A green high-strength foamed gypsum and its preparation method

Abstract

The present invention relates to the technical field of foamed gypsum, and specifically discloses a green high-strength foamed gypsum. Its raw materials by mass include: 30-60 parts of gypsum, 5-15 parts of cement, 1-2 parts of nanocrystalline whiskers, 1-2 parts of tourmaline powder, 4-10 parts of sulfonated flame-retardant mesoporous silicon, 1-5 parts of graphene oxide, 1-2 parts of acrylamide, 0.01-0.1 part of potassium permanganate, 1-2 parts of water reducer, 1-2 parts of retarder, 1-2 parts of thickener, 1-2 parts of foam stabilizer, and 1-3 parts of chemical foaming agent; the sulfonated flame-retardant mesoporous silicon uses fatty alcohol polyoxyethylene ether as a mesoporous template, takes tetraethyl orthosilicate as a precursor and is compounded with aluminum dihydrogen phosphate, and then is obtained through sulfonation treatment. The present invention also discloses a preparation method of the above-mentioned green high-strength foamed gypsum.

Description

Technical Field

[0001] The present invention relates to the technical field of foamed gypsum, and particularly to a green high-strength foamed gypsum and a preparation method thereof. Background Art

[0002] At present, the construction industry has achieved unprecedented high-speed development. The implementation of building energy-saving policies has promoted the development of wall thermal insulation materials. Organic thermal insulation materials such as foam plastics are widely used in wall materials. However, their poor fire resistance, anti-aging performance, and large deformation coefficient restrict the faster development of this thermal insulation material. Compared with organic thermal insulation materials such as foam plastics, inorganic thermal insulation materials have the advantages of good fire resistance, strong flame retardancy, small deformation coefficient, and strong anti-aging performance.

[0003] Currently, the inorganic thermal insulation material is mainly cement-based vitrified microbead inorganic thermal insulation mortar. The dry density of this mortar is large, basically between 400 - 600 kg / m 3 ³, the thermal conductivity is basically between 0.080 - 0.120 W / (m·K), the drying shrinkage rate is large, which is easy to cause wall cracking, and it is extremely easy to produce an efflorescence phenomenon in humid air parts, affecting the appearance and thermal insulation effect.

[0004] Gypsum building materials are formed by foaming, and a large number of closed and fine pores are formed inside, which can greatly reduce the thermal conductivity, thus having thermal insulation and heat insulation properties. In the current technology, the aeration foaming method has simple process operation, but it is difficult to control the gas generation amount in the gypsum mixed slurry, resulting in uneven pore size and distribution inside the gypsum mold, and it is extremely easy to crack during room temperature gelling and drying, with poor fire and heat insulation effects; while using protein-based foaming agents is restricted by limited material sources and short shelf life, which restricts large-scale popularization and application in industrial production.

[0005] At the same time, the existing gypsum thermal insulation materials also have the defect of high penetration absorption, and the strength loss is too high after multiple freeze-thaw cycles. Therefore, it has great practical significance to research and explore a lightweight, high-strength, fire and heat-insulating green foamed gypsum. Summary of the Invention

[0006] The purpose of the present invention is to solve the defects existing in the prior art, and to provide a green high-strength foamed gypsum and a preparation method thereof.

[0007] A green high-strength foamed gypsum, the raw materials of which by mass include: 30-60 parts of gypsum, 5-15 parts of cement, 1-2 parts of nanocrystalline whiskers, 1-2 parts of tourmaline powder, 4-10 parts of sulfonated flame-retardant mesoporous silicon, 1-5 parts of graphene oxide, 1-2 parts of acrylamide, 0.01-0.1 parts of potassium permanganate, 1-2 parts of water reducing agent, 1-2 parts of setting retarder, 1-2 parts of thickening agent, 1-2 parts of foam stabilizer, 1-3 parts of chemical foaming agent; The sulfonated flame-retardant mesoporous silicon uses fatty alcohol polyoxyethylene ether as a mesoporous template, takes tetraethyl orthosilicate as a precursor and is compounded with aluminum dihydrogen phosphate, and then is obtained through sulfonation treatment.

[0008] Preferably, the gypsum is desulfurized gypsum.

[0009] Preferably, the cement is P.O.52.5 portland cement.

[0010] Preferably, the nanocrystalline whiskers are at least one of nano zinc oxide, nano tin oxide, and nano zinc hydroxy stannate.

[0011] Preferably, the water reducing agent is a naphthalene-based water reducing agent or a polycarboxylate water reducing agent.

[0012] Preferably, the thickening agent is hydroxypropyl methylcellulose or / and polyvinyl alcohol.

