Graphite-phase carbon nitride fireproof coating as well as application and application method thereof

Abstract

The invention relates to the technical field of tunnel fireproof materials, and provides a graphite-phase carbon nitride fireproof coating as well as application and an application method thereof. The coating comprises the following components in parts by mass: 40-60 parts of alkali-activated cement, 2-4 parts of redispersible latex powder, 2-4 parts of polyvinyl alcohol, 11-14 parts of expanded vermiculite, 11-14 parts of expanded perlite, 5-7 parts of sepiolite, 1-3 parts of hollow floating beads, 2-4 parts of magnesium hydroxide, 5-8 parts of aluminum hydroxide and 0.5-2 parts of g-C3N4. The graphite-phase carbon nitride fireproof coating provided by the invention has excellent fireproof performance, cracking resistance, working performance, impermeability, thermal stability and chemical stability, the bonding strength reaches 0.31 MPa, the fire endurance reaches 3.1 h, and the efficiency of removing NOx through visible light catalysis reaches 232 [mu] mol / (h.m < 2 >).

Description

[0001] This application is a divisional application. The application number of the original application is 202211639839.0, the application date is December 20, 2022, and the name of the invention is "A graphite phase carbon nitride fire retardant coating and its application and application method." Technical Field

[0002] The present invention relates to the technical field of tunnel fireproof materials, in particular to a graphite phase carbon nitride fireproof coating and an application and an application method thereof. Background Art

[0003] The preparation of tunnel fire-retardant coatings uses a large amount of cement. The "two-grinding, one-burning" process for preparing ordinary Portland cement clinker emits significant amounts of carbon dioxide, severely hindering the achievement of the "dual carbon" goals. Patent CN201310157218.3 discloses a tunnel fire-retardant coating composed of geopolymers, expanded perlite, expanded vermiculite, brucite fiber, sepiolite, hydroxymethyl cellulose, and a fatty alcohol sulfonate air-entraining agent. The geopolymers are composed of silica fume, kaolin, calcium-based bentonite, calcium oxide, sodium carbonate, sodium chloride, sodium sulfate, and low-calcium fly ash. The coating exhibits high bond strength and excellent fire resistance, but the high concentration of geopolymers and the complex preparation method hinder cost reduction. Patent CN201710401285.3 discloses an alkali slag tunnel fire retardant coating using a composite activator and a preparation method thereof. The coating is composed of slag, polypropylene fiber, redispersible latex powder, polyvinyl alcohol, expanded vermiculite, expanded perlite, sepiolite, hollow floating beads, magnesium hydroxide, and aluminum hydroxide, with water glass and neutral sodium salt as composite activators; the coating is green and environmentally friendly and has high bonding strength, good fire resistance and freeze-thaw resistance, but the addition of water glass will shorten the drying time of the fire retardant coating and affect normal construction. On the other hand, with the progress of industrialization, a large amount of harmful and toxic pollutants are continuously discharged into the environment. Among them, nitrogen oxides (NO x ) not only causes a variety of environmental problems, but also poses a threat to human health. x With the increase of NO emissions, traditional physical and chemical treatment methods have been difficult to meet the requirements of modern society. Therefore, there is an urgent need to develop a method that can reduce carbon emissions and promote NO x New tunnel fire retardant coating with purification. Summary of the Invention

[0004] The purpose of the present invention is to overcome the problems existing in the prior art and provide a graphite phase carbon nitride fire retardant coating and its application and application method.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a graphite phase carbon nitride fire retardant coating comprising the following components in parts by mass:

[0007] 40-60 parts of alkali-activated cement, 2-4 parts of redispersible latex powder, 2-4 parts of polyvinyl alcohol, 11-14 parts of expanded vermiculite, 11-14 parts of expanded perlite, 5-7 parts of sepiolite, 1-3 parts of hollow floating beads, 2-4 parts of magnesium hydroxide, 5-8 parts of aluminum hydroxide, and 0.5-2 parts of g-C3N4.

[0008] Preferably, the alkali activated cement comprises the following components in parts by weight: 85-95 parts of precursor, 5-15 parts of alkali activator;

[0009] The mass ratio of slag to nickel slag in the precursor is 30-40:60-70;

[0010] The mass ratio of potassium hydroxide to sodium carbonate in the alkaline activator is 40-50:50-60.

