A high-salt high-humidity environment mass concrete crack rapid repairing method

Abstract

The application discloses a kind of high-salt high-humidity environment mass concrete crack fast repair methods, comprising: S1: the concrete crack is cleaned, adopts high-pressure airflow to blow the inside and surface of crack, remove the impurities such as dust, loose debris etc. in crack, then with prepared salt-removing solution, to low-pressure spray mode is to crack inside and surrounding concrete is sprayed and handled;S2: water and crack repair material are poured into mixer according to mass ratio 0.04-0.1:1, and stirred for 5-15 minutes, to obtain crack repair material;S3: crack repair material is injected to interface treatment good concrete crack inside, after filling, using low-frequency vibration to remove air bubble, ensure that crack repair material fills up cracked concrete;The scheme can effectively improve the salt resistance and moisture resistance of crack repair material, reduce the internal temperature of concrete and fast repair ability, avoid crack repair material to fall off, aging and other phenomena, improve the durability and safety of mass concrete structure under high-salt high-humidity environment.

Description

Technical Field

[0001] This invention relates to the field of building repair technology, and in particular to a method for rapid repair of cracks in large-volume concrete in high-salt and high-humidity environments. Background Technology

[0002] Large-volume concrete structures (such as cross-sea bridges, port terminals, and permanent buildings on distant islands and reefs) are prone to temperature and shrinkage cracks during casting and subsequent use due to their large size and concentrated heat release from hydration. These cracks are particularly dangerous in high-salt and high-humidity environments. On the one hand, high humidity accelerates moisture migration within the concrete, exacerbating crack propagation. On the other hand, chloride and sulfate ions in the environment can seep into the concrete through cracks, causing steel reinforcement corrosion. Simultaneously, the expansion of salt crystals at the cracks further damages the integrity of the concrete structure, leading to wider cracks, repair layer detachment, and seriously threatening structural safety and service life.

[0003] Existing methods for repairing cracks in large-volume concrete in high-salt and high-humidity environments suffer from several drawbacks. First, the repair materials are susceptible to erosion by salt and humidity, leading to a rapid decline in adhesion and difficulty in maintaining repair effectiveness. Second, they exhibit weak resistance to salt and moisture erosion, easily forming secondary cracks in high-salt and high-humidity environments. Third, they have poor compatibility with the concrete substrate, insufficient aging resistance, and unsatisfactory repair results. Furthermore, they suffer from long construction cycles and high costs. Therefore, developing a rapid repair method for large-volume concrete cracks that can adapt to high-salt and high-humidity environments, provides durable repairs, has strong resistance to salt erosion, and is easy to implement has become a pressing technical challenge in this field. Summary of the Invention

[0004] To address the problems in the existing technology, this invention provides a method for rapid repair of large-volume concrete cracks in high-salt and high-humidity environments. Through the rational design of materials and processes, it can effectively improve the salt and moisture resistance of concrete repair materials, reduce the internal temperature of concrete, and enhance rapid repair capabilities, effectively preventing phenomena such as crack repair material detachment, aging, and secondary cracking.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] This invention provides a method for rapid repair of cracks in large-volume concrete in high-salt and high-humidity environments, comprising the following steps:

[0007] S1: Clean the surface of the concrete cracks by blowing the inside and surface of the cracks with high-pressure airflow to remove dust, loose debris and other impurities. Then, use a prepared desalination solution to spray the inside and surrounding concrete of the cracks with low-pressure spraying to complete the interface treatment of the concrete cracks.

[0008] S2: Pour water and crack repair material into a mixer at a mass ratio of 0.04-0.1:1 and mix for 5-15 minutes to obtain crack repair material;

[0009] S3: Inject the crack repair material into the concrete cracks after the interface treatment. After filling, use low-frequency vibration to remove air bubbles and ensure that the crack repair material fills the cracked concrete.

[0010] Furthermore, the raw material components of the desalination solution described in this scheme, by weight, include: 30-40 parts of ethylenediaminetetraacetic acid, 25-35 parts of sodium citrate, 5-10 parts of polyacrylamide, and 5-15 parts of water.

