Method for repairing concrete crack in alpine region

Abstract

The invention discloses an alpine region concrete crack repairing method, and relates to the field of bridges. Comprising the following steps that the thermal expansion coefficient of a to-be-repaired concrete structure and the size of a crack needing to be repaired are obtained; determining the thermal expansion coefficient and fluidity of the repairing material according to the thermal expansion coefficient of the concrete structure to be repaired and the size of the crack to be repaired; the composition of the repairing material is determined according to the thermal expansion coefficient and fluidity of the repairing material, and the repairing material is prepared; repairing a crack, needing to be repaired, of the concrete structure to be repaired by using a repairing material to obtain repaired concrete; and a hydrophobic material is brushed on the repaired concrete surface, curing is conducted, and the repaired concrete structure is obtained. The thermal expansion coefficient of the repairing material can be kept consistent with that of an original concrete structure, the repairing material and an original concrete material are subjected to coordinated deformation in a multi-time freezing and thawing cycle environment, and generation of new cracks is reduced.

Description

Technical Field

[0001] The present application relates to the field of bridge technology, and in particular to a method for repairing concrete cracks in high-altitude cold regions. Background Art

[0002] In recent years, my country's bridge construction has developed rapidly. More and more large bridges have been built in projects in high-altitude cold areas of the plateau, such as the Sichuan-Tibet Railway, Qinghai-Tibet Railway, and Xinjiang North-South Xinjiang Loop Railway. Due to the low annual average temperature, large temperature difference, strong ultraviolet radiation, and long freezing period in Sichuan-Tibet and Xinjiang, seasonal frost damage is very likely to occur, which poses a major technical challenge to the construction and operation and maintenance of bridge concrete structures. Long-term seasonal freeze-thaw cycles in high-altitude cold areas can cause cracks in bridge concrete, seriously affecting the normal operation of bridges. At present, bridges in service in high-altitude plateau areas such as Sichuan-Tibet have developed bridge cracks of varying degrees, which have affected the healthy service status of the bridges and need to be repaired. Summary of the invention

[0003] The present application provides a method for repairing concrete cracks in high-altitude cold regions to solve the problem of existing bridge cracks that affect the healthy service status of bridges.

[0004] In a first aspect, the present application provides a method for repairing concrete cracks in a high-cold region, comprising the following steps:

[0005] Obtain the thermal expansion coefficient of the concrete structure to be repaired and the size of the crack to be repaired;

[0006] Determine the thermal expansion coefficient and fluidity of the repair material according to the thermal expansion coefficient of the concrete structure to be repaired and the size of the crack to be repaired;

[0007] Determining the composition of the repair material according to the thermal expansion coefficient and fluidity of the repair material, and preparing the repair material;

[0008] Using the repair material to repair the cracks in the concrete structure to be repaired, to obtain repaired concrete;

[0009] The repaired concrete surface is coated with water-repellent material and maintained to obtain a repaired concrete structure.

[0010] In the present application, the thermal expansion coefficient and fluidity of the repair material are determined according to the thermal expansion coefficient of the concrete structure to be repaired and the size of the crack to be repaired, so that the thermal expansion coefficient of the repair material can be consistent with the original concrete structure, and the repair material and the original concrete material can coordinate deformation under multiple freeze-thaw cycles to reduce the generation of new cracks. In addition, the appropriate fluidity of the repair material allows the repair material to be injected into the crack tip and microcracks, completely repairing the original cracks and improving the integrity and density of the concrete structure. By applying a hydrophobic material on the surface of the repaired concrete and maintaining it, the hydrophobic layer can isolate external water and discharge internal water, reducing the probability of cracks in the repaired concrete structure being affected by freeze-thaw cycles.

[0011] In some embodiments, the size of the crack includes the crack depth and the crack opening. The volume of the crack to be repaired can be obtained from the crack depth and the crack opening. According to the crack volume to be repaired, a corresponding amount of repair material can be configured. At the same time, according to the crack depth, the fluidity of the repair material can be calculated so that the repair material can be injected into the crack tip and microcracks to completely repair the original crack and ensure the integrity and density of the concrete structure.