[0011] Preferably, the particle size of the redispersible latex powder is 125-145 meshes and the specific gravity is 7.5-8.5 mL / g; the particle size of the polyvinyl alcohol is 90-110 meshes.

[0012] Preferably, the particle size of the expanded vermiculite is 0.5-2 mm, and the bulk density of the expanded vermiculite is 480-580 kg / m 3 The particle size of the expanded perlite is 2 to 4 mm, and the bulk density of the expanded perlite is 65 to 85 kg / m 3 The bulk density of the sepiolite is 600-700 kg / m 3 The particle size of the hollow floating beads is 0.6 to 1.2 mm, and the bulk density of the hollow floating beads is 380 to 480 kg / m 3 .

[0013] Preferably, the average particle size of the magnesium hydroxide is 65 to 85 μm; the average particle size of the aluminum hydroxide is 12 to 18 μm.

[0014] Preferably, the preparation method of g-C3N4 comprises the following steps:

[0015] Melamine and ammonium chloride are mixed, calcined and ground in sequence to obtain the g-C3N4.

[0016] Preferably, the mass ratio of melamine to ammonium chloride is 4-8:20-40;

[0017] The heating rate of the calcination is 2-4°C / min, the target temperature of the calcination is 500-600°C, and the holding time to reach the target temperature is 3.5-4.5h; the particle size of the grinding is 0.05-5μm.

[0018] The present invention also provides application of the graphite phase carbon nitride fire retardant coating in tunnels.

[0019] The present invention also provides a method for applying the graphite phase carbon nitride fire retardant coating in a tunnel, comprising the following steps:

[0020] The graphite phase carbon nitride fire retardant coating is mixed with water, and coating and curing are performed in sequence to obtain a fire retardant coating.

[0021] Preferably, the mass ratio of water to graphite phase carbon nitride fire retardant coating is 70-90:100; the thickness of the fire retardant coating is 18-22 mm; the curing temperature is 18-22° C., and the curing time is 26-30 days.

[0022] The beneficial effects of the present invention are:

[0023] 1. The present invention provides a graphite-phase carbon nitride fire-retardant coating, in which no silicate cement is used as raw material, thereby avoiding the problem of carbon dioxide release caused by the decomposition of calcium carbonate in the production process of silicate cement, reducing the greenhouse effect and carbon emissions; the present invention adopts a cheaper potassium hydroxide and sodium carbonate composite activator instead of the commonly used NaOH activator, thereby reducing costs; the present invention adopts a cheaper nickel slag to partially replace the slag, thereby realizing the solid waste utilization of slag and nickel slag and reducing environmental pressure.

[0024] 2. In the graphite phase carbon nitride fire retardant coating provided by the present invention, the K contained in the composite activator + , which has high activity and can improve the fire resistance of the coating; the graphite phase carbon nitride fire retardant coating provided by the present invention has more excellent fire resistance, crack resistance, workability, and impermeability, and has small drying shrinkage; the fire retardant coating provided by the present invention has more superior thermal stability and chemical stability, and exhibits higher corrosion resistance to strong acids and strong alkalis.

[0025] 3. The present invention provides a graphite carbon nitride fire retardant coating. Since nickel slag is less active than slag, the hydration product is generated slowly and will not be wrapped on the surface of g-C3N4 in large quantities, thus not inhibiting the photocatalytic effect of g-C3N4. The fire retardant coating provided by the present invention has excellent photocatalytic performance and can purify NO in the air. xThe fire retardant coating provided by the present invention has a higher visible light utilization rate. Compared with the traditional photocatalyst TiO2 that can only undergo photocatalytic reaction under ultraviolet light drive, g-C3N4 broadens the utilization of the spectrum, effectively realizes the response and absorption of visible light, and is more suitable for air purification under light irradiation in non-sunlight and highly polluted areas such as tunnels.