[0011] Furthermore, the method for preparing the desalination solution described in this scheme includes the following steps:

[0012] (1) Measure ethylenediaminetetraacetic acid, sodium citrate and water separately using a weighing scale, then pour them into a container and stir for 10-20 minutes;

[0013] (2) Add polyacrylamide to the container and continue stirring for 15-20 minutes to obtain a desalination solution.

[0014] Furthermore, the raw material components of the crack repair material described in this scheme, by weight, include: 30-40 parts of sulfoaluminate cement, 5-10 parts of fly ash, 2-16 parts of silica fume, 3-10 parts of slag powder, 2-8 parts of glass microspheres, 10-50 parts of sand, 2-5 parts of UHPC salt-resistant low-heat quick-setting agent, 0.5-2.5 parts of fiber, and 4-13 parts of water.

[0015] Furthermore, the preparation method of the crack repair material described in this scheme includes the following steps:

[0016] (1) Calculate the sulfoaluminate cement, fly ash, silica fume, slag powder, glass microspheres, sand and water separately and then transport them to the mixer and mix for 8-15 minutes.

[0017] (2) Add the fiber to the mixer and mix for 5-15 minutes;

[0018] (3) Add UHPC salt-resistant low-heat quick-setting agent to the mixer and continue mixing for 10-20 minutes to obtain crack repair material.

[0019] Furthermore, the sulfoaluminate cement strength grade described in this scheme is any one or more combinations of 42.5 and 52.5.

[0020] Furthermore, the sand described in this plan is standard sand with a sieve mesh size of 30-70 mesh.

[0021] Furthermore, the fiber described in this solution is any one or more combinations of steel fiber, basalt fiber, steel-like polyvinyl alcohol fiber, polyoxymethylene fiber, and polypropylene fiber.

[0022] Furthermore, the molecular structure of the UHPC salt-resistant, low-heat quick-setting agent described in this scheme is as follows:

[0023]

[0024] The structural formula for R is:

[0025]

[0026] In the above formula, x, y, and n are integers, representing the number of repeating units in each part of the UHPC salt-resistant low-heat quick-setting agent. The range of x is 10-50, the range of y is 0-1, and the range of n is 0-1; R2 is CH2 or CH2CH2CH3, and R3 is CH3 or CH2CH3.

[0027] Furthermore, the preparation method of the UHPC salt-resistant, low-heat accelerator described in this scheme is as follows:

[0028] (1) A comb-shaped macromolecule is obtained by amidation reaction of amino POSS and graphene oxide GO, wherein the molar ratio of amino POSS to graphene oxide GO is 0.5-2:1, the reaction temperature is 20-60℃, and the reaction time is 3-10 hours.

[0029] (2) The obtained comb-shaped macromolecules are modified by amidation reaction with unsaturated carboxylic acid monomers to prepare carboxyl-terminated comb-shaped macromolecules, wherein the molar ratio of unsaturated carboxylic acid monomers to comb-shaped macromolecules is 1-14:1, the reaction temperature is 20-55℃, and the reaction time is 4-8 hours.

[0030] (3) The obtained carboxyl-terminated comb-shaped macromolecule is copolymerized with an alkenyl silane coupling agent to obtain the UHPC salt-resistant, low-heat, quick-setting agent. The molar ratio of alkenyl silane coupling agent to carboxyl-terminated comb-shaped macromolecule is 1-12:1, the reaction temperature is 40-70℃, and the reaction time is 3-9 hours.

[0031] Furthermore, the unsaturated carboxylic acid monomers described in this scheme are sodium acrylate, sodium methacrylate, potassium acrylate, or potassium methacrylate.

[0032] Furthermore, the alkenylsilane coupling agent described in this scheme is γ-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, allyltrimethoxysilane, or allyltriethoxysilane.

[0033] By adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0034] 1) This solution, through the rational design of materials and processes, can effectively improve the salt and moisture resistance of crack repair materials, reduce the internal temperature of concrete and improve the rapid repair capability, effectively avoid the phenomena of crack repair materials falling off, aging and secondary cracking, and improve the durability and safety of large-volume concrete structures in high-salt and high-humidity environments.

