A concrete self-repairing waterproof admixture and a preparation method thereof

Abstract

The application discloses a concrete self-repairing waterproof admixture and a preparation method thereof, and particularly relates to the technical field of light building materials. The concrete self-repairing waterproof admixture is composed of the following components in mass parts: 30-50 parts of silane emulsion, 15-30 parts of self-repairing microcapsules, 1.0-5.0 parts of non-ionic emulsifier, 0.5-1.0 parts of defoaming agent, 0.5-3.0 parts of dispersing agent, 0.5-2 parts of antioxidant, and 40-65 parts of deionized water. The concrete self-repairing waterproof admixture can greatly improve the impermeability of concrete, effectively prevent water permeation, enhance the waterproof effect of the concrete structure, prolong the service life of the concrete structure, and meet the waterproof requirements of various complex projects.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lightweight building materials, and particularly relates to a self-repairing waterproof concrete admixture and a preparation method thereof. BACKGROUND

[0002] As a widely used building material, concrete has attracted much attention for its performance. In many fields such as construction, bridge, road, and water conservancy engineering, the structural strength, durability, and waterproof performance of concrete are key factors to ensure the quality of the project. However, there are some unavoidable problems in the practical application of traditional concrete, especially under complex environmental conditions.

[0003] Firstly, cracks are likely to occur in concrete during long-term use due to temperature changes, load actions, and chemical erosion. These cracks not only reduce the strength and durability of the structure, but also lead to water penetration, further exacerbating the corrosion of internal steel bars and the deterioration of concrete. Secondly, the waterproof performance of concrete often fails to meet the needs of some special projects, such as hydraulic structures, basements, and underground engineering. Once the waterproof performance fails, it will cause serious leakage problems, affecting the normal use and service life of the project.

[0004] In addition, for the concrete structures that have already been formed, maintenance and reinforcement work often face many difficulties. Traditional maintenance methods usually require a lot of time and manpower, and may cause some damage to the original structure. Therefore, developing a self-repairing waterproof concrete admixture that can form an intelligent repair system inside the concrete, while enhancing the waterproof performance of the concrete, improving the reliability of the concrete structure and the convenience of maintenance, has become a research hotspot in the field of building materials. SUMMARY

[0005] The purpose of the present application is to solve the problems of insufficient structural strength, durability, and waterproof performance of concrete in the prior art, and to provide a self-repairing waterproof concrete admixture that can enhance the waterproof performance of concrete and improve the reliability of concrete structures to meet the needs of high-performance applications.

[0006] To achieve the above-mentioned purpose, the technical solution adopted by the present application is as follows: a self-repairing waterproof concrete admixture, which is composed of the following components in mass ratio: silane emulsion: 30-50 parts, self-repairing microcapsules: 15-30 parts, non-ionic emulsifier: 1.0-5.0 parts, defoaming agent: 0.5-1.0 parts, dispersing agent: 0.5-3.0 parts, antioxidant: 0.5-2 parts, and deionized water: 40-65 parts.

[0007] The antioxidant is a compound of formula 1:

[0008] Formula 1;

[0009] R1 in the formula 1 is a substituent, and specifically R1 is methyl, tert-butyl, phenyl, or ethyl.

[0010] Further, the silane emulsion is at least one of dodecyltrimethoxysilane or tridecafluorooctyltriethoxysilane.

[0011] Further, the wall material of the self-repairing microcapsule is at least one of urea-formaldehyde resin, melamine-formaldehyde resin, or polyurethane; the core material of the self-repairing microcapsule is at least one of methyl methacrylate or bisphenol A type epoxy resin; and the average particle size of the self-repairing microcapsule ranges from 100 to 300 μm.