[0026] 4. The graphite phase carbon nitride fire retardant coating provided by the present invention has a bonding strength of 0.31MPa and a fire resistance limit of 3.1h. It can remove NO by visible light catalysis. x The efficiency reached 232 μmol / (h·m 2 ). DETAILED DESCRIPTION

[0027] The present invention provides a graphite phase carbon nitride fire retardant coating comprising the following components in parts by mass:

[0028] 40-60 parts of alkali-activated cement, 2-4 parts of redispersible latex powder, 2-4 parts of polyvinyl alcohol, 11-14 parts of expanded vermiculite, 11-14 parts of expanded perlite, 5-7 parts of sepiolite, 1-3 parts of hollow floating beads, 2-4 parts of magnesium hydroxide, 5-8 parts of aluminum hydroxide, and 0.5-2 parts of g-C3N4.

[0029] In the present invention, alkali-activated cement, redispersible latex powder and polyvinyl alcohol are used as bonding materials; expanded vermiculite, expanded perlite, sepiolite and hollow floating beads are used as thermal insulation materials; magnesium hydroxide and aluminum hydroxide are used as additives. The polyvinyl alcohol is preferably cold-soluble polyvinyl alcohol.

[0030] In the present invention, the mass fraction of alkali-activated cement is 40 to 60 parts, preferably 45 to 55 parts, and more preferably 48 to 52 parts.

[0031] In the present invention, the mass fraction of the redispersible latex powder is 2 to 4 parts, preferably 2.5 to 3.5 parts, and more preferably 2.7 to 3.3 parts.

[0032] In the present invention, the mass fraction of polyvinyl alcohol is 2 to 4 parts, preferably 2.5 to 3.5 parts, and more preferably 2.7 to 3.3 parts.

[0033] In the present invention, the mass fraction of expanded vermiculite is 11 to 14 parts, preferably 12 to 13 parts, and more preferably 12.2 to 12.8 parts.

[0034] In the present invention, the mass fraction of expanded perlite is 11 to 14 parts, preferably 12 to 13 parts, and more preferably 12.2 to 12.8 parts.

[0035] In the present invention, the mass fraction of sepiolite is 5 to 7 parts, preferably 5.5 to 6.5 parts, and more preferably 5.7 to 6.3 parts.

[0036] In the present invention, the mass fraction of the hollow floating beads is 1 to 3 parts, preferably 1.5 to 2.5 parts, and more preferably 1.7 to 2.3 parts.

[0037] In the present invention, the mass fraction of magnesium hydroxide is 2 to 4 parts, preferably 2.5 to 3.5 parts, and more preferably 2.7 to 3.3 parts.

[0038] In the present invention, the mass fraction of aluminum hydroxide is 5 to 8 parts, preferably 6 to 7 parts, and more preferably 6.2 to 6.8 parts.

[0039] In the present invention, the mass fraction of g-C3N4 is 0.5 to 2 parts, preferably 1 to 1.5 parts, and more preferably 1.2 to 1.3 parts.

[0040] In the present invention, the alkali-activated cement comprises the following components in parts by mass: 85 to 95 parts of a precursor and 5 to 15 parts of an alkali activator.

[0041] In the present invention, the mass fraction of the precursor is preferably 85 to 95 parts, more preferably 87 to 93 parts, and even more preferably 89 to 91 parts.

[0042] In the present invention, the mass fraction of the base activator is preferably 5 to 15 parts, more preferably 7 to 13 parts, and even more preferably 9 to 11 parts.

[0043] In the present invention, the mass ratio of slag to nickel slag in the precursor is preferably 30-40:60-70, more preferably 32-38:62-68, and even more preferably 34-36:64-66.

[0044] In the present invention, the mass ratio of potassium hydroxide to sodium carbonate in the alkaline activator is preferably 40-50:50-60, more preferably 42-48:52-58, and even more preferably 44-46:54-56.

[0045] In the present invention, the particle size of the redispersible latex powder is preferably 125-145 mesh, more preferably 130-140 mesh, and more preferably 132-138 mesh; the specific gravity is preferably 7.5-8.5 mL / g, more preferably 7.7-8.3 mL / g, and more preferably 7.9-8.1 mL / g; the particle size of the polyvinyl alcohol is preferably 90-110 mesh, more preferably 95-105 mesh, and more preferably 98-102 mesh.