[0035] 2) This solution uses a prepared desalination solution to desalinate the inside and surrounding concrete of the cracks, thereby improving the adhesion and bonding between the crack repair material and the concrete crack surface.

[0036] 3) The UHPC salt-resistant, low-heat-resistant, quick-setting agent in this crack repair material is prepared by amidation reaction of amino POSS with graphene oxide (GO) to obtain a comb-like macromolecule. Then, it is modified by amidation reaction with unsaturated carboxylic acid monomers to prepare a carboxyl-terminated comb-like macromolecule. Finally, it is obtained by copolymerization reaction to obtain the UHPC salt-resistant, low-heat-resistant, quick-setting agent. Its macromolecular POSS structure, alkenyl silane coupling agent, and graphene oxide (GO) contain a large number of Si-O skeletons, carboxyl groups, and hydroxyl groups. The synergistic effect of the three can significantly improve the salt resistance and early mechanical properties of UHPC, accelerate the hydration rate, reduce the heat of hydration, and inhibit shrinkage. This avoids the performance failure of concrete crack repair materials under high salt and high humidity concentrations, which can lead to cracking, detachment, and secondary cracking of crack repair materials. In addition, the graphene oxide (GO) introduced into the molecular structure can increase the specific surface area of ​​the concrete system, promote cement hydration, and thus significantly improve the early mechanical properties of UHPC, thereby improving the durability and safety of large-volume concrete structures under high salt and high humidity conditions.

[0037] 4) The UHPC salt-resistant, low-heat accelerator synthesized in this design exhibits excellent salt resistance, accelerates hydration rate, reduces heat of hydration, and inhibits shrinkage, while significantly improving the early mechanical properties of concrete. Firstly, the amino-POSS and graphene oxide (GO) structures possess macromolecular rigidity and a dense network structure, preventing the penetration of salt ions and moisture. Secondly, amino-POSS contains Si-O-Si bonds, exhibiting high chemical stability and withstanding harsh high-salt and high-humidity environments. Furthermore, GO contains hydroxyl and carboxyl groups, which interact with calcium ions and the surface of cement particles, inhibiting cement hydration and thus reducing the exothermic heat and temperature rise during hydration. Finally, amino-POSS and the introduced long side chains contain a Si-O skeleton, which has a significant nucleation effect on calcium silicate formed during cement hydration, accelerating early cement hydration and effectively improving the setting and early strength of concrete.

[0038] 5) Unlike the current mainstream approach of salt-resistant, low-heat accelerators, this solution fully utilizes the flexibility and performance control capabilities of molecular structure design. Based on the concept of molecular structure design, it innovatively introduces a chemically synthesized accelerator with a unique molecular structure. By using amidation and copolymerization reactions, a unique octopus-like structure is formed, increasing the surface area and spatial effect of the accelerator, as well as the types and content of functional groups. This comprehensively improves the adaptability and effectiveness of the salt-resistant, low-heat accelerator in large-volume concrete under high-salt and high-humidity environments. Macroscopically, it reduces the shrinkage rate and heat of hydration of UHPC, shortens the setting time, and improves early strength. It effectively prevents cracking, detachment, and secondary cracking of crack repair materials, and enhances the durability and safety of repair materials. It has significant performance advantages and application prospects. Detailed Implementation

[0039] The present invention will be further described in detail below with reference to the embodiments. It should be particularly noted that the following embodiments are for illustrative purposes only and do not limit the scope of the invention. Similarly, the following embodiments are only some, not all, embodiments of the present invention, and all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] This embodiment proposes a rapid repair method for cracks in large-volume concrete in high-salt and high-humidity environments, which includes the following steps:

[0041] S1: Clean the surface of the concrete cracks by blowing the inside and surface of the cracks with high-pressure airflow to remove dust, loose debris and other impurities. Then, use a prepared desalination solution to spray the inside and surrounding concrete of the cracks with low-pressure spraying to complete the interface treatment of the concrete cracks.

[0042] S2: Pour water and crack repair material into a mixer at a mass ratio of 0.04-0.1:1 and mix for 5-15 minutes to obtain crack repair material;

[0043] S3: Inject the crack repair material into the concrete cracks after the interface treatment. After filling, use low-frequency vibration to remove air bubbles and ensure that the crack repair material fills the cracked concrete.

