Modified brucite fiber reinforced magnesium phosphate cement-based patching material and application thereof

Abstract

The invention relates to the technical field of cement-based patching materials, in particular to a modified brucite fiber reinforced magnesium phosphate cement-based patching material and application thereof. The repairing material comprises the following components in parts by weight: 60-70 parts of magnesium oxide, 15-20 parts of phosphate, 5-9 parts of a retarder, 3-5 parts of modified brucite fibers and 10-15 parts of water. The modified brucite fiber is prepared by the following method: (1) soaking brucite fiber in a dihydric phosphate solution, separating out the brucite fiber after soaking, washing and drying to obtain pretreated fiber; and (2) placing the pretreated fiber in an absolute ethyl alcohol solution of methyltrimethoxysilane, then reacting under a heating condition, separating out the fiber after the reaction is completed, and drying to obtain the modified brucite fiber. The problem that the fluidity, the bonding strength and the fracture toughness of a magnesium phosphate cement-based thin layer repairing material doped with fibers cannot be considered at the same time is effectively solved.

Description

Technical Field

[0001] The invention relates to the technical field of cement-based repair materials, and in particular to a modified brucite fiber-reinforced magnesium phosphate cement-based repair material and application thereof. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention, and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] Thin layer repair is a maintenance construction technology for non-structural diseases such as pitting, peeling and potholes on concrete pavements. The construction process is simple and does not require long-term traffic closures. It can save a lot of construction costs, material costs and maintenance time, effectively delay the spread and spread of road diseases, and extend the service life of roads.

[0004] Commonly used thin-layer repair materials for concrete pavements include silicate cement-based materials, sulfoaluminate cement-based materials, and organic polymer mortars. However, although silicate cement has low cost and readily available raw materials, it sets and hardens slowly, requires film maintenance to prevent water evaporation and avoid early cracking, and cannot meet the needs of rapid restoration of traffic. Although sulfoaluminate cement-based thin-layer repair materials can set and harden quickly and have the advantage of high early strength, they have obvious shrinkage in the later stage, weakened bonding with old concrete, and insufficient durability of the repair. Organic polymer repair mortar has high bonding strength, good flexibility, and can set and harden quickly, but it is expensive and prone to aging.

[0005] Magnesium phosphate cement has the characteristics of fast hardening and early strength, high bonding strength and small drying shrinkage, and is very suitable for thin-layer repair of concrete pavement. However, the thin-layer repair material needs to have sufficient fluidity to fully fill the cracks and potholes of the concrete pavement and form a dense interface transition zone. The water-cement ratio of magnesium phosphate cement is much lower than that of silicate cement. After the addition of fibers, more slurry is required to wrap it, resulting in a decrease in the fluidity of magnesium phosphate cement-based materials. In addition, there is currently no effective water reducer for magnesium phosphate cement, and the fluidity of magnesium phosphate cement-based thin-layer repair materials can only be improved by increasing the water-cement ratio, and increasing the water-cement ratio usually leads to a decrease in bonding strength. Therefore, although the addition of fibers can obtain magnesium phosphate cement-based repair materials with high crack resistance, high toughness and high flexural strength, their fluidity is relatively poor, which further affects their bonding properties, that is, the existing magnesium phosphate cement-based thin-layer repair materials have the problem that fluidity, bonding strength and fracture toughness cannot be taken into account at the same time. Summary of the invention

[0006] The present invention provides a modified brucite fiber-reinforced magnesium phosphate cement-based repair material and its application, effectively overcoming the problem that the fluidity, bond strength, and fracture toughness of the magnesium phosphate cement-based thin-layer repair material doped with fibers cannot be balanced. Specifically, the technical solution of the present invention is as follows.

[0007] First, the present invention discloses a modified brucite fiber-reinforced magnesium phosphate cement-based repair material, which comprises the following components: 60-70 parts by weight of magnesium oxide, 15-20 parts by weight of phosphate, 5-9 parts by weight of retarder, 3-5 parts by weight of modified brucite fiber, and 10-15 parts by weight of water. Wherein: the modified brucite fiber comprises brucite fiber and a coating layer constructed by methyltrimethoxysilane connected to its surface through Si-O-Mg covalent bonds.

[0008] Furthermore, the modified brucite fiber is prepared by the following method: (1) Immerse the brucite fiber in a dihydrogen phosphate solution, then separate the brucite fiber after completion, wash it, and dry it to obtain pretreated fiber for standby.