[0012] In some embodiments, in the process of determining the thermal expansion coefficient and fluidity of the repair material according to the thermal expansion coefficient of the concrete structure to be repaired and the size of the crack to be repaired, the thermal expansion coefficient of the repair material is V1, and the thermal expansion coefficient of the concrete structure to be repaired is V2, wherein 0.9≤V1 / V2≤1.1. The closer the thermal expansion coefficient of the repair material is to the thermal expansion coefficient of the concrete structure to be repaired, the more likely the concrete structure can deform together after the repair is completed, thereby reducing the occurrence of secondary cracks, reducing the further development of cracks, and improving the strength of the repaired concrete. The thermal expansion coefficient of the concrete structure to be repaired can be obtained by strain gauge measurement, and the thermal expansion coefficient of the repair material can be obtained by dilatometer method.

[0013] In some embodiments, the repair material includes sulphoaluminate cement, silicate cement, slag, silica fume, limestone powder, polycarboxylate water reducer, retarder and inorganic salt early strength agent. The above-mentioned repair material has early high strength characteristics, can quickly form strength under cold conditions, and has frost resistance, can withstand multiple thawing cycles, and improves the strength and service life of the repaired concrete structure. The proportions of sulphoaluminate cement, silicate cement, slag, silica fume, limestone powder, polycarboxylic acid water reducer, retarder and inorganic salt early strength agent can be selected according to the actual expansion coefficient and fluidity of the repair material. In some embodiments, the mass ratio can also be (600-800):(100-200):(100-200):(50-100):(50-100):(2-3):(2-3):(1-8). Polycarboxylic acid water reducer includes polyester polycarboxylic acid water reducer, polyether polycarboxylic acid water reducer, amide / imide polycarboxylic acid water reducer and amphoteric polycarboxylic acid water reducer, among which Sika 530P can be selected as the polycarboxylic acid water reducer. Inorganic retarders mainly include phosphates, metaphosphates, zinc salts, ferric sulfate, copper sulfate, fluorosilicates and boric acid, etc. Organic retarders include hydroxycarboxylic acids and their salts (such as citric acid, gluconic acid), polyols and their derivatives (such as molasses), etc. Boric acid can be selected as the retarder, and inorganic salt early strength agents can be selected from at least one of calcium formate, calcium chloride and sodium sulfate.

[0014] In some embodiments, the fluidity of the repair material is 300-400 mm, which means that the repair material can flow a distance of 300-400 mm under the measurement conditions specified in Chapter 13 of "Test Method for Homogeneity of Concrete Admixtures" (GB / T 8077-2012). Within this fluidity range, it can be ensured that the repair material can be injected into the crack tip and microcracks, completely repair the original cracks, ensure the integrity and density of the concrete structure, and reduce the further development of the cracks.

[0015] In some embodiments, the repair material is used to repair the cracks in the concrete structure to be repaired, and the grouting pressure of the repaired concrete is 0.2-0.8 MPa. The grouting pressure of the repair is within this range, which can allow the repair material to enter the fine cracks, while reducing the damage of the grouting pressure to the concrete structure to be repaired, reducing the generation of secondary cracks, and improving the strength and service life of the repaired concrete structure.

[0016] In some embodiments, the hydrophobic material is applied to the repaired concrete surface and maintained, so that in the repaired concrete structure, the application area of ​​the hydrophobic material at least covers the repaired area and extends 30 to 50 cm. The application area of ​​the hydrophobic material at least covers the repaired area and extends 30 to 50 cm can protect the repaired concrete structure, reduce rainwater leakage to the repaired area, reduce the generation of secondary cracks, improve the strength of the repaired concrete structure, and improve the service life of the repaired concrete structure.

[0017] In some embodiments, the hydrophobic material includes silane compounds, nano-SiO2, polyaniline, a curing agent and an organic solvent. After the above-mentioned hydrophobic material is coated, the outer surface is hydrophobic, and the side in contact with the concrete can allow the normal discharge of water from the concrete respiration. The different characteristics of the two surfaces constitute a "diode"-like structure, isolating external water and discharging internal water, reducing the probability of cracks in the repaired concrete structure due to the freeze-thaw cycle. Improve the frost resistance and UV aging resistance of the concrete structure, and extend the service life of the concrete structure in the service stage. The silane compound can be selected from at least one of hexadecyltrichlorosilane, methyltrimethoxysilane, and octyltrichlorosilane. The curing agent can be selected from polydimethylsiloxane. The organic solvent is selected from at least one of ethyl acetate, anhydrous ethanol, acetone, and hexane.