[0012] Further, the preparation method of the self-repairing microcapsule is as follows:

[0013] Methyl methacrylate is mixed with an emulsifier to form an oil phase. Then the oil phase is slowly added to an aqueous phase containing urea-formaldehyde resin, while high-speed shearing emulsification is performed, and the emulsification time is 30 minutes. After the emulsification is completed, the obtained emulsion is transferred to a reactor for a curing reaction. As the reaction proceeds, the wall material gradually wraps the core material to form a microcapsule structure.

[0014] After the curing reaction is completed, the microcapsule is separated from the reaction solution, and then the microcapsule is washed multiple times with a detergent such as deionized water to remove residual unreacted monomers, emulsifiers, and other impurities. The washed microcapsule is dried to obtain a self-repairing microcapsule with a particle size ranging from 100 to 300 μm.

[0015] Further, the non-ionic emulsifier is at least one of stearyl alcohol polyoxyethylene ether or isomeric tridecanol polyoxyethylene ether.

[0016] Further, the defoaming agent is polydimethylsiloxane.

[0017] Further, the dispersing agent is at least one of sodium polycarboxylate or sodium lignosulfonate.

[0018] Further, the antioxidant is any one of the compounds represented by the following structures:

[0019] ; .

[0020] A preparation method of a concrete self-repairing waterproof admixture includes the following steps:

[0021] a. The deionized water is added to a reaction container, and the non-ionic emulsifier, defoaming agent, and dispersing agent are added under stirring at 1000-1200 rpm until they are completely dissolved or uniformly emulsified to obtain a mixed solution A;

[0022] b. Reduce the rotation speed to 500-800 rpm, add the silane emulsion to the mixture A, stir until uniform, to obtain mixture B;

[0023] c. Add the self-healing microcapsule to the mixture B, stir at 200-400 rpm for 20-40 minutes, until the self-healing microcapsule is uniformly dispersed and no obvious sedimentation, to obtain mixture C;

[0024] d. Filter the mixture C to obtain a concrete self-healing waterproof admixture;

[0025] Further, the step c is carried out under nitrogen atmosphere.

[0026] Further, the step d is filtered using a 50-80 mesh sieve.

[0027] The phenolic hydroxyl group in the antioxidant molecule has high reactivity, which can capture free radicals (such as oxygen, ultraviolet or heat-induced free radicals) in the environment by hydrogen donation. When the concrete admixture is exposed to an oxidizing environment, the antioxidant molecule prevents the occurrence of chain oxidation reaction, thereby protecting the components such as silane emulsion and self-healing microcapsule from degradation. During the preparation of the admixture, the antioxidant can prolong the storage period and service life of the admixture by interrupting the oxidation chain reaction. The antioxidant works synergistically with other components in the admixture. The silane emulsion provides a hydrophobic barrier, while the antioxidant ensures that the barrier does not fail under long-term environmental stress. When the concrete cracks, the self-healing microcapsule releases the core material, and the antioxidant protects the repair process from free radical interference, maintaining the repair efficiency.

[0028] Each component solves the three core problems of concrete through synergistic effect: the silane emulsion forms a hydrophobic layer, blocking water penetration, the self-healing microcapsule breaks under stress, releasing the core material to fill the cracks, and the antioxidant inhibits oxidative degradation, ensuring long-term performance stability. The silane emulsion, as the main waterproof component, forms a hydrophobic film on the surface of the concrete, reduces the surface tension, and prevents water intrusion. Its alkyl chain provides hydrophobicity, and the fluorinated group enhances weather resistance. The self-healing microcapsule wall material protects the core material, and when the concrete cracks under stress, the wall material breaks, the core material flows out and solidifies, filling the cracks and achieving self-repair. The non-ionic emulsifier helps emulsify the silane emulsion and microcapsule during the preparation step, reduces the interfacial tension, and ensures uniform mixing of the components. The synergistic defoamer avoids bubbles affecting the integrity of the waterproof layer. The defoamer can eliminate the bubbles generated by stirring, prevent the formation of pores in the concrete, and indirectly enhance the waterproofness and repair effect. The dispersant promotes the dispersion of each component and prevents the sedimentation of the microcapsule. Deionized water is used as the reaction medium to adjust the viscosity of the system and avoid impurities interfering with the chemical reaction.