[0046] In the present invention, the particle size of the expanded vermiculite is preferably 0.5 to 2 mm, more preferably 1 to 1.5 mm, and more preferably 1.1 to 1.4 mm; the bulk density of the expanded vermiculite is preferably 480 to 580 kg / m 3 , more preferably 500~560kg / m 3 , more preferably 520-540 kg / m 3 The particle size of the expanded perlite is preferably 2 to 4 mm, more preferably 2.5 to 3.5 mm, and more preferably 2.7 to 3.3 mm; the bulk density of the expanded perlite is preferably 65 to 85 kg / m 3 , more preferably 70 to 80 kg / m 3 , more preferably 72 to 78 kg / m 3 The bulk density of the sepiolite is preferably 600 to 700 kg / m 3 , more preferably 620~680kg / m 3 , more preferably 640-660 kg / m 3 The particle size of the hollow floating beads is preferably 0.6 to 1.2 mm, more preferably 0.8 to 1.0 mm, and more preferably 0.85 to 0.95 mm; the bulk density of the hollow floating beads is preferably 380 to 480 kg / m 3 , more preferably 400~460kg / m 3 , more preferably 420-440 kg / m 3 .

[0047] In the present invention, the average particle size of the magnesium hydroxide is preferably 65 to 85 μm, more preferably 70 to 80 μm, and more preferably 72 to 78 μm; the average particle size of the aluminum hydroxide is preferably 12 to 18 μm, more preferably 14 to 16 μm, and more preferably 14.5 to 15.5 μm.

[0048] In the present invention, the preparation method of g-C3N4 comprises the following steps:

[0049] Melamine and ammonium chloride are mixed, calcined and ground in sequence to obtain the g-C3N4.

[0050] In the present invention, the mass ratio of melamine to ammonium chloride is preferably 4-8:20-40, more preferably 5-7:25-35, and even more preferably 5.5-6.5:27-33.

[0051] In the present invention, the sample is taken out after calcination, cooled naturally, and then ground.

[0052] In the present invention, the heating rate of the calcination is preferably 2-4°C / min, more preferably 2.5-3.5°C / min, more preferably 2.7-3.3°C / min; the target temperature of the calcination is preferably 500-600°C, more preferably 520-580°C, more preferably 540-560°C; the holding time to reach the target temperature is preferably 3.5-4.5h, more preferably 3.7-4.3h, more preferably 3.9-4.1h; the target temperature of the cooling is preferably 20-30°C, more preferably 22-28°C, more preferably 24-26°C; the particle size of the grinding is preferably 0.05-5μm, more preferably 1-4.5μm, more preferably 2-3.5μm.

[0053] The present invention also provides application of the graphite phase carbon nitride fire retardant coating in tunnels.

[0054] The present invention also provides a method for applying the graphite phase carbon nitride fire retardant coating in a tunnel, comprising the following steps:

[0055] The graphite phase carbon nitride fire retardant coating is mixed with water, and coating and curing are performed in sequence to obtain a fire retardant coating.

[0056] In the present invention, the mixing is preferably performed by first mixing the alkali activator with water and then adding other components.

[0057] In the present invention, prior to coating, the base layer is preferably cleaned and wetted with water. The base layer cleaning is to remove dust, debris, and oil stains from the inner wall surface of the tunnel; the water wetting is to wet the wall surface with water and then dry it until the surface is free of water. The coating is preferably performed 2 to 4 times, more preferably 3 times.

[0058] In the present invention, after the coating is completed, the phenomenon of shedding is observed. If shedding is found, it needs to be re-brushed, and then curing is performed to obtain the fire-retardant coating.

[0059] In the present invention, the mass ratio of water to graphite phase carbon nitride fire retardant coating is preferably 70-90:100, more preferably 75-85:100, and more preferably 77-83:100; the thickness of the fire retardant coating is preferably 18-22 mm, more preferably 19-21 mm, and more preferably 19.5-20.5 mm; the curing temperature is preferably 18-22°C, more preferably 19-21°C, and more preferably 19.5-20.5°C; the curing time is preferably 26-30 days, more preferably 27-29 days, and more preferably 27.5-28.5 days.

