Environment-friendly concrete water reducing agent and preparation method thereof

Abstract

The invention discloses an environment-friendly concrete water reducing agent and a preparation method thereof. The water reducing agent is prepared from the following raw materials in parts by weight: 25 to 60 parts of polycarboxylic acid water reducing agent mother liquor, 1.5 to 3 parts of modified early strength agent, 0.1 to 0.6 part of defoaming agent, 6 to 15 parts of water-retaining agent, 1.5 to 3.5 parts of dispersing agent, 0.4 to 1.2 parts of air entraining agent and 3 to 6 parts of retarder. The preparation method comprises the following steps: dissolving lignosulfonate in water, adjusting the pH value to 9-11, adding hydrogen peroxide, carrying out a reaction at 60-65 DEG C for 2-4 h, and carrying out drying so as to obtain modified lignosulfonate; the modified early strength agent is prepared from sodium citrate, nano silicon dioxide and a silane coupling agent according to the weight ratio of (3 to 5): 1: (0.08 to 0.12). The water reducer provided by the invention has the advantages of efficient water reduction, stable delayed coagulation, early strength and coagulation promotion and environmental friendliness.

Description

Technical Field

[0001] This application relates to the field of concrete technology, and in particular to an environmentally friendly concrete water-reducing agent and its preparation method. Background Technology

[0002] With the increasing demand for high-performance concrete in the construction industry, concrete water-reducing agents, as key admixtures for improving the workability and strength of concrete, face many challenges in their technological development. Traditional lignin sulfonate and naphthalene-based water-reducing agents suffer from low water reduction rates and poor adaptability. While the current mainstream polycarboxylate-based water-reducing agents have advantages such as adjustable molecular structure and high water reduction rates, they still have shortcomings in practical applications, such as insufficient early strength development and unstable retarding effects. Furthermore, some water-reducing agents are also insufficient in terms of environmental performance, making it difficult to meet the development requirements of green buildings. Summary of the Invention

[0003] In order to solve at least one of the above-mentioned technical problems, and to develop an environmentally friendly water-reducing agent that combines high efficiency in water reduction, stable retarding, early strength and accelerated setting, this application provides an environmentally friendly concrete water-reducing agent and its preparation method.

[0004] In one aspect, this application provides an environmentally friendly concrete water-reducing agent, which comprises the following raw materials by weight: 25-60 parts of polycarboxylate water-reducing agent mother liquor, 1.5-3 parts of modified early strength agent, 0.1-0.6 parts of defoamer, 6-15 parts of water-retaining agent, 1.5-3.5 parts of dispersant, 0.4-1.2 parts of air-entraining agent, and 3-6 parts of retarder; The retarder is an oxidically modified lignin sulfonate, and its preparation method includes the following steps: The modified lignin sulfonate is prepared by dissolving lignin sulfonate in water, adjusting the pH to 9-11, adding hydrogen peroxide, reacting at 60-65℃ for 2-4 hours, and drying. The amount of hydrogen peroxide used is 5-10% of the weight of lignin sulfonate. The modified early strength agent includes sodium citrate, nano silica, and silane coupling agent in a weight ratio of (3-5):1:(0.08-0.12).

[0005] Through the above technical solutions, this application utilizes an environmentally friendly concrete water-reducing agent with specifically designed components. This agent addresses the existing technical problems of low water reduction rate, insufficient early strength, and unstable retarding effect, improving the setting time of concrete and enhancing its compressive strength. Specifically, the retarder, through optimized molecular structure, can stably adsorb onto the surface of cement particles, delaying the crystallization process of hydration products, regulating setting time, and improving workability. The modified early-strength agent, composed of sodium citrate, nano-silica, and a silane coupling agent, utilizes sodium citrate to promote cement mineral dissolution, nano-silica to provide hydration nucleation sites, and the silane coupling agent to ensure uniform dispersion of nanomaterials. The synergistic effect of these three components significantly enhances early strength. The polycarboxylate superplasticizer mother liquor works synergistically with the above-mentioned modified components to ensure water reduction while simultaneously improving concrete setting time and compressive strength. The stable hydration film formed by the water-retaining agent and the uniform bubble structure constructed by the air-entraining agent further enhance the concrete's durability and compressive strength. It effectively solves the technical problems of traditional water-reducing agents in terms of water reduction rate, early strength, unstable retardation effect and environmental performance.

[0006] In some embodiments of this application, the preparation method of the modified early strength agent includes the following steps: mixing sodium citrate and nano silica in a weight ratio to obtain a mixture, adding a silane coupling agent to the mixture, ball milling, and drying to obtain the modified early strength agent.