[0013] Preferably, the chemical foaming agent is an aqueous hydrogen peroxide solution.

[0014] Preferably, the sulfonated flame-retardant mesoporous silicon is prepared by the following specific operations: Add fatty alcohol polyoxyethylene ether to water and stir evenly, add tetraethyl orthosilicate and aluminum dihydrogen phosphate thereto, stir at 40-50 °C for 5-10 min, adjust the pH value of the system to 8-9, stir for 5-10 h, add 4-ethylbenzenesulfonic acid, stir at 150-160 °C for 1-2 h, cool down to 40-60 °C, filter, wash the filter cake, and dry it under vacuum.

[0015] Preferably, the mass ratio of fatty alcohol polyoxyethylene ether, tetraethyl orthosilicate, aluminum dihydrogen phosphate, and 4-ethylbenzenesulfonic acid is 1-3:2-4:1-2:0.1-1.

[0016] The preparation method of the above-mentioned green high-strength foamed gypsum includes the following steps:

[0017] S1. Stir the sulfonated flame-retardant mesoporous silicon with gypsum, cement, nanocrystalline whiskers, tourmaline powder, and foam stabilizer for 1-3 min to obtain a premix;

[0018] S2. Add graphene oxide into water, ultrasonically disperse for 5 - 10 min, add acrylamide and continue to ultrasonically disperse for 5 - 10 min, purge with nitrogen for 5 - 10 min, seal and irradiate with cobalt - 60, the irradiation dose is 20 - 30 kGy, filter, wash with water, and dry in vacuum; then add it together with water - reducing agent, retarder, thickener, and potassium permanganate into water and stir for 1 - 3 min to obtain a composite admixture;

[0019] S3. Add the composite admixture into the premix and stir for 1 - 3 min, add a chemical foaming agent and continue to stir for 5 - 10 s, pour, foam, demold after molding for 2 - 4 h, and cure.

[0020] Preferably, in S2, the ultrasonic frequency is 5 - 10 kHz.

[0021] Preferably, in S2, the irradiation dose rate is 2.9 - 3.0 kGy / h.

[0022] Beneficial effects:

[0023] 1. Through irradiation treatment in the present invention, acrylamide is grafted onto graphene oxide, endowing it with amphiphilic properties, which can effectively promote the uniform dispersion of water - reducing agent, retarder, thickener, potassium permanganate and other admixtures into the premix, and improve the performance of gypsum board.

[0024] 2. In the present invention, fatty alcohol polyoxyethylene ether is used as the mesoporous template, tetraethyl orthosilicate is used as the precursor, and it is compounded with aluminum dihydrogen phosphate to obtain a flame - retardant mesoporous silicon material, which can effectively improve the heat - resistant and flame - retardant properties. After sulfonation treatment on the surface, it can combine with the amino groups on the surface of the grafted graphene oxide in the composite admixture to form a dense body with a gel structure, thereby improving the flexural strength of the system, reducing shrinkage, and preventing structural cracking; at the same time, a three - dimensional cross - linking effect is generated, and together with fine gypsum particles, a dense colloidal structure is formed, which not only has high strength, but also can effectively block the infiltration of water, and has excellent freeze - thaw resistance, that is, the freeze - thaw cycle after freezing has no effect on its anti - permeability characteristics.

[0025] 3. The grafted graphene oxide and nanocrystalline whiskers in the present invention can effectively promote the uniform dispersion of the chemical foaming agent in the system, promote the foaming of gypsum, not only can produce fine foam, promote the stable generation of foam, and form a uniform gypsum board, but also can improve the early hydration rate, enhance the strength of the hardened body, and cooperate with tourmaline powder to have good radiation protection performance.

[0026] 4. The present invention is green and environmentally friendly, ensuring that the gypsum board has fire - prevention, heat - insulation and radiation - protection characteristics. Different building materials can be formulated according to needs, its hardness meets the requirements of the highest - grade exterior wall materials, and it can resist at least 9 freeze - thaw cycles; and the material is ground into powder physically and can be recycled, greatly reducing the cost investment. The present invention improves the overall performance of the gypsum board, is convenient for construction pouring, and is suitable for large - scale popularization and application. Description of the Drawings

[0027] Figure 1 It is a comparison chart of the bulk density and noise reduction coefficient of the foamed gypsum obtained in Example 5 and Comparative Examples 1-2.

[0028] Figure 2 It is a comparison chart of the compressive strength and flexural strength of the foamed gypsum obtained in Example 5 and Comparative Examples 1-2.

[0029] Figure 3 It is a comparison chart of the thermal conductivity and drying shrinkage rate of the foamed gypsum obtained in Example 5 and Comparative Examples 1-2.

