Air entraining workability regulator and preparation method thereof

Abstract

The invention relates to the field of concrete admixtures, in particular to an air-entraining workability regulator and a preparation method thereof. The regulator comprises the following components in parts by mass: 220-300 parts of a monomer A, 30-80 parts of a monomer B, 14-20 parts of an air entraining agent mixture, 1-3 parts of 1% ferrous sulfate, 4-5 parts of a redox initiator, 60-70 parts of acrylic acid, 0.6-1 part of a chain transfer agent, 35-40 parts of a pH regulator and 240-500 parts of water. During preparation, normal-temperature polymerization is performed through a one-step method. The modifier has high water-reducing rate, excellent air entraining and bubble stability and viscosity reduction functions, is suitable for machine-made sand, high-strength concrete and the like, can improve workability, and is simple in process, low in energy consumption and suitable for large-scale production.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of concrete admixtures, in particular to an air entraining and workability adjusting agent and a preparation method thereof. BACKGROUND

[0002] In concrete engineering, polycarboxylate superplasticizer has important significance in realizing air entraining function. Appropriate and stable air bubbles can improve the workability of concrete, reduce bleeding segregation, and buffer the stress generated by freeze-thaw cycles, thereby improving the frost resistance of concrete, especially in cold regions or hydraulic structures.

[0003] Currently, polycarboxylate superplasticizer realizes air entraining function mainly by several common methods. Among them, the commonly used method is physical compounding method, which mixes ordinary polycarboxylate superplasticizer with rosin or saponin air entraining agent, but this method has problems such as poor compatibility and uneven air bubbles; patent CN109867758 A introduces hydrophobic chains by methacrylate esterification of fatty alcohol polyoxyethylene ether, but this process needs to be reacted at a high temperature of 90-130℃ for 5-8 hours, and needs to be completed in multiple steps, which is complicated; patent CN112778466B uses block polyether method, which uses benzyl glycidyl ether modified polyether monomer, but the process is relatively complex.

[0004] In addition, the existing technology has poor compatibility with machine-made sand and low-quality aggregate, and is prone to segregation and bleeding; poor air bubble stability is also a major problem, and the air content loss of the physical compounding system within 1 hour can reach more than 50%.

[0005] These existing problems have their inherent reasons. First, the introduction position of the hydrophobic group is unreasonable, which leads to imbalance of steric hindrance and electrostatic repulsion, affecting the overall performance. Second, the traditional persulfate initiation method requires high temperature conditions, which makes the free radical yield insufficient, thereby affecting the reaction effect. Third, due to the lack of stable bubble structure, large bubbles are easily combined and broken, resulting in poor air bubble stability.

[0006] Therefore, how to provide an adjusting agent that can realize stable air entraining without reducing the water-reducing rate, has a simple preparation process, can significantly improve the air entraining performance, introduces small and non-broken air bubbles, and is suitable for different types of cement and aggregate quality, is a technical problem that technicians in the field need to solve. SUMMARY

[0007] To solve the problems existing in the prior art, the present application provides an air entraining and workability adjusting agent and a preparation method thereof, which has a simple preparation process, can significantly improve the air entraining performance, introduces small and non-broken air bubbles, and can stably exist in concrete.

[0008] The application provides an air entraining and workability adjusting agent, which is prepared from the following raw materials in mass fraction: 220-300 parts of monomer A, 30-80 parts of monomer B, 14-20 parts of an air entraining agent mixture, 1-3 parts of 1% ferrous sulfate, 4-5 parts of an initiator, 60-70 parts of acrylic acid, 0.4-1 part of a chain transfer agent, 35-40 parts of a pH regulator and 240-500 parts of water. The monomer A is methoxyallyl polyoxyethylene ether, methylallyl polyoxyethylene ether or ethylene glycol monovinyl polyoxyethylene ether, and the monomer B is methoxy polyethylene glycol methacrylate or ethoxy polyethylene glycol acrylate. The air entraining agent mixture is a mixture of fatty alcohol polyoxyethylene ether, sodium sulfosuccinic acid mono-diester, lauric acid diethanolamide and fatty acid polyoxyethylene ether sodium sulfate.

