High-freezing-resistance and high-permeability concrete crack repairing material and preparation process thereof

Abstract

The invention relates to the technical field of concrete structure repair, and particularly discloses a high-freezing-resistance and high-permeability concrete crack repair material and a preparation process thereof. The repairing material comprises the following components in parts by weight: 10-50 parts of acrylic acid, 12-50 parts of methyl methacrylate, 0.2-3.0 parts of a cross-linking agent, 0.05-2 parts of an oxidizing agent, 0.01-1 part of a reducing agent and 2-10 parts of watermelon leaf powder-saturated lime water suspension. The repairing material disclosed by the invention not only has good permeability, can penetrate into microcracks, but also has good frost resistance, so that the repairing material can be well applied to repairing of weight cracks of a concrete structure in a low-temperature environment.

Description

Technical Field

[0001] The present invention relates to the field of concrete repair material preparation, and in particular to a high-freeze-resistance and high-permeability concrete crack repair material and a preparation process thereof. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance 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 those skilled in the art.

[0003] As one of the most widely used building materials in modern construction, concrete plays a key role in various infrastructure projects, such as bridges, roads, and dams, due to its advantages such as low cost, high strength, and strong plasticity. However, during long-term use, concrete structures are inevitably affected by various factors such as environmental factors, loads, and the material properties themselves, which will produce microcracks. Especially in cold regions, where concrete structures are subjected to freeze-thaw cycles, the problem of microcracks is more prominent. When microcracks exist within the concrete, water will penetrate through these microcracks. When the water freezes in a low-temperature environment, its volume expands, causing huge frost heave stress, causing the microcracks to continue to expand and connect, thereby weakening the strength and durability of the concrete structure, reducing its service life, increasing the maintenance cost of the project, and even posing a safety hazard.

[0004] Currently, numerous methods exist for repairing microcracks in concrete, including surface treatment, filling, and grouting. Surface treatment typically involves applying a waterproof coating or patching material to the concrete surface. This method only partially seals surface microcracks and is difficult to reach deeper microcracks. Furthermore, the bonding strength between the repair material and the concrete matrix is limited, making the repair effect difficult to maintain in harsh environments such as freeze-thaw cycles. Filling generally involves filling the microcracks with patching material, but this requires rigorous cleaning and filling procedures. If not handled properly, new interface defects can easily form between the filling material and the concrete, compromising the repair effect. While grouting can repair deeper microcracks, it presents numerous challenges, such as the grouting material's pourability, compatibility with concrete, and curing properties in low-temperature environments, significantly limiting its application in cold regions. Furthermore, most existing repair materials lack adequate frost resistance, and are prone to cracking and flaking under freeze-thaw cycles, failing to effectively prevent further microcrack development. Summary of the Invention

[0005] In view of this, the present invention provides a high frost resistance and high permeability concrete crack repair material and its preparation process, which can be well applied to repair the weight cracks of concrete structures in low temperature environments. Specifically, the technical solution of the present invention is as follows.

[0006] First, the present invention provides a high-freeze resistance and high-permeability concrete crack repair material, which includes components in the following proportions: 10 to 50 parts by weight of acrylic acid, 12 to 50 parts by weight of methyl methacrylate, 0.2 to 3.0 parts by weight of a cross-linking agent, 0.05 to 2 parts by weight of an oxidizing agent, 0.01 to 1 part by weight of a reducing agent, and 2 to 10 parts by weight of a watermelon leaf powder-saturated lime water suspension.

[0007] Furthermore, the watermelon leaf powder-saturated lime water suspension is prepared by the following method: soaking the watermelon leaf powder in saturated lime water, and the suspension is obtained after completion.

[0008] Furthermore, the mass ratio of the watermelon leaf powder to saturated lime water is 1-5:2-5. Optionally, the fineness of the watermelon leaf powder is 100-200 mesh.

