Preparation method and application of waterproof and impermeable magnesium phosphate cement-based material

Abstract

The present application relates to the field of magnesium phosphate cement-based materials, and specifically discloses a preparation method of a waterproof and anti-permeation magnesium phosphate cement-based material and application thereof. The preparation method comprises the following steps: taking 80-100 parts by weight of magnesium phosphate cement, 5-8 parts by weight of a setting and hardening regulator, 10-14 parts by weight of a hydrophobic agent prepared by the present application, 7-10 parts by weight of modified graphene oxide and 30-40 parts by weight of active slag powder. After the above raw materials are uniformly mixed, 25-32 parts by weight of mixing water is added, and a magnesium phosphate cement-based material is obtained. The present application takes magnesium phosphate cement as the main component, and adds the hydrophobic agent, modified graphene oxide and active slag powder, so that the problems of insufficient waterproofness and anti-chloride ion erosion of the magnesium phosphate cement coating are overcome, and the magnesium phosphate cement-based material has good crack resistance and secondary protection capability, and can effectively resist the erosion of water and chloride ions.

Description

Technical Field

[0001] This invention relates to the field of magnesium phosphate cement-based materials, specifically to a method for preparing a waterproof and impermeable magnesium phosphate cement-based material and its application. Background Technology

[0002] Offshore platforms, bridges, wharves, and seawalls in marine engineering are primarily constructed using marine concrete. Because these concrete structures are constantly exposed to the high salinity and humidity of the marine environment, they are susceptible to corrosion and cracking. The reinforcing steel in the concrete structure is particularly vulnerable to rust and even breakage under seawater erosion, significantly reducing its resistance to waves and wind. Applying anti-corrosion coatings to the surface of these concrete structures is an effective solution. Current anti-corrosion materials mainly include organic, inorganic, and organic-inorganic composite types. Organic coatings and organic-inorganic composite coatings have poor weather resistance, and the coating layer is prone to aging and cracking under long-term exposure to wind and sun. Inorganic coatings (such as silicate cement-based coatings) have poor resistance to chloride ion erosion, allowing seawater to easily penetrate into the concrete.

[0003] Magnesium phosphate cement (MPC) is a special type of cement mainly composed of recalcined magnesium oxide and phosphate. It hardens rapidly when mixed with water and boasts advantages such as good durability, strong adhesion, and high strength. However, MPC coatings lack sufficient waterproofing and resistance to chloride ion erosion, especially in the aforementioned marine engineering environments. This is because struvite, a hydration product of MPC, dissolves into phosphate, ammonium, and magnesium ions upon water erosion, which then migrate and are lost with the water, increasing the porosity of the MPC coating and reducing its protective ability. Therefore, traditional MPC materials are insufficient to meet the requirements for long-term protection of concrete structures in marine engineering. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a method for preparing a waterproof and impermeable magnesium phosphate cement-based material and its application. This magnesium phosphate cement-based material exhibits excellent waterproof and impermeable capabilities, thereby providing better protection for concrete structures. Specifically, the technical solution of this invention is as follows.

[0005] In a first aspect, the present invention discloses a method for preparing a waterproof and impermeable magnesium phosphate cement-based material, comprising the following steps:

[0006] (1) Mix the solution of fluorinated silane in anhydrous ethanol with magnesium phosphate cement powder, and then heat and dry the mixture to obtain a hydrophobic agent.

[0007] (2) Add graphene oxide to a solution containing Ca2+ A dispersion was formed in the solution, and the graphene oxide was separated after standing. Then, the graphene oxide was dispersed in tea extract, and water-soluble carbonate was added and the mixture was stirred to react. After completion, the solid was separated and dried to obtain modified graphene oxide.

[0008] (3) Add the slag powder to the alkaline solution and then react under heating conditions. Then separate the slag powder, wash and dry it to obtain the activated slag powder.

[0009] (4) Take 80-100 parts by weight of magnesium phosphate cement, 10-14 parts by weight of the above-mentioned hydrophobic agent, 7-10 parts by weight of modified graphene oxide, 30-40 parts by weight of activated slag powder, and 5-8 parts by weight of setting regulator. Mix the above raw materials evenly and then add 25-32 parts by weight of mixing water to obtain magnesium phosphate cement-based material.

