Composite material for fireproof air pipe and preparation method of composite material

Abstract

The invention belongs to the technical field of building materials, and particularly relates to a composite material for a fireproof air duct and a preparation method of the composite material. The composite material for the fireproof air pipe is prepared from the following raw materials in parts by mass: 10 to 15 parts of cement, 10 to 15 parts of polished tile waste residue, 10 to 15 parts of modified powder, 12 to 17 parts of modified superfine slag powder, 14 to 18 parts of expanded perlite, 2 to 4 parts of zinc borate, 5 to 8 parts of magnesium hydroxide, 1.5 to 3.0 parts of basalt chopped fiber, 0.3 to 0.8 part of polycarboxylate superplasticizer, 0.1 to 0.3 part of hydroxypropyl methyl cellulose and 30 to 35 parts of water. The composite material disclosed by the invention is high in breaking strength, excellent in high-temperature resistance and suitable for preparing the fireproof air pipe.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, specifically relating to a composite material for fireproof air ducts and its preparation method. Background Technology

[0002] With the rapid development of modern building technology and the increasing demands for building safety, fire safety has become a crucial aspect of building design, construction, and acceptance. Fire-resistant ducts, as a key component of ventilation and smoke extraction systems, directly affect the reliability of the entire system and the overall fire resistance of the building.

[0003] In recent years, fire-resistant air ducts based on cement-based materials have received widespread attention due to their excellent fire resistance, environmental friendliness, and structural integrity. Cement-based materials possess inherent advantages such as non-combustibility, low smoke, non-toxicity, and high-temperature resistance, enabling them to maintain structural integrity and thermal insulation performance during a fire, effectively preventing the penetration of flames and high-temperature smoke. However, traditional cement-based materials also have significant drawbacks, such as high weight, high brittleness, poor impact and bending resistance, susceptibility to cracking, and poor workability, limiting their application in complex working conditions and large-span air ducts.

[0004] Chinese patent CN106810156B discloses a fiber-reinforced silicate fireproof board produced by mixing industrial waste residue. The fiber-reinforced silicate fireproof board produced by using polished brick waste residue and carbide slag has a low thermal conductivity and good high-temperature dimensional stability, and can be used as the panel of various building passive fire protection systems.

[0005] The existing technology adds a lot of polishing brick waste and carbide slag to the materials, which will result in insufficient mechanical properties of the fireproof air duct materials. If the material strength is low, the products are easily damaged during transportation and use, and cannot meet the normal use requirements, resulting in a short service life. Summary of the Invention

[0006] The purpose of this invention is to provide a composite material for fireproof air ducts and a method for preparing the same.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A composite material for fireproof air ducts comprises the following raw materials in parts by weight: 10-15 parts cement, 10-15 parts polished brick waste, 10-15 parts modified powder, 12-17 parts modified slag powder, 14-18 parts expanded perlite, 2-4 parts zinc borate, 5-8 parts magnesium hydroxide, 1.5-3.0 parts basalt chopped fibers, 0.3-0.8 parts polycarboxylate superplasticizer, 0.1-0.3 parts hydroxypropyl methylcellulose, and 30-35 parts water.

[0009] Preferably, the cement is P.II.42.5 silicate cement.

[0010] Preferably, the method for preparing the modified powder includes the following steps:

[0011] (1) Soak fly ash cenospheres in hydrochloric acid, stir, wash with water until neutral, and dry to obtain pretreated fly ash cenospheres.

[0012] (2) Dissolve La(NO3)3·6H2O in water to obtain lanthanum nitrate solution. Add pretreated fly ash celery beads to lanthanum nitrate solution, stir, add ammonia water to adjust pH to 10-11, stir at 60-65℃ for 2-4 hours, let stand for aging, filter, wash, and obtain solid.

[0013] (3) After drying the solid, place it in a muffle furnace and heat it up in a programmed manner. Then, let it cool naturally to room temperature, grind and sieve it to obtain the modified powder.

[0014] Preferably, the concentration of hydrochloric acid is 5-8 mol / L.