[0044] The raw material components of the desalination solution described in this scheme, by weight, include: 30-40 parts of ethylenediaminetetraacetic acid, 25-35 parts of sodium citrate, 5-10 parts of polyacrylamide, and 5-15 parts of water.

[0045] Furthermore, the method for preparing the desalination solution described in this scheme includes the following steps:

[0046] (1) Measure ethylenediaminetetraacetic acid, sodium citrate and water separately using a weighing scale, then pour them into a container and stir for 10-20 minutes;

[0047] (2) Add polyacrylamide to the container and continue stirring for 15-20 minutes to obtain a desalination solution.

[0048] Furthermore, the raw material components of the crack repair material described in this scheme, by weight, include: 30-40 parts of sulfoaluminate cement, 5-10 parts of fly ash, 2-16 parts of silica fume, 3-10 parts of slag powder, 2-8 parts of glass microspheres, 10-50 parts of sand, 2-5 parts of UHPC salt-resistant low-heat quick-setting agent, 0.5-2.5 parts of fiber, and 4-13 parts of water.

[0049] The preparation method of the crack repair material described in this scheme includes the following steps:

[0050] (1) Calculate the sulfoaluminate cement, fly ash, silica fume, slag powder, glass microspheres, sand and water separately and then transport them to the mixer and mix for 8-15 minutes.

[0051] (2) Add the fiber to the mixer and mix for 5-15 minutes;

[0052] (3) Add UHPC salt-resistant low-heat quick-setting agent to the mixer and continue mixing for 10-20 minutes to obtain crack repair material.

[0053] Furthermore, the sulfoaluminate cement strength grade described in this scheme is any one or more combinations of 42.5 and 52.5.

[0054] The sand described in this plan is standard sand with a sieve mesh size of 30-70 mesh.

[0055] The fibers described in this solution are any one or more combinations of steel fibers, basalt fibers, steel-like polyvinyl alcohol fibers, polyoxymethylene fibers, and polypropylene fibers.

[0056] Furthermore, the molecular structure of the UHPC salt-resistant, low-heat quick-setting agent described in this scheme is as follows:

[0057]

[0058] The structural formula for R is:

[0059]

[0060] In the above formula, x, y, and n are integers, representing the number of repeating units in each part of the UHPC salt-resistant low-heat quick-setting agent. The range of x is 10-50, the range of y is 0-1, and the range of n is 0-1; R2 is CH2 or CH2CH2CH3, and R3 is CH3 or CH2CH3.

[0061] Furthermore, the preparation method of the UHPC salt-resistant, low-heat accelerator described in this scheme is as follows:

[0062] (1) A comb-shaped macromolecule is obtained by amidation reaction of amino POSS and graphene oxide GO, wherein the molar ratio of amino POSS to graphene oxide GO is 0.5-2:1, the reaction temperature is 20-60℃, and the reaction time is 3-10 hours.

[0063] (2) The obtained comb-shaped macromolecules are modified by amidation reaction with unsaturated carboxylic acid monomers to prepare carboxyl-terminated comb-shaped macromolecules, wherein the molar ratio of unsaturated carboxylic acid monomers to comb-shaped macromolecules is 1-14:1, the reaction temperature is 20-55℃, and the reaction time is 4-8 hours.

[0064] (3) The obtained carboxyl-terminated comb-shaped macromolecule is copolymerized with an alkenyl silane coupling agent to obtain the UHPC salt-resistant, low-heat, quick-setting agent. The molar ratio of alkenyl silane coupling agent to carboxyl-terminated comb-shaped macromolecule is 1-12:1, the reaction temperature is 40-70℃, and the reaction time is 3-9 hours.

[0065] The unsaturated carboxylic acid monomers described in this scheme are sodium acrylate, sodium methacrylate, potassium acrylate, or potassium methacrylate; the alkenyl silane coupling agents described in this scheme are γ-methacryloyloxypropyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, allyltrimethoxysilane, or allyltriethoxysilane.