[0010] Further, in step (1), the mass fraction of the fluorinated silane in the solution is 3.5-5%. Optionally, the fluorinated silane includes any one of polyperfluoroalkylsiloxane, perfluorooctyltrichlorosilane, tridecafluorooctyltriethoxysilane, tridecafluorooctyltrimethoxysilane, heptadecafluorodecyltriethoxysilane, etc.

[0011] Further, in step (1), the ratio of magnesium phosphate cement to solution is 1g:4~6.5ml.

[0012] Furthermore, in step (1), the heating temperature is 50~60℃ and the time is 20~40min. During the heating process, the mixture is stirred continuously to accelerate the volatilization of ethanol in the mixture.

[0013] Further, in step (2), the graphene reacts with Ca... 2+ The solution has a material-to-liquid ratio of 1g:20~40ml. Optionally, the solution containing Ca... 2+ The mass fraction of the solution is 1~1.5%.

[0014] Further, in step (2), the substance containing Ca 2+ The solution includes at least one of calcium chloride solution, calcium nitrate solution, and calcium acetate solution. Optionally, the standing time is 10-15 minutes.

[0015] Further, in step (2), the ratio of graphene oxide to tea extract is 1g:80~110ml. Optionally, the tea extract is obtained by soaking tea leaves in hot water at 60~85℃ for 20~30 minutes, removing tea residue, and cooling to room temperature.

[0016] Further, in step (2), the mass fraction of carbonate in the tea extract is 1-2%. Optionally, the carbonate includes at least one of sodium carbonate, potassium carbonate, and ammonium carbonate.

[0017] Furthermore, in step (2), the stirring reaction time is 5-10 min. The drying temperature is 40-50℃, and the drying time is 1-1.5 hours.

[0018] Further, in step (3), the ratio of slag powder to alkaline solution is 1g:15~25ml. The heating temperature is 60~70℃, and the reaction time is 25~40min. Optionally, the alkaline solution includes at least one of hydroxide solution, potassium hydroxide solution, etc. The concentration of the alkaline solution is 2~4mol / L. The silicon-oxygen tetrahedron and aluminum-oxygen tetrahedron inert network structure on the surface of the slag powder particles is in OH... - Under the action of calcium ions, the particles are destroyed and depolymerized, causing the Si-O-Si, Si-O-Al, and Al-O-Al bonds to break, thereby increasing the reactivity of the slag powder particles. They can form cementing components such as hydrated calcium silicate and calcium aluminate with calcium ions.

[0019] Further, in step (3), the slag powder is washed until neutral, then dried at 80~90℃ for 1~2 hours, ground after completion, and then passed through a 200~300 mesh sieve to obtain the active slag powder.

[0020] Furthermore, in step (4), the setting agent includes at least one of borax, triethanolamine, zinc sulfate, etc.

[0021] Secondly, this invention discloses the application of the chloride ion-resistant magnesium phosphate cement-based material prepared by the above method in marine engineering, water conservancy engineering, and construction engineering.

[0022] Compared with the prior art, the technical solution of the present invention has at least the following beneficial effects:

[0023] (1) This invention uses magnesium phosphate cement as the base component, and adds the aforementioned hydrophobic agent, modified graphene oxide, and active slag powder to it. This not only overcomes the problem of insufficient waterproof and chloride ion erosion resistance of magnesium phosphate cement coatings, but also gives the waterproof and seepage-resistant magnesium phosphate cement-based material of this invention good crack resistance and secondary protection capabilities. Specifically: The hydrophobic agent of this invention uses magnesium phosphate cement powder as a carrier, and loads fluorosilanes on its surface to form a hydrophobic layer. After the hydrophobic agent is dispersed in the coating, it can construct a hydrophobic system, giving the formed protective coating good waterproof and seepage-resistant properties, thereby preventing chloride ions from penetrating the coating and eroding the steel structure. On the other hand, after the hydrophobic agent enters the coating, it is protected by the hydrophobic layer, keeping the internal magnesium phosphate cement particles in an unhydrated state and retaining them in the formed coating, thus giving the coating secondary protection capabilities. This is because after the fluorosilanes on the hydrophobic agent are eroded and destroyed during the service of the coating, the magnesium phosphate cement particles will quickly undergo a hydration reaction upon contact with water to form a gelling substance, which can seal the seepage pores and channels, thereby preventing further water penetration.