[0030] Figure 4 It is a graph showing the change in the permeability coefficient of the foamed gypsum obtained in Example 5 and Comparative Examples 1-2 after different numbers of freeze-thaw cycles. Detailed Embodiments

[0031] The present invention will be further explained below in conjunction with specific embodiments.

[0032] The foam stabilizer used below is a cement foam stabilizer (DX-550), purchased from Guangzhou Dongxing Fine Chemical Co., Ltd. The naphthalene series water reducer used below is purchased from Shandong Wanshan Chemical Co., Ltd. (specification: FDN-C). The polycarboxylate water reducer used below is Sika polycarboxylate water reducer 540P, purchased from Shanghai Hengchuang Chemical Co., Ltd.

[0033] Example 1

[0034] A green high-strength foamed gypsum, the raw materials of which include: 30 kg of desulfurized gypsum, 5 kg of P.O.52.5 portland cement, 1 kg of nano-zinc oxide whiskers, 1 kg of tourmaline powder, 4 kg of sulfonated flame-retardant mesoporous silicon, 1 kg of graphene oxide, 1 kg of acrylamide, 0.01 kg of potassium permanganate, 1 kg of naphthalene series water reducer, 1 kg of sodium gluconate, 1 kg of hydroxypropyl methylcellulose, 1 kg of foam stabilizer, and 1 kg of hydrogen peroxide aqueous solution with a mass fraction of 28%.

[0035] The sulfonated flame-retardant mesoporous silicon is prepared by the following specific operations: Add 1 kg of AEO-9 to 20 kg of water and stir evenly, add 2 kg of tetraethyl orthosilicate and 1 kg of aluminum dihydrogen phosphate thereto, stir at a speed of 100 r / min for 5 min, the stirring temperature is 40 °C, adjust the pH value of the system to 8-9 with ammonia water with a mass fraction of 5%, stir for 5 h, add 0.1 kg of 4-ethylbenzenesulfonic acid, stir at a temperature of 150 °C for 1 h, the stirring pressure is 0.5 MPa, cool down to 40 °C, filter, wash the filter cake, and dry it under vacuum.

[0036] The preparation method of the above-mentioned green high-strength foamed gypsum includes the following steps:

[0037] S1. Mix the sulfonated flame-retardant mesoporous silica with desulfurized gypsum, P.O. 52.5 portland cement, nano-zinc oxide whiskers, tourmaline powder, and foam stabilizer, and stir at a speed of 100 r / min for 1 min to obtain a premix;

[0038] S2. Add graphene oxide to 5 kg of water, ultrasonically disperse for 5 min at an ultrasonic frequency of 5 kHz, add acrylamide, continue ultrasonic dispersion for 5 min, purge with nitrogen for 5 min, seal and send it to a cobalt-60 irradiation chamber for irradiation with an irradiation dose of 20 kGy and an irradiation dose rate of 2.9 kGy / h, filter, wash once with deionized water, and dry in vacuum; then add it with naphthalene-based water reducer, sodium gluconate, hydroxypropyl methylcellulose, and potassium permanganate to 30 kg of water, and stir at a speed of 100 r / min for 1 min to obtain a composite admixture;

[0039] S3. Add the composite admixture to the premix, stir at a speed of 100 r / min for 1 min, add an aqueous hydrogen peroxide solution, continue stirring for 5 s, pour into a mold for foaming, demold after molding for 2 h, and cure.

[0040] Example 2

[0041] A green high-strength foamed gypsum, the raw materials of which include: 60 kg of desulfurized gypsum, 15 kg of P.O. 52.5 portland cement, 2 kg of nano-tin oxide whiskers, 2 kg of tourmaline powder, 10 kg of sulfonated flame-retardant mesoporous silica, 5 kg of graphene oxide, 2 kg of acrylamide, 0.1 kg of potassium permanganate, 2 kg of naphthalene-based water reducer, 2 kg of sodium gluconate, 2 kg of polyvinyl alcohol, 2 kg of foam stabilizer, and 3 kg of an aqueous hydrogen peroxide solution with a mass fraction of 32%.

[0042] The sulfonated flame-retardant mesoporous silica is prepared by the following specific operations: Add 3 kg of AEO-9 to 40 kg of water and stir evenly, add 4 kg of tetraethyl orthosilicate and 2 kg of aluminum dihydrogen phosphate thereto, stir at a speed of 500 r / min for 10 min, with a stirring temperature of 50 °C, adjust the pH value of the system to 8 - 9 with 10% ammonia water by mass, stir for 10 h, add 1 kg of 4-ethylbenzenesulfonic acid, stir at a temperature of 160 °C for 2 h, with a stirring pressure of 0.8 MPa, cool down to 60 °C, filter, wash the filter cake, and dry in vacuum.