[0066] The following comparative examples and embodiments illustrate the UHPC salt-resistant, low-heat, quick-setting agent involved in this solution.

[0067] Example 1

[0068] This embodiment provides a formula for a large-volume concrete crack repair material, the components of which, by weight, include: 40 parts of sulfoaluminate cement; 5 parts of fly ash; 2 parts of silica fume; 10 parts of slag powder; 2 parts of glass microspheres; 10 parts of sand; 0.5 parts of fiber; 4 parts of water; and 2 parts of UHPC salt-resistant low-heat quick-setting agent.

[0069] The preparation method of the UHPC salt-resistant low-heat quick-setting agent in the components includes the following:

[0070] A comb-like macromolecule was prepared by amidation reaction of 8.476 g of amino POSS and 40.871 g of GO at 20 °C for 3 hours. Then, 0.940 g of sodium acrylate was added, and the reaction was carried out at 20 °C for 4 hours. Finally, the product was copolymerized with 0.248 g of γ-methacryloyloxypropyltrimethoxysilane at 40 °C for 3 hours to obtain the UHPC salt-resistant, low-heat, quick-setting agent.

[0071] Example 2

[0072] This embodiment provides a formula for a large-volume concrete crack repair material, the components of which, by weight, include: 30 parts of sulfoaluminate cement; 10 parts of fly ash; 16 parts of silica fume; 3 parts of slag powder; 8 parts of glass microspheres; 50 parts of sand; 2.5 parts of fiber; 13 parts of water; and 3 parts of UHPC salt-resistant low-heat quick-setting agent.

[0073] The preparation method of the UHPC salt-resistant low-heat quick-setting agent in the components includes:

[0074] A comb-like macromolecule was prepared by amidation reaction of 7.564 g of amino POSS and 9.095 g of GO at 40 °C for 10 hours. Then, 13.466 g of sodium methacrylate was added and reacted at 35 °C for 8 hours. Finally, the product was copolymerized with 15.831 g of vinyltrimethoxysilane at 70 °C for 9 hours to obtain the UHPC salt-resistant, low-heat, quick-setting agent.

[0075] Example 3

[0076] This embodiment provides a formula for a large-volume concrete crack repair material, the components of which, by weight, include: 35 parts sulfoaluminate cement; 8 parts fly ash; 12 parts silica fume; 4 parts slag powder; 8 parts glass microspheres; 35 parts sand; 1.5 parts fiber; 6 parts water; and 5 parts UHPC salt-resistant low-heat quick-setting agent.

[0077] The preparation method of the UHPC salt-resistant low-heat quick-setting agent in the components includes:

[0078] A comb-like macromolecule was prepared by amidation reaction of 10.225 g of aminoPOSS and 12.365 g of GO at 60 °C for 5 hours. Then, 6.010 g of potassium methacrylate was added and reacted at 55 °C for 6 hours. Finally, the product was copolymerized with 9.817 g of allyltrimethoxysilane at 60 °C for 6 hours to obtain the UHPC salt-resistant, low-heat, quick-setting agent.

[0079] Comparative Example 1

[0080] Using a commercially available alkaline powdered accelerator as Comparative Example 1, the amount of alkaline powdered accelerator used was 5 parts out of a total of 100 parts.

[0081] Comparative Example 2

[0082] Using commercially available alkali-free powder as Comparative Example 2, the amount of alkali-free powder used was 4 parts out of a total of 100 parts of quick-setting agent.

[0083] Comparative Example 3

[0084] Using commercially available alkali-free liquid as comparative example 3, the amount of alkali-free liquid used was 4 parts based on a total of 100 parts of quick-setting agent.

[0085] Comparative Test

[0086] 1. Heat release during cement hydration

[0087] To investigate the effect of the UHPC salt-resistant low-heat accelerator synthesized in this scheme on the heat of hydration release of the repair material, the heat of hydration release of the repair material mixed with the UHPC salt-resistant low-heat accelerator prepared in Examples 1-3 and the accelerator mixed with Comparative Examples 1-3 was tested under the same water addition conditions.