[0024] (2) Graphene oxide distributed in the coating layer can cut off the capillary channels of water seepage, which helps to further improve the waterproof and seepage-resistant properties of the magnesium phosphate cement-based material coating. However, graphene oxide is prone to agglomeration and is not easy to disperse in the coating, which is not conducive to fully exerting the above-mentioned effects of graphene oxide. Therefore, the present invention first disperses graphene oxide in a coating containing Ca 2+In the solution, calcium ions are loaded onto the graphene oxide by utilizing the complexation between the functional groups on the graphene oxide and calcium ions. Furthermore, the present invention further involves adding carbonates to the treated graphene oxide in tea extract, thereby forming active calcium carbonate particles on the graphene oxide. These calcium carbonate particles loaded on the graphene oxide act as steric hindrances, helping to reduce the aggregation of graphene, improve its dispersibility in the coating layer, and enhance the waterproof and impermeable properties of the coating layer. Simultaneously, because the tea extract contains a large amount of polyphenols from tea, whose phenyl hydroxyl groups readily lose electrons and become electronegative, they easily undergo electrostatic adsorption with the calcium ions loaded on the graphene oxide, hindering the transformation of the intermediate metastable calcium carbonate (such as amorphous or aragonite type) formed by the reaction of calcium ions with carbonate ions into stable calcium carbonate (aragonite type), thus converting the calcium ions loaded on the graphene oxide into active calcium carbonate. After dispersing graphene oxide in the coating, it re-dissolves during the subsequent hydration reaction of magnesium phosphate cement and forms calcium hydroxide with the hydroxide ions provided by the hydration reaction. It further reacts with the activated slag powder to form cementitious components such as hydrated calcium silicate and calcium aluminate. This allows graphene oxide, activated slag powder and magnesium phosphate cement hydration products to interweave and combine, improving the strength of the coating layer, thereby enhancing the coating layer's resistance to wind and wave impact and extending the service life of the coating layer. Attached Figure Description

[0025] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention and do not constitute an undue limitation of the invention.

[0026] Figure 1 The following are test graphs showing the chloride ion diffusion coefficient tests performed in Examples 1-3. Detailed Implementation

[0027] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as those skilled in the art. The preferred embodiments and materials described in this invention are for illustrative purposes only. The technical solutions of the present invention will now be further described with reference to specific embodiments.

[0028] Example 1

[0029] A method for preparing a waterproof and impermeable magnesium phosphate cement-based material includes the following steps:

[0030] (1) Dissolve tridefluorooctyltriethoxysilane in anhydrous ethanol to form a 3.5% solution by mass, and then spray the solution onto magnesium phosphate cement powder (the ratio of the two materials to the liquid is 1g:6.5ml) and stir evenly. After completion, dry the resulting mixture at 50℃ for 40min to obtain the hydrophobic agent.

[0031] (2) Graphene oxide and a 1.5% calcium chloride solution were mixed at a ratio of 1g:30ml and stirred until a dispersion was formed. After standing for 10 minutes, the solid was separated by centrifugation. The solid was then added to the tea extract (the ratio of solid to liquid was 1g:80ml) and dispersed evenly. Potassium carbonate was then added at a ratio of 1.5% (by mass) of the extract and stirred until homogeneous. After the reaction was completed, the mixture was stirred for 10 minutes, then the solid was separated by centrifugation and dried at 40℃ for 1.5 hours to obtain modified graphene oxide. The tea extract was prepared in advance as follows: tea leaves were soaked in hot water at 85℃ for 20 minutes, then filtered to remove tea residue, and the resulting extract was cooled to room temperature.