[0015] Preferably, the concentration of the lanthanum nitrate solution is 0.1-0.5 mol / L, and the pretreated fly ash celery beads are added to the lanthanum nitrate solution at a solid-liquid ratio of 1 g: 14-16 mL.

[0016] Preferably, the programmed temperature rise conditions are as follows: rise to 300-400℃ at 5-10℃ / min and hold for 1-2 hours; then rise to 700-800℃ at 3-8℃ / min and hold for 2-3 hours.

[0017] Existing technologies often incorporate excessive polished brick waste and carbide slag into the composite materials of fireproof ducts, leading to a decrease in the material's flexural strength. The composite material system of this invention improves flexural strength by adding modified powders. Analysis shows that fly ash cenospheres, after acid treatment, have a rougher surface and are loaded with La2O3. The La2O3 forms La-O-Si covalent bonds with the silicon-oxygen bonds in the CSH gel, a cement hydration product, which strengthens the matrix-filler interface bonding and improves the flexural strength of the composite material.

[0018] Preferably, the preparation method of modified slag powder includes the following steps:

[0019] (1) Add calcium oxide to slag powder to obtain a mixture, so that the calcium-silicon molar ratio in the mixture is (1.5-1.6):1. Add water to the mixture and perform wet grinding to obtain a wet-ground mixture.

[0020] (2) Add water to the wet-milled mixture, heat and react, filter and dry after the reaction to obtain modified slag powder.

[0021] Preferably, the wet grinding conditions are: wet grinding for 20-25 minutes at a rotation speed of 250-300 r / min.

[0022] Preferably, the heating reaction conditions are: 80-85℃, 300-350 r / min, for 3-4 hours.

[0023] This invention incorporates modified slag powder into composite materials, which significantly improves the high-temperature resistance of the composites. Analysis shows that modification addresses the issue of the relatively smooth surface of the slag powder particles, reducing particle agglomeration. Simultaneously, the addition of calcium oxide brings the calcium-silicon molar ratio in the mixture to 1.5-1.6:1, which activates the dissolution of the silica-alumina components in the slag and promotes the reaction of active SiO2, Al2O3, and Ca. 2+ The reaction produces hydrated calcium silicate, hydrated calcium aluminate, and hydrated calcium aluminosilicate. Through the heating step, more high-temperature resistant phases are generated, which fill the pores of the composite material and improve the structural integrity at high temperatures.

[0024] This invention provides a method for preparing the composite material for fireproof air ducts, comprising the following steps:

[0025] (1) Mix the raw materials of the composite material used for fireproof air ducts to obtain a mixture;

[0026] (2) Add the mixture into the mold, cure it, demold it, and obtain the composite material for fireproof air ducts.

[0027] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows:

[0028] 1. The composite material of this invention not only possesses excellent flexural strength and high-temperature resistance, but also exhibits good dimensional stability. Under high-temperature environments, the material is not easily deformed or cracked, effectively maintaining the integrity and airtightness of the fireproof duct structure, and significantly improving safety protection capabilities in fire situations.

[0029] 2. The composite material of this invention solves the problem of low mechanical properties caused by polished brick waste residue. Through the compounding of multiple components, the performance of the composite material is comprehensively improved. It is environmentally friendly and non-toxic, meets the strict requirements of modern buildings for green and safe materials, extends the service life of air ducts, reduces the later maintenance cost, and has significant economic and social benefits. Detailed Implementation

[0030] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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.

[0031] All raw materials used in the following embodiments of the present invention are commercially available products:

[0032] Polycarboxylate superplasticizer: Liaoning Kelong Fine Chemical Co., Ltd., model S-409. Cement: P.II.42.5 silicate cement. Fly ash cenospheres: Hebei Tianyu Daguan Culture Media Co., Ltd., specification: fine white cenospheres, 40 mesh. Polishing tile waste: waste residue generated from polishing ceramic tile surfaces, sieved through a 180-mesh sieve. Slag powder: Lingshou Ruikai Mineral Products Co., Ltd., grade S95. Expanded perlite: 20 mesh, Lingshou Shuochuan Mineral Products Processing Plant. Hydroxypropyl methylcellulose: Chengdu Jinran Chemical Co., Ltd. Basalt chopped fiber: Taian Hongfa New Materials Co., Ltd., 6mm.