[0009] (2) Place the pretreated fiber in a solvent in which methyltrimethoxysilane is dissolved, and then react under heating conditions. After completion, separate the fiber and dry it to obtain the modified brucite fiber.

[0010] Furthermore, in step (1), the mass ratio of the pretreated fiber to the brucite fiber is 1:10-20. Optionally, the length of the brucite fiber is 10-30 mm, and the aspect ratio is 100-1200.

[0011] Furthermore, in step (1), the mass fraction of the dihydrogen phosphate solution is 5-10%. Optionally, the dihydrogen phosphate includes at least one of ammonium dihydrogen phosphate, potassium dihydrogen phosphate, etc.

[0012] Furthermore, in step (1), the immersion time is 10-15 min. During this process, part of the brucite fiber dissolves and releases Mg 2+ and OH - , which further reacts with H2PO4 - / HPO4 2- to form magnesium phosphate salt. On the one hand, by the above reaction, the surface alkalinity of the brucite fiber is neutralized, which helps to enhance the subsequent interfacial bonding with methyltrimethoxysilane. Moreover, the above reaction can also expose more hydroxyl groups on the surface of the brucite fiber, enhancing the reaction activity. On the other hand, after the magnesium phosphate salt is loaded on the fiber surface, it also increases the surface roughness of the fiber, which helps to enhance the bonding force between the fiber and the repair material and improve the crack resistance of the repair material.

[0013] Further, in step (1), the drying temperature is 30 - 60°C and the time is 10 - 30 min. Optionally, the fibers are washed with clean water or the like to remove the residual ammonium dihydrogen phosphate solution on the surface.

[0014] Further, in step (2), the mass ratio of the pretreated fibers to the anhydrous ethanol solution of methyltrimethoxysilane is 1:10 - 20.

[0015] Further, in step (2), the mass fraction of methyltrimethoxysilane in the solvent is 2 - 5%. Optionally, the solvent includes anhydrous ethanol, aqueous ethanol solution, etc.

[0016] Further, in step (2), the heating temperature is 30 - 60°C and the reaction time is 20 - 30 min. During this process, the hydroxyl groups on the surface of the brucite fibers react with the silanols formed by the hydrolysis of methyltrimethoxysilane to form Si - O - Mg covalent bonds, so that methyltrimethoxysilane is anchored on the surface of the brucite fibers through covalent bonds to form a coating layer.

[0017] Further, in step (2), the drying temperature is 40 - 80°C and the time is 15 - 60 min.

[0018] Further, the retarder includes at least one of borax, boric acid, zinc sulfate, etc.

[0019] Further, the phosphate includes at least one of ammonium dihydrogen phosphate, potassium dihydrogen phosphate, etc.

[0020] Further, the magnesium oxide includes dead - burned magnesia, etc. Optionally, the fineness of the magnesium oxide is not less than 200 mesh.

[0021] Secondly, the present invention discloses the application of the modified brucite fiber - reinforced magnesium phosphate cement - based repair material in the repair of building walls, concrete pavements, etc.

[0022] Compared with the prior art, the technical solution of the present invention has at least the following beneficial effects: As mentioned above, although adding fibers to magnesium phosphate cement-based repair materials helps to enhance crack resistance, toughness and flexural strength, it will also cause the fluidity of such repair materials to be significantly reduced, which in turn makes it difficult for the repair materials to fully fill cracks, pits, etc. to form a dense interface transition zone, causing the repair materials to fall off easily. To this end, the present invention uses brucite fibers with special ingredients as a substrate, and first uses a dihydrogen phosphate solution to pre-treat the surface thereof. Then the present invention further uses methyltrimethoxysilane to surface-treat the obtained pre-treated brucite fibers, thereby obtaining modified brucite fibers with a coating layer constructed by methyltrimethoxysilane connected to the surface of the fiber by Si-O-Mg covalent bonds. After being added to the repair material, due to its hydrophobicity, it will not absorb too much free water to compete with the hydration reaction of magnesium phosphate cement, thereby maintaining high fluidity of the repair material, which is convenient for better infiltration of the repair base layer. The results show that the fluidity of the repair material of the present invention is similar to that when the fibers are not added. Secondly, after the repair material is filled into the repair part, as the hydration reaction proceeds, the coating layer on the surface of the modified brucite fiber is gradually hydrolyzed under the acidic conditions provided by the hydration of magnesium phosphate cement, and then the magnesium hydroxide on the surface of the brucite fiber reacts with the phosphate to form struvite, which is the same as the hydration product of the repair material, so that there is no interface between the fiber and the repair material matrix, and the toughening effect of the fiber is fully exerted, which effectively solves the problem that the fluidity, bonding strength and fracture toughness of magnesium phosphate cement-based thin layer repair materials cannot be taken into account at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0024] Figure 1 Micrograph of pristine brucite fibers used in Example 1 below.