[0007] Through the above technical solution, this application combines sodium citrate, nano-silica, and a silane coupling agent using the aforementioned preparation method. This addresses the technical challenges of traditional modified early-strength agents in improving the compressive strength of concrete, such as unstable effects and poor compatibility with water-reducing agents, thereby improving the compressive strength of concrete. Specifically, the silane coupling agent forms stable Si-O-Si covalent bonds with the hydroxyl groups on the surface of nano-silica through its siloxane groups, while its organic-terminal amino groups form ionic bonds with the carboxyl groups of sodium citrate, constructing a composite system with a core-shell structure. This modification effectively overcomes the inherent defects of using them alone: ​​on the one hand, it solves the problem of easy agglomeration of nano-silica, ensuring its uniform dispersion in cement paste; on the other hand, it regulates the solubilizing effect of sodium citrate, avoiding excessively vigorous reactions that lead to excessively rapid early hydration rates in the cement paste, thus affecting workability. The modified early strength agent prepared by the above preparation method can organically combine the nucleation effect of nanomaterials with the complexation effect of organic acid radicals to form a gradient enhancement system, thereby solving the technical problems of unstable effect and poor compatibility with water-reducing agents in improving the compressive strength of concrete by traditional modified early strength agents.

[0008] In some embodiments of this application, the average particle size of nano-silica is 10-50 nm; the ball milling parameters are as follows: ball milling at 50-70°C for 2-4 hours.

[0009] In some embodiments of this application, the weight ratio of the retarder to the modified early strength agent is 1.5-2.5:1.

[0010] Through the above technical solution, this application can effectively improve both the setting time and early strength of concrete by adjusting the weight ratio of retarder and modified early strength agent.

[0011] In some embodiments of this application, the air-entraining agent is a triterpenoid saponin; the water-retaining agent includes hydroxypropyl starch ether.

[0012] Through the above technical solution, this application, by using the above-mentioned air-entraining agent and water-retaining agent, and in combination with other components, can effectively improve the setting time and early strength of concrete.

[0013] In some embodiments of this application, the polycarboxylate superplasticizer mother liquor is a water-reducing polycarboxylate superplasticizer mother liquor.

[0014] In some embodiments of this application, the defoamer is an organosilicone defoamer.

[0015] Through the above technical solution, this application can effectively improve the setting time and early strength of concrete by using the above-mentioned type of polycarboxylate superplasticizer mother liquor and defoamer.

[0016] In some embodiments of this application, the dispersant is sodium polyacrylate.

[0017] Secondly, this application provides a method for preparing an environmentally friendly concrete water-reducing agent, characterized in that the preparation method includes the following steps: S1. Mix the polycarboxylate superplasticizer mother liquor with water and stir at 40-50℃ for 10-15 minutes; S2. Add the modified early strength agent, retarder, water-retaining agent and dispersant in sequence, stir at 35-45℃ for 20-30 minutes, then add the remaining ingredients, homogenize and stir for 5-10 minutes, cool, filter and package to obtain the water-reducing agent.

[0018] Through the above technical solution, this application can ensure the uniform dispersion and stability of each component through the above preparation method, thereby preparing a stable and environmentally friendly water-reducing agent.

[0019] In some embodiments of this application, the mixing ratio of polycarboxylate superplasticizer mother liquor to water in step S1 is 1:(1.2-2.5).

[0020] In summary, the present invention has at least one of the following beneficial technical effects: 1. This application presents an environmentally friendly concrete water-reducing agent designed with specific components, which addresses the technical problems of low water reduction rate, insufficient early strength, and unstable retarding effect in existing technologies. It improves the setting time of concrete and enhances its compressive strength. Specifically, the retarder, through optimized molecular structure, can stably adsorb onto the surface of cement particles, delaying the crystallization process of hydration products, regulating setting time, and improving workability. The modified early-strength agent, composed of sodium citrate, nano-silica, and a silane coupling agent, utilizes sodium citrate to promote cement mineral dissolution, nano-silica to provide hydration nucleation sites, and the silane coupling agent to ensure uniform dispersion of nanomaterials; the synergistic effect of these three components significantly improves early strength. The polycarboxylate superplasticizer mother liquor works synergistically with the above-mentioned modified components to ensure water reduction while simultaneously improving concrete setting time and compressive strength. The stable hydration film formed by the water-retaining agent and the uniform bubble structure constructed by the air-entraining agent further enhance the concrete's durability and compressive strength. It effectively solves the technical problems of traditional water-reducing agents in terms of water reduction rate, early strength, unstable retardation effect and environmental performance. Detailed Implementation

[0021] The present application will be further described in detail below with reference to the following examples and embodiments.

