High frost resistance and high permeability concrete crack repairing material and its preparation process

Abstract

The application relates to the technical field of concrete structure repairing, and particularly discloses a high-anti-freezing and high-permeability concrete crack repairing material and a preparation process thereof.The repairing material comprises the following components in the following proportions: 10-50 parts of acrylic acid by weight, 12-50 parts of methyl methacrylate by weight, 0.2-3.0 parts of a crosslinking agent by weight, 0.05-2 parts of an oxidizing agent by weight, 0.01-1 part of a reducing agent by weight and 2-10 parts of a watermelon leaf powder-saturated lime water suspension by weight.The repairing material has good permeability and can penetrate into micro cracks, and has good anti-freezing performance, so that the repairing material can be well applied to repairing of concrete structure cracks in a low-temperature environment.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of concrete repair material preparation, and particularly relates to a high frost resistance and high permeability concrete crack repair material and a preparation process thereof. BACKGROUND

[0002] The information disclosed in this Background section is for the purpose of increasing the understanding of the background of the present application and does not necessarily constitute an admission that this information forms a prior art with respect to the present application.

[0003] As one of the most widely used building materials in modern construction engineering, concrete plays a key role in various infrastructure constructions, such as bridges, roads, dams, etc., due to its low cost, high strength, and strong plasticity. However, during the long-term use of concrete structures, micro-cracks inevitably occur due to environmental factors, load effects, and material properties. In cold regions, the problem of micro-cracks is more prominent due to freeze-thaw cycles. When micro-cracks exist in concrete, water can penetrate through these cracks, and the volume expansion caused by ice formation at low temperatures will generate a large frost heaving stress, leading to the continuous expansion and connection of micro-cracks, which in turn weakens the strength and durability of the concrete structure, reduces the service life, increases the maintenance cost of the project, and even may cause safety hazards.

[0004] Currently, there are many methods for repairing concrete micro-cracks, such as surface treatment, filling, and grouting. Surface treatment usually involves applying waterproof paint or repair materials to the surface of the concrete. This method can only seal the surface micro-cracks to some extent, and it is difficult to reach the deeper internal micro-cracks. Moreover, the bonding strength between the repair material and the concrete matrix is limited, and the repair effect cannot be maintained in harsh environments such as freeze-thaw cycles. The filling method generally fills repair materials into the micro-cracks, but the cleaning and filling process of the micro-cracks requires high precision. If not handled properly, new interface defects may be formed between the filling material and the concrete, affecting the repair effect. Although the grouting method can repair deeper micro-cracks, there are many problems with the grouting material, such as its groutability, compatibility with concrete, and solidification performance in low-temperature environments, which greatly limits its application in cold regions. In addition, most existing repair materials have insufficient frost resistance, and under the action of freeze-thaw cycles, the repair materials themselves are prone to cracking and peeling, which cannot effectively prevent the further development of micro-cracks. SUMMARY

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

[0006] Firstly, the present application provides a high frost resistance and high permeability concrete crack repair material, comprising components in the following proportions: acrylic acid 10-50 parts by weight, methyl methacrylate 12-50 parts by weight, crosslinking agent 0.2-3.0 parts by weight, oxidizing agent 0.05-2 parts by weight, reducing agent 0.01-1 parts by weight, and watermelon leaf powder-saturated lime water suspension 2-10 parts by weight.

[0007] Further, the watermelon leaf powder-saturated lime water suspension is prepared by immersing watermelon leaf powder in saturated lime water, and is obtained after completion.

[0008] Further, 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] Further, the immersion time is 2-3 hours. Preferably, the immersion is carried out under heating conditions of 50-65℃.

[0010] Further, the crosslinking agent comprises at least one of N,N'-methylenebisacrylamide, ethylene glycol dimethacrylate, etc.

[0011] Further, the oxidizing agent comprises at least one of persulfate, dibenzoyl peroxide, etc.

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

[0013] Secondly, the present application provides a preparation method of the high frost resistance and high permeability concrete crack repair material, comprising the following steps:

[0014] (1) uniformly mixing the acrylic acid, methyl methacrylate, and oxidizing agent to obtain A agent.

[0015] (2) uniformly mixing the watermelon leaf powder-saturated lime water suspension, crosslinking agent, and reducing agent to obtain B agent.

[0016] (3) mixing the A agent and B agent uniformly before use to obtain the crack repair material.