[0018] In some embodiments, the coating thickness of the hydrophobic material is 0.5 to 2 mm. When the coating thickness of the hydrophobic material is within this range, it can further isolate external water and drain internal water, thereby reducing the probability of cracks in the repaired concrete structure due to freeze-thaw cycles. It improves the frost resistance and UV aging resistance of the concrete structure and extends the service life of the concrete structure in service.

[0019] In some embodiments, the hydrophobic material is applied to the repaired concrete surface and cured, so that in the repaired concrete structure, the hydrophobic layer formed by the application of the hydrophobic material has a contact angle of greater than 150° between the outer surface of the hydrophobic layer and water after curing. The contact angle of greater than 150° between the outer surface of the hydrophobic layer and water can improve the hydrophobicity, reduce the entry of external moisture into the repaired concrete structure, improve the service life of the concrete structure, and reduce the cracking of the concrete. The outer surface of the hydrophobic layer refers to the side of the hydrophobic layer away from the concrete repair structure, that is, the side in contact with the air. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0021] Figure 1 This is a flow chart of an embodiment of a method for repairing concrete cracks in high-cold areas of the present application.

[0022] Figure 2 This is a schematic diagram of the protection of the repaired concrete by the hydrophobic layer according to an embodiment of the method for repairing concrete cracks in high-altitude cold regions of the present application. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the present application clearer, the technical solution of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present application.

[0024] In recent years, my country's bridge construction has developed rapidly. More and more large bridges have been built in projects in high-altitude cold areas of the plateau, such as the Sichuan-Tibet Railway, Qinghai-Tibet Railway, and Xinjiang North-South Xinjiang Loop Railway. Due to the low annual average temperature, large temperature difference, strong ultraviolet radiation, and long freezing period in Sichuan-Tibet and Xinjiang, seasonal frost damage is very likely to occur, which poses a major technical challenge to the construction and operation and maintenance of bridge concrete structures. Long-term seasonal freeze-thaw cycles in high-altitude cold areas can cause cracks in bridge concrete, seriously affecting the normal operation of bridges. At present, bridges in service in high-altitude plateau areas such as Sichuan-Tibet have developed bridge cracks of varying degrees, which have affected the healthy service status of the bridges and need to be repaired.

[0025] Alpine areas refer to extremely cold climate zones formed due to high altitude or high latitude. The annual average temperature is usually below 0℃, with a huge temperature difference between day and night, high temperature during the day and low temperature at night, and strong ultraviolet rays. The thermal expansion and contraction of bridges are very obvious. There is also a significant seasonal freeze-thaw cycle, with ice expanding in winter and melting and collapsing in spring. This periodic freeze-thaw effect causes great damage to bridges and easily leads to the generation of a large number of cracks, affecting the reliability of bridges. Existing bridge repair methods usually have the problem of secondary cracks after repair, or the original cracks are not completely repaired, and the cracks continue to increase and deepen, which makes the bridge condition worse.

[0026] In view of this, the present application provides a method for repairing concrete cracks in high-altitude cold regions to solve the problem of existing bridge cracks that affect the healthy service status of bridges.

[0027] First, as Figure 1 As shown, the present application provides a method for repairing concrete cracks in high-cold areas, comprising the following steps:

[0028] S10, obtaining the thermal expansion coefficient of the concrete structure to be repaired and the size of the crack to be repaired;

[0029] S20, determining the thermal expansion coefficient and fluidity of the repair material according to the thermal expansion coefficient of the concrete structure to be repaired and the size of the crack to be repaired;

[0030] S30, determining the composition of the repair material according to the thermal expansion coefficient and fluidity of the repair material, and preparing the repair material;

[0031] S40, using a repair material to repair cracks in the concrete structure to be repaired, to obtain repaired concrete;

[0032] S50. Apply water-repellent material on the repaired concrete surface and perform curing to obtain a repaired concrete structure.