[0032] (3) Add the slag powder to a 2.5 mol / L sodium hydroxide solution at a ratio of 1 g: 25 ml, and then heat to 70 °C and react for 25 min. After the reaction is complete, filter out the slag powder, wash it with water until it is neutral, dry it at 90 °C for 1 hour, grind it, and then pass it through a 200 mesh sieve to obtain the activated slag powder.

[0033] (4) Take 80 parts by weight of magnesium phosphate cement, 5 parts by weight of triethanolamine, 10 parts by weight of the hydrophobic agent prepared in this embodiment, 7 parts by weight of modified graphene oxide, and 30 parts by weight of activated slag powder. Mix the above raw materials evenly and then add 25 parts by weight of mixing water and stir evenly to obtain magnesium phosphate cement-based material.

[0034] The compressive strength of the magnesium phosphate cement-based material prepared in this embodiment was tested according to the "Test Method for Strength of Cement Mortar (ISO Method)" (GB / T 17671-1999).

[0035] The water resistance of the magnesium phosphate cement-based material prepared in this embodiment was tested according to the "Test Procedure for Hydraulic Concrete" (DL / T5150-2001).

[0036] The chloride ion erosion resistance of the magnesium phosphate cement-based material prepared in this embodiment was tested according to the "Test Method for Chloride Ion Diffusion Coefficient of Cement" (JC / T 1086-2008). Figure 1 (As shown).

[0037] The test results for the above performance indicators are as follows: compressive strength (7d) = 82.36 MPa, water seepage height = 1.4 mm, chloride ion diffusion coefficient = 6.08 × 10⁻⁶. -13 m 2 / s.

[0038] Example 2

[0039] A method for preparing a waterproof and impermeable magnesium phosphate cement-based material includes the following steps:

[0040] (1) Dissolve polyperfluoroalkylsiloxane in anhydrous ethanol to form a 4% (w / w) solution, and then spray the solution onto magnesium phosphate cement powder (the ratio of the two materials to the liquid is 1g:5.5ml) and stir evenly. After completion, dry the resulting mixture at 60℃ for 30min to obtain the hydrophobic agent.

[0041] (2) Graphene oxide and a 1.0% calcium nitrate solution were mixed at a ratio of 1g:40ml and stirred until a dispersion was formed. After standing for 15 minutes, the solid was separated by centrifugation. The solid was then added to the tea extract (the ratio of solid to liquid was 1g:100ml) and dispersed evenly. Sodium carbonate was then added at a ratio of 2% (by mass) of sodium carbonate in the extract and stirred until homogeneous. After the reaction was completed, the mixture was stirred for 5 minutes, and then the solid was separated by centrifugation. The solid was dried at 50℃ for 1 hour to obtain modified graphene oxide. The tea extract was prepared in advance as follows: tea leaves were soaked in hot water at 80℃ for 25 minutes, then filtered to remove tea residue, and the resulting extract was cooled to room temperature.

[0042] (3) Add the slag powder to a 2 mol / L sodium hydroxide solution at a ratio of 1 g: 20 ml, and then heat to 65 °C for 30 min. After the reaction is complete, filter out the slag powder, wash it with water until neutral, dry it at 80 °C for 1.5 hours, grind it, and then pass it through a 300 mesh sieve to obtain the activated slag powder.

[0043] (4) Take 92 parts by weight of magnesium phosphate cement, 7 parts by weight of borax, 13 parts by weight of the hydrophobic agent prepared in this embodiment, 9 parts by weight of modified graphene oxide, and 35 parts by weight of activated slag powder. Mix the above raw materials evenly and then add 30 parts by weight of mixing water and stir evenly to obtain magnesium phosphate cement-based material.

[0044] The compressive strength, water impermeability, and chloride ion erosion resistance of the magnesium phosphate cement-based material prepared in this embodiment were tested using the same method as in Example 1 above. Figure 1 (As shown). The results are as follows: compressive strength (7d) = 84.61 MPa, seepage height = 1.1 mm, chloride ion diffusion coefficient = 7.54 × 10⁻⁶. -13m 2 / s.