[0009] In an embodiment, the air entraining agent mixture is prepared by mixing fatty alcohol polyoxyethylene ether, sodium sulfosuccinic acid mono-diester, lauric acid diethanolamide and fatty acid polyoxyethylene ether sodium sulfate in a mass ratio of 1-2:3.5-6.5:4.5-8.5:2-3.

[0010] In an embodiment, the initiator is a redox initiator, which comprises an oxidizing agent and a reducing agent, and the mass ratio of the oxidizing agent to the reducing agent is 5-7:1.

[0011] In an embodiment, the oxidizing agent in the redox initiator is a mixture of hydrogen peroxide and sodium hypophosphite, and the reducing agent is L-ascorbic acid.

[0012] In an embodiment, the mass ratio of the hydrogen peroxide to the sodium hypophosphite is 3:1-2.

[0013] In an embodiment, the hydrogen peroxide has a mass concentration of 27.5%.

[0014] In an embodiment, the chain transfer agent is one or a mixture of several of mercaptoacetic acid, 2-mercapto propionic acid, 3-mercapto propionic acid, mercaptoethanol and sodium bisulfite.

[0015] In an embodiment, the 1% ferrous sulfate is a 1% ferrous sulfate heptahydrate solution.

[0016] In an embodiment, the pH regulator is a 32% sodium hydroxide aqueous solution.

[0017] The application further provides a preparation method of the air entraining and workability adjusting agent, which comprises the following steps: S1, the monomer A, monomer B, 1% ferrous sulfate, air entraining agent mixture and oxidizing agent are placed in the reactor, the reaction temperature is adjusted to 20-45℃, then the mixture of acrylic acid, reducing agent, chain transfer agent and water is added uniformly; the dropwise addition stage lasts for 110-120min, and the dropwise addition rate is constant; S2, keep warm for 30-40min, after the reaction is completed, add pH regulator to adjust the pH to 5-8, thereby obtaining the air-entraining and workability regulator.

[0018] Compared with the prior art, the air-entraining and workability regulator provided by the present application introduces a hydrophobic side chain, cooperates with a polyether side chain, introduces a small air bubble, reduces surface tension, reduces the viscosity of a concrete slurry, improves the workability of concrete, improves the state retention of concrete, and is particularly suitable for machine-made sand concrete, solves the problem of poor cohesiveness caused by poor particle type and poor grading, and adds air-entraining and foam stabilizing components, enhances the strength of the bubble liquid film, reduces bubble merging and rupture, and reduces air content loss. The preparation method of the air-entraining and workability regulator provided by the present application has simple steps, short production time and mild process conditions. By using the air-entraining and workability regulator provided by the present application, high water-reducing and air-entraining effects can be achieved, the use of air-entraining agents is reduced, good water retention effect is achieved, the amount of water-retaining agents is reduced, and the production cost of concrete is effectively reduced. DETAILED DESCRIPTION

[0019] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and completely below in combination with the embodiments of the present application. Obviously, the described embodiments are 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.

[0020] The air-entraining and workability regulator and the preparation method thereof of the present application are further described through the following examples, comparative examples, and net slurry and concrete verification. Unless otherwise specified, the raw materials, reagents or devices used in the examples and comparative examples can be obtained from conventional commercial channels or can be obtained by existing technical methods. Unless otherwise specified, the test or test method is a conventional method in the art.

[0021] Example 1 The air-entraining and workability regulator provided in Example 1 includes monomer A 250 parts, monomer B 30 parts, air entraining agent mixture 15 parts, 1% ferrous sulfate 2.4 parts, initiator 4.9 parts, acrylic acid 64 parts, chain transfer agent 0.4 parts, pH regulator 29 parts and water 240 parts by mass fraction; The monomer A is methoxyallyl polyoxyethylene ether, and the monomer B is ethoxylated polyethylene glycol acrylate; The air-entraining agent mixture is prepared by mixing fatty alcohol polyoxyethylene ether, sodium sulfosuccinate monoester, diethanolamide laurate and sodium fatty acid polyoxyethylene ether sulfate in a mass ratio of 1:3.5:8.5:2.