[0022] Unless otherwise specified, all ingredients in this application are commercially available.

[0023] With the increasing demand for high-performance concrete in the construction industry, concrete water-reducing agents, as key admixtures for improving the workability and strength of concrete, face many challenges in their technological development. Traditional lignin sulfonate and naphthalene-based water-reducing agents suffer from low water reduction rates and poor adaptability. While the current mainstream polycarboxylate-based water-reducing agents have advantages such as adjustable molecular structure and high water reduction rates, they still have shortcomings in practical applications, such as insufficient early strength development and unstable retarding effects. Furthermore, some water-reducing agents are also insufficient in terms of environmental performance, making it difficult to meet the development requirements of green buildings.

[0024] In order to solve at least one of the above-mentioned technical problems, and to develop an environmentally friendly water-reducing agent that combines high efficiency in water reduction, stable retarding, early strength and accelerated setting, this application provides an environmentally friendly concrete water-reducing agent and its preparation method.

[0025] In one aspect, this application provides an environmentally friendly concrete water-reducing agent, which comprises the following raw materials by weight: 25-60 parts of polycarboxylate water-reducing agent mother liquor, 1.5-3 parts of modified early strength agent, 0.1-0.6 parts of defoamer, 6-15 parts of water-retaining agent, 1.5-3.5 parts of dispersant, 0.4-1.2 parts of air-entraining agent, and 3-6 parts of retarder; The retarder is an oxidically modified lignin sulfonate, and its preparation method includes the following steps: The modified lignin sulfonate is prepared by dissolving lignin sulfonate in water, adjusting the pH to 9-11, adding hydrogen peroxide, reacting at 60-65℃ for 2-4 hours, and drying. The amount of hydrogen peroxide used is 5-10% of the weight of lignin sulfonate. The modified early strength agent includes sodium citrate, nano silica, and silane coupling agent in a weight ratio of (3-5):1:(0.08-0.12).

[0026] Through the above technical solutions, this application utilizes an environmentally friendly concrete water-reducing agent with specifically designed components. This agent addresses the existing technical problems of low water reduction rate, insufficient early strength, and unstable retarding effect, improving the setting time of concrete and enhancing its compressive strength. Specifically, the retarder, through optimized molecular structure, can stably adsorb onto the surface of cement particles, delaying the crystallization process of hydration products, regulating setting time, and improving workability. The modified early-strength agent, composed of sodium citrate, nano-silica, and a silane coupling agent, utilizes sodium citrate to promote cement mineral dissolution, nano-silica to provide hydration nucleation sites, and the silane coupling agent to ensure uniform dispersion of nanomaterials. The synergistic effect of these three components significantly enhances early strength. The polycarboxylate superplasticizer mother liquor works synergistically with the above-mentioned modified components to ensure water reduction while simultaneously improving concrete setting time and compressive strength. The stable hydration film formed by the water-retaining agent and the uniform bubble structure constructed by the air-entraining agent further enhance the concrete's durability and compressive strength. It effectively solves the technical problems of traditional water-reducing agents in terms of water reduction rate, early strength, unstable retardation effect and environmental performance.

[0027] In some embodiments of this application, the preparation method of the modified early strength agent includes the following steps: mixing sodium citrate and nano silica in a weight ratio to obtain a mixture, adding a silane coupling agent to the mixture, ball milling, and drying to obtain the modified early strength agent.

[0028] Through the above technical solution, this application combines sodium citrate, nano-silica, and a silane coupling agent using the aforementioned preparation method. This addresses the technical challenges of traditional modified early-strength agents in improving the compressive strength of concrete, such as unstable effects and poor compatibility with water-reducing agents, thereby improving the compressive strength of concrete. Specifically, the silane coupling agent forms stable Si-O-Si covalent bonds with the hydroxyl groups on the surface of nano-silica through its siloxane groups, while its organic-terminal amino groups form ionic bonds with the carboxyl groups of sodium citrate, constructing a composite system with a core-shell structure. This modification effectively overcomes the inherent defects of using them alone: ​​on the one hand, it solves the problem of easy agglomeration of nano-silica, ensuring its uniform dispersion in cement paste; on the other hand, it regulates the solubilizing effect of sodium citrate, avoiding excessively vigorous reactions that lead to excessively rapid early hydration rates in the cement paste, thus affecting workability. The modified early strength agent prepared by the above preparation method can organically combine the nucleation effect of nanomaterials with the complexation effect of organic acid radicals to form a gradient enhancement system, thereby solving the technical problems of unstable effect and poor compatibility with water-reducing agents in improving the compressive strength of concrete by traditional modified early strength agents.