[0088] The repair material uses the following unified basic formula, replacing the accelerators in the examples and comparative examples to obtain the experimental group. The basic formula components include: 35 parts sulfoaluminate cement, 7.5 parts fly ash, 9 parts silica fume, 6.5 parts slag powder, 5 parts glass microspheres, 30 parts sand, 3.5 parts accelerator, and 8.5 parts water.

[0089] The preparation methods for the crack repair materials for each test group include the following steps:

[0090] (1) Sulfoaluminate cement, fly ash, silica fume, slag powder, glass microspheres, sand and water are weighed by a meter and then transported to a mixer and mixed for 12 minutes.

[0091] (2) Add the quick-setting agent to the mixer and continue mixing for 15 minutes to obtain the crack repair material.

[0092] Given the special circumstance that the heat of hydration cannot be added to the fiber, the above basic formula discards the fiber component in the repair material formula mentioned above in this embodiment, and the median value of the remaining components is taken.

[0093] By replacing the accelerator in the basic formulation components, experimental groups corresponding to Examples 1-3 and Comparative Examples 1-3 were obtained. The examples used were repair materials containing the UHPC salt-resistant low-heat accelerator synthesized in Examples 1-3 of this scheme, and the comparative examples 1-3 were repair materials containing commercially available accelerators. The test results of the heat of hydration release of the repair materials are shown in Table 1.

[0094] Table 1. Test results of hydration heat release of repair materials

[0095]

[0096] As shown in Table 1, the UHPC salt-resistant low-heat quick-setting agent repair material synthesized with the additives in this embodiment has a low heat release of hydration, which is lower than that of the comparative proportions with commercially available quick-setting agents. This indicates that the UHPC salt-resistant low-heat quick-setting agent has excellent performance in reducing cement temperature, which can significantly reduce the temperature difference between the repair material and the original concrete, and is beneficial for crack repair.

[0097] 2. Mechanical properties of remediation materials at different salt concentrations

[0098] To investigate the effect of the UHPC salt-resistant, low-heat accelerator synthesized in this scheme on the early strength development of the repair material, the following unified basic formula was used in this test repair material, with the accelerators of the examples and comparative examples replaced to obtain the experimental group. The basic formula components include: 35 parts sulfoaluminate cement, 7.5 parts fly ash, 9 parts silica fume, 6.5 parts slag powder, 5 parts glass microspheres, 30 parts sand, 3.5 parts accelerator, 1.5 parts fiber, and 8.5 parts water.

[0099] The preparation methods for the crack repair materials for each test group include the following steps:

[0100] (1) Sulfoaluminate cement, fly ash, silica fume, slag powder, glass microspheres, sand and water are weighed by a meter and then transported to a mixer and mixed for 12 minutes.

[0101] (2) Add the fiber to the mixer and mix for 10 minutes;

[0102] (3) Add the quick-setting agent to the mixer and continue mixing for 15 minutes to obtain the crack repair material.

[0103] According to GB / T 749-2008, after molding the specimens, the surface was immediately covered with a waterproof film. After demolding, the specimens were placed in water at (20±1)℃ for 7 days and then divided into two groups. One group continued to be cured in water, and the other group was immersed in 5% Na2SO4 solution for curing. After curing for 28 days, the specimens were taken out and their mechanical properties were measured. The corrosion resistance coefficient (K) was calculated. The test results are shown in Table 2.

[0104] Table 2 Test results of mechanical properties of repair materials / MPa

[0105]

[0106] As can be seen from Table 2, the UHPC salt-resistant low-heat quick-setting agent synthesized by the method of this scheme significantly improves the compressive strength and flexural strength of the large-volume concrete crack repair material under high salt and high humidity environment. This indicates that the prepared UHPC salt-resistant low-heat quick-setting agent can promote the strength development of the repair material under high salt and high humidity environment, which is conducive to restoring the service function of damaged concrete and meeting the service design requirements.

[0107] 3. Repair effects of repair materials at different salt concentrations

[0108] To investigate the repair effect of the UHPC salt-resistant, low-heat-resistant accelerator synthesized in this scheme on the repair material under different salt concentrations and humidity environments, the comparative example in this test uses the basic formula in the mechanical property test, but replaces the accelerator in the comparative example to obtain the experimental group of the comparative example; the formulas of Examples 1-3 are used as the experimental group of the examples.

