiber and flame-retardant filler to further improve the density of the internal structure of the concrete, thereby increasing the mechanical strength of the concrete. When a fire occurs, the sodium carboxymethylcellulose solution not only absorbs moisture but also can be carbonized, thus improving the flame-retardant effect of the concrete and extending the rescue time for the middle and high-rise residents.

[0157] In Example 15, during the preparation of the coated macroporous silica particles, short aramid fiber filaments were not added. Compared with Example 4, the flame-retardant concrete prepared in Example 15 had lower initial strength and strength after high-temperature treatment than the corresponding values in Example 4, and the number of cracks was greater than that in Example 4. This shows that short aramid fiber filaments can improve the mechanical strength of concrete, thereby enhancing the flame-retardant effect of the flame-retardant concrete.

[0158] In Example 16, during the preparation of the coated macroporous silica particles, an aqueous polyvinyl alcohol solution of the same mass was used to replace the molten polyurethane. Compared with Example 4, the flame-retardant concrete prepared in Example 16 had lower initial strength and strength after high-temperature treatment than the corresponding values in Example 4, and the number of cracks was greater than that in Example 4. This shows that the aqueous polyvinyl alcohol solution can easily cause the macroporous silica particles to absorb the mixing water in the mixture, affecting the hydration of the concrete. The film layer formed by polyurethane is water-proof, enabling the concrete to have higher mechanical strength. After a fire occurs, the polyurethane absorbs heat and melts to play a bonding effect to ensure the mechanical strength of the concrete, and after carbonization at a relatively high temperature, it can form a carbon layer to achieve the flame-retardant effect.

[0159] Combining Example 1 and Comparative Examples 1-4 and referring to Table 1, it can be seen that in Comparative Example 1, no filling fibers and flame-retardant fillers were added to the raw materials, and in Comparative Example 2, no flame-retardant filler was added to the raw materials. Compared with Example 1, the flame-retardant concrete prepared in Comparative Examples 1 and 2 had lower initial strength and strength after high-temperature treatment than the corresponding values in Example 1, and the number of cracks was greater than that in Example 1. This shows that the combination of flame-retardant fillers and filling fibers can improve the mechanical strength and flame-retardant effect of concrete.

[0160] In Comparative Example 3, aluminum hydroxide of the same mass was used to replace antimony trioxide and coated ammonium polyphosphate in the flame-retardant filler raw materials, and in Comparative Example 4, ammonium polyphosphate of the same mass was used to replace coated ammonium polyphosphate in the flame-retardant filler raw materials. Compared with Example 1, the flame-retardant concrete prepared in Comparative Examples 3 and 4 had lower initial strength and strength after high-temperature treatment than the corresponding values in Example 1, and the number of cracks was greater than that in Example 1. This shows that the combination of aluminum hydroxide, antimony trioxide, and coated ammonium polyphosphate can improve the mechanical strength of concrete through the filling effect in the mixture. After a fire occurs, using their good flame-retardant effect can improve the flame retardancy of the concrete and extend the safe evacuation time of high-rise residents.

[0161] This specific embodiment is only an explanation of the present application and is not a limitation thereof. After reading this specification, those skilled in the art can make modifications to this embodiment without creative contributions as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A flame-retardant concrete, characterized in that, It is made from the following raw materials in parts by weight: 200 - 250 parts of cement, 40 - 60 parts of fly ash, 35 - 55 parts of silica fume, 850 - 1000 parts of crushed stone, 700 - 900 parts of sand, 150 - 160 parts of water, 4.5 - 6.0 parts of water reducing agent, 10 - 18 parts of filling fiber, and 24 - 40 parts of flame retardant filler; the flame retardant filler is composed of aluminum hydroxide, antimony trioxide and coated ammonium polyphosphate with a weight ratio of 1:1 - 2:1 - 2; the filling fiber is composed of basalt fiber and hydrophobic seaweed fiber with a weight ratio of 1:0.5 - 1; the hydrophobic seaweed fiber is obtained by soaking seaweed fiber in silane coupling agent KH - 570, then evenly spraying molten polyurethane resin solution on the surface and then evenly spraying carbon nitride particles, and the weight ratio of seaweed fiber, molten polyurethane resin solution and carbon nitride particles is 1:0.1 - 0.3:0.1 - 0.

4.

2. A flame-retardant concrete according to claim 1, characterized in that: The flame retardant concrete also includes 2 - 8 parts of coated macroporous silica gel particles.

3. A flame-retardant concrete according to claim 2, wherein The coated macroporous silica gel particles are obtained by coating macroporous silica gel particles with molten polyurethane resin solution and then bonding short cut aramid fibers.

4. A flame-retardant concrete according to claim 1, wherein The coated ammonium polyphosphate is obtained by coating ammonium polyphosphate particles with polyurethane resin.

5. A flame-retardant concrete according to claim 1, characterized in that, The surfaces of the aluminum hydroxide and antimony trioxide are modified with sodium alginate solution.

6. A method for preparing a flame-retardant concrete according to any one of claims 1-5, characterized in that, It includes the following steps: S1. Weigh cement, mix it evenly with aluminum hydroxide and antimony trioxide, and then evenly spray 1 / 12 - 1 / 10 of the total amount of water to obtain cement mixture. S2. Weigh fly ash and silica fume, mix them evenly to obtain powder material. S3. Weigh crushed stone and sand, mix them evenly to obtain aggregate. S4. Weigh filling fiber and coated ammonium polyphosphate, mix them evenly to obtain filling material. S5. Weigh the cement mixture and the powder material, mix them evenly, mix the aggregate and the filling material evenly, then add the remaining water and water reducing agent, and mix them evenly to obtain the mixing material. S6. The mixing material is cast and cured to obtain the flame retardant concrete.

7. The preparation method of a flame-retardant concrete according to claim 6, characterized in that, S3. Evenly spray sodium carboxymethyl cellulose solution on the surface of the crushed stone, and the weight ratio of the crushed stone to the sodium carboxymethyl cellulose solution is 100:0.2 - 1. Then add the coated macroporous silica gel particles, mix them evenly, dry them, and then mix them evenly with sand to obtain the aggregate.

8. The preparation method of a flame-retardant concrete according to claim 7, characterized in that, The coated macroporous silica gel particles are prepared by the following method: Evenly spray molten polyurethane on the surface of the macroporous silica gel particles, then evenly spray short cut aramid fibers, and dry them to obtain the macroporous silica gel particles; the molten polyurethane forms a polyurethane film with a thickness of 0.2 - 1 mm, and the weight ratio of the macroporous silica gel particles to the short cut aramid fibers is 1:0.5 - 1.2.

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