[0045] Example 3

[0046] A method for preparing a waterproof and impermeable magnesium phosphate cement-based material includes the following steps:

[0047] (1) Dissolve heptadecafluorodecyltriethoxysilane in anhydrous ethanol to form a 5% solution by mass, and then spray the solution onto magnesium phosphate cement powder (the ratio of the two materials to the solution is 1g:4ml) and stir evenly. After completion, dry the resulting mixture at 60℃ for 20min to obtain the hydrophobic agent.

[0048] (2) Graphene oxide and a 1.5% (w / w) calcium acetate solution were mixed at a ratio of 1g:20ml and stirred until homogeneous to form a dispersion. After standing for 15 minutes, the solid was separated by centrifugation. The solid was then added to the tea extract (the ratio of solid to liquid was 1g:110ml) and dispersed evenly. Ammonium carbonate was then added at a ratio of 1% (w / w) of ammonium carbonate in the extract and stirred until homogeneous. After the reaction was completed, the mixture was stirred for 8 minutes, and then the solid was separated by centrifugation. The solid was dried at 50℃ for 1.0 hour to obtain modified graphene oxide. The tea extract was prepared in advance as follows: tea leaves were soaked in hot water at 60℃ for 30 minutes, then filtered to remove tea residue, and the resulting extract was cooled to room temperature.

[0049] (3) Add the slag powder to a 4 mol / L potassium hydroxide solution at a ratio of 1 g: 15 ml, and then heat to 60 °C for 40 min. After the reaction is complete, filter out the slag powder, wash it with water until it is neutral, dry it at 80 °C for 2 hours, grind it, and then pass it through a 300 mesh sieve to obtain the activated slag powder.

[0050] (5) Take 100 parts by weight of magnesium phosphate cement, 8 parts by weight of zinc sulfate, 14 parts by weight of the hydrophobic agent prepared in this embodiment, 10 parts by weight of modified graphene oxide, and 40 parts by weight of activated slag powder. Mix the above raw materials evenly and then add 32 parts by weight of mixing water and stir evenly to obtain magnesium phosphate cement-based material.

[0051] The compressive strength, water impermeability, and chloride ion erosion resistance of the magnesium phosphate cement-based material prepared in this embodiment were tested using the same method as in Example 1 above. Figure 1 (As shown). The results are as follows: compressive strength (7d) = 81.79 MPa, seepage height = 0.8 mm, chloride ion diffusion coefficient = 6.92 × 10⁻⁶. -13 m 2 / s.

[0052] Example 4

[0053] A method for preparing a waterproof and seepage-resistant magnesium phosphate cement-based material includes the following steps: taking 80 parts by weight of magnesium phosphate cement, 5 parts by weight of triethanolamine, 7 parts by weight of modified graphene oxide prepared according to the method in Example 1 above, and 30 parts by weight of activated slag powder. After mixing the above raw materials evenly, 15 parts by weight of mixing water are added and stirred evenly to obtain the magnesium phosphate cement-based material.

[0054] The compressive strength, water permeability, and chloride ion erosion resistance of the magnesium phosphate cement-based material prepared in this embodiment were tested using the same method as in Example 1 above. The results were as follows: compressive strength (7d) = 86.12 MPa, water permeation height = 8.2 mm, and chloride ion diffusion coefficient = 1.71 × 10⁻⁶. -12 m 2 / s.

[0055] Example 5

[0056] A method for preparing a waterproof and impermeable magnesium phosphate cement-based material includes the following steps: taking 92 parts by weight of magnesium phosphate cement, 7 parts by weight of borax, 13 parts by weight of the hydrophobic agent prepared according to the method of Example 2 above, 9 parts by weight of graphene oxide, and 35 parts by weight of active slag powder prepared according to the method of Example 2 above. After mixing the above raw materials evenly, add 30 parts by weight of mixing water and stir evenly to obtain the magnesium phosphate cement-based material.

[0057] The compressive strength, water permeability, and chloride ion attack resistance of the magnesium phosphate cement-based material prepared in this embodiment were tested using the same method as in Example 1 above. The results were as follows: compressive strength (7d) = 74.27 MPa, water permeability height = 2.6 mm, and chloride ion diffusion coefficient = 2.16 × 10⁻⁶. -13 m 2 / s.