[0060] The technical solutions provided by the present invention are described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0061] Example 1

[0062] 6 g of melamine and 30 g of ammonium chloride were thoroughly mixed, heated to 550 ° C at a heating rate of 3 ° C / min and kept warm for 4 hours. After the end of the heat preservation, it was naturally cooled to 25 ° C. The sample was ground to obtain g-C3N4 with a particle size of 0.1 μm;

[0063] 6 kg of alkaline activator (the mass ratio of potassium hydroxide and sodium carbonate in the alkaline activator is 2:3) is mixed with 80 kg of water, and then 34 kg of precursor (the mass ratio of slag and nickel slag in the precursor is 2:3), 4 kg of redispersible latex powder with a specific gravity of 7.5 mL / g and a particle size of 125 mesh, 4 kg of cold-soluble polyvinyl alcohol with a particle size of 90 mesh, and 14 kg of particle size of 0.5 mm and a bulk density of 488 kg / m 3 14kg of expanded vermiculite, particle size 2mm, bulk density 65kg / m 3 Expanded perlite, 7kg bulk density is 611kg / m 3 3kg of sepiolite, particle size is 0.6mm, bulk density is 387kg / m 3 hollow floating beads, 4 kg of magnesium hydroxide with an average particle size of 65 μm, 8 kg of aluminum hydroxide with an average particle size of 12 μm, and 2 kg of g-C3N4 with a particle size of 0.1 μm to obtain a graphite phase carbon nitride fire retardant coating;

[0064] Clean the dust, residue and oil stains on the surface of the inner wall of the tunnel, spray water on the wall surface to moisten it, and dry it until there is no water on the surface. Then manually apply the prepared fire retardant coating on the surface of the inner wall of the tunnel, apply it twice, and observe whether there is any shedding. If there is shedding, it needs to be re-applied. Finally, it is cured at 20℃ for 28 days to obtain a fire retardant coating with a thickness of 19mm.

[0065] The basic properties of the graphite phase carbon nitride fire retardant coating obtained in this example were measured according to GB28375-2012 "Concrete Structure Fire Retardant Coatings", and according to the international standard "ISO / DIS22197-1" for photocatalytic gas purification, a homemade visible light catalytic NO removal method was used. x The test device was used to evaluate the air purification performance of the graphite phase carbon nitride fire retardant coating. The bonding strength of the graphite phase carbon nitride fire retardant coating obtained in this embodiment was 0.24MPa, the fire resistance limit was 3.1h, and the visible light catalytic removal of NO x The efficiency is 232 μmol / (h·m 2 ).

[0066] Example 2

[0067] 5 g of melamine and 29 g of ammonium chloride were thoroughly mixed, heated to 580 ° C at a heating rate of 3.5 ° C / min and kept warm for 4.2 hours. After the end of the heat preservation, it was naturally cooled to 27 ° C. The sample was ground to obtain g-C3N4 with a particle size of 2.5 μm;

[0068] 5 kg of alkaline activator (the mass ratio of potassium hydroxide and sodium carbonate in the alkaline activator is 9:11) is mixed with 85 kg of water, and then 45 kg of precursor (the mass ratio of slag and nickel slag in the precursor is 7:13), 3 kg of redispersible latex powder with a specific gravity of 8 mL / g and a particle size of 135 mesh, 3 kg of cold-soluble polyvinyl alcohol with a particle size of 100 mesh, and 13 kg of particle size of 1 mm and a bulk density of 531 kg / m 3 13kg of expanded vermiculite, particle size 3mm, bulk density 75kg / m 3 Expanded perlite, 6kg bulk density is 656kg / m 3 2kg of sepiolite, particle size is 0.9mm, bulk density is 434kg / m 3 hollow floating beads, 3 kg of magnesium hydroxide with an average particle size of 75 μm, 6 kg of aluminum hydroxide with an average particle size of 15 μm, and 1 kg of g-C3N4 with a particle size of 2.5 μm to obtain a graphite phase carbon nitride fire retardant coating;

[0069] Clean the dust, residue and oil stains on the surface of the inner wall of the tunnel, spray water on the wall surface to moisten it, and dry it until there is no water on the surface. Then manually apply the prepared fire retardant coating on the surface of the inner wall of the tunnel, apply it three times, and observe whether there is any shedding. If there is shedding, it needs to be re-applied. Finally, it is cured at 19.5℃ for 27 days to obtain a fire retardant coating with a thickness of 20mm.