[0017] Compared with the prior art, the technical scheme of the present application has at least the following beneficial effects:

[0018] The repair material of the present application can form a polymer three-dimensional network structure by cross-linking polymerization of the acrylic acid and methyl methacrylate, so that the repair material has good overall strength, flexibility, thermal stability and chemical corrosion resistance, thereby ensuring good chemical durability. At the same time, the repair material of the present application also adds watermelon leaf powder modified by saturated lime water. On the one hand, the cellulose and hemicellulose in the watermelon leaf powder expose more hydroxyl groups after the deacetylation reaction under the action of saturated lime water, and at the same time, the lignin structure in the watermelon leaf powder releases polar groups such as phenolic hydroxyl groups, which can form hydrogen bonds with carboxyl groups in the polymer three-dimensional network structure, not only improving the low-temperature toughness of the repair material to facilitate good repair performance at low temperature. Moreover, the formation of the above hydrogen bonds is also conducive to the formation of a more firm interface between the watermelon leaf powder and the polymer three-dimensional network structure. On the other hand, the watermelon leaf powder treated by saturated lime water is beneficial to the dissolution of polysaccharide molecules, thereby reducing the freezing point of the solution, and its porous structure can physically block the expansion of ice crystals, reducing the amount of ice crystals generated, so that the repair material of the present application still has good workability in a low-temperature environment. On the other hand, the watermelon leaf powder treated by saturated lime water introduces a large amount of Ca²⁺, which can form a combination with the carboxyl groups in the polymer three-dimensional network structure, enhance the stability of the network structure, and reduce the freezing point, improve the frost resistance and durability of the repair material. BRIEF DESCRIPTION OF DRAWINGS

[0019] The accompanying drawings, which form a part of the present description, are included to provide a further understanding of the application and are incorporated in and constitute a part of this application. Embodiments of the present application will be described and explained with additional specificity and detail with the accompanying drawings in which:

[0020] Figure 1 Sample picture of the crack repair material prepared for the following Example 1.

[0021] Figure 2 Picture of the repair effect of the repair material on the crack prepared for the following Example 1.

[0022] Figure 3 Sample picture of the crack repair material prepared for the following Example 2.

[0023] Figure 4 Sample picture of the crack repair material prepared for the following Example 3.

[0024] Figure 5 Sample picture of the crack repair material prepared for the following Example 4. DETAILED DESCRIPTION

[0025] The application will be further described in connection with the following specific examples. It should be understood that these examples are only used to illustrate but not to limit the scope of the application. The experimental methods in the following examples, if not otherwise specified, are generally carried out according to the conventional conditions or according to the conditions recommended by the manufacturers.

[0026] Unless otherwise defined, all technical and scientific terms used in the application have the same meanings as those familiar to one skilled in the art. The reagents or raw materials used in the application can be purchased through conventional routes. Unless otherwise specified, the reagents or raw materials used in the application are used according to the conventional methods in the art or according to the product instructions. In addition, any method and material similar or equivalent to those described can be applied to the methods of the application. The technical solutions of the application will be further described in connection with specific examples.

[0027] Example 1:

[0028] A high-antifreeze high-permeability concrete crack repair material is prepared, including the following steps:

[0029] (1) Mix 200 mesh watermelon leaf powder with saturated limewater at a mass ratio of 3:4, heat to 60°C, and keep for 2.5 hours, and continuously stir during the process. After completion, a watermelon leaf powder-saturated limewater suspension is obtained, which is ready for use.

[0030] (2) Weigh the components according to the following proportions: acrylic acid 35 parts by weight, methyl methacrylate 40 parts by weight, crosslinking agent (N,N'-methylene bisacrylamide) 2 parts by weight, oxidizing agent (ammonium persulfate) 0.08 parts by weight, reducing agent (sodium bisulfite) 0.025 parts by weight, and the watermelon leaf powder-saturated limewater suspension prepared in this example 6 parts by weight.

[0031] (3) Uniformly mix the acrylic acid, methyl methacrylate, and oxidizing agent to obtain A agent.

[0032] (4) Mix the watermelon leaf powder-saturated limewater suspension, crosslinking agent, and reducing agent uniformly to obtain B agent.

[0033] (5) Mix the A agent and B agent uniformly to obtain the crack repair material, as shown in Figure 1 .

[0034] Performance test:

[0035] 1. Anti-chemical erosion performance test: the crack repair material prepared in the example is poured into a mold to form a test piece. Then the test piece is immersed in simulated seawater, NaCl solution (concentration 6 wt.%), hydrochloric acid (pH = 2), and sodium hydroxide solution (pH = 10), respectively. After 30 days, the test piece is taken out, dried in a 45°C vacuum drying oven, and weighed. The results are shown in the following table, which shows that the crack repair material prepared in the example has excellent anti-chemical erosion performance.