[0022] The initiator is a redox initiator, comprising an oxidant and a reducing agent. The oxidant is a mixture of 3 parts of 27.5% hydrogen peroxide and 1.2 parts of sodium hypophosphite; the reducing agent is 0.7 parts of L-ascorbic acid. The chain transfer agent is mercaptoacetic acid; the 1% ferrous sulfate is a 1% (w / w) solution of ferrous sulfate heptahydrate; and the pH adjuster is a 32% (w / w) aqueous solution of sodium hydroxide.

[0023] The specific preparation steps of Example 1 include: S1. Place the monomer A, monomer B, 1% ferrous sulfate, air-entraining agent mixture and oxidant in a reactor, adjust the reaction temperature to 20℃-45℃, and then uniformly add a mixture of acrylic acid, reducing agent, chain transfer agent and water over 110-120 min. S2. Incubate for 35 minutes. After the reaction is complete, add a pH adjuster to adjust the pH to 5-8 to obtain the air-entraining and workability regulator.

[0024] Example 2 The difference between Example 2 and Example 1 is that the air-entraining agent mixture is 14 parts, specifically, it is a mixture of fatty alcohol polyoxyethylene ether, sodium sulfosuccinate monoester, diethanolamide laurate and sodium fatty acid polyoxyethylene ether sulfate in a mass ratio of 1:5.5:5.5:2; the remaining raw material components and preparation process are the same as in Example 1.

[0025] Example 3 The difference from Example 1 is that the air-entraining agent mixture is 16 parts, specifically, it is a mixture of fatty alcohol polyoxyethylene ether, sodium sulfosuccinate monoester, diethanolamide laurate and sodium fatty acid polyoxyethylene ether sulfate in a mass ratio of 2:6.5:4.5:3; the remaining raw material components and preparation process are the same as in Example 1.

[0026] Example 4 The difference from Example 1 is that the air-entraining agent mixture is 14 parts, specifically, it is a mixture of fatty alcohol polyoxyethylene ether, sodium sulfosuccinate monoester, diethanolamide laurate and sodium fatty acid polyoxyethylene ether sulfate in a mass ratio of 1:4.5:6.5:2; the remaining raw material components and preparation process are the same as in Example 1.

[0027] Examples 1-4 are shown in Table 1.

[0028] Table 1

[0029] Comparative Example 1 Comparative Example 1 is a regulator prepared without adding monomer B and the mixture of air-entraining agent based on Example 1. The amount of monomer A added is 280 parts; the other raw material components and preparation process are the same as in Example 1.

[0030] Comparative Example 2 Comparative Example 2 is a regulator prepared without adding the air-entraining agent mixture based on Example 1. The remaining raw material components and preparation process are the same as in Example 1.

[0031] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that the air-entraining agent mixture is added in step S2, after the temperature is maintained for 35 minutes and the reaction is completed, and then the pH adjuster and air-entraining agent mixture are added together.

[0032] Comparative Example 4 The difference between Comparative Example 4 and Example 1 is that the air-entraining mixture is 16 parts, no diethanolamide of laurate is added, and the ratio of fatty alcohol polyoxyethylene ether, sodium sulfosuccinate monoester and sodium fatty acid polyoxyethylene ether sulfate is 6.5:6.5:3. The remaining raw material components and preparation process are the same as in Example 1.

[0033] Comparative Example 5 The difference between Comparative Example 5 and Example 1 is that the air-entraining mixture is 16 parts, no fatty alcohol polyoxyethylene ether is added, and the ratio of sodium sulfosuccinate monoester, diethanolamide laurate and sodium fatty acid polyoxyethylene ether sulfate is 6.5:6.5:3. The remaining raw material components and preparation process are the same as in Example 1.

[0034] Comparative Example 6 The difference between Comparative Example 6 and Example 3 is that sodium sulfosuccinate monoester was replaced with an existing concrete air-entraining agent product, specifically model HS-AE-151.

[0035] Comparative Examples 1-6 are shown in Table 2.

[0036] Table 2

[0037] Note: In Tables 1 and 2, a, b, c, and d are respectively fatty alcohol polyoxyethylene ether, sodium sulfosuccinate monoester, diethanolamide laurate, and sodium fatty acid polyoxyethylene ether sulfate; HS-AE-151 is a concrete air-entraining agent product of Shanghai Qiaming International Trade Co., Ltd.