[0025] Figure 2 This is a micrograph of modified brucite fibers prepared in Example 1 below. DETAILED DESCRIPTION

[0026] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. The experimental methods in the following examples without specifying specific conditions are usually carried out under conventional conditions or under conditions recommended by the manufacturer.

[0027] Unless otherwise defined, all professional and scientific terms used in this invention have the same meanings as those familiar to persons skilled in the art. The reagents or raw materials used in this invention can all be obtained by conventional means. Unless otherwise specified, the reagents or raw materials used in this invention are used in accordance with the conventional methods in the art or in accordance with the product instructions.

[0028] In addition, any methods and materials similar or equivalent to the described content can be applied to the method of this invention. The technical solution of this invention will be further described below in conjunction with the accompanying drawings of the specification and specific embodiments.

[0029] Example 1 The preparation of a modified brucite fiber-reinforced magnesium phosphate cement-based repair material comprises the following steps: 1. Preparation of modified brucite fibers: (1) Brucite fibers with a length of 30 mm and a diameter of 0.03 mm (as shown) are mixed with an ammonium dihydrogen phosphate solution with a mass fraction of 10% according to a solid-liquid ratio of 1 g:10 g and soaked for 10 min. After completion, the brucite fibers are filtered out, washed with clear water, and dried at 30 °C for 30 min to obtain pretreated fibers for standby. Figure 1

[0030] (2) The pretreated fibers are mixed with an absolute ethanol solution with a mass fraction of 2% of methyltrimethoxysilane according to a solid-liquid ratio of 1 g:10 g and stirred evenly, and then heated to 40 °C and kept warm for 30 min. After completion, the fibers are filtered out and dried at 40 °C for 60 min to obtain modified brucite fibers (as shown) for standby. Figure 2

[0031] 2. Take the following components in proportion: 60 parts by weight of dead-burned magnesia with a fineness of 300 mesh, 15 parts by weight of ammonium dihydrogen phosphate powder, 5 parts by weight of borax, 3 parts by weight of the modified brucite fibers of this example, and 10 parts by weight of water.

[0032] 3. Pour the dead-burned magnesia, ammonium dihydrogen phosphate, borax, and modified brucite fibers into a planetary mortar mixer and stir at a rate of 145 r / min for 60 s to obtain a mixed powder. Then add the water and stir at a rate of 290 r / min for 180 s to obtain the magnesium phosphate cement-based repair material.

[0033] Performance test: According to GB / T 8077-2023 "Test Methods for Homogeneity of Concrete Admixtures", GB / T 17671-2021 "Test Methods for the Strength of Cement Mortar" and JGJ 70-2009 "Test Methods for Basic Properties of Building Mortars", the fluidity, compressive strength and tensile bond strength of the magnesium phosphate cement-based repair material prepared in this example were tested. The fracture toughness test was carried out using an electronic universal testing machine, and it was calculated based on the area of the load-displacement curve of the specimen during the three-point bending test. The results are shown in Table 1 below: Table 1 。

[0034] Example 2 Preparation of a modified brucite fiber-reinforced magnesium phosphate cement-based repair material, comprising the following steps: 1. Preparation of modified brucite fibers: (1) Mix brucite fibers with a length of 10 mm and a diameter of 0.05 mm with an ammonium dihydrogen phosphate solution with a mass fraction of 7% according to a solid-liquid ratio of 1 g:15 g, soak for 10 min, then filter out the brucite fibers, wash with clean water and dry at 60 °C for 10 min to obtain pretreated fibers for standby.

[0035] (2) Mix the pretreated fibers with an anhydrous ethanol solution with a mass fraction of 5% of methyltrimethoxysilane according to a solid-liquid ratio of 1 g:10 g, stir evenly, and then heat to 50 °C and keep warm for 25 min. After completion, filter out the fibers and dry at 80 °C for 15 min to obtain modified brucite fibers for standby.