[0058] Example 6

[0059] A method for preparing a waterproof and impermeable magnesium phosphate cement-based material includes the following steps:

[0060] (1) Graphene oxide and a 1.5% (w / w) calcium acetate solution were mixed at a ratio of 1 g: 20 ml and stirred until homogeneous to form a dispersion. After standing for 15 min, the solid was separated by centrifugation. The solid was then added to water (the ratio of solid to liquid was 1 g: 110 ml) and dispersed evenly. Ammonium carbonate was then added to the water at a ratio of 1% (w / w) and stirred until homogeneous. After the reaction was completed, the mixture was stirred for 8 min, and then the solid was separated by centrifugation. The solid was dried at 50 °C for 1.0 h to obtain modified graphene oxide.

[0061] (2) Take 100 parts by weight of magnesium phosphate cement, 8 parts by weight of zinc sulfate, 14 parts by weight of the hydrophobic agent prepared according to the method of Example 3 above, 10 parts by weight of the modified graphene oxide prepared in this embodiment, and 40 parts by weight of the active slag powder prepared according to the method of Example 3 above. Mix the above raw materials evenly and then add 32 parts by weight of mixing water and stir evenly to obtain magnesium phosphate cement-based material.

[0062] The compressive strength, water permeability, and chloride ion erosion resistance of the magnesium phosphate cement-based material prepared in this embodiment were tested using the same method as in Example 1 above. The results were as follows: compressive strength (7d) = 77.54 MPa, water permeation height = 1.7 mm, and chloride ion diffusion coefficient = 4.02 × 10⁻⁶. -13 m 2 / s.

[0063] Example 7

[0064] A method for preparing a waterproof and impermeable magnesium phosphate cement-based material includes the following steps: taking 92 parts by weight of magnesium phosphate cement, 7 parts by weight of borax, 13 parts by weight of the hydrophobic agent prepared according to the method of Example 2 above, 9 parts by weight of modified graphene oxide, and 35 parts by weight of slag powder that has not been treated in step (3) of Example 2. After mixing the above raw materials evenly, add 30 parts by weight of mixing water and stir evenly to obtain the magnesium phosphate cement-based material.

[0065] The compressive strength, water permeability, and chloride ion erosion resistance of the magnesium phosphate cement-based material prepared in this embodiment were tested using the same method as in Example 1 above. The results were as follows: compressive strength (7d) = 70.42 MPa, water permeation height = 1.9 mm, and chloride ion diffusion coefficient = 9.39 × 10⁻⁶. -12 m 2 / s.

[0066] Example 8

[0067] A method for preparing a waterproof and impermeable magnesium phosphate cement-based material includes the following steps:

[0068] (1) Graphene oxide and calcium chloride solution with a mass fraction of 1.5% were mixed at a ratio of 1g:30ml and stirred until uniform to form a dispersion. After standing for 10min, the solid was separated by centrifugation to obtain modified graphene oxide.

[0069] (2) Take 80 parts by weight of magnesium phosphate cement, 5 parts by weight of triethanolamine, 10 parts by weight of the hydrophobic agent prepared according to the method of Example 1 above, 7 parts by weight of the modified graphene oxide prepared in this example, and 30 parts by weight of the active slag powder prepared according to the method of Example 1 above. Mix the above raw materials evenly and then add 25 parts by weight of mixing water and stir evenly to obtain magnesium phosphate cement-based material.

[0070] The compressive strength, water permeability, and chloride ion erosion resistance of the magnesium phosphate cement-based material prepared in this embodiment were tested using the same method as in Example 1 above. The results were as follows: compressive strength (7d) = 73.18 MPa, water permeation height = 2.2 mm, chloride ion diffusion coefficient = 2.54 × 10⁻⁶. -13 m 2 / s.

[0071] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., should be included within the protection scope of the present invention.