[0029] Compared with the prior art, the present application has the following advantages:

[0030] 1. Significantly enhance the waterproof performance of concrete: The self-repairing waterproof admixture for concrete described in the present application can greatly improve the impermeability of concrete, effectively prevent water penetration, enhance the waterproof effect of concrete structure, and meet the waterproof needs of various complex projects.

[0031] 2. Effectively improve the self-repairing ability of concrete: The self-repairing microcapsules in the self-repairing waterproof admixture for concrete described in the present application can release the core material when cracks form in concrete, achieving automatic repair of cracks, significantly improving the self-healing performance of concrete, prolonging the service life of concrete structure, and reducing maintenance costs.

[0032] 3. Significantly improve the durability of concrete: The addition of the anti-aging agent described in the present application effectively prevents the degradation of components such as silane emulsion and self-repairing microcapsules, enhances the stability of concrete under long-term environmental stress, improves the erosion resistance of concrete, and enables it to maintain good performance in complex environmental conditions. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 NMR chart of the anti-aging agent 1 described in the present application. DETAILED DESCRIPTION

[0034] The technical solutions of the present application will be described in detail below in combination with the drawings in the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0035] Preparation Example 1

[0036] Synthesis of anti-aging agent 1: ;

[0037] Step 1: Under a nitrogen atmosphere, add 15.00 g of intermediate 1, 12.98 g of raw material 2, 10.99 g of triethylamine, and 250 ml of DMSO to the reaction system, heat to 85℃ and react for 16 h; after cooling, adjust the pH of the system to neutral with 0.1 mol / L HCl, wash the organic phase with water five times, and then wash with saturated NaCl solution twice; finally, dry the combined organic phase with anhydrous Na2SO4, spin dry, pass through a silica gel column, use a mixture of petroleum ether and ethyl acetate as the eluent, spin dry the solution, and obtain 11.84 g of intermediate 1. MS [M+H] + = 394.

[0038] Second step: under nitrogen atmosphere, 11.84g of intermediate 1, 8.60g of raw material 3, 0.39g of triphenyl phosphine, 0.03g of palladium on carbon, 5.77g of sodium tert-butoxide and 250ml of toluene were added into the reaction system, and the reaction was refluxed at 120℃ for 12 hours; after the reaction was completed, the temperature was slightly lowered, and diatomite was used for filtration; after the filtrate was cooled to room temperature, it was washed with water for three times, and the organic phase was reserved; then the water phase was extracted with ethyl acetate, and the organic phase was dried with anhydrous magnesium sulfate, filtered, and rotary evaporated; silica gel column chromatography was performed, petroleum ether and ethyl acetate mixture were used as eluent, and rotary evaporation was performed, to obtain 11.08g of antioxidant 1. MS [M+H] = 574. NMR is shown in + Figure 1 .

[0039] Preparation Example 2

[0040] Antioxidant 2 was prepared in Preparation Example 2, referring to the preparation method of Preparation Example 1, raw material 1 therein was replaced by: , and the rest was the same as Preparation Example 1. MS [M+H] = 616. +

[0041] Preparation Example 3

[0042] Antioxidant 3 was prepared in Preparation Example 3, referring to the preparation method of Preparation Example 1, raw material 1 therein was replaced by: , and the rest was the same as Preparation Example 1. MS [M+H] = 636. +

[0043] Preparation Example 4

[0044] Antioxidant 4 was prepared in Preparation Example 4, referring to the preparation method of Preparation Example 1, raw material 1 therein was replaced by: , and the rest was the same as Preparation Example 1. MS [M+H] = 588. +

[0045] Example 1

[0046] Preparation of a concrete self-repairing waterproof admixture:

[0047] 1. Mass ratio of raw materials:

[0048] Silane emulsion: 45 parts, selected from dodecyltrimethoxysilane, purchased from Shanghai Huayuan Century Trading Co., Ltd.;

[0049] Self-repairing microcapsules: 20 parts, the wall material is selected from urea-formaldehyde resin, and the core material is selected from methyl methacrylate;

[0050] Nonionic emulsifier: 3 parts, selected from stearyl polyoxyethylene ether;

[0051] ​​​​Defoaming agent: 0.8 parts, selected from polydimethylsiloxane;

[0052] Dispersant: 2 parts, selected from sodium lignosulfonate;

[0053] Antioxidant: 1 part, selected from the antioxidant 1 synthesized in Preparation Example 1;

[0054] Deionized water: 50 parts.

[0055] 2. Preparation of self-repairing microcapsules:

[0056] Methyl methacrylate is mixed with emulsifiers to form an oil phase. Then the oil phase is slowly added to the water phase containing urea-formaldehyde resin while high-speed shearing emulsification is carried out, with an emulsification time of 30 minutes. After the emulsification is completed, the obtained emulsion is transferred to a reactor for curing reaction. As the reaction proceeds, the wall material gradually wraps the core material, forming a microcapsule structure.

[0057] After the curing reaction is completed, the microcapsules are separated from the reaction solution, and then the microcapsules are washed multiple times with deionized water and other detergents to remove residual unreacted monomers, emulsifiers and other impurities. The washed microcapsules are dried to obtain self-repairing microcapsules with a particle size of 100-300 μm.

[0058] 3. Preparation method:

[0059] a. 50 parts of deionized water are added to a reaction vessel, and under stirring at 1000 rpm, 3 parts of non-ionic emulsifier, 0.8 parts of defoaming agent and 2 parts of dispersant are added in sequence, and stirring is carried out until complete dissolution or uniform emulsification, to obtain a mixed solution A.

[0060] b. Reduce the stirring speed to 600 rpm, and add 45 parts of silane emulsion to the mixed solution A, and stir for 20 minutes to ensure that the silane emulsion is fully dispersed and uniform, to obtain a mixed solution B.

[0061] c. Under a nitrogen atmosphere, 20 parts of self-repairing microcapsules are added to the mixed solution B, and stirring is carried out at a speed of 300 rpm for 30 minutes until the self-repairing microcapsules are uniformly dispersed and there is no obvious sedimentation, to obtain a mixed solution C.

[0062] d. The mixed solution C is filtered through a 60-mesh screen to remove undispersed particles and impurities, to obtain a concrete self-repairing waterproof admixture.

[0063] Examples 2-4

[0064] A concrete self-repairing waterproof admixture is prepared by referring to the preparation method of Example 1, and replacing the antioxidant therein with the antioxidants 2-4 synthesized in Preparation Examples 2-4 in sequence, and the rest remains the same as in Example 1.

[0065] Comparative Example 1

[0066] A kind of preparation of concrete self-repair waterproof admixture, with reference to the preparation method of example 1, the anti-aging agent in it is replaced with comparative compound 1, the rest remains the same as example 1.

[0067] Comparative compound 1: It is N,N-diphenyl-p-phenylenediamine (antioxidant H), commonly used antioxidant in industry.

[0068] Comparative example 2

[0069] A kind of preparation of concrete self-repair waterproof admixture, with reference to the preparation method of example 1, without adding the anti-aging agent in it, the rest remains the same as example 1.

[0070] Comparative example 3

[0071] A kind of preparation of concrete self-repair waterproof admixture, with reference to the preparation method of example 1, the mass fraction of silane emulsion in it is replaced with 20 parts, the rest remains the same as example 1.

[0072] Comparative example 4

[0073] A kind of preparation of concrete self-repair waterproof admixture, with reference to the preparation method of example 1, the mass fraction of self-repair microcapsule in it is replaced with 5 parts, the rest remains the same as example 1.