[0029] In some embodiments of this application, the average particle size of nano-silica is 10-50 nm; the ball milling parameters are as follows: ball milling at 50-70°C for 2-4 hours.

[0030] In some embodiments of this application, the weight ratio of the retarder to the modified early strength agent is 1.5-2.5:1.

[0031] Through the above technical solution, this application can effectively improve both the setting time and early strength of concrete by adjusting the weight ratio of retarder and modified early strength agent.

[0032] In some embodiments of this application, the air-entraining agent is a triterpenoid saponin; the water-retaining agent includes hydroxypropyl starch ether.

[0033] Through the above technical solution, this application, by using the above-mentioned air-entraining agent and water-retaining agent, and in combination with other components, can effectively improve the setting time and early strength of concrete.

[0034] In some embodiments of this application, the polycarboxylate superplasticizer mother liquor is a water-reducing polycarboxylate superplasticizer mother liquor.

[0035] In some embodiments of this application, the defoamer is an organosilicone defoamer.

[0036] Through the above technical solution, this application can effectively improve the setting time and early strength of concrete by using the above-mentioned type of polycarboxylate superplasticizer mother liquor and defoamer.

[0037] In some embodiments of this application, the dispersant is sodium polyacrylate.

[0038] Secondly, this application provides a method for preparing an environmentally friendly concrete water-reducing agent, characterized in that the preparation method includes the following steps: S1. Mix the polycarboxylate superplasticizer mother liquor with water and stir at 40-50℃ for 10-15 minutes; S2. Add the modified early strength agent, retarder, water-retaining agent and dispersant in sequence, stir at 35-45℃ for 20-30 minutes, then add the remaining ingredients, homogenize and stir for 5-10 minutes, cool, filter and package to obtain the water-reducing agent.

[0039] Through the above technical solution, this application can ensure the uniform dispersion and stability of each component through the above preparation method, thereby preparing a stable and environmentally friendly water-reducing agent.

[0040] In some embodiments of this application, the mixing ratio of polycarboxylate superplasticizer mother liquor to water in step S1 is 1:(1.2-2.5). Specific Implementation

[0041] Preparation Examples 1 to 3, and the preparation of retarder; Preparation Example 1 This preparation example provides a retarder, which is an oxidized modified lignin sulfonate, and its preparation method includes the following steps: 100g of lignin sulfonate (specifically sodium lignin sulfonate) was dissolved in 500mL of water, the pH was adjusted to 9, 5g of hydrogen peroxide was added, the mixture was reacted at 60℃ for 4h, and then spray-dried to obtain modified lignin sulfonate.

[0042] Preparation Example 2 This preparation example provides a retarder, which is an oxidized modified lignin sulfonate, and its preparation method includes the following steps: 100g of lignin sulfonate (specifically sodium lignin sulfonate) was dissolved in 500mL of water, the pH was adjusted to 10, 7.5g of hydrogen peroxide was added, the mixture was reacted at 63℃ for 3h, and then spray-dried to obtain modified lignin sulfonate.

[0043] Preparation Example 3 This preparation example provides a retarder, which is an oxidized modified lignin sulfonate, and its preparation method includes the following steps: 100g of lignin sulfonate (specifically sodium lignin sulfonate) was dissolved in 500mL of water, the pH was adjusted to 11, 10g of hydrogen peroxide was added, the mixture was reacted at 65℃ for 2h, and then spray-dried to obtain modified lignin sulfonate.

[0044] Preparation Examples 4 to 6, preparation of modified early strength agents; Preparation Example 4 This preparation example provides a modified early strength agent, the preparation method of which includes the following steps: 300g of sodium citrate and 100g of nano-silica were mixed, and 8g of silane coupling agent KH-550 was added. The mixture was ball-milled at 50℃ for 4 hours and dried at 80℃ to obtain the modified early strength agent. The average particle size of the nano-silica was 10-50nm.

[0045] Preparation Example 5 This preparation example provides a modified early-strength agent, which is prepared by the following steps: 400g of sodium citrate and 100g of nano-silica are mixed, 10g of silane coupling agent KH-550 is added, the mixture is ball-milled at 60℃ for 3h, and dried at 80℃ to obtain the modified early-strength agent. The average particle size of the nano-silica is 10-50nm.