[0043] The preparation method of the above green high-strength foamed gypsum includes the following steps:

[0044] S1. Mix the sulfonated flame-retardant mesoporous silica with desulfurized gypsum, P.O. 52.5 portland cement, nano-tin oxide whiskers, tourmaline powder, and foam stabilizer, and stir at a speed of 200 r / min for 3 min to obtain a premix;

[0045] S2. Add graphene oxide to 15 kg of water, ultrasonically disperse for 10 min at an ultrasonic frequency of 10 kHz, add acrylamide, continue ultrasonic dispersion for 10 min, purge with nitrogen for 10 min, seal and send it to a cobalt-60 irradiation chamber for irradiation with an irradiation dose of 30 kGy and an irradiation dose rate of 3 kGy / h, filter, wash 3 times with deionized water, and dry in vacuum; then add it together with naphthalene-based water reducer, sodium gluconate, polyvinyl alcohol, and potassium permanganate to 50 kg of water, and stir at a speed of 200 r / min for 3 min to obtain a composite admixture;

[0046] S3. Add the composite admixture to the premix, stir at a speed of 200 r / min for 3 min, add an aqueous hydrogen peroxide solution, continue stirring for 10 s, pour it into a mold for foaming, demold after molding for 4 h, and cure.

[0047] Example 3

[0048] A green high-strength foamed gypsum, the raw materials of which include: 40 kg of desulfurized gypsum, 12 kg of P.O. 52.5 portland cement, 1.3 kg of nano-tin oxide whiskers, 1.8 kg of tourmaline powder, 6 kg of sulfonated flame-retardant mesoporous silica, 4 kg of graphene oxide, 1.3 kg of acrylamide, 0.08 kg of potassium permanganate, 1.3 kg of polycarboxylate water reducer, 1.8 kg of sodium gluconate, 1.3 kg of hydroxypropyl methylcellulose, 1.8 kg of foam stabilizer, and 2.5 kg of an aqueous hydrogen peroxide solution with a mass fraction of 29%.

[0049] The sulfonated flame-retardant mesoporous silica is prepared by the following specific operations: Add 1.5 kg of AEO-9 to 35 kg of water and stir evenly, add 2.5 kg of tetraethyl orthosilicate and 1.8 kg of aluminum dihydrogen phosphate thereto, stir at a speed of 200 r / min for 8 min, with the stirring temperature being 43 °C, adjust the pH value of the system to 8-9 with 8% ammonia water by mass fraction, stir for 7 h, add 0.7 kg of 4-ethylbenzenesulfonic acid, stir at a temperature of 152 °C for 100 min, with the stirring pressure being 0.6 MPa, cool down to 55 °C, filter, wash the filter cake, and dry in vacuum.

[0050] The preparation method of the above green high-strength foamed gypsum includes the following steps:

[0051] S1. Mix the sulfonated flame-retardant mesoporous silica with desulfurized gypsum, P.O. 52.5 portland cement, nano-tin oxide whiskers, tourmaline powder, and foam stabilizer, and stir at a speed of 150 r / min for 2 min to obtain a premix;

[0052] S2. Add graphene oxide to 10 kg of water, ultrasonically disperse for 7 min at an ultrasonic frequency of 9 kHz, add acrylamide, continue ultrasonic dispersion for 6 min, purge with nitrogen for 9 min, seal and send it into a cobalt-60 irradiation chamber for irradiation. The irradiation dose is 22 kGy, the irradiation dose rate is 2.94 kGy / h, filter, wash twice with deionized water, and dry in vacuum; then add it to 40 kg of water together with a polycarboxylate water reducer, sodium gluconate, hydroxypropyl methylcellulose, and potassium permanganate, and stir at a speed of 150 r / min for 2 min to obtain a composite admixture;

[0053] S3. Add the composite admixture to the premix, stir at a speed of 150 r / min for 2 min, add an aqueous hydrogen peroxide solution, continue stirring for 9 s, pour it into a mold for foaming, demold after molding for 2.5 h, and cure.

[0054] Example 4

[0055] A green high-strength foamed gypsum, the raw materials of which include: 50 kg of desulfurized gypsum, 8 kg of P.O. 52.5 portland cement, 1.7 kg of nano-hydroxy stannic acid zinc whiskers, 1.2 kg of tourmaline powder, 8 kg of sulfonated flame-retardant mesoporous silica, 2 kg of graphene oxide, 1.7 kg of acrylamide, 0.02 kg of potassium permanganate, 1.7 kg of polycarboxylate water reducer, 1.2 kg of sodium gluconate, 1.7 kg of hydroxypropyl methylcellulose, 1.4 kg of foam stabilizer, and 1.5 kg of an aqueous hydrogen peroxide solution with a mass fraction of 31%.

