Concrete self-repairing waterproof admixture and preparation method thereof

Abstract

The invention discloses a concrete self-repairing waterproof admixture and a preparation method of the concrete self-repairing waterproof admixture, and particularly relates to the technical field of light building materials. The self-repairing coating is prepared from the following components in parts by mass: 30 to 50 parts of silane emulsion, 15 to 30 parts of self-repairing microcapsules, 1.0 to 5.0 parts of a nonionic emulsifier, 0.5 to 1.0 part of a de-foaming agent, 0.5 to 3.0 parts of a dispersing agent, 0.5 to 2 parts of an anti-aging agent and 40 to 65 parts of de-ionized water. The concrete self-repairing waterproof admixture can greatly improve the impermeability of concrete, effectively prevent moisture permeation, enhance the waterproof effect of a 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, in particular 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 engineering. However, traditional concrete has some unavoidable problems in practical application, especially under complex environmental conditions.

[0003] Firstly, concrete is prone to cracking due to temperature changes, load effects, and chemical erosion during long-term use. 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 waterproofing fails, it will cause serious leakage problems, affecting the normal use and 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 concrete, improving the reliability of concrete structures 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 waterproofness 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, consisting 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, deionized water: 40-65 parts. The antioxidant is a compound of formula 1: Formula 1; R1 in the formula 1 is a substituent, and R1 is specifically methyl, tert-butyl, phenyl, or ethyl.

[0007] Further, the silane emulsion is at least one of dodecyltrimethoxysilane or tridecafluorooctyltriethoxysilane.

[0008] 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.

[0009] Further, the preparation method of the self-repairing microcapsule is as follows: 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. After emulsification for 30 minutes, 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.

[0010] After the curing reaction is completed, the microcapsule is separated from the reaction solution, and then washed with a detergent such as deionized water for multiple times 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.

[0011] Further, the non-ionic emulsifier is at least one of stearyl alcohol polyoxyethylene ether or isomeric tridecanol polyoxyethylene ether.

[0012] Further, the defoaming agent is polydimethylsiloxane.

[0013] Further, the dispersing agent is at least one of sodium polycarboxylate or sodium lignosulfonate.

[0014] Further, the antioxidant is any one of the compounds represented by the following structures: ; .

[0015] A preparation method of a concrete self-repairing waterproof admixture includes the following steps: 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 completely dissolved or uniformly emulsified to obtain a mixed solution A; b. The stirring speed is reduced to 500-800 rpm, and the silane emulsion is added to the mixed solution A and stirred uniformly to obtain a mixed solution B; c. Adding the self-healing microcapsules to the mixed solution B and stirring at a speed of 200-400 rpm for 20-40 minutes until the self-healing microcapsules are uniformly dispersed and there is no obvious sedimentation, obtaining a mixed solution C; d. Filtering the mixed solution C to obtain a concrete self-healing waterproof admixture; Further, the step c is carried out under a nitrogen atmosphere.

[0016] Further, the step d is filtered using a 50-80 mesh sieve.

[0017] The phenolic hydroxyl group in the anti-aging agent molecule has high reactivity, which can capture free radicals (such as oxygen, ultraviolet or heat-induced free radicals) in the environment through hydrogen donation. When the concrete admixture is exposed to an oxidizing environment, the anti-aging agent molecule prevents the occurrence of chain oxidation reaction, thereby protecting the components such as silane emulsion and self-healing microcapsules from degradation. During the preparation of the admixture, the anti-aging agent can prolong the storage period and service life of the admixture by interrupting the oxidation chain reaction. The anti-aging agent works synergistically with other components in the admixture. The silane emulsion provides a hydrophobic barrier, while the anti-aging agent ensures that the barrier does not fail under long-term environmental stress. When a concrete crack forms, the self-healing microcapsule releases the core material, and the anti-aging agent protects the repair process from free radical interference, maintaining the repair efficiency.

[0018] 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 crack, and the anti-aging agent 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 from penetrating. 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 crack is stressed, the wall material breaks, the core material flows out and solidifies, filling the crack and achieving self-repair. The non-ionic emulsifier helps emulsify the silane emulsion and microcapsules 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 microcapsules from settling. Deionized water is used as a reaction medium to adjust the viscosity of the system and avoid impurities interfering with the chemical reaction.

[0019] Compared with the prior art, the present application has the following advantages: 1. Significantly enhances the waterproof performance of concrete: the concrete self-healing waterproof admixture of 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.