[0033] In the present application, the thermal expansion coefficient and fluidity of the repair material are determined according to the thermal expansion coefficient of the concrete structure to be repaired and the size of the crack to be repaired, so that the thermal expansion coefficient of the repair material can be consistent with the original concrete structure, and the repair material and the original concrete material can coordinate deformation under multiple freeze-thaw cycles to reduce the generation of new cracks. In addition, the appropriate fluidity of the repair material allows the repair material to be injected into the crack tip and microcracks, completely repairing the original cracks and improving the integrity and density of the concrete structure. By applying a hydrophobic material on the surface of the repaired concrete and maintaining it, the hydrophobic layer can isolate external water and discharge internal water, reducing the probability of cracks in the repaired concrete structure being affected by freeze-thaw cycles.

[0034] In combination with the first aspect, in some embodiments provided in the present application, the size of the crack includes the depth of the crack and the opening of the crack. The opening of a concrete crack is the crack width, which refers to the straight-line distance between the walls on both sides of the crack, and is directly related to the degree of influence of the crack on the structural performance. The measurement of the crack width can be obtained by direct observation, using a crack width meter or laser scanning technology. The volume of the crack to be repaired can be obtained by the depth of the crack and the opening of the crack. According to the volume of the crack to be repaired, a corresponding amount of repair material can be configured. At the same time, according to the crack depth, the fluidity of the repair material can be calculated, so that the repair material can be injected into the crack tip and microcracks to completely repair the original cracks and ensure the integrity and density of the concrete structure.

[0035] In combination with the first aspect, in some embodiments provided in the present application, in the determination of the thermal expansion coefficient and fluidity of the repair material according to the thermal expansion coefficient of the concrete structure to be repaired and the size of the crack to be repaired, the thermal expansion coefficient of the repair material is V1, and the thermal expansion coefficient of the concrete structure to be repaired is V2, wherein 0.9≤V1 / V2≤1.1. The thermal expansion coefficient of the concrete structure refers to the length or volume change rate of the concrete material per unit temperature change when the temperature changes. The closer the thermal expansion coefficient of the repair material is to the thermal expansion coefficient of the concrete structure to be repaired, the more likely the concrete structure can deform together after the repair is completed, thereby reducing the occurrence of secondary cracks, reducing the further development of cracks, and improving the strength of the repaired concrete. The thermal expansion coefficient of the concrete structure to be repaired can be obtained by strain gauge measurement, and the thermal expansion coefficient of the repair material can be obtained by the dilatometer method.

[0036] In combination with the first aspect, in some embodiments provided in the present application, the repair material includes sulphoaluminate cement, silicate cement, slag, silica fume, limestone powder, polycarboxylate water reducer, retarder and inorganic salt early strength agent. The above-mentioned repair material has early high strength characteristics, can quickly form strength under cold conditions, and has frost resistance, can withstand multiple thawing cycles, and improves the strength and service life of the repaired concrete structure. The proportions of sulphoaluminate cement, silicate cement, slag, silica fume, limestone powder, polycarboxylic acid water reducer, retarder and inorganic salt early strength agent can be selected according to the actual expansion coefficient and fluidity of the repair material. In some embodiments, the mass ratio can also be (600-800):(100-200):(100-200):(50-100):(50-100):(2-3):(2-3):(1-8). Polycarboxylic acid water reducer includes polyester polycarboxylic acid water reducer, polyether polycarboxylic acid water reducer, amide / imide polycarboxylic acid water reducer and amphoteric polycarboxylic acid water reducer, among which Sika 530P can be selected as the polycarboxylic acid water reducer. Inorganic retarders mainly include phosphates, metaphosphates, zinc salts, ferric sulfate, copper sulfate, fluorosilicates and boric acid, etc. Organic retarders include hydroxycarboxylic acids and their salts (such as citric acid, gluconic acid), polyols and their derivatives (such as molasses), etc. Boric acid can be selected as the retarder, and inorganic salt early strength agents can be selected from at least one of calcium formate, calcium chloride and sodium sulfate.