[0036] 2. Take the following components: 65 parts by weight of dead-burned magnesia with a fineness of 200 mesh, 18 parts by weight of ammonium dihydrogen phosphate powder, 7 parts by weight of borax, 4 parts by weight of the modified brucite fibers of this example, and 13 parts by weight of water.

[0037] 3. Pour the dead-burned magnesia, ammonium dihydrogen phosphate, borax, and modified brucite fibers into a planetary mortar mixer and stir at a rate of 145 r / min for 60 s to obtain a mixed powder. Then add the water and stir at a rate of 290 r / min for 180 s to obtain the magnesium phosphate cement-based repair material.

[0038] Performance test: The same method as in Example 1 above was used to test the performance indicators of the magnesium phosphate cement-based repair material prepared in this example. The results are shown in Table 2 below: Table 2 。

[0039] Example 3 Preparation of a modified brucite fiber-reinforced magnesium phosphate cement-based repair material, comprising the following steps: 1. Preparation of modified brucite fibers: (1) Mix brucite fibers with a length of 20 mm and a diameter of 0.04 mm with a 5% mass fraction potassium dihydrogen phosphate solution at a solid-liquid ratio of 1 g:20 g, soak for 15 min, then filter out the brucite fibers, wash with clear water, and dry at 45 °C for 20 min to obtain pretreated fibers for standby.

[0040] (2) Mix the pretreated fibers with an anhydrous ethanol solution with a 3% mass fraction of methyltrimethoxysilane at a solid-liquid ratio of 1 g:20 g, stir evenly, then heat to 60 °C and keep warm for 20 min. After completion, filter out the fibers and dry at 60 °C for 30 min to obtain modified brucite fibers for standby.

[0041] 2. Take the following components in proportion: 70 parts by weight of dead-burned magnesia with a fineness of 400 mesh, 20 parts by weight of potassium dihydrogen phosphate powder, 9 parts by weight of boric acid, 5 parts by weight of the modified brucite fibers of this example, and 15 parts by weight of water.

[0042] 3. Pour the dead-burned magnesia, potassium dihydrogen phosphate, boric acid, and modified brucite fibers into a planetary mortar mixer and stir at a rate of 145 r / min for 60 s to obtain a mixed powder. Then add the water and stir at a rate of 290 r / min for 180 s to obtain the magnesium phosphate cement-based repair material.

[0043] Performance test: Use the same method as in Example 1 above to test the performance indicators of the magnesium phosphate cement-based repair material prepared in this example. The results are shown in Table 3 below: Table 3 。

[0044] Example 4 Preparation of a magnesium phosphate cement-based repair material, comprising the following steps: 1. Take the following components in proportion: 60 parts by weight of dead-burned magnesia with a fineness of 300 mesh, 15 parts by weight of ammonium dihydrogen phosphate powder, 5 parts by weight of borax, and 10 parts by weight of water.

[0045] 2. Pour the dead-burned magnesia, ammonium dihydrogen phosphate, and borax into a planetary mortar mixer and stir at a rate of 145 r / min for 60 s to obtain a mixed powder. Then add the water and stir at a rate of 290 r / min for 180 s to obtain the magnesium phosphate cement-based repair material.

[0046] Performance test: The same method as in Example 1 above was used to test the performance indicators of the magnesium phosphate cement-based repair material prepared in this example, and the results are shown in Table 4 below: Table 4 。

[0047] Example 5 Preparation of a PVA fiber-reinforced magnesium phosphate cement-based repair material, comprising the following steps: 1. Take the following components in proportion: 65 parts by weight of dead-burned magnesia with a fineness of 200 mesh, 18 parts by weight of ammonium dihydrogen phosphate powder, 7 parts by weight of borax, 4 parts by weight of PVA fibers (length 10 mm, diameter 0.05 mm), and 13 parts by weight of water.

[0048] 2. Pour the dead-burned magnesia, ammonium dihydrogen phosphate, borax, and PVA fibers into a planetary mortar mixer and stir at a rate of 145 r / min for 60 s to obtain a mixed powder. Then add the water and stir at a rate of 290 r / min for 180 s to obtain the magnesium phosphate cement-based repair material.