[0009] Furthermore, the soaking time is 2 to 3 hours. Preferably, the soaking is carried out under heating conditions of 50 to 65°C.

[0010] Furthermore, the cross-linking agent includes at least one of N,N'-methylenebisacrylamide, ethylene glycol dimethacrylate, and the like.

[0011] Furthermore, the oxidant includes at least one of persulfate, dibenzoyl peroxide, etc.

[0012] Furthermore, the reducing agent includes at least one of sodium bisulfite, sodium thiosulfate, N,N-dimethylaniline, etc.

[0013] Secondly, the present invention provides a method for preparing the high frost resistance and high permeability concrete crack repair material, comprising the following steps: (1) The acrylic acid, methyl methacrylate and oxidant are uniformly mixed to obtain agent A.

[0014] (2) Mix the watermelon leaf powder-saturated lime water suspension, a cross-linking agent, and a reducing agent to obtain agent B.

[0015] (3) Before use, mix the agent A and the agent B evenly to obtain the crack repair material.

[0016] Compared with the prior art, the technical solution of the present invention has at least the following beneficial effects: The repair material of the present invention forms a three-dimensional polymer network structure through cross-linking polymerization of acrylic acid and methyl methacrylate, resulting in excellent overall strength, flexibility, thermal stability, and chemical resistance, thereby ensuring excellent chemical durability. Furthermore, the repair material of the present invention also incorporates watermelon leaf powder that has been modified with saturated lime water. On the one hand, the cellulose and hemicellulose in the watermelon leaf powder undergo deacetylation under the action of saturated lime water, exposing more hydroxyl groups. Simultaneously, the lignin structure in the watermelon leaf powder releases polar groups such as phenolic hydroxyl groups, which can form hydrogen bonds with carboxyl groups and other groups in the three-dimensional polymer network structure. This not only improves the low-temperature toughness of the repair material, but also facilitates the maintenance of good repair performance at low temperatures. Furthermore, the formation of these hydrogen bonds facilitates a stronger interfacial bond between the watermelon leaf powder and the three-dimensional polymer network structure. Furthermore, the treatment of the watermelon leaf powder with saturated lime water facilitates the dissolution of polysaccharide molecules, thereby lowering the freezing point of the solution. Furthermore, its porous structure physically blocks the expansion of ice crystals, reducing ice crystal formation, thus ensuring that the repair material of the present invention maintains good workability even in low-temperature environments. On the other hand, a large amount of Ca²⁺ is introduced into the watermelon leaf powder after treatment with saturated lime water, which can form a bond with the carboxyl groups in the three-dimensional network structure of the polymer, enhance the stability of the network structure, lower the freezing point, and improve the antifreeze durability of the repair material. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings, which constitute part of the present invention, are intended to provide a further understanding of the present invention and are not intended to limit the present invention. The following describes the embodiments of the present invention in detail with reference to the accompanying drawings, wherein: Figure 1 This is a sample picture of the crack repair material prepared in the following Example 1.

[0018] Figure 2 This is a diagram showing the repair effect of the repair material prepared in the following Example 1 on cracks.

[0019] Figure 3 This is a sample picture of the crack repair material prepared in the following Example 2.

[0020] Figure 4 This is a sample picture of the crack repair material prepared in the following Example 3.

[0021] Figure 5 This is a sample picture of the crack repair material prepared in the following Example 4. DETAILED DESCRIPTION

[0022] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are intended to illustrate the present invention only and are not intended to limit the scope of the invention. The experimental methods in the following examples, for which specific conditions are not specified, are generally performed under conventional conditions or as recommended by the manufacturer.

[0023] Unless otherwise defined, all professional and scientific terms used in the present invention have the same meaning as those familiar to those skilled in the art. The reagents or raw materials used in the present invention can be purchased through conventional channels. If not otherwise specified, the reagents or raw materials used in the present invention are used in a conventional manner in this area or according to the product instructions. In addition, any method and material similar to or equivalent to the described content can be applied to the inventive method. Now, technical solutions of the present invention are further described in conjunction with specific embodiments.