[0033] Example 1

[0034] This embodiment provides a composite material for fireproof air ducts, comprising the following raw materials in parts by weight: 12 parts cement, 14 parts polished brick waste, 13 parts modified powder, 15 parts modified slag powder, 17 parts expanded perlite, 3 parts zinc borate, 6 parts magnesium hydroxide, 2 parts basalt chopped fiber, 0.5 parts polycarboxylate superplasticizer, 0.2 parts hydroxypropyl methylcellulose, and 32 parts water.

[0035] The method for preparing the modified powder includes the following steps:

[0036] (1) Soak fly ash cenospheres in 6 mol / L hydrochloric acid at a solid-liquid ratio (g / mL) of 1:10, stir at 80℃ for 3.5 h, wash with water until neutral, and dry to obtain pretreated fly ash cenospheres;

[0037] (2) Dissolve La(NO3)3·6H2O in water to obtain a lanthanum nitrate solution with a concentration of 0.2mol / L. Add the pretreated fly ash celery beads to the lanthanum nitrate solution with a solid-liquid ratio of 1g:15mL. Stir at 250rpm for 15min. Add ammonia water to adjust the pH to 10. Stir at 60℃ for 3h. The reaction produces La(OH)3 colloid that is deposited on the surface of the microbeads. Let stand for 13h for aging. After filtration, wash with ethanol 3 times.

[0038] (3) After drying at 60℃, place it in a muffle furnace and program the temperature to rise: raise it to 350℃ at 7℃ / min and keep it at 1 hour; then raise it to 750℃ at 5℃ / min and keep it at 2 hours to convert La(OH)3 into La2O3. After cooling naturally to room temperature, grind it through a 200-mesh sieve to obtain modified powder.

[0039] The preparation method of modified slag powder includes the following steps:

[0040] (1) Add calcium oxide to slag powder to obtain a mixture with a calcium-silicon molar ratio of 1.5:1. Add water to the mixture and wet grind it for 25 minutes at a liquid-solid ratio of 1.5 mL / g and a rotation speed of 250 r / min to obtain a wet-ground mixture.

[0041] (2) Add water to the wet-milled mixture to make the liquid-solid ratio 7 mL / g, react at 85°C and 350 r / min for 3.5 h, filter after the reaction, and dry at 120°C for 10 h to obtain modified slag powder.

[0042] The method for preparing the composite material for fireproof air ducts includes the following steps:

[0043] (1) Mix the raw materials of the composite material used for fireproof air ducts to obtain a mixture;

[0044] (2) Add the mixture into the mold and cure it. The curing conditions are: cure for 30 hours at a curing temperature of 25℃ and a humidity of 65%RH. After demolding, cure for 7 days at a temperature of 30℃ and a humidity of 60%RH. Demold to obtain the composite material for fireproof air duct.

[0045] Example 2

[0046] This embodiment provides a composite material for fireproof air ducts, comprising the following raw materials in parts by weight: 10 parts cement, 15 parts polished brick waste, 10 parts modified powder, 12 parts modified slag powder, 18 parts expanded perlite, 2 parts zinc borate, 8 parts magnesium hydroxide, 1.5 parts basalt chopped fiber, 0.8 parts polycarboxylate superplasticizer, 0.1 parts hydroxypropyl methylcellulose, and 35 parts water.

[0047] The method for preparing the modified powder includes the following steps:

[0048] (1) Soak fly ash cenospheres in 6 mol / L hydrochloric acid at a solid-liquid ratio (g / mL) of 1:10, stir at 80℃ for 3 h, wash with water until neutral, and dry to obtain pretreated fly ash cenospheres.