[0056] The sulfonated flame-retardant mesoporous silica is prepared by the following specific operations: Add 2.5 kg of AEO-9 to 25 kg of water and stir evenly, add 3.5 kg of tetraethyl orthosilicate and 1.2 kg of aluminum dihydrogen phosphate thereto, stir at a speed of 400 r / min for 6 min, the stirring temperature is 47 °C, adjust the pH value of the system to 8 - 9 with 6% ammonia water by mass fraction, stir for 9 h, add 0.3 kg of 4-ethylbenzenesulfonic acid, stir at a temperature of 158 °C for 80 min, the stirring pressure is 0.7 MPa, cool down to 45 °C, filter, wash the filter cake, and dry in vacuum.

[0057] The preparation method of the above green high-strength foamed gypsum includes the following steps:

[0058] S1. Mix the sulfonated flame-retardant mesoporous silica with desulfurized gypsum, P.O. 52.5 portland cement, nano-hydroxy stannic acid zinc whiskers, tourmaline powder, and foam stabilizer, and stir at a speed of 150 r / min for 2 min to obtain a premix;

[0059] S2. Add graphene oxide to 10 kg of water, ultrasonically disperse for 9 min at an ultrasonic frequency of 7 kHz, add acrylamide, continue ultrasonic dispersion for 8 min, purge with nitrogen for 7 min, seal and send it into a cobalt-60 irradiation chamber for irradiation. The irradiation dose is 28 kGy, the irradiation dose rate is 2.94 kGy / h, filter, wash twice with deionized water, and dry in vacuum; then add it to 40 kg of water together with polycarboxylate superplasticizer, sodium gluconate, hydroxypropyl methylcellulose, and potassium permanganate, and stir at a speed of 150 r / min for 2 min to obtain a composite admixture;

[0060] S3. Add the composite admixture to the premix, stir at a speed of 150 r / min for 2 min, add an aqueous hydrogen peroxide solution, continue stirring for 7 s, pour it into a mold for foaming, demold after molding for 3.5 h, and cure.

[0061] Example 5

[0062] A green high-strength foamed gypsum, the raw materials of which include: 45 kg of desulfurized gypsum, 10 kg of P.O.52.5 portland cement, 1.5 kg of nano-zinc oxide whiskers, 1.5 kg of tourmaline powder, 7 kg of sulfonated flame-retardant mesoporous silica, 3 kg of graphene oxide, 1.5 kg of acrylamide, 0.05 kg of potassium permanganate, 1.5 kg of polycarboxylate superplasticizer, 1.5 kg of sodium gluconate, 1.5 kg of polyvinyl alcohol, 1.5 kg of foam stabilizer, and 2 kg of an aqueous hydrogen peroxide solution with a mass fraction of 30%.

[0063] The sulfonated flame-retardant mesoporous silica is prepared by the following specific operations: Add 2 kg of AEO-9 to 30 kg of water and stir evenly, add 3 kg of tetraethyl orthosilicate and 1.5 kg of aluminum dihydrogen phosphate thereto, stir at a speed of 300 r / min for 7 min, the stirring temperature is 45 °C, adjust the pH value of the system to 8-9 with 7% ammonia water by mass fraction, stir for 8 h, add 0.5 kg of 4-ethylbenzenesulfonic acid, stir at a temperature of 155 °C for 90 min, the stirring pressure is 0.65 MPa, cool down to 50 °C, filter, wash the filter cake, and dry in vacuum.

[0064] The preparation method of the above-mentioned green high-strength foamed gypsum includes the following steps:

[0065] S1. Mix the sulfonated flame-retardant mesoporous silica with desulfurized gypsum, P.O.52.5 portland cement, nano-zinc oxide whiskers, tourmaline powder, and foam stabilizer, and stir at a speed of 150 r / min for 2 min to obtain a premix;

[0066] S2. Add graphene oxide to 10 kg of water, ultrasonically disperse for 8 min at an ultrasonic frequency of 8 kHz, add acrylamide, continue ultrasonic dispersion for 7 min, purge with nitrogen for 8 min, seal and send it into a cobalt-60 irradiation chamber for irradiation. The irradiation dose is 25 kGy and the irradiation dose rate is 2.94 kGy / h. Filter, wash twice with deionized water, and dry in vacuum; then add it to 40 kg of water together with a polycarboxylate water reducer, sodium gluconate, polyvinyl alcohol, and potassium permanganate, and stir at a speed of 150 r / min for 2 min to obtain a composite admixture.