[0037] In combination with the first aspect, in some embodiments provided in the present application, the fluidity of the repair material is 300 to 400 mm. It means that the repair material can flow a distance of 300 to 400 mm under the measurement conditions specified in Chapter 13 of the Test Method for Homogeneity of Concrete Admixtures (GB / T8077-2012). Within this fluidity range, it can be ensured that the repair material can be injected into the crack tip and microcracks, completely repair the original cracks, ensure the integrity and density of the concrete structure, and reduce the further development of the cracks. The fluidity of the repair material includes but is not limited to 300 mm, 310 mm, 320 mm, 330 mm, 340 mm, 350 mm, 360 mm, 370 mm, 380 mm, 390 mm or 400 mm.

[0038] In combination with the first aspect, in some embodiments provided in the present application, the use of the repair material to repair the cracks that need to be repaired in the concrete structure to be repaired, the repair grouting pressure in the repaired concrete is 0.2 to 0.8 MPa. The repair grouting pressure within this range can allow the repair material to enter the micro-cracks, while reducing the damage of the grouting pressure to the concrete structure to be repaired, reducing the generation of secondary cracks, and improving the strength and service life of the repaired concrete structure. The repair grouting pressure includes but is not limited to 0.2MPa, 0.3MPa, 0.4MPa, 0.5MPa, 0.6MPa, 0.7MPa or 0.8MPa.

[0039] In combination with the first aspect, in some embodiments provided in the present application, the hydrophobic material is applied to the surface of the repaired concrete and maintained, so that in the repaired concrete structure, the application area of ​​the hydrophobic material at least covers the repair area and extends 30 to 50 cm. The application area of ​​the hydrophobic material at least covers the repair area and extends 30 to 50 cm. This can protect the repaired concrete structure, reduce the leakage of rainwater to the repaired area, reduce the occurrence of secondary cracks, improve the strength of the repaired concrete structure, and improve the service life of the repaired concrete structure. The extension range includes but is not limited to 30cm, 35cm, 40cm, 45cm or 50cm.

[0040] In combination with the first aspect, in some embodiments provided in the present application, the hydrophobic material comprises a silane compound, nano-SiO2, polyaniline, a curing agent and an organic solvent. Figure 2As shown, the outer surface is hydrophobic, and the side in contact with the concrete can allow the normal discharge of water from the concrete respiration. The different characteristics of the two surfaces form a "diode"-like structure, isolating external water and discharging internal water, reducing the probability of cracks in the repaired concrete structure due to freeze-thaw cycles. Improve the frost resistance and UV aging resistance of the concrete structure, and extend the service life of the concrete structure in the service stage. The silane compound can be selected from at least one of hexadecyltrichlorosilane, methyltrimethoxysilane, and octyltrichlorosilane. The curing agent can be selected from polydimethylsiloxane. The organic solvent is selected from at least one of ethyl acetate, anhydrous ethanol, acetone, and hexane.

[0041] In combination with the first aspect, in some embodiments provided in the present application, the coating thickness of the hydrophobic material is 0.5 to 2 mm. Within this range, the coating thickness of the hydrophobic material can further isolate external water and drain internal water, reducing the probability of cracks in the repaired concrete structure being affected by freeze-thaw cycles. Improve the frost resistance and UV aging resistance of the concrete structure, and extend the service life of the concrete structure in service. The coating thickness of the hydrophobic material includes but is not limited to 0.5 mm, 0.8 mm, 1.0 mm, 1.2 mm, 1.5 mm, 1.7 mm or 2.0 mm.

[0042] In combination with the first aspect, in some embodiments provided in the present application, the hydrophobic material is applied to the repaired concrete surface and cured, so that in the repaired concrete structure, the hydrophobic layer formed by the application of the hydrophobic material, after curing, has a contact angle between the outer surface of the hydrophobic layer and water greater than 150°. The contact angle between the outer surface of the hydrophobic layer and water greater than 150° can improve the hydrophobicity, reduce the entry of external moisture into the repaired concrete structure, increase the service life of the concrete structure, and reduce the cracking of the concrete. The outer surface of the hydrophobic layer refers to the side of the hydrophobic layer away from the concrete repair structure, that is, the side in contact with the air.