[0036]

[0037] 2. Anti-freezing performance test: the crack repair material prepared in the example is filled into the artificial cracks (width 2 mm, length 20 mm, depth 10 mm) of the concrete test piece. After 7 days, the flexural strength and compressive strength (denoted as pre-freeze-thaw cycle strength) of the concrete test piece (as shown in Figure 2 ) are tested. Then the test piece is subjected to freeze-thaw cycle according to the "Standard Test Methods for Basic Properties of Building Mortar" (JGJ / T70-2009). After completion, the flexural strength and compressive strength (denoted as post-freeze-thaw cycle strength) are tested again, and the strength retention rate is calculated. The flexural strength retention rate = post-freeze-thaw cycle flexural strength / pre-freeze-thaw cycle flexural strength, and the compressive strength retention rate = post-freeze-thaw cycle compressive strength / pre-freeze-thaw cycle compressive strength. The results are shown in the following table. It can be seen that the crack repair material prepared in the example not only has excellent anti-chemical erosion performance, but also has good anti-freezing performance.

[0038]

[0039] Example 2:

[0040] A high anti-freezing and high permeability concrete crack repair material is prepared, comprising the following steps:

[0041] (1) Mix 100 mesh watermelon leaf powder with saturated lime water at a mass ratio of 5:5, heat to 50°C, and keep for 3 hours, and continuously stir during the process. After completion, a watermelon leaf powder-saturated lime water suspension is obtained, which is ready for use.

[0042] (2) The components are weighed according to the following proportions: acrylic acid 10 parts by weight, methyl methacrylate 12 parts by weight, crosslinking agent (ethylene glycol dimethacrylate) 0.2 parts by weight, oxidizing agent (potassium persulfate) 0.05 parts by weight, reducing agent (sodium thiosulfate) 0.01 parts by weight, and the watermelon leaf powder-saturated lime water suspension prepared in the example 2 parts by weight.

[0043] (3) The acrylic acid, methyl methacrylate, and oxidizing agent are uniformly mixed to obtain A agent.

[0044] (4) Mix the watermelon leaf powder-saturated lime water suspension, crosslinking agent, reducing agent uniformly to obtain B agent.

[0045] (5) Mix the A agent and B agent uniformly to obtain the crack repair material, as shown in Figure 3 .

[0046] Performance test: The crack repair material prepared in this example was tested for chemical corrosion resistance and frost resistance using the same method as in Example 1 above, and the results are shown in the table below. It can be seen that the crack repair material prepared in this example not only has excellent chemical corrosion resistance, but also has good frost resistance.

[0047] Chemical corrosion resistance test results

[0048]

[0049] Frost resistance test results

[0050] .

[0051] Example 3:

[0052] A high frost resistance and high permeability concrete crack repair material is prepared, including the following steps:

[0053] (1) Mix 150 mesh watermelon leaf powder with saturated lime water at a mass ratio of 1:2, heat to 65°C, and keep for 2 hours, and continuously stir during the process. The watermelon leaf powder-saturated lime water suspension is obtained, ready for use.

[0054] (2) Weigh the components as follows: acrylic acid 50 parts by weight, methyl methacrylate 50 parts by weight, crosslinking agent (N,N'-methylene bisacrylamide) 3 parts by weight, oxidizing agent (dibenzoyl peroxide) 2 parts by weight, reducing agent (N,N-dimethylaniline) 1 part by weight, and the watermelon leaf powder-saturated lime water suspension prepared in this example 10 parts by weight.

[0055] (3) Mix the acrylic acid, methyl methacrylate, and oxidizing agent uniformly to obtain A agent.

[0056] (4) Mix the watermelon leaf powder-saturated lime water suspension, crosslinking agent, and reducing agent uniformly to obtain B agent.

[0057] (5) Mix the A agent and B agent uniformly to obtain the crack repair material, as shown in Figure 4 .

[0058] Performance test: the same method as in Example 1 above was used to test the chemical resistance and freeze resistance of the crack repair material prepared in this example, and the results are shown in the table below. It can be seen that the crack repair material prepared in this example not only has excellent chemical resistance, but also has good freeze resistance.

[0059] Chemical resistance test results

[0060]

[0061] Freeze resistance test results

[0062] .

[0063] Example 4:

[0064] A high freeze-resistant and high-permeability concrete crack repair material was prepared, including the following steps:

[0065] (1) The components were weighed as follows: acrylic acid 35 parts by weight, methyl methacrylate 40 parts by weight, crosslinking agent (N,N'-methylene bisacrylamide) 2 parts by weight, oxidizing agent (ammonium persulfate) 0.08 parts by weight, reducing agent (sodium bisulfite) 0.025 parts by weight, and water 6 parts by weight.

[0066] (2) The acrylic acid, methyl methacrylate and oxidizing agent were mixed uniformly to obtain A agent.

[0067] (3) The water, crosslinking agent and reducing agent were mixed uniformly to obtain B agent.