[0067] S3. Add the composite admixture to the premix, stir at a speed of 150 r / min for 2 min, add an aqueous hydrogen peroxide solution, continue stirring for 8 s, pour it into a mold for foaming, demold after 3 h of molding, and cure.

[0068] Comparative Example 1

[0069] A green high-strength foamed gypsum, the raw materials of which include: 45 kg of desulfurized gypsum, 10 kg of P.O. 52.5 portland cement, 1.5 kg of nano-zinc oxide whiskers, 1.5 kg of tourmaline powder, 7 kg of sulfonated flame-retardant mesoporous silica, 3 kg of graphene oxide, 1.5 kg of acrylamide, 0.05 kg of potassium permanganate, 1.5 kg of polycarboxylate water reducer, 1.5 kg of sodium gluconate, 1.5 kg of polyvinyl alcohol, 1.5 kg of foam stabilizer, and 2 kg of an aqueous hydrogen peroxide solution with a mass fraction of 30%.

[0070] The sulfonated flame-retardant mesoporous silica is prepared by the following specific operations: Add 2 kg of AEO-9 to 30 kg of water and stir evenly, add 3 kg of tetraethyl orthosilicate and 1.5 kg of aluminum dihydrogen phosphate thereto, stir at a speed of 300 r / min for 7 min, the stirring temperature is 45 °C, adjust the pH value of the system to 8-9 with 7% ammonia water by mass fraction, stir for 8 h, filter, wash the filter cake, and dry in vacuum.

[0071] The preparation method of the above green high-strength foamed gypsum includes the following steps:

[0072] S1. Mix the sulfonated flame-retardant mesoporous silica with desulfurized gypsum, P.O. 52.5 portland cement, nano-zinc oxide whiskers, tourmaline powder, and foam stabilizer, and stir at a speed of 150 r / min for 2 min to obtain a premix.

[0073] S2. Add graphene oxide to 10 kg of water, ultrasonically disperse for 8 min at an ultrasonic frequency of 8 kHz, add acrylamide, continue to ultrasonically disperse for 7 min, purge with nitrogen for 8 min, seal and send it into a cobalt-60 irradiation chamber for irradiation. The irradiation dose is 25 kGy and the irradiation dose rate is 2.94 kGy / h. Filter, wash twice with deionized water, and dry in vacuum; then add it together with polycarboxylate superplasticizer, sodium gluconate, polyvinyl alcohol, and potassium permanganate to 40 kg of water and stir at a speed of 150 r / min for 2 min to obtain a composite admixture;

[0074] S3. Add the composite admixture to the premix, stir at a speed of 150 r / min for 2 min, add an aqueous hydrogen peroxide solution, continue to stir for 8 s, pour it into a mold for foaming, demold after molding for 3 h, and cure.

[0075] Comparative Example 2

[0076] A green high-strength foamed gypsum, the raw materials of which include: 45 kg of desulfurized gypsum, 10 kg of P.O.52.5 portland cement, 1.5 kg of nano-zinc oxide whiskers, 1.5 kg of tourmaline powder, 7 kg of sulfonated flame-retardant mesoporous silica, 3 kg of graphene oxide, 0.05 kg of potassium permanganate, 1.5 kg of polycarboxylate superplasticizer, 1.5 kg of sodium gluconate, 1.5 kg of polyvinyl alcohol, 1.5 kg of foam stabilizer, and 2 kg of an aqueous hydrogen peroxide solution with a mass fraction of 30%.

[0077] The sulfonated flame-retardant mesoporous silica is prepared by the following specific operations: Add 2 kg of AEO-9 to 30 kg of water and stir evenly, add 3 kg of tetraethyl orthosilicate and 1.5 kg of aluminum dihydrogen phosphate thereto, stir at a speed of 300 r / min for 7 min, the stirring temperature is 45 °C, adjust the pH value of the system to 8-9 with 7% ammonia water by mass fraction, stir for 8 h, add 0.5 kg of 4-ethylbenzenesulfonic acid, stir at a temperature of 155 °C for 90 min, the stirring pressure is 0.65 MPa, cool down to 50 °C, filter, wash the filter cake, and dry in vacuum.

[0078] The preparation method of the above-mentioned green high-strength foamed gypsum includes the following steps:

[0079] S1. Mix the sulfonated flame-retardant mesoporous silica with desulfurized gypsum, P.O.52.5 portland cement, nano-zinc oxide whiskers, tourmaline powder, and foam stabilizer, and stir at a speed of 150 r / min for 2 min to obtain a premix;

[0080] S2. Add graphene oxide together with polycarboxylate superplasticizer, sodium gluconate, polyvinyl alcohol, and potassium permanganate to 40 kg of water and stir at a speed of 150 r / min for 2 min to obtain a composite admixture;

[0081] S3. Add the composite admixture to the premix, stir at a speed of 150 r / min for 2 min, add the hydrogen peroxide aqueous solution, continue to stir for 8 s, pour it into the mold for foaming, demold after molding for 3 h, and cure.