[0109] The preparation methods for the crack repair materials of each experimental group include the following steps:

[0110] (1) Sulfoaluminate cement, fly ash, silica fume, slag powder, glass microspheres, sand and water are weighed by a meter and then transported to a mixer and mixed for 12 minutes.

[0111] (2) Add the fiber to the mixer and mix for 10 minutes;

[0112] (3) Add the quick-setting agent to the mixer and continue mixing for 15 minutes to obtain the crack repair material.

[0113] In this experiment, C60 grade concrete was selected as the specimen to be repaired, and its mix proportion is shown in Table 3. The cement used was Chengde Jinyu P·O 42.5 cement, the sand was Zone II continuously graded natural medium sand with a fineness modulus of 2.8 and a mud content of less than 2.1%, the aggregate was 5~20 mm continuously graded crushed stone, and the dosage of polycarboxylate superplasticizer was 0.2% of the mass of cementitious materials. The specimens were molded according to GB / T 50081-2019.

[0114] Concrete cracks were created using the steel sheet method, with a uniform crack length of 60 mm. Steel sheets with thicknesses of 0.2 mm and 0.8 mm were fabricated according to the predetermined crack width. During pouring, the steel sheets were vertically inserted into the mold to create a through crack, and the surface was immediately covered with a waterproof film. The molds were then cured in 2% Na2SO4, 5% Na2SO4, and 8% Na2SO4 solutions for 6 hours, respectively. After the concrete had reached a certain strength and was no longer deformable, the steel sheets were slowly and vertically pulled out. After curing for another 18 hours, the concrete was demolded and then cured in 2% Na2SO4, 5% Na2SO4, and 8% Na2SO4 solutions for 28 days. The cracked side was placed upwards. A crack repair material was prepared using a water-to-crack-repair-material mass ratio of 0.07:1 and used to repair the concrete cracks. The test results are shown in Table 4.

[0115] Table 3. C60 concrete mix proportions / kg / m³ 3

[0116]

[0117] Table 4 Repair Effects of Repair Materials

[0118]

[0119] Note: The numbers in the table represent the repair statuses as follows:

[0120] 1. Completely repaired, with no visible cracks, and the filled area is smooth.

[0121] 2. Partial repair, no visible cracks, slight dents visible at the joints.

[0122] 3. Partial repair: minor cracks in some areas at the joint.

[0123] 4. Partial repair; obvious cracks in some areas at the joint.

[0124] 5. No repair effect; obvious cracks exist at the joint, and the filling material is loose.

[0125] As shown in Table 4, the UHPC salt-resistant low-heat quick-setting agent synthesized by this method has excellent repair effects under different salt solution environments and can completely repair cracks. This indicates that the prepared UHPC salt-resistant low-heat quick-setting agent can promote the repair of cracks in the repair material under high salt environment, thereby extending the service life of civil engineering.

[0126] The above description is only a part of the embodiments of the present invention and does not limit the scope of protection of the present invention. Any equivalent device or equivalent process transformation made based on the content of the present invention specification, or direct or indirect application in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for rapid repair of cracks in large-volume concrete in high-salt and high-humidity environments, characterized in that, Includes the following steps: S1: Clean the surface of the concrete cracks, and then use a desalination solution to spray the concrete inside and around the cracks with a low-pressure spraying method to complete the interface treatment of the concrete cracks. S2: Pour water and crack repair material into a mixer at a mass ratio of 0.04-0.1:1 and mix for 5-15 minutes to obtain crack repair material; S3: Inject the crack repair material into the cracks in the treated concrete. After filling, use low-frequency vibration to remove air bubbles so that the crack repair material fills the cracked concrete. The raw material components of the crack repair material, by weight, include: 30-40 parts of sulfoaluminate cement, 5-10 parts of fly ash, 2-16 parts of silica fume, 3-10 parts of slag powder, 2-8 parts of glass microspheres, 10-50 parts of sand, 2-5 parts of UHPC salt-resistant low-heat quick-setting agent, 0.5-2.5 parts of fiber, and 4-13 parts of water. The molecular structure of the UHPC salt-resistant, low-heat, quick-setting agent is as follows: The structural formula for R1 is: In the above formula, x, y, and n are integers, representing the number of repeating units in each part of the UHPC salt-resistant low-heat quick-setting agent. The range of x is 10-50, the range of y is 0-1, and the range of n is 0-1. R2 is CH2, and R3 is CH3 or CH2CH3.