Claims

1. A method for preparing a waterproof and impermeable magnesium phosphate cement-based material, characterized in that, Includes the following steps: (1) Mix the solution of fluorinated silane in anhydrous ethanol with magnesium phosphate cement powder, and then heat and dry the resulting mixture to obtain a hydrophobic agent. (2) Add graphene oxide to a solution containing Ca 2+ A dispersion is formed in the solution, and the graphene oxide is separated after standing. Then the graphene oxide is dispersed in tea extract, water-soluble carbonate is added and the mixture is stirred to react. After the reaction is completed, the solid is separated and dried to obtain modified graphene oxide. (3) Add the slag powder to the alkaline solution and react it under heating conditions; then separate the slag powder, wash and dry it to obtain the active slag powder; (4) Take 80-100 parts by weight of magnesium phosphate cement, 10-14 parts by weight of the above-mentioned hydrophobic agent, 7-10 parts by weight of modified graphene oxide, 30-40 parts by weight of active slag powder, and 5-8 parts by weight of setting regulator; mix the above raw materials evenly and add 25-32 parts by weight of mixing water to obtain magnesium phosphate cement-based material.

2. The preparation method of the waterproof and impermeable magnesium phosphate cement-based material according to claim 1, characterized in that, In step (1), the mass fraction of fluorosilane in the solution is 3.5-5%; Alternatively, the fluorinated silane may include any one of polyperfluoroalkylsiloxane, perfluorooctyltrichlorosilane, tridecafluorooctyltriethoxysilane, tridecafluorooctyltrimethoxysilane, and heptadecafluorodecyltriethoxysilane.

3. The preparation method of the waterproof and impermeable magnesium phosphate cement-based material according to claim 1, characterized in that, In step (1), the ratio of magnesium phosphate cement to solution is 1g:4~6.5ml; Alternatively, in step (1), the heating temperature is 50~60℃ and the time is 20~40min, with continuous stirring during the heating process.

4. The preparation method of the waterproof and impermeable magnesium phosphate cement-based material according to claim 1, characterized in that, In step (2), the graphene oxide reacts with Ca... 2+ The solution has a material-to-liquid ratio of 1g:20~40ml; or, in step (2), the solution containing Ca... 2+ The mass fraction of the solution is 1~1.5%.

5. The preparation method of the waterproof and impermeable magnesium phosphate cement-based material according to claim 1, characterized in that, In step (2), the substance containing Ca 2+ The solution includes at least one of calcium chloride solution, calcium nitrate solution, and calcium acetate solution; or, in step (2), the standing time is 10-15 min.

6. The preparation method of the waterproof and impermeable magnesium phosphate cement-based material according to claim 1, characterized in that, In step (2), the ratio of graphene oxide to tea extract is 1g:80~110ml; or, the tea extract is obtained by soaking tea leaves in hot water at 60~85℃ for 20~30 minutes, removing tea residue, and cooling to room temperature.

7. The preparation method of the waterproof and impermeable magnesium phosphate cement-based material according to claim 1, characterized in that, In step (2), the mass fraction of carbonate in the tea extract is 1-2%; Alternatively, in step (2), the carbonate includes at least one of sodium carbonate, potassium carbonate, and ammonium carbonate; Alternatively, in step (2), the stirring reaction time is 5 to 10 minutes; Alternatively, in step (2), the drying temperature is 40~50℃ and the drying time is 1~1.5 hours.

8. The preparation method of the waterproof and impermeable magnesium phosphate cement-based material according to claim 1, characterized in that, In step (3), the ratio of slag powder to alkaline solution is 1g:15~25ml; the heating temperature is 60~70℃, and the reaction time is 25~40min; Alternatively, the alkaline solution may include at least one of sodium hydroxide solution and potassium hydroxide solution; the concentration of the alkaline solution is 2-4 mol / L. Alternatively, in step (3), the slag powder is washed until neutral, then dried at 80-90°C for 1-2 hours, ground, and then passed through a 200-300 mesh sieve to obtain the active slag powder.

9. The method for preparing the waterproof and impermeable magnesium phosphate cement-based material according to any one of claims 1-8, characterized in that, In step (4), the setting agent includes at least one of borax, triethanolamine, and zinc sulfate.

10. The application of the waterproof and impermeable magnesium phosphate cement-based material obtained by the preparation method according to any one of claims 1-9 in the fields of marine engineering, water conservancy engineering or construction engineering.

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