[0082] Perform performance tests on the foamed gypsum obtained in Example 5 and Comparative Examples 1-2 as follows:

[0083] 1. Refer to GB / T8624-2012 "Classification of the Burning Behavior of Building Materials and Products" to determine the burning behavior grade of the specimen.

[0084] The burning behavior grades of the foamed gypsum obtained in Example 5 and Comparative Examples 1-2 are both A1.

[0085] 2. Refer to GB / T18696.2-2002 "Measurement of Sound Absorption Coefficient and Acoustic Impedance in Acoustic Impedance Tube - Part 2: Transfer Function Method" to determine the noise reduction coefficient of the specimen. The noise reduction coefficient is the average value of the sound absorption coefficients at frequencies of 125 Hz, 250 Hz, 500 Hz, 1000 Hz, and 2000 Hz. Refer to GB / T 17671-2021 "Test Method for the Strength of Cement Mortar (ISO Method)" to test the compressive strength and flexural strength of the specimen.

[0086] As Figure 1 and Figure 2 shown, the foamed gypsum obtained in Example 5 has a small bulk density, high noise reduction coefficient, compressive strength, and flexural strength, all of which are superior to those of Comparative Examples 1-2 (P < 0.05), indicating that the foamed gypsum obtained in Example 5 has a good foaming effect and can effectively enhance the compressive and flexural strengths.

[0087] 3. Refer to GB / T 10295-2008 "Determination of Steady-State Thermal Resistance and Related Characteristics of Thermal Insulation Materials - Heat Flow Meter Method" to determine the thermal conductivity of the specimen; refer to GB / T 29417-2012 "Test Method for Dry Shrinkage Cracking Performance of Cement Mortar and Concrete" to determine the dry shrinkage rate of the specimen.

[0088] As Figure 3 shown, the foamed gypsum obtained in Example 5 and Comparative Example 1 has smaller thermal conductivity and dry shrinkage rate, and there is no significant difference between the two (P > 0.05); but both groups are superior to Comparative Example 2 (P < 0.05).

[0089] 4. Refer to GB / T 50082-2009 "Standard Test Method for Long-Term Performance and Durability of Ordinary Concrete" to determine the permeability coefficient of the specimen after different numbers of freeze-thaw cycles.

[0090] As Figure 4As shown, the permeability coefficients of the foamed gypsum obtained in Example 5 and Comparative Example 1 are always low, while the permeability coefficient of the foamed gypsum obtained in Comparative Example 2 increases significantly with the increase in the number of freeze-thaw cycles.

[0091] This is because in the present invention, fatty alcohol polyoxyethylene ether is used as the mesoporous template, tetraethyl orthosilicate is used as the precursor, and it is compounded with aluminum dihydrogen phosphate to prepare a flame-retardant mesoporous silicon material, which can effectively improve the heat resistance and flame retardancy. Then, sulfonation treatment is carried out on the surface of the flame-retardant mesoporous silicon material, which can combine with the amino groups on the surface of the grafted graphene oxide in the composite admixture to form a dense body with a gel structure, thereby improving the flexural strength of the system, reducing shrinkage, preventing structural cracking, and at the same time generating a three-dimensional cross-linking effect, forming a dense colloidal structure together with fine gypsum particles. It not only has high hardness, but also can effectively block the infiltration of water and has excellent freeze-thaw resistance, that is, the freeze-thaw cycle after freezing has no effect on its anti-seepage characteristics. The present invention is irradiated to graft acrylamide onto graphene oxide, making it have amphiphilic properties, which can effectively promote the uniform dispersion of water-reducing agents, retarders, thickeners, potassium permanganate and other admixtures into the premix. The grafted graphene oxide and nanocrystalline whiskers cooperate to effectively promote the uniform dispersion of the chemical foaming agent in the system, promote the stable generation of foam, thereby generating fine foam, forming a uniform foamed gypsum board, and enhancing the strength of the hardened body.