[0049] Performance test: The same method as in Example 1 above was used to test the performance indicators of the magnesium phosphate cement-based repair material prepared in this example, and the results are shown in Table 5 below: Table 5 。

[0050] Example 6 Preparation of a brucite fiber-reinforced magnesium phosphate cement-based repair material, comprising the following steps: 1. Take the following components in proportion: 70 parts by weight of dead-burned magnesia with a fineness of 400 mesh, 20 parts by weight of potassium dihydrogen phosphate powder, 9 parts by weight of boric acid, 5 parts by weight of brucite fibers (length 20 mm, diameter 0.04 mm), and 15 parts by weight of water.

[0051] 2. Pour the dead-burned magnesia, potassium dihydrogen phosphate, boric acid, and brucite fibers into a planetary mortar mixer and stir at a rate of 145 r / min for 60 s to obtain a mixed powder. Then add the water and stir at a rate of 290 r / min for 180 s to obtain the magnesium phosphate cement-based repair material.

[0052] Performance test: The same method as in Example 1 above was used to test the performance indicators of the magnesium phosphate cement-based repair material prepared in this example, and the results are shown in Table 6 below: Table 6 。

[0053] Example 7 Preparation of a modified brucite fiber-reinforced magnesium phosphate cement-based repair material, comprising the following steps: 1. Preparation of modified brucite fibers: Mix brucite fibers with a length of 30 mm and a diameter of 0.03 mm with an absolute ethanol solution containing 2% by mass of methyltrimethoxysilane according to a solid-liquid ratio of 1 g:10 g, stir evenly, and then heat to 40 °C and keep warm for 30 min. After completion, filter out the fibers, and dry them at 40 °C for 60 min to obtain modified brucite fibers for standby.

[0054] 2. Take the following components: 60 parts by weight of dead-burned magnesia with a fineness of 300 mesh, 15 parts by weight of ammonium dihydrogen phosphate powder, 5 parts by weight of borax, 3 parts by weight of the modified brucite fibers of this example, and 10 parts by weight of water.

[0055] 3. Pour the dead-burned magnesia, ammonium dihydrogen phosphate, borax, and modified brucite fibers into a planetary mortar mixer and stir at a rate of 145 r / min for 60 s to obtain a mixed powder. Then add the water and stir at a rate of 290 r / min for 180 s to obtain the magnesium phosphate cement-based repair material.

[0056] Performance test: Use the same method as in Example 1 above to test the performance indexes of the magnesium phosphate cement-based repair material prepared in this example. The results are shown in Table 7 below: Table 7 。

[0057] Example 8 Preparation of a modified brucite fiber-reinforced magnesium phosphate cement-based repair material, comprising the following steps: 1. Preparation of modified brucite fibers: Mix brucite fibers with a length of 10 mm and a diameter of 0.05 mm with an ammonium dihydrogen phosphate solution with a mass fraction of 7% according to a solid-liquid ratio of 1 g:15 g, soak for 10 min, after completion, filter out the brucite fibers, wash them with clear water, and dry them at 60 °C for 20 min to obtain modified brucite fibers for standby.

[0058] 2. Take the following components: 65 parts by weight of dead-burned magnesia with a fineness of 200 mesh, 18 parts by weight of ammonium dihydrogen phosphate powder, 7 parts by weight of borax, 4 parts by weight of the modified brucite fibers of this example, and 13 parts by weight of water.

[0059] 3. Pour the dead-burned magnesia, ammonium dihydrogen phosphate, borax, and modified brucite fibers into a planetary mortar mixer and stir at a rate of 145 r / min for 60 s to obtain a mixed powder. Then add the water and stir at a rate of 290 r / min for 180 s to obtain the magnesium phosphate cement-based repair material.

[0060] Performance test: Use the same method as in Example 1 above to test the performance indicators of the magnesium phosphate cement-based repair material prepared in this example. The results are shown in Table 8 below: Table 8 。

[0061] Example 9 Preparation of a modified PVA fiber-reinforced magnesium phosphate cement-based repair material includes the following steps: 1. Preparation of modified PVA fibers: (1) Mix PVA fibers with a length of 20 mm and a diameter of 0.04 mm with a 5% mass fraction potassium dihydrogen phosphate solution in a solid-liquid ratio of 1 g:20 g, soak for 15 min, then filter out the PVA fibers, wash with clear water, and dry at 45 °C for 20 min to obtain pretreated fibers for standby.

[0062] (2) Mix the pretreated fibers with an anhydrous ethanol solution with a 3% mass fraction of methyltrimethoxysilane in a solid-liquid ratio of 1 g:20 g, stir evenly, and then heat to 60 °C and keep warm for 20 min. After completion, filter out the fibers and dry at 60 °C for 30 min to obtain modified PVA fibers for standby.