[0049] (2) Dissolve La(NO3)3·6H2O in water to obtain a lanthanum nitrate solution with a concentration of 0.5 mol / L. Add the pretreated fly ash celery beads to the lanthanum nitrate solution with a solid-liquid ratio of 1 g: 14 mL. Stir at 250 rpm for 20 min. Add ammonia water to adjust the pH to 10. Stir at 60℃ for 4 h. The reaction produces La(OH)3 colloid that is deposited on the surface of the microbeads. Let stand for 12 h to age. After filtration, wash with ethanol 3 times.

[0050] (3) After drying at 60℃, place it in a muffle furnace and heat it up at 10℃ / min to 300℃ and keep it at that temperature for 1 hour; then heat it up at 8℃ / min to 700℃ and keep it at that temperature for 2 hours to convert La(OH)3 into La2O3. Then cool it naturally to room temperature and grind it through a 200-mesh sieve to obtain modified powder.

[0051] The preparation method of modified slag powder includes the following steps:

[0052] (1) Add calcium oxide to slag powder to obtain a mixture with a calcium-silicon molar ratio of 1.5:1. Add water to the mixture and wet grind it for 25 minutes at a liquid-solid ratio of 1.5 mL / g and a rotation speed of 250 r / min to obtain a wet-ground mixture.

[0053] (2) Add water to the wet-milled mixture to make the liquid-solid ratio 7 mL / g, react at 85°C and 350 r / min for 3 h, filter after the reaction, and dry at 120°C for 10 h to obtain modified slag powder.

[0054] The method for preparing the composite material for fireproof air ducts includes the following steps:

[0055] (1) Mix the raw materials of the composite material used for fireproof air ducts to obtain a mixture;

[0056] (2) Add the mixture into the mold and cure it. The curing conditions are: cure for 30 hours at a curing temperature of 25℃ and a humidity of 65%RH. After demolding, cure for 7 days at a temperature of 30℃ and a humidity of 60%RH. Demold to obtain the composite material for fireproof air duct.

[0057] Example 3

[0058] This embodiment provides a composite material for fireproof air ducts, comprising the following raw materials in parts by weight: 15 parts cement, 10 parts polished brick waste, 15 parts modified powder, 12 parts modified slag powder, 18 parts expanded perlite, 2 parts zinc borate, 8 parts magnesium hydroxide, 1.5 parts basalt chopped fiber, 0.8 parts polycarboxylate superplasticizer, 0.1 parts hydroxypropyl methylcellulose, and 35 parts water.

[0059] The method for preparing the modified powder includes the following steps:

[0060] (1) Soak fly ash cenospheres in 6 mol / L hydrochloric acid at a solid-liquid ratio (g / mL) of 1:10, stir at 80℃ for 4 h, wash with water until neutral, and dry to obtain pretreated fly ash cenospheres.

[0061] (2) Dissolve La(NO3)3·6H2O in water to obtain a lanthanum nitrate solution with a concentration of 0.1mol / L. Add the pretreated fly ash celery beads to the lanthanum nitrate solution with a solid-liquid ratio of 1g:16mL. Stir at 250rpm for 10min. Add ammonia water to adjust the pH to 11. Stir at 60℃ for 2h. The reaction produces La(OH)3 colloid that is deposited on the surface of the microbeads. Let stand for 15h for aging. After filtration, wash with ethanol 3 times.

[0062] (3) After drying at 60℃, place it in a muffle furnace and heat it up at 5℃ / min to 400℃ and keep it at that temperature for 1 hour; then heat it up at 3℃ / min to 800℃ and keep it at that temperature for 2 hours to convert La(OH)3 into La2O3. Then cool it naturally to room temperature and grind it through a 200-mesh sieve to obtain modified powder.

[0063] The preparation method of modified slag powder includes the following steps:

[0064] (1) Add calcium oxide to slag powder to obtain a mixture with a calcium-silicon molar ratio of 1.6:1. Add water to the mixture and wet grind it for 25 minutes at a liquid-solid ratio of 1.5 mL / g and a rotation speed of 250 r / min to obtain a wet-ground mixture.