[0092] The above is only the preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution of the present invention and its inventive concept, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. A green high-strength foamed gypsum, characterized in that, Its raw materials by mass parts include: 30 - 60 parts of gypsum, 5 - 15 parts of cement, 1 - 2 parts of nanocrystalline whiskers, 1 - 2 parts of tourmaline powder, 4 - 10 parts of sulfonated flame - retardant mesoporous silica, 1 - 5 parts of graphene oxide, 1 - 2 parts of acrylamide, 0.01 - 0.1 parts of potassium permanganate, 1 - 2 parts of water - reducing agent, 1 - 2 parts of retarding agent, 1 - 2 parts of thickening agent, 1 - 2 parts of foam stabilizer, 1 - 3 parts of chemical foaming agent; The sulfonated flame - retardant mesoporous silica is prepared by using fatty alcohol polyoxyethylene ether as the mesoporous template, taking tetraethyl orthosilicate as the precursor and compounding it with aluminum dihydrogen phosphate, and then undergoing sulfonation treatment; The preparation method of the green high - strength foamed gypsum includes the following steps: S1. Stir the sulfonated flame - retardant mesoporous silica with gypsum, cement, nanocrystalline whiskers, tourmaline powder, and foam stabilizer for 1 - 3 min to obtain a premix; S2. Add graphene oxide into water, ultrasonically disperse for 5 - 10 min, add acrylamide and continue ultrasonically dispersing for 5 - 10 min, purge with nitrogen for 5 - 10 min, seal and irradiate with cobalt - 60, the irradiation dose is 20 - 30 kGy, filter, wash with water, and vacuum dry; then add it together with the water - reducing agent, retarding agent, thickening agent, and potassium permanganate into water and stir for 1 - 3 min to obtain a composite admixture; S3. Add the composite admixture into the premix and stir for 1 - 3 min, add the chemical foaming agent and continue stirring for 5 - 10 s, pour, foam, demold after molding for 2 - 4 h, and cure.

2. The green high-strength foamed gypsum according to claim 1, wherein The gypsum is desulfurized gypsum; the cement is P.O.52.5 Portland cement.

3. The green high-strength foamed gypsum according to claim 1, characterized in that, The nanocrystalline whiskers are at least one of nano - zinc oxide, nano - tin oxide, and nano - zinc hydroxy stannate.

4. The green high-strength foamed gypsum according to claim 1, wherein, The water - reducing agent is a naphthalene - based water - reducing agent or a polycarboxylate water - reducing agent; the thickening agent is hydroxypropyl methylcellulose or / and polyvinyl alcohol.

5. The green high-strength foamed gypsum according to claim 1, wherein The chemical foaming agent is an aqueous hydrogen peroxide solution.

6. The green high-strength foamed gypsum according to claim 1, wherein, The sulfonated flame - retardant mesoporous silica is prepared by the following specific operation: Add fatty alcohol polyoxyethylene ether into water and stir evenly, add tetraethyl orthosilicate and aluminum dihydrogen phosphate thereto, stir at 40 - 50 °C for 5 - 10 min, adjust the pH value of the system to 8 - 9, stir for 5 - 10 h, add 4 - ethylbenzenesulfonic acid, stir at 150 - 160 °C for 1 - 2 h, cool down to 40 - 60 °C, filter, wash the filter cake, and vacuum dry.

7. The green high-strength foamed gypsum according to claim 6, characterized in that, The mass ratio of fatty alcohol polyoxyethylene ether, tetraethyl orthosilicate, aluminum dihydrogen phosphate, and 4 - ethylbenzenesulfonic acid is 1 - 3:2 - 4:1 - 2:0.1 - 1.

8. A method for preparing the green high-strength foamed gypsum according to any one of claims 1-7, characterized in that, It includes the following steps: S1. Stir the sulfonated flame - retardant mesoporous silica with gypsum, cement, nanocrystalline whiskers, tourmaline powder, and foam stabilizer for 1 - 3 min to obtain a premix; S2. Add graphene oxide into water, ultrasonically disperse for 5 - 10 min, add acrylamide and continue ultrasonically dispersing for 5 - 10 min, purge with nitrogen for 5 - 10 min, seal and irradiate with cobalt - 60, the irradiation dose is 20 - 30 kGy, filter, wash with water, and vacuum dry; then add it together with the water - reducing agent, retarding agent, thickening agent, and potassium permanganate into water and stir for 1 - 3 min to obtain a composite admixture; S3. Add the composite admixture into the premix and stir for 1 - 3 min, add the chemical foaming agent and continue stirring for 5 - 10 s, pour, foam, demold after molding for 2 - 4 h, and cure.

9. The preparation method of the green high-strength foamed gypsum according to claim 8, characterized in that, In S2, the ultrasonic frequency is 5 - 10 kHz.

10. The preparation method of the green high-strength foamed gypsum according to claim 8, characterized in that, In S2, the irradiation dose rate is 2.9 - 3.0 kGy / h.

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