[0070] The basic properties of the graphite phase carbon nitride fire retardant coating obtained in this example were measured according to GB28375-2012 "Concrete Structure Fire Retardant Coatings", and according to the international standard "ISO / DIS22197-1" for photocatalytic gas purification, a homemade visible light catalytic NO removal method was used. x The test device was used to evaluate the air purification performance of the graphite phase carbon nitride fire retardant coating. The bonding strength of the graphite phase carbon nitride fire retardant coating obtained in this embodiment was 0.27MPa, the fire resistance limit was 2.9h, and the visible light catalytic removal of NO x The efficiency is 141 μmol / (h·m 2 ).

[0071] Example 3

[0072] 7.5 g of melamine and 36 g of ammonium chloride were thoroughly mixed, heated to 520 ° C at a heating rate of 2.5 ° C / min and kept warm for 3.7 hours. After the end of the heat preservation, it was naturally cooled to 24 ° C. The sample was ground to obtain g-C3N4 with a particle size of 5 μm;

[0073] 3 kg of alkaline activator (the mass ratio of potassium hydroxide and sodium carbonate in the alkaline activator is 1:1) is mixed with 75 kg of water, and then 57 kg of precursor (the mass ratio of slag and nickel slag in the precursor is 3:7), 2 kg of redispersible latex powder with a specific gravity of 8.5 mL / g and a particle size of 145 mesh, 2 kg of cold-soluble polyvinyl alcohol with a particle size of 110 mesh, and 11 kg of particle size of 2 mm and a bulk density of 576 kg / m 3 11kg of expanded vermiculite, particle size 4mm, bulk density 85kg / m 3 Expanded perlite, 5kg bulk density is 696kg / m 3 The sepiolite has a particle size of 1.2 mm and a bulk density of 472 kg / m 3 hollow floating beads, 2 kg of magnesium hydroxide with an average particle size of 85 μm, 5.5 kg of aluminum hydroxide with an average particle size of 18 μm, and 0.5 kg of g-C3N4 with a particle size of 5 μm to obtain a graphite phase carbon nitride fire retardant coating;

[0074] Clean the dust, residue and oil stains on the surface of the inner wall of the tunnel, spray water on the wall surface to moisten it, and dry it until there is no water on the surface. Then manually apply the prepared fire retardant coating on the surface of the inner wall of the tunnel, apply it twice, and observe whether there is any shedding. If there is shedding, it needs to be re-applied. Finally, it is cured at 20.5℃ for 28.5 days to obtain a fire retardant coating with a thickness of 21mm.

[0075] The basic properties of the graphite phase carbon nitride fire retardant coating obtained in this example were measured according to GB28375-2012 "Concrete Structure Fire Retardant Coatings", and according to the international standard "ISO / DIS22197-1" for photocatalytic gas purification, a homemade visible light catalytic NO removal method was used. x The test device was used to evaluate the air purification performance of the graphite phase carbon nitride fire retardant coating. The bonding strength of the graphite phase carbon nitride fire retardant coating obtained in this embodiment was 0.31MPa, the fire resistance limit was 2.7h, and the visible light catalytic removal of NO x The efficiency is 87 μmol / (h·m 2 ).

[0076] Comparative Example 1

[0077] 3 kg of alkaline activator (the mass ratio of potassium hydroxide and sodium carbonate in the alkaline activator is 1:1) is mixed with 75 kg of water, and then 57 kg of precursor (the mass ratio of slag and nickel slag in the precursor is 3:7), 2 kg of redispersible latex powder with a specific gravity of 8.5 mL / g and a particle size of 145 mesh, 2 kg of cold-soluble polyvinyl alcohol with a particle size of 110 mesh, and 11 kg of particle size of 2 mm and a bulk density of 576 kg / m 3 11kg of expanded vermiculite, particle size 4mm, bulk density 85kg / m 3 Expanded perlite, 5kg bulk density is 696kg / m 3 The sepiolite has a particle size of 1.2 mm and a bulk density of 472 kg / m 3 hollow floating beads, 2 kg of magnesium hydroxide with an average particle size of 85 μm, 5.5 kg of aluminum hydroxide with an average particle size of 18 μm, and 0.5 kg of titanium dioxide to obtain a titanium dioxide fire retardant coating;

[0078] Clean the dust, residue and oil stains on the surface of the inner wall of the tunnel, spray water on the wall surface to moisten it, and dry it until there is no water on the surface. Then manually apply the prepared fire retardant coating on the surface of the inner wall of the tunnel, apply it twice, and observe whether there is any shedding. If there is shedding, it needs to be re-applied. Finally, it is cured at 20.5℃ for 28.5 days to obtain a fire retardant coating with a thickness of 21mm.