[0063] 2. Take the following components in proportion: 70 parts by weight of dead-burned magnesia with a fineness of 400 mesh, 20 parts by weight of potassium dihydrogen phosphate powder, 9 parts by weight of boric acid, 5 parts by weight of the modified PVA fibers of this example, and 15 parts by weight of water.

[0064] 3. Pour the dead-burned magnesia, potassium dihydrogen phosphate, boric acid, and modified PVA fibers into a planetary mortar mixer and stir at a rate of 145 r / min for 60 s to obtain a mixed powder. Then add the water and stir at a rate of 290 r / min for 180 s to obtain the magnesium phosphate cement-based repair material.

[0065] Performance test: Use the same method as in Example 1 above to test the performance indicators of the magnesium phosphate cement-based repair material prepared in this example. The results are shown in Table 9 below: Table 9 。

[0066] The above are only the preferred embodiments of the present invention and are 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 perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A modified brucite fiber-reinforced magnesium phosphate cement-based repair material, characterized in that, It comprises the following components: 60 - 70 parts by weight of magnesium oxide, 15 - 20 parts by weight of phosphate, 5 - 9 parts by weight of retarder, 3 - 5 parts by weight of modified brucite fiber, and 10 - 15 parts by weight of water; wherein: the modified brucite fiber comprises brucite fiber and a coating layer constructed by methyltrimethoxysilane connected to its surface through Si - O - Mg covalent bonds.

2. The modified brucite fiber-reinforced magnesium phosphate cement-based repair material according to claim 1, wherein The modified brucite fiber is prepared by the following method: (1) Immerse the brucite fiber in a dihydrogen phosphate solution, then separate the brucite fiber after completion, wash it and dry it to obtain pretreated fiber for standby; (2) Place the pretreated fiber in a solvent in which methyltrimethoxysilane is dissolved, and then react under heating conditions. After completion, separate the fiber and dry it to obtain the modified brucite fiber.

3. The modified brucite fiber-reinforced magnesium phosphate cement-based repair material according to claim 2, characterized in that, In step (1), the mass ratio of the pretreated fiber to the brucite fiber is 1:10 - 20; Optionally, in step (1), the mass fraction of the dihydrogen phosphate solution is 8 - 20%; Optionally, in step (1), the dihydrogen phosphate includes at least one of ammonium dihydrogen phosphate and potassium dihydrogen phosphate; Optionally, in step (1), the length of the brucite fiber is 10 - 30 mm, and the aspect ratio is 100 - 1200.

4. The modified brucite fiber-reinforced magnesium phosphate cement-based repair material according to claim 2, characterized in that, In step (1), the soaking time is 10 - 15 min; Optionally, in step (1), the drying temperature is 30 - 60 °C, and the time is 10 - 30 min; Optionally, in step (1), the fiber is washed with clear water.

5. The modified brucite fiber-reinforced magnesium phosphate cement-based repair material according to claim 2, characterized in that, In step (2), the mass ratio of the pretreated fiber to the anhydrous ethanol solution of methyltrimethoxysilane is 1:10 - 20.

6. The modified brucite fiber-reinforced magnesium phosphate cement-based repair material according to claim 2, wherein In step (2), the mass fraction of methyltrimethoxysilane in the solvent is 2 - 5%; optionally, the solvent includes any one of anhydrous ethanol and ethanol aqueous solution.

7. The modified brucite fiber-reinforced magnesium phosphate cement-based repair material according to claim 2, wherein, In step (2), the heating temperature is 30 - 60 °C, and the reaction time is 20 - 30 min; optionally, in step (2), the drying temperature is 40 - 80 °C, and the time is 15 - 60 min.

8. The modified brucite fiber-reinforced magnesium phosphate cement-based repair material according to any one of claims 1-7, characterized in that The retarder includes at least one of borax, boric acid, and zinc sulfate; Optionally, the phosphate includes at least one of ammonium dihydrogen phosphate and potassium dihydrogen phosphate.

9. The modified brucite fiber-reinforced magnesium phosphate cement-based repair material according to any one of claims 1-7, characterized in that, The magnesium oxide includes dead - burned magnesia; optionally, the fineness of the magnesium oxide is not less than 200 mesh.

10. Application of the magnesium phosphate cement - based repair material reinforced with the modified brucite fiber according to any one of claims 1 - 9 in the repair of building walls or concrete pavements.

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