[0020] 2. Effectively improve the self-repairing ability of concrete: The self-repairing microcapsules in the self-repairing waterproof admixture for concrete can release the core material when the concrete cracks, achieving automatic repair of the cracks, significantly improving the self-healing performance of the concrete, prolonging the service life of the concrete structure, and reducing maintenance costs.

[0021] 3. Significantly improve the durability of concrete: The addition of the anti-aging agent 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 under complex environmental conditions. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 NMR chart of the anti-aging agent 1 according to the present application. DETAILED DESCRIPTION

[0023] 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, rather than all the 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.

[0024] Preparation Example 1 Synthesis of the anti-aging agent 1: ; First step: under a nitrogen atmosphere, 15.00 g of intermediate 1, 12.98 g of raw material 2, 10.99 g of triethylamine and 250 ml of DMSO were added to the reaction system, heated to 85℃ for 16 h; after cooling, the pH of the system was adjusted to neutral with 0.1 mol / L HCl, the organic phase was washed with water five times, and then washed with saturated NaCl solution twice; finally, the combined organic phase was dried with anhydrous Na2SO4, rotary evaporated, purified on a silica gel column, using a mixture of petroleum ether and ethyl acetate as the eluent, rotary evaporated the solution, and 11.84 g of intermediate 1 was obtained. MS [M+H] + = 394.

[0025] Second step: under nitrogen atmosphere, 11.84 g of intermediate 1, 8.60 g of raw material 3, 0.39 g of triphenyl phosphine, 0.03 g of palladium on carbon, 5.77 g of sodium tert-butoxide and 250 ml 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 combined organic phase was dried with anhydrous magnesium sulfate, filtered and rotary evaporated; silica gel column chromatography was performed with petroleum ether and ethyl acetate mixture as eluent, and rotary evaporation was performed to obtain 11.08 g of antioxidant 1. MS [M+H] = 574. NMR is shown in + Figure 1 .

[0026] Preparation Example 2 Antioxidant 2 was prepared in Preparation Example 2, referring to the preparation method of Preparation Example 1, wherein raw material 1 was replaced by: , and the rest was the same as Preparation Example 1. MS [M+H] = 616. +

[0027] Preparation Example 3 Antioxidant 3 was prepared in Preparation Example 3, referring to the preparation method of Preparation Example 1, wherein raw material 1 was replaced by: , and the rest was the same as Preparation Example 1. MS [M+H] = 636. +

[0028] Preparation Example 4 Antioxidant 4 was prepared in Preparation Example 4, referring to the preparation method of Preparation Example 1, wherein raw material 1 was replaced by: , and the rest was the same as Preparation Example 1. MS [M+H] = 588. +

[0029] Example 1

[0030] Preparation of a concrete self-repairing waterproof admixture: 1. Mass ratio of raw materials: Silane emulsion: 45 parts, selected from dodecyltrimethoxysilane, purchased from Shanghai Huayuan Century Trading Co., Ltd.; Self-repairing microcapsules: 20 parts, the wall material is selected from urea-formaldehyde resin, and the core material is selected from methyl methacrylate; Nonionic emulsifier: 3 parts, selected from stearyl polyoxyethylene ether; Defoaming agent: 0.8 parts, selected from polydimethylsiloxane; Dispersing agent: 2 parts, selected from sodium lignosulfonate; Antioxidant: 1 part, selected from antioxidant 1 synthesized in Preparation Example 1; Deionized water: 50 parts. ​​​​

[0031] 2. Preparation of self-repairing microcapsules: Methyl methacrylate is mixed with emulsifier 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, the emulsification time is 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 to form a microcapsule structure.

[0032] After the curing reaction is completed, the microcapsules are separated from the reaction solution, and then the microcapsules are washed multiple times with detergents such as deionized water 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.

[0033] 3. Preparation method: a. 50 parts of deionized water are added to a reaction vessel, under stirring at 1000 rpm, 3 parts of non-ionic emulsifier, 0.8 parts of defoaming agent and 2 parts of dispersing agent are added in turn, stirring until completely dissolved or emulsified uniformly, to obtain a mixed solution A.

[0034] b. Reduce the stirring speed to 600 rpm, add 45 parts of silane emulsion to the mixed solution A, stir for 20 minutes to ensure that the silane emulsion is fully dispersed and uniform, to obtain a mixed solution B.

[0035] c. Under nitrogen atmosphere, 20 parts of self-repairing microcapsules are added to the mixed solution B, stirring at a speed of 300 rpm for 30 minutes until the self-repairing microcapsules are uniformly dispersed and no obvious sedimentation is observed, to obtain a mixed solution C.