[0024] Example 1: A preparation method of a high frost resistance and high permeability concrete crack repair material comprises the following steps: (1) Mix 200-mesh watermelon leaf powder and saturated lime water in a mass ratio of 3:4, heat to 60°C, and keep warm for 2.5 hours while stirring continuously. After completion, a watermelon leaf powder-saturated lime water suspension is obtained and set aside.

[0025] (2) Weigh the following components in the following proportions: 35 parts by weight of acrylic acid, 40 parts by weight of methyl methacrylate, 2 parts by weight of a crosslinking agent (N,N'-methylenebisacrylamide), 0.08 parts by weight of an oxidizing agent (ammonium persulfate), 0.025 parts by weight of a reducing agent (sodium bisulfite), and 6 parts by weight of the watermelon leaf powder-saturated lime water suspension prepared in this example.

[0026] (3) The acrylic acid, methyl methacrylate and oxidant are mixed uniformly to obtain agent A.

[0027] (4) Mix the watermelon leaf powder-saturated lime water suspension, the cross-linking agent, and the reducing agent to obtain Agent B.

[0028] (5) Mix the agent A and the agent B evenly to obtain the crack repair material, such as Figure 1 shown.

[0029] Performance testing: 1. Chemical Erosion Resistance Testing: The crack repair material prepared in this example was poured into a mold to form a test specimen. The specimen was then immersed in simulated seawater, a 6 wt.% NaCl solution, hydrochloric acid (pH = 2), and a sodium hydroxide solution (pH = 10). After 30 days, the specimen was removed, dried in a 45°C vacuum drying oven, and weighed. The results are shown in the table below, demonstrating that the crack repair material prepared in this example exhibits excellent chemical resistance to the aforementioned chemicals.

[0030] 2. Frost resistance test: The crack repair material prepared in this example was filled into artificial cracks on concrete specimens (width 2 mm, length 20 mm, depth 10 mm). After 7 days, the concrete specimens (such as Figure 2 The flexural strength and compressive strength (denoted as the strength before freeze-thaw cycles) of the test piece were measured. Then, the test piece was subjected to freeze-thaw cycles according to the "Standard for Test Methods for Basic Properties of Building Mortar" (JGJ / T70-2009). After completion, the flexural strength and compressive strength (denoted as the strength after freeze-thaw cycles) were tested again, and the strength retention rate was calculated. Among them: flexural strength retention rate = flexural strength after freeze-thaw cycles / flexural strength before freeze-thaw cycles, compressive strength retention rate = compressive strength after freeze-thaw cycles / compressive strength before freeze-thaw cycles, and the results are shown in the table below. It can be seen that the crack repair material prepared in this embodiment not only exhibits excellent resistance to chemical erosion, but also has good frost resistance.

[0031] Example 2: A preparation method of a high frost resistance and high permeability concrete crack repair material comprises the following steps: (1) Mix 100-mesh watermelon leaf powder and saturated lime water in a mass ratio of 5:5, heat to 50°C, and keep warm for 3 hours while stirring continuously. After completion, a watermelon leaf powder-saturated lime water suspension is obtained and set aside.

[0032] (2) Weigh the following components in the following proportions: 10 parts by weight of acrylic acid, 12 parts by weight of methyl methacrylate, 0.2 parts by weight of a crosslinking agent (ethylene glycol dimethacrylate), 0.05 parts by weight of an oxidizing agent (potassium persulfate), 0.01 parts by weight of a reducing agent (sodium thiosulfate), and 2 parts by weight of the watermelon leaf powder-saturated lime water suspension prepared in this example.

[0033] (3) The acrylic acid, methyl methacrylate and oxidant are mixed uniformly to obtain agent A.