[0038] Performance testing The regulator was prepared according to the above examples and comparative examples. According to GB / T 8076-2008 "Concrete Admixtures", the air release time, initial slump, spread and 1-hour slump and spread of the concrete in the examples and comparative examples were tested. The initial air content and 1-hour air content of the concrete were tested according to the methods in GB / T50080-2016 "Test Methods for Performance of Ordinary Concrete Mixtures".

[0039] Experiment 1 The test was conducted using concrete with a C30 mix proportion. The specific mix proportions of the concrete are shown in Table 3.

[0040] Table 3

[0041] After preparing concrete according to the proportions in Table 3, 2.6% of the modifiers prepared in Examples 1-4 and Comparative Examples 1-3 were added, and performance tests were conducted. The test results are shown in Table 4.

[0042] Table 4

[0043] As shown in Table 4, the air-entraining workability modifiers of the present invention (Examples 1-4) exhibited significantly better overall performance than the comparative examples in the C30 concrete system. The initial slump / spread of Examples 1-4 were all 235 / 580-585 mm, slightly higher than Comparative Examples 1 and 2 (215 / 580 mm), and close to Comparative Example 3 (230 / 590 mm), indicating good initial dispersion performance. After 1 hour, the slump / spread of the examples remained at 225 / 535-545 mm, with minimal loss; while the spread of Comparative Example 1 decreased to 465 mm after 1 hour, and Comparative Examples 2 and 3 decreased to 500 mm, significantly lower than the examples. This demonstrates that the modifier of the present invention can more effectively maintain the long-term workability of concrete and meet the needs of longer-term construction. The initial gas content of the examples was 4.6%-4.9%, and the gas content remained at 3.6%-3.8% after 1 hour, with a loss rate of only about 20%. In contrast, the gas content of Comparative Example 1 decreased from 2.8% to 0.7% after 1 hour, with a loss rate of 75%. The gas content loss rates of Comparative Examples 2 and 3 after 1 hour were 47% and 49%, respectively. This result confirms that the present invention, through molecular structure design (synergy between hydrophobic side chains and hydrophilic backbones) and optimization of the gas-entraining agent mixture, can effectively reduce bubble coalescence and breakage, significantly improve bubble stability, and solve the problem of excessively rapid gas content loss in traditional systems.

[0044] Comparative Example 1 exhibited problems of "poor encapsulation, poor cohesion, and water bleeding." Comparative Example 2 showed slightly improved cohesion but still experienced water bleeding. Comparative Example 3 showed "blackening on the surface" (possibly related to poor compatibility of the air-entraining agent). In contrast, Examples 1-4 all achieved "good workability," with no problems such as water bleeding or segregation. This indicates that the single-component design of the present invention not only avoids the stratification or compatibility problems of traditional compound formulations but also significantly improves the encapsulation and cohesion of concrete with aggregates by adjusting the molecular structure compatibility, making it particularly suitable for complex systems such as manufactured sand.

[0045] Based on the experimental results of Example 1 and Comparative Examples 1-4, the addition of monomer B can increase the air content of concrete, thereby improving the workability of concrete; the addition of the air-entraining agent mixture during the polymerization process can significantly increase the air content of concrete, improve the workability of concrete, and significantly reduce the air content loss; the addition of monomer B and the air-entraining agent mixture has no significant effect on the initial water-reducing effect of the regulator, but improves the slump retention performance of concrete.