[0036] 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.

[0037] Examples 2-4 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 turn, and the rest remains the same as Example 1.

[0038] Comparative Example 1 A concrete self-repairing waterproof admixture is prepared by referring to the preparation method of Example 1, and replacing the antioxidant therein with Comparative Compound 1, and the rest remains the same as Example 1.

[0039] Comparative Compound 1: N,N-Diphenyl-p-phenylenediamine (antioxidant H), a commonly used antioxidant in industry.

[0040] Comparative Example 2 A kind of preparation of concrete self-repair waterproof admixture, with reference to the preparation method of example 1, without adding the antioxidant therein, the rest remains the same as example 1.

[0041] Comparative example 3 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 therein is replaced by 20 parts, the rest remains the same as example 1.

[0042] Comparative example 4 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 therein is replaced by 5 parts, the rest remains the same as example 1.

[0043] Performance test: 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 penetration crystalline waterproof material" and T / CECS 913-2021 "cement concrete self-repair performance test method standard" carry out anti-permeation pressure ratio test, the results are shown in table 1.

[0044] 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 penetration crystalline waterproof material" and T / CECS 913-2021 "cement concrete self-repair performance test method standard" carry out anti-permeation pressure recovery rate test, the results are shown in table 1.

[0045] 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" carries out corrosion coefficient test, the results are shown in table 1.

[0046] Table 1. performance test data of a kind of concrete self-repair waterproof admixture prepared in example and comparative example.

[0047] 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 Compared with the comparative examples, the inventive examples show significantly superior performance in all the test indexes, while the comparative examples show consistent performance decline. In terms of 28d impermeability pressure ratio, the inventive examples maintain a high level, while the comparative examples show a clear downward trend, especially when the antioxidant is completely removed or the ingredient ratio is insufficient, the impermeability ability drops sharply. For impermeability pressure recovery rate, the inventive examples exhibit excellent self-repairing effect, strong and stable recovery ability, while the comparative examples show a significant decay in recovery rate. In terms of corrosion resistance coefficient, the inventive examples embody stronger anti-erosion durability, good performance, while the comparative examples expose 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 water resistance, self-repairing and durability of concrete.

[0048] 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 invention is composed of the following components in the following mass ratios: 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, dispersant: 0.5-3.0 parts, antioxidant: 0.5-2 parts, and deionized water: 40-65 parts; The antioxidant is a compound of formula 1: Formula 1; R1 in Formula 1 is a substituent, and specific R1 is: methyl, tert-butyl, phenyl, or ethyl.

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

3. The concrete self-repairing waterproof admixture according to claim 1, characterized in that: The self-repairing microcapsule is composed of a wall material and a core material; The wall material is urea-formaldehyde resin; The core material is methyl methacrylate; The average particle size of the self-repairing microcapsules ranges from 100 to 300 μm.

4. The concrete self-repairing waterproof admixture according to claim 1, characterized in that: The nonionic emulsifier is stearyl alcohol polyoxyethylene ether.

5. The concrete self-repairing waterproof admixture according to claim 1, characterized in that: The defoaming agent is polydimethylsiloxane.

6. The concrete self-repairing waterproof admixture according to claim 1, characterized in that: The dispersant is sodium lignin sulfonate.

7. The concrete self-repairing waterproof admixture according to claim 1, characterized in that: The antioxidant is any one of the compounds shown in the following structures: ； 。 8. A method for preparing a concrete self-repairing waterproof admixture according to any one of claims 1 to 7, characterized in that: The following steps are involved: a. The deionized water was added to the reaction vessel, and under stirring at 1000-1200rpm, the nonionic emulsifier, defoamer and dispersant were added and stirred until completely dissolved or emulsified to obtain a mixed solution A; b. Reduce the speed to 500-800rpm, add the silane emulsion to the mixture A, stir evenly to obtain a mixture B; c. Add the self-repairing microcapsules to the mixed solution B and stir at a speed of 200-400 rpm for 20-40 minutes until the self-repairing microcapsules are uniformly dispersed and there is no obvious sedimentation to obtain a mixed solution C; d. Filtering the mixed solution C to obtain a concrete self-repairing waterproof admixture.

9. The method for preparing a concrete self-repairing waterproof admixture according to claim 8, characterized in that: The step c is carried out under a nitrogen atmosphere.

10. The method for preparing a concrete self-repairing waterproof admixture according to claim 8, characterized in that: The step d is filtered using a 50-80 mesh screen.

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