[0065] (2) Add water to the wet-milled mixture to make the liquid-solid ratio 7 mL / g, react at 85°C and 350 r / min for 3 h, filter after the reaction, and dry at 120°C for 10 h to obtain modified slag powder.

[0066] The method for preparing the composite material for fireproof air ducts includes the following steps:

[0067] (1) Mix the raw materials of the composite material used for fireproof air ducts to obtain a mixture;

[0068] (2) Add the mixture into the mold and cure it. The curing conditions are: cure for 30 hours at a curing temperature of 25℃ and a humidity of 65%RH. After demolding, cure for 7 days at a temperature of 30℃ and a humidity of 60%RH. Demold to obtain the composite material for fireproof air duct.

[0069] Comparative Example 1

[0070] The difference between this comparative example and Example 1 is that the modified powder was replaced with fly ash cenospheres (Lingshou County Ruikai Mineral Products Co., Ltd.).

[0071] Comparative Example 2

[0072] The difference between this comparative example and Example 1 is that the total number of modified powder and modified slag powder remains the same, but the proportions are changed.

[0073] 13 parts of modified powder and 15 parts of modified slag powder were replaced with 20 parts of modified powder and 8 parts of modified slag powder.

[0074] Comparative Example 3

[0075] The difference between this comparative example and Example 1 is that the modified slag powder is replaced with slag powder.

[0076] Comparative Example 4

[0077] The difference between this comparative example and Example 1 is that the reaction time of the mixture in the preparation method of the modified slag powder is 5 hours.

[0078] Comparative Example 5

[0079] The difference between this comparative example and Example 1 is that the modified slag powder is prepared by reacting the mixture for 2 hours.

[0080] Comparative Example 6

[0081] The difference between this comparative example and Example 1 is that the calcium-silicon molar ratio in the mixture is 1.7:1 in the preparation method of the modified slag powder.

[0082] Comparative Example 7

[0083] The difference between this comparative example and Example 1 is that the calcium-silicon molar ratio in the mixture is 1.4:1 in the preparation method of the modified slag powder.

[0084] Performance testing

[0085] The composite materials prepared in Examples 1-3 and Comparative Examples 1-7 were subjected to performance tests. The thickness was 9 mm and the size was 2440 mm × 1220 mm.

[0086] 1. Flexural strength at room temperature: Tested according to GB / T3001-2017 "Test method for flexural strength of refractory materials at room temperature".

[0087] 2. Impact strength: Tested according to GB / T1043.1-2008, using unnotched specimens.

[0088] 3. Fire resistance: The evaluation shall be based on GB8624-2012 "Classification of Combustion Performance of Building Materials and Products".

[0089] 4. High temperature stability: After holding at 1000℃ for 5 hours, the average deformation rate was tested. The length / width deformation rate = (length after heating - initial length) ÷ initial length × 100%. Then, the deformation rates in the length and width directions were added together and the average value was calculated to obtain the average deformation rate.

[0090] The results are shown in Table 1.

[0091] Table 1 Test Results

[0092]

[0093] As shown in Table 1, the composite materials of Examples 1-3 exhibit excellent overall performance, with an apparent density of less than 0.9 g / cm³. 3 It also has excellent flexural strength and impact resistance, as well as good high-temperature resistance.

[0094] In Comparative Example 1, the composite material using unmodified fly ash cenospheres exhibited decreased flexural strength, and at high temperatures, the lack of stable La2O3 grain boundaries resulted in reduced heat resistance.

[0095] In Comparative Example 2, the ratio of modified powder to modified slag powder was changed, resulting in insufficient density and a decrease in impact resistance.

[0096] In Comparative Example 3, replacing the modified slag powder with slag powder resulted in a decrease in high-temperature resistance.

[0097] In Comparative Example 4, the reaction time was too long, resulting in a decrease in mechanical properties. Analysis suggests this was due to excessive reaction during the preparation of the modified powder, which consumed excessive Ca. 2+ / Si 4+ This leads to excessive gel phase formation and increased brittleness.