[0079] The basic properties of the titanium dioxide fire retardant coating obtained in this comparative example were measured according to GB28375-2012 "Concrete Structure Fire Retardant Coatings", and according to the international standard "ISO / DIS22197-1" for photocatalytic gas purification, a homemade visible light catalytic NO removal method was used. x The test device was used to evaluate the air purification performance of titanium dioxide fire retardant coating. The bonding strength of titanium dioxide fire retardant coating was 0.29MPa, the fire resistance limit was 2.6h, and the visible light catalytic removal of NO x The efficiency is 57 μmol / (h·m 2 ).

[0080] From the above examples, it can be seen that the present invention provides a graphite phase carbon nitride fire retardant coating with excellent fire resistance, crack resistance, workability, impermeability, and excellent thermal stability and chemical stability. The bonding strength reaches 0.31MPa, the fire resistance limit reaches 3.1h, and the visible light catalytic removal of NO x The efficiency reached 232 μmol / (h·m 2 ).

[0081] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A graphite phase carbon nitride fire retardant coating, characterized in that: Contains the following components in parts by weight: 40kg alkali activated cement, 4kg redispersible latex powder, 4kg polyvinyl alcohol, 14kg expanded vermiculite, 14kg expanded perlite, 7kg sepiolite, 3kg hollow floating beads, 4kg magnesium hydroxide, 8kg aluminum hydroxide, 42kg g-C3N; The alkali activated cement comprises the following components by mass: 34 kg of precursor, 6 kg of alkali activator; The mass ratio of slag to nickel slag in the precursor is 2:3; The mass ratio of potassium hydroxide to sodium carbonate in the alkaline activator is 2:3; The preparation method of g-C3N4 comprises the following steps: Mixing melamine and ammonium chloride, calcining and grinding in sequence to obtain the g-C3N4; The mass ratio of melamine to ammonium chloride is 6:30; The heating rate of the calcination is 3°C / min, the target temperature of the calcination is 550°C, and the holding time to reach the target temperature is 4h; the particle size of the grinding is 0.1 μm.

2. The graphite phase carbon nitride fire retardant coating according to claim 1, characterized in that: The particle size of the redispersible latex powder is 125 meshes and the specific gravity is 7.5 mL / g; the particle size of the polyvinyl alcohol is 90 meshes.

3. The graphite phase carbon nitride fire retardant coating according to claim 2, characterized in that: The particle size of the expanded vermiculite is 0.5 mm, and the bulk density of the expanded vermiculite is 488 kg / m 3 The particle size of the expanded perlite is 2 mm, and the bulk density of the expanded perlite is 65 kg / m 3 The bulk density of the sepiolite is 611kg / m 3 The particle size of the hollow floating beads is 0.6 mm, and the bulk density of the hollow floating beads is 387 kg / m 3 .

4. The graphite phase carbon nitride fire retardant coating according to claim 3, characterized in that: The average particle size of the magnesium hydroxide is 65 μm; the average particle size of the aluminum hydroxide is 12 μm.

5. Use of the graphite phase carbon nitride fire retardant coating according to any one of claims 1 to 4 in tunnels.

6. The method for applying the graphite phase carbon nitride fire retardant coating in a tunnel according to any one of claims 1 to 4, characterized in that: It includes the following steps: The graphite phase carbon nitride fire retardant coating is mixed with water, and then coated and cured in sequence to obtain a fire retardant coating.

7. The application method according to claim 6, characterized in that: The mass ratio of water to graphite phase carbon nitride fire retardant coating is 80:100; the thickness of the fire retardant coating is 19 mm; the curing temperature is 20° C., and the curing time is 28 days.