[0046] In Comparative Examples 4-6, under the same dosage (2.6%), the overall performance of Comparative Examples 4-6 was significantly worse than that of Examples 1 or 3 due to the absence or substitution of components in the air-entraining agent mixture. The initial air content of Comparative Examples 4 and 5 was 4.2%-4.3%, which was close to 4.6% of Example 1, but the air content after 1 hour was only 1.8%-2.1%, with a loss rate of over 50%, and large bubbles escaped from the surface. The initial air content of Comparative Example 6 dropped to 3.8%, and the air content after 1 hour was only 1.5%, with a loss rate of 60.5%. In contrast, Example 1 had an air content of 3.7% after 1 hour, a loss rate of only 19.6%, and no large bubble problem. This indicates that the bubble-stabilizing effect of lauric acid diethanolamide, the bubble-refining effect of fatty alcohol polyoxyethylene ether, and the bubble-uniform dispersion effect of sodium sulfosuccinate monoester are all indispensable in the air-entraining agent mixture. The three work together to enhance the strength of the bubble liquid film and inhibit merging and rupture. However, the absence or substitution of components will destroy this synergistic effect, leading to a sharp drop in bubble stability. The 1-hour slump / spread of Comparative Examples 4-6 was significantly lower than that of Example 1, and Comparative Example 6 exhibited bleeding problems. This is because the abnormal composition of the air-entraining agent mixture resulted in poor bubble stability, making it impossible to continuously buffer the friction between slurry particles through microbubbles, thereby exacerbating the loss of slump / spread. In contrast, the air-entraining system of Example 1 was stable and could maintain slurry fluidity for a long time, confirming the crucial role of the compatibility of the air-entraining agent mixture components in maintaining workability.

[0047] Comparative Examples 4-6 all exhibited "poor encapsulation," with Comparative Examples 4 and 6 showing poor cohesion, and Comparative Example 6 also exhibiting bleeding. This contrasts sharply with Example 1, which showed "good workability." The reason for this is that the hydrophilic-hydrophobic balance of lauric acid diethanolamide can improve the encapsulation of aggregates by the slurry, the fatty alcohol polyoxyethylene ether can reduce the surface tension of the slurry to optimize cohesion, and sodium mono- and disulfosuccinate can improve the compatibility of the components. The absence of any component or its replacement with a conventional air-entraining agent (HS-AE-151) will disrupt the interfacial bonding between the slurry and aggregates, leading to a decrease in encapsulation and cohesion, and even bleeding.

[0048] In summary, the air-entraining workability regulator of the present invention can maintain a high slump retention rate and stable gas content for a long time while ensuring initial workability, and has excellent overall workability performance.

[0049] Experiment 2 The test was conducted using concrete with a C50 mix proportion. The specific mix proportions of the concrete are shown in Table 5.

[0050] Table 5

[0051] After preparing the concrete according to the proportions in Table 5, add 2.6% of an admixture and conduct performance tests. The admixture formula is Point-S4407 commercially available from Kezhijie New Materials Group (Guangdong) Co., Ltd., and the regulators prepared in Examples 1-4 and Comparative Examples 1-3 of this invention in a 2:1 ratio to prepare a 10% admixture. After adjusting the admixture dosage, the initial spread of the concrete is (600±20).

[0052] The test results are shown in Table 6.

[0053] Table 6

[0054] As shown in Table 6, under the condition of achieving the same initial expansion (600 mm), the air-entraining workability regulator of the present invention (Examples 1-4) shows significant advantages over Comparative Examples 1-3 in terms of dosage, venting time, and workability. The specific analysis is as follows: The dosage in Examples 1-4 was only 2.1%, lower than 2.6% in Comparative Examples 1 and 2, and 2.4% in Comparative Example 3. At the same spread (600 mm), the lower dosage means that the modifier of the present invention has higher water-reducing efficiency, achieving the same flowability while reducing dosage, thus helping to reduce concrete production costs. The venting times of Examples 1-4 were significantly shorter than those of Comparative Examples 1-3, indicating that the concrete paste had lower viscosity and better fluidity. This is beneficial for solving the high viscosity problem in concrete systems such as manufactured sand concrete. The venting times of Comparative Examples 4-6 were much longer than those of Examples 1-4. The extended venting time directly reflects the increased viscosity of the concrete paste. This is because lauric acid diethanolamide can reduce interparticle friction by optimizing bubble size distribution, fatty alcohol polyoxyethylene ether can reduce interfacial tension of components to improve paste fluidity, and sodium sulfosuccinate monoester can improve the compatibility between the air-entraining agent and polycarboxylic acid molecules. In contrast, the comparative examples, due to abnormal components, had uneven bubble distribution and decreased interfacial compatibility, resulting in increased paste flow resistance and failing to achieve the "soft paste" state of the Examples.