[0098] In Comparative Example 5, insufficient reaction time resulted in decreased mechanical properties. Analysis indicated that the reaction was incomplete during powder modification, leading to insufficient CSH gel formation, a loose structure, poor density, and decreased impact strength.

[0099] In Comparative Example 6, an increase in the calcium-silicon molar ratio led to a decrease in impact resistance. Analysis suggests that a high calcium-silicon molar ratio generates excess Ca(OH)₂, which easily expands and cracks at high temperatures. Simultaneously, the reduction in the ductile phase further contributes to the decrease in impact resistance.

[0100] In Comparative Example 7, a decrease in the calcium-silicon molar ratio resulted in poorer high-temperature resistance and flexural strength. Analysis suggests that insufficient calcium limits CSH gel formation, leading to low structural strength.

[0101] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A composite material for fireproof air ducts, characterized in that, The raw materials include the following parts by weight: 10-15 parts cement, 10-15 parts polished brick waste, 10-15 parts modified powder, 12-17 parts modified slag powder, 14-18 parts expanded perlite, 2-4 parts zinc borate, 5-8 parts magnesium hydroxide, 1.5-3.0 parts basalt chopped fiber, 0.3-0.8 parts polycarboxylate superplasticizer, 0.1-0.3 parts hydroxypropyl methylcellulose, and 30-35 parts water; the modified powder is obtained by first acid washing fly ash and then loading it with La2O3.

2. The composite material for fireproof air ducts according to claim 1, characterized in that, The cement is P.II.42.5 silicate cement.

3. The composite material for fireproof air ducts according to claim 1, characterized in that, The method for preparing the modified powder includes the following steps: (1) Soak fly ash cenospheres in hydrochloric acid, stir, wash with water until neutral, and dry to obtain pretreated fly ash cenospheres. (2) Dissolve La(NO3)3·6H2O in water to obtain lanthanum nitrate solution. Add pretreated fly ash celery beads to lanthanum nitrate solution, stir, add ammonia water to adjust pH, stir at 60-65℃ for 2-4h, let stand for aging, filter, wash, and obtain solid. (3) After drying the solid, place it in a muffle furnace and heat it up in a programmed manner. Then, let it cool naturally to room temperature, grind and sieve it to obtain the modified powder.

4. The composite material for fireproof air ducts according to claim 3, characterized in that, The concentration of hydrochloric acid is 5-8 mol / L.

5. The composite material for fireproof air ducts according to claim 3, characterized in that, The concentration of lanthanum nitrate solution is 0.1-0.5 mol / L. Pretreated fly ash celery beads are added to the lanthanum nitrate solution at a solid-liquid ratio of 1 g: 14-16 mL.

6. The composite material for fireproof air ducts according to claim 3, characterized in that, The temperature program conditions are as follows: raise the temperature to 300-400℃ at a rate of 5-10℃ / min and hold for 1-2 hours; then raise the temperature to 700-800℃ at a rate of 3-8℃ / min and hold for 2-3 hours.

7. The composite material for fireproof air ducts according to claim 1, characterized in that, The preparation method of modified slag powder includes the following steps: (1) Add calcium oxide to slag powder to obtain a mixture, so that the calcium-silicon molar ratio in the mixture is (1.5-1.6):

1. Add water to the mixture and perform wet grinding to obtain a wet-ground mixture. (2) Add water to the wet-milled mixture, heat and react, filter and dry after the reaction to obtain modified slag powder.

8. The composite material for fireproof air ducts according to claim 7, characterized in that, The wet grinding conditions are: wet grinding for 20-25 minutes at a speed of 250-300 r / min.

9. The composite material for fireproof air ducts according to claim 7, characterized in that, The conditions for the heating reaction are: 80-85℃, 300-350 r / min, for 3-4 hours.

10. A method for preparing a composite material for fireproof air ducts according to any one of claims 1-9, characterized in that, Includes the following steps: (1) Mix the raw materials of the composite material used for fireproof air ducts to obtain a mixture; (2) Add the mixture into the mold, cure it, demold it, and obtain the composite material for fireproof air duct.

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