2. The method for rapid repair of large-volume concrete cracks in high-salt and high-humidity environments according to claim 1, characterized in that, Surface cleaning of concrete cracks includes: using high-pressure airflow to blow away the inside and surface of the cracks to remove impurities, including dust and / or loose debris.

3. The method for rapid repair of large-volume concrete cracks in high-salt and high-humidity environments according to claim 1, characterized in that, The raw material components of the desalination solution, by weight, include: 30-40 parts of ethylenediaminetetraacetic acid, 25-35 parts of sodium citrate, 5-10 parts of polyacrylamide, and 5-15 parts of water.

4. The method for rapid repair of large-volume concrete cracks in high-salt and high-humidity environments according to claim 3, characterized in that, The method for preparing the desalination solution includes the following steps: After measuring ethylenediaminetetraacetic acid, sodium citrate, and water separately using a weighing scale, pour them into a container and stir for 10-20 minutes. Add polyacrylamide to the container and continue stirring for 15-20 minutes to obtain a desalination solution.

5. The method for rapid repair of large-volume concrete cracks in high-salt and high-humidity environments according to any one of claims 1 to 4, characterized in that, The preparation method of the crack repair material includes the following steps: Sulfoaluminate cement, fly ash, silica fume, slag powder, glass microspheres, sand, and water are weighed separately and then transported to a mixer for 8-15 minutes. Add the fiber to the mixer and mix for 5-15 minutes; Add UHPC salt-resistant low-heat quick-setting agent to the mixer and continue mixing for 10-20 minutes; Crack repair material was obtained.

6. The method for rapid repair of large-volume concrete cracks in high-salt and high-humidity environments according to claim 5, characterized in that, The sulfoaluminate cement has a strength grade of 42.5 or 52.5, which is any one or more combinations thereof; The sand is standard sand with a sieve mesh size of 30-70 mesh; The fiber is any one or a combination of steel fiber, basalt fiber, steel-like polyvinyl alcohol fiber, polyoxymethylene fiber, and polypropylene fiber.

7. The method for rapid repair of large-volume concrete cracks in high-salt and high-humidity environments according to claim 1, characterized in that, The preparation method of the UHPC salt-resistant low-heat quick-setting agent includes the following steps: A comb-shaped macromolecule was obtained by amidation reaction of amino POSS with graphene oxide GO, wherein the molar ratio of amino POSS to graphene oxide GO was 0.5-2:1, the reaction temperature was 20-60℃, and the reaction time was 3-10 hours. The obtained comb-shaped macromolecules were modified by amidation reaction with unsaturated carboxylic acid monomers to prepare carboxyl-terminated comb-shaped macromolecules. The molar ratio of unsaturated carboxylic acid monomers to comb-shaped macromolecules was 1-14:1, the reaction temperature was 20-55℃, and the reaction time was 4-8 hours. The prepared carboxyl-terminated comb-like macromolecules are copolymerized with an alkenylsilane coupling agent to obtain the UHPC salt-resistant, low-heat, rapid-setting agent. The molar ratio of the alkenylsilane coupling agent to the carboxyl-terminated comb-like macromolecules is 1-12:1, the reaction temperature is 40-70℃, and the reaction time is 3-9 hours.

8. The method for rapid repair of large-volume concrete cracks in high-salt and high-humidity environments according to claim 7, characterized in that, The unsaturated carboxylic acid monomer is sodium acrylate, sodium methacrylate, potassium acrylate, or potassium methacrylate.

9. The method for rapid repair of large-volume concrete cracks in high-salt and high-humidity environments according to claim 7, characterized in that, The alkenylsilane coupling agent is γ-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, allyltrimethoxysilane, or allyltriethoxysilane.

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