[0055] Comparative Example 1 showed poor workability and a hard slurry; Comparative Example 2 showed moderate workability; Comparative Example 3 showed slightly better workability; while Examples 1-4 all showed good workability, with soft slurries and no issues of hardness, brittleness, or stickiness. This indicates that the regulator of the present invention can not only improve the lubricity of the slurry through its air-entraining function, but also enhance the encapsulation and cohesiveness of the aggregate by optimizing its molecular structure, thus solving the problem that traditional water-reducing agents easily lead to stiff slurries and poor workability at low dosages.

[0056] In summary, the air-entraining workability regulator of the present invention, while ensuring high flowability, has significant performance advantages over comparative examples 1-3 due to its lower dosage, better flowability and superior workability. It is especially suitable for concrete engineering scenarios with high requirements for water reduction efficiency and slurry state.

[0057] Although this document frequently uses terms such as monomer A, monomer B, air-entraining agent mixture, ferrous sulfate, initiator, acrylic acid, chain transfer agent, and pH adjuster, the possibility of using other terms is not excluded. These terms are used merely for the convenience of describing and explaining the essence of the invention; interpreting them as any additional limitation would be contrary to the spirit of the invention.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An air-entraining workability regulator, characterized in that: The raw materials, by mass fraction, include 220-300 parts of monomer A, 30-80 parts of monomer B, 14-20 parts of air-entraining agent mixture, 1-3 parts of 1% ferrous sulfate, 4-5 parts of initiator, 60-70 parts of acrylic acid, 0.4-1 parts of chain transfer agent, 35-40 parts of pH adjuster, and 240-500 parts of water; The monomer A is methoxyallyl polyoxyethylene ether, methallyl polyoxyethylene ether, or ethylene glycol monovinyl polyoxyethylene ether, and the monomer B is methoxy polyethylene glycol methacrylate or ethoxy polyethylene glycol acrylate. The air-entraining agent mixture is a mixture of fatty alcohol polyoxyethylene ether, sodium sulfosuccinate monoester, diethanolamide laurate, and sodium fatty acid polyoxyethylene ether sulfate.

2. The air-entraining workability regulator according to claim 1, characterized in that: The air-entraining agent mixture is prepared by mixing fatty alcohol polyoxyethylene ether, sodium sulfosuccinate monoester, diethanolamide laurate and sodium fatty acid polyoxyethylene ether sulfate in a mass ratio of 1-2:3.5-6.5:4.5-8.5:2-3.

3. The air-entraining workability regulator according to claim 1, characterized in that: The initiator is a redox initiator, comprising an oxidant and a reductant, wherein the mass ratio of the oxidant to the reductant is 5-7:

1.

4. The air-entraining workability regulator according to claim 3, characterized in that: The redox initiator consists of a mixture of hydrogen peroxide and sodium hypophosphite as the oxidant and L-ascorbic acid as the reducing agent.

5. The air-entraining workability regulator according to claim 4, characterized in that: The mass ratio of hydrogen peroxide to sodium hypophosphite is 3:1-2.

6. The air-entraining workability regulator according to claim 4, characterized in that: The hydrogen peroxide has a mass concentration of 27.5%.

7. The air-entraining workability regulator according to claim 1, characterized in that: The chain transfer agent is one or a mixture of several of the following: mercaptoacetic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, mercaptoethanol, and sodium bisulfite.

8. The air-entraining workability regulator according to claim 1, characterized in that: The 1% ferrous sulfate is a 1% (w / w) ferrous sulfate heptahydrate solution.

9. The air-entraining workability regulator according to claim 1, characterized in that: The pH adjuster is a 32% sodium hydroxide aqueous solution.

10. A method for preparing an air-entraining and workability regulator as described in any one of claims 1-9, characterized in that, Includes the following steps: S1. Place the monomer A, monomer B, 1% ferrous sulfate, air-entraining agent mixture and oxidant in a reactor, adjust the reaction temperature to 20℃-45℃, and then uniformly add a mixture of acrylic acid, reducing agent, chain transfer agent and water; the dropping stage lasts for 110-120 min, and the dropping rate is constant. S2. Incubate and mature for 30-40 minutes. After the reaction is complete, add a pH adjuster to adjust the pH to 5-8 to obtain the air-entraining and workability regulator.

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