[0068] (4) The A agent and B agent were mixed uniformly to obtain the crack repair material, as shown in Figure 5 .

[0069] Performance test: the same method as in Example 1 above was used to test the freeze resistance of the crack repair material prepared in this example, and the results are shown in the table below.

[0070]

[0071] Example 5:

[0072] A high freeze-resistant and high-permeability concrete crack repair material was prepared, including the following steps:

[0073] (1) 100 mesh watermelon leaf powder was mixed with water in a mass ratio of 5:5, heated to 50°C and kept for 3 hours, and stirred continuously during the process. After completion, a watermelon leaf powder suspension was obtained and reserved.

[0074] (2) Weighing each component in the following proportions: acrylic acid 10 parts by weight, methyl methacrylate 12 parts by weight, crosslinking agent (ethylene glycol dimethacrylate) 0.2 parts by weight, oxidizing agent (potassium persulfate) 0.05 parts by weight, reducing agent (sodium thiosulfate) 0.01 parts by weight, and the watermelon leaf powder suspension prepared in this embodiment 2 parts by weight.

[0075] (3) Homogenize the acrylic acid, methyl methacrylate, and oxidizing agent to obtain A agent.

[0076] (4) Mix the watermelon leaf powder suspension, crosslinking agent, and reducing agent to obtain B agent.

[0077] (5) Mix the A agent and B agent uniformly to obtain the crack repair material.

[0078] Performance test: The crack repair material prepared in this embodiment was tested for freeze resistance using the same method as in Example 1 above, and the results are shown in the table below.

[0079]

[0080] Example 6:

[0081] A high-antifreeze high-permeability concrete crack repair material is prepared, including the following steps:

[0082] (1) Weighing each component in the following proportions: acrylic acid 50 parts by weight, methyl methacrylate 50 parts by weight, crosslinking agent (N,N'-methylene bisacrylamide) 3 parts by weight, oxidizing agent (dibenzoyl peroxide) 2 parts by weight, reducing agent (N,N-dimethylaniline) 1 part by weight, and saturated lime water 10 parts by weight.

[0083] (2) Homogenize the acrylic acid, methyl methacrylate, and oxidizing agent to obtain A agent.

[0084] (3) Mix the saturated lime water, crosslinking agent, and reducing agent to obtain B agent.

[0085] (4) Mix the A agent and B agent uniformly to obtain the crack repair material.

[0086] Performance test: The crack repair material prepared in this embodiment was tested for freeze resistance using the same method as in Example 1 above, and the results are shown in the table below.

[0087]

[0088] The above merely describes the preferred embodiments of the present application and is not used to limit the present application, and although the present application is described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments, or equivalently replace some technical features thereof. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A highly frost-resistant and highly permeable concrete crack repair material, characterized in that, The product 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 crosslinking agent, 0.05-2 parts by weight of oxidizing agent, 0.01-1 parts by weight of reducing agent, and 2-10 parts by weight of watermelon leaf powder-saturated lime water suspension. The watermelon leaf powder-saturated lime water suspension is prepared by soaking watermelon leaf powder in saturated lime water. The mass ratio of watermelon leaf powder to saturated lime water is 1-5:2-5.

2. The high freeze-thaw resistant and high permeability concrete crack repair material according to claim 1, characterized in that, The fineness of the watermelon leaf powder is 100-200 mesh.

3. The high freeze-thaw resistant and high permeability concrete crack repair material according to claim 1, characterized in that, The soaking time is 2 to 3 hours.

4. The high freeze-thaw resistant and high permeability concrete crack repair material according to claim 1, characterized in that, The soaking is carried out under heating conditions of 50~65℃.

5. The high freeze-thaw resistant and high permeability concrete crack repair material according to any one of claims 1-4, characterized in that, The crosslinking agent includes at least one of N,N'-methylenebisacrylamide and ethylene glycol dimethacrylate.

6. The high freeze-thaw resistant and high permeability concrete crack repair material according to any one of claims 1-4, characterized in that, The oxidizing agent includes at least one of persulfate and benzoyl peroxide.

7. The high freeze-thaw resistant and high permeability concrete crack repair material according to any one of claims 1-4, characterized in that, The reducing agent includes at least one of sodium bisulfite, sodium thiosulfate, and N,N-dimethylaniline.

8. The method for preparing the high frost-resistant and high-permeability concrete crack repair material according to any one of claims 1-7, characterized in that, Includes the following steps: (1) The acrylic acid, methyl methacrylate and oxidant are mixed evenly to obtain agent A; (2) Mix the watermelon leaf powder-saturated lime water suspension, crosslinking agent, and reducing agent to obtain agent B; (3) Mix the A agent and B agent evenly before use to obtain the crack repair material.

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