[0034] (4) Mix the watermelon leaf powder-saturated lime water suspension, the cross-linking agent, and the reducing agent to obtain Agent B.

[0035] (5) Mix the agent A and the agent B evenly to obtain the crack repair material, such as Figure 3 shown.

[0036] Performance Testing: The crack repair material prepared in this example was tested for chemical corrosion resistance and frost resistance using the same methods as in Example 1. The results are shown in the table below. It can be seen that the crack repair material prepared in this example not only exhibits excellent chemical corrosion resistance but also has good frost resistance.

[0037] Chemical corrosion resistance test results Antifreeze performance test results .

[0038] Example 3: A preparation method of a high frost resistance and high permeability concrete crack repair material comprises the following steps: (1) Mix 150-mesh watermelon leaf powder and saturated lime water in a mass ratio of 1:2, heat to 65°C, and keep warm for 2 hours while stirring continuously. After completion, a watermelon leaf powder-saturated lime water suspension is obtained and set aside.

[0039] (2) Weigh the following components in the following proportions: 50 parts by weight of acrylic acid, 50 parts by weight of methyl methacrylate, 3 parts by weight of a crosslinking agent (N,N'-methylenebisacrylamide), 2 parts by weight of an oxidizing agent (dibenzoyl peroxide), 1 part by weight of a reducing agent (N,N-dimethylaniline), and 10 parts by weight of the watermelon leaf powder-saturated lime water suspension prepared in this example.

[0040] (3) The acrylic acid, methyl methacrylate and oxidant are mixed uniformly to obtain agent A.

[0041] (4) Mix the watermelon leaf powder-saturated lime water suspension, the cross-linking agent, and the reducing agent to obtain Agent B.

[0042] (5) Mix the agent A and the agent B evenly to obtain the crack repair material, such as Figure 4 shown.

[0043] Performance Testing: The crack repair material prepared in this example was tested for chemical corrosion resistance and frost resistance using the same methods as in Example 1. The results are shown in the table below. It can be seen that the crack repair material prepared in this example not only exhibits excellent chemical corrosion resistance but also has good frost resistance.

[0044] Chemical corrosion resistance test results Antifreeze performance test results .

[0045] Example 4: A preparation method of a high frost resistance and high permeability concrete crack repair material comprises the following steps: (1) Weigh the following components in the following proportions: 35 parts by weight of acrylic acid, 40 parts by weight of methyl methacrylate, 2 parts by weight of a crosslinking agent (N,N'-methylenebisacrylamide), 0.08 parts by weight of an oxidizing agent (ammonium persulfate), 0.025 parts by weight of a reducing agent (sodium bisulfite), and 6 parts by weight of water.

[0046] (2) The acrylic acid, methyl methacrylate and oxidant are mixed uniformly to obtain agent A.

[0047] (3) Mix the clean water, cross-linking agent, and reducing agent to obtain Agent B.

[0048] (4) Mix the agent A and the agent B evenly to obtain the crack repair material, such as Figure 5 shown.

[0049] Performance test: The antifreeze performance of the crack repair material prepared in this embodiment was tested using the same method as in the above embodiment 1. The results are shown in the table below.

[0050] Example 5: A preparation method of a high frost resistance and high permeability concrete crack repair material comprises the following steps: (1) Mix 100-mesh watermelon leaf powder and clean water in a mass ratio of 5:5, heat to 50°C, and keep warm for 3 hours while stirring continuously. After completion, a watermelon leaf powder suspension is obtained and set aside.

[0051] (2) Weigh the following components in the following proportions: 10 parts by weight of acrylic acid, 12 parts by weight of methyl methacrylate, 0.2 parts by weight of a crosslinking agent (ethylene glycol dimethacrylate), 0.05 parts by weight of an oxidizing agent (potassium persulfate), 0.01 parts by weight of a reducing agent (sodium thiosulfate), and 2 parts by weight of the watermelon leaf powder suspension prepared in this example.