[0043] In summary, the thermal expansion coefficient and fluidity of the repair material can be determined according to the thermal expansion coefficient of the concrete structure to be repaired and the size of the crack to be repaired, so that the thermal expansion coefficient of the repair material can be consistent with the original concrete structure, and the repair material and the original concrete material can coordinate deformation under multiple freeze-thaw cycles to reduce the generation of new cracks. In addition, the appropriate fluidity of the repair material allows the repair material to be injected into the crack tip and microcracks, completely repairing the original cracks and improving the integrity and density of the concrete structure. By applying a hydrophobic material on the surface of the repaired concrete and maintaining it, the hydrophobic layer can isolate external water and drain internal water, reducing the probability of cracks in the repaired concrete structure being affected by freeze-thaw cycles.

[0044] In the description of this specification, the description with reference to the terms "one embodiment / method", "some embodiments / methods", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment / method or example are included in at least one embodiment / method or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment / method or example. Moreover, the specific features, structures, materials or characteristics described may be combined in a suitable manner in any one or more embodiments / methods or examples. In addition, those skilled in the art may combine and combine the different embodiments / methods or examples described in this specification and the features of the different embodiments / methods or examples, unless they are contradictory.

[0045] It should be noted that, in the present application, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or equipment. In the absence of more restrictions, the elements defined by the sentence "comprise one..." do not exclude the existence of other identical elements in the process, method, article or equipment including the elements. In the present application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically stipulated.

[0046] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A method for repairing concrete cracks in high-cold areas, characterized in that: The following steps are involved: Obtain the thermal expansion coefficient of the concrete structure to be repaired and the size of the crack to be repaired; Determine the thermal expansion coefficient and fluidity of the repair material according to the thermal expansion coefficient of the concrete structure to be repaired and the size of the crack to be repaired; Determining the composition of the repair material according to the thermal expansion coefficient and fluidity of the repair material, and preparing the repair material; Using the repair material to repair the cracks in the concrete structure to be repaired, to obtain repaired concrete; The repaired concrete surface is coated with water-repellent material and maintained to obtain a repaired concrete structure.

2. The method for repairing concrete cracks in high-cold areas as claimed in claim 1, characterized in that: The size of the crack includes the depth of the crack and the opening of the crack.

3. The method for repairing concrete cracks in high-cold areas as claimed in claim 1, characterized in that: In the method of determining the thermal expansion coefficient and fluidity of the repair material according to the thermal expansion coefficient of the concrete structure to be repaired and the size of the crack to be repaired, the thermal expansion coefficient of the repair material is V1, and the thermal expansion coefficient of the concrete structure to be repaired is V2, wherein 0.9≤V1 / V2≤1.

1.

4. The method for repairing concrete cracks in high-cold areas as claimed in claim 1, characterized in that: The repair material includes sulphoaluminate cement, silicate cement, slag, silica fume, limestone powder, polycarboxylic acid water reducer, retarder and inorganic salt early strength agent.

5. The method for repairing concrete cracks in high-cold areas as claimed in claim 1, characterized in that: The fluidity of the repair material is 300-400 mm.

6. The method for repairing concrete cracks in high-cold areas as claimed in claim 1, characterized in that: The repair material is used to repair the cracks in the concrete structure to be repaired, so that the grouting pressure of the repaired concrete is 0.2-0.8 MPa.

7. The method for repairing concrete cracks in high-cold areas as claimed in claim 1, characterized in that: The hydrophobic material is applied to the repaired concrete surface and maintained, so that in the repaired concrete structure, the application area of ​​the hydrophobic material at least covers the repair area and extends within a range of 30 to 50 cm.

8. The method for repairing concrete cracks in high-cold areas as claimed in claim 1, characterized in that: The hydrophobic material comprises silane compounds, nano-SiO2, polyaniline, a curing agent and an organic solvent.

9. The method for repairing concrete cracks in high-cold areas as claimed in claim 1, characterized in that: The coating thickness of the hydrophobic material is 0.5 to 2 mm.

10. The method for repairing concrete cracks in high-cold areas as claimed in claim 1, characterized in that: The hydrophobic material is applied to the repaired concrete surface and then cured, so that in the repaired concrete structure, a hydrophobic layer formed by applying the hydrophobic material has a contact angle of greater than 150° between the outer surface of the hydrophobic layer and water after curing.

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