[0074] Performance test:

[0075] 1. Take the concrete using a kind of concrete self-repair waterproof admixture prepared in example and comparative example as sample, reference GB 18445-2012 "cement-based permeable crystalline waterproof material" and T / CECS 913-2021 "cement concrete self-repair performance test method standard" to carry out anti-permeation pressure ratio test, the results are shown in table 1.

[0076] 2. Take the concrete using a kind of concrete self-repair waterproof admixture prepared in example and comparative example as sample, reference GB 18445-2012 "cement-based permeable crystalline waterproof material" and T / CECS 913-2021 "cement concrete self-repair performance test method standard" to carry out anti-permeation pressure recovery rate test, the results are shown in table 1.

[0077] 3. Take the concrete using a kind of concrete self-repair waterproof admixture prepared in example and comparative example as sample, reference GB / T 749-2008 "cement anti-sulfate erosion test method" to carry out corrosion resistance coefficient test, the results are shown in table 1.

[0078] Table 1. Performance test data of a kind of concrete self-repair waterproof admixture prepared in example and comparative example.

[0079] 28d resistance pressure ratio (%) Resistance pressure recovery rate (%) Erosion resistance coefficient (K) Example 1 434 93.6 1.16 Example 2 425 91.2 1.10 Example 3 440 95.0 1.25 Example 4 419 92.4 1.18 Comparative Example 1 389 81.4 0.83 Comparative Example 2 237 62.1 0.57 Comparative Example 3 384 78.0 0.82 Comparative Example 4 375 80.5 0.79

[0080] Compared with the comparative examples, the example group shows significantly superior performance in all test indicators, while the comparative example group shows consistent performance decline. In terms of 28d impermeability pressure ratio, the example group maintains a high level, while the comparative example group presents a significant downward trend, especially when the antioxidant is completely removed or the ingredient ratio is insufficient, the impermeability ability drops sharply. For the impermeability pressure recovery rate, the example group exhibits excellent self-repairing effect, strong and stable recovery ability, while the comparative example group shows a significant decay in recovery rate. In terms of the corrosion resistance coefficient, the example group embodies stronger anti-erosion durability, good performance, while the comparative example group exposes obvious vulnerability, generally low anti-erosion ability. These trends collectively indicate the core role of the antioxidant described in the present application in improving the waterproofness, self-repairing and durability of concrete.

[0081] Although embodiments of the present application have been shown and described, it is to be understood that various modifications, substitutions, replacements and variations can be made to these embodiments without departing from the principles and spirit of the present application, the scope of the present application being defined by the appended claims and their equivalents.

Claims

1. A concrete self-repairing waterproof admixture, characterized in that, The silane emulsion, the self-repairing microcapsule, the non-ionic emulsifier, the defoaming agent, the dispersing agent, the anti-aging agent and the deionized water are respectively 30-50 parts, 15-30 parts, 1.0-5.0 parts, 0.5-1.0 parts, 0.5-3.0 parts, 0.5-2 parts and 40-65 parts. The anti-aging agent is a compound of the formula 1: Formula 1; R1 in the formula 1 is a substituent, and specifically, R1 is any one of a methyl group, a tert-butyl group, a phenyl group and an ethyl group. The self-repairing microcapsule is composed of a wall material and a core material. The wall material is a urea-formaldehyde resin. The core material is methyl methacrylate. The average particle size of the self-repairing microcapsule ranges from 100 to 300 microns.

2. A concrete self-healing waterproof admixture according to claim 1, characterized in that, The silane emulsion is dodecyltrimethoxysilane.

3. The self-healing waterproofing admixture for concrete according to claim 1, wherein The non-ionic emulsifier is a stearyl alcohol polyoxyethylene ether.

4. The self-healing waterproofing admixture for concrete according to claim 1, wherein The defoaming agent is polydimethylsiloxane.

5. The self-healing waterproofing admixture for concrete as claimed in claim 1, wherein, The dispersing agent is sodium lignosulfonate.

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