[0052] (3) The acrylic acid, methyl methacrylate and oxidant are mixed uniformly to obtain agent A.

[0053] (4) Mix the watermelon leaf powder suspension, the cross-linking agent, and the reducing agent to obtain Agent B.

[0054] (5) Mix the agent A and the agent B evenly to obtain the crack repair material.

[0055] Performance test: The antifreeze performance of the crack repair material prepared in this embodiment was tested using the same method as in the above embodiment 1. The results are shown in the table below.

[0056] Example 6: A preparation method of a high frost resistance and high permeability concrete crack repair material comprises the following steps: (1) Weigh the following components in the following proportions: 50 parts by weight of acrylic acid, 50 parts by weight of methyl methacrylate, 3 parts by weight of a crosslinking agent (N,N'-methylenebisacrylamide), 2 parts by weight of an oxidizing agent (dibenzoyl peroxide), 1 part by weight of a reducing agent (N,N-dimethylaniline), and 10 parts by weight of saturated lime water.

[0057] (2) The acrylic acid, methyl methacrylate and oxidant are mixed uniformly to obtain agent A.

[0058] (3) Mix the saturated lime water, cross-linking agent, and reducing agent to obtain Agent B.

[0059] (4) Mix the agent A and the agent B evenly to obtain the crack repair material.

[0060] Performance test: The antifreeze performance of the crack repair material prepared in this embodiment was tested using the same method as in the above embodiment 1. The results are shown in the table below.

[0061] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein with equivalents. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A high frost resistance and high permeability concrete crack repair material, characterized in that: The invention comprises the following components in the following proportions: 10-50 parts by weight of acrylic acid, 12-50 parts by weight of methyl methacrylate, 0.2-3.0 parts by weight of a cross-linking agent, 0.05-2 parts by weight of an oxidizing agent, 0.01-1 parts by weight of a reducing agent, and 2-10 parts by weight of a watermelon leaf powder-saturated lime water suspension.

2. The high frost resistance and high permeability concrete crack repair material according to claim 1, characterized in that: The watermelon leaf powder-saturated lime water suspension is prepared by the following method: the watermelon leaf powder is soaked in saturated lime water, and the suspension is obtained after completion.

3. The high frost resistance and high permeability concrete crack repairing material according to claim 2, characterized in that: The mass ratio of the watermelon leaf powder to saturated lime water is 1-5:2-5.

4. The high frost resistance and high permeability concrete crack repairing material according to claim 2, characterized in that: The fineness of the watermelon leaf powder is 100-200 meshes.

5. The high frost resistance and high permeability concrete crack repairing material according to claim 2, characterized in that: The soaking time is 2 to 3 hours.

6. The high frost resistance and high permeability concrete crack repairing material according to claim 2, characterized in that: The soaking is carried out under a heating condition of 50-65°C.

7. The high frost resistance and high permeability concrete crack repairing material according to any one of claims 1 to 6, characterized in that: The cross-linking agent includes at least one of N,N'-methylenebisacrylamide and ethylene glycol dimethacrylate.

8. The high frost resistance and high permeability concrete crack repairing material according to any one of claims 1 to 6, characterized in that: The oxidant comprises at least one of persulfate and dibenzoyl peroxide.

9. The high frost resistance and high permeability concrete crack repairing material according to any one of claims 1 to 6, characterized in that: The reducing agent includes at least one of sodium bisulfite, sodium thiosulfate, and N,N-dimethylaniline.

10. The method for preparing the high frost resistance and high permeability concrete crack repairing material according to any one of claims 1 to 9, characterized in that: The steps include: (1) uniformly mixing the acrylic acid, methyl methacrylate and oxidant to obtain agent A; (2) mixing the watermelon leaf powder-saturated lime water suspension, a cross-linking agent, and a reducing agent to obtain agent B; (3) Before use, mix the agent A and the agent B evenly to obtain the crack repair material.

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