[0046] Preparation Example 6 This preparation example provides a modified early-strength agent, which is prepared by the following steps: 500g of sodium citrate and 100g of nano-silica are mixed, 12g of silane coupling agent KH-550 is added, the mixture is ball-milled at 70℃ for 2h, and dried at 80℃ to obtain the modified early-strength agent. The average particle size of the nano-silica is 10-50nm.

[0047] Examples 1-8 Example 1 This embodiment provides an environmentally friendly concrete water-reducing agent, which comprises the following raw materials by weight: The formula consists of 50 parts polycarboxylate superplasticizer mother liquor, 2.5 parts modified early strength agent, 0.5 parts defoamer, 12 parts water-retaining agent, 2 parts dispersant, 1 part air-entraining agent, and 5 parts retarder. All other parameters remain the same as in Example 1.

[0048] The retarder in this embodiment was prepared by the preparation method of Preparation Example 1.

[0049] The modified early strength agent in this embodiment was prepared by the preparation method of Preparation Example 4.

[0050] The dispersant in this embodiment is sodium polyacrylate; CAS number is 9003-04-7.

[0051] In this embodiment, the air-entraining agent is a triterpenoid saponin; The water-retaining agent in this embodiment is hydroxypropyl starch ether; CAS number is 9049-76-7.

[0052] In this embodiment, the defoamer is an organosilicone defoamer; The polycarboxylate superplasticizer mother liquor in this embodiment is a water-reducing polycarboxylate superplasticizer mother liquor with a water reduction rate of ≥35%.

[0053] The preparation method of the environmentally friendly concrete water-reducing agent in this embodiment includes the following steps: S1. Mix the polycarboxylate superplasticizer mother liquor with water and stir at 40°C for 12 minutes; S2. Add the modified early strength agent, retarder, water-retaining agent and dispersant in sequence, stir at 35°C for 28 minutes, then add the air-entraining agent and defoamer, homogenize and stir for 8 minutes, cool, filter and package to obtain the water-reducing agent.

[0054] In step S1, the mixing ratio of polycarboxylate superplasticizer mother liquor to water is 1:2.

[0055] Example 2 The difference between this embodiment and Embodiment 1 is that in the environmentally friendly concrete water-reducing agent in this embodiment, the total weight of the modified early-strength agent and the retarder is 7.5 parts, wherein the weight ratio of the retarder and the modified early-strength agent is 1.5:1.

[0056] Example 3 The difference between this embodiment and Embodiment 1 is that in the environmentally friendly concrete water-reducing agent in this embodiment, the total weight of the modified early-strength agent and the retarder is 7.5 parts, wherein the weight ratio of the retarder and the modified early-strength agent is 2.2:1.

[0057] Example 4 The difference between this embodiment and Embodiment 1 is that in the environmentally friendly concrete water-reducing agent in this embodiment, the total weight of the modified early-strength agent and the retarder is 7.5 parts, wherein the weight ratio of the retarder and the modified early-strength agent is 2.5:1.

[0058] Example 5 The difference between this embodiment and Embodiment 1 is that the environmentally friendly concrete water-reducing agent in this embodiment includes the following raw materials in parts by weight: 25 parts polycarboxylate superplasticizer mother liquor, 2 parts modified early strength agent, 0.1 parts defoamer, 6 parts water-retaining agent, 1.5 parts dispersant, 0.4 parts air-entraining agent, and 4 parts retarder; Example 6 The difference between this embodiment and Embodiment 1 is that the environmentally friendly concrete water-reducing agent in this embodiment includes the following raw materials by weight: 60 parts polycarboxylate water-reducing agent mother liquor, 3 parts modified early-strength agent, 0.6 parts defoamer, 15 parts water-retaining agent, 3.5 parts dispersant, 1.2 parts air-entraining agent, and 6 parts retarder. All other parameters remain the same as in Embodiment 1.

[0059] Example 7 The difference between this embodiment and Example 1 is that the retarder in this embodiment is prepared by the preparation method of Example 2.

[0060] The modified early-strength agent in this embodiment was prepared by the method of Preparation Example 5. All other parameters remained the same as in Example 1.

[0061] Example 8 The difference between this embodiment and Example 1 is that the retarder in this embodiment is prepared by the preparation method of Example 3.

[0062] The modified early-strength agent in this embodiment was prepared by the method described in Example 5. All other parameters remained the same as in Example 1.

[0063] Comparative Example 1 The difference between this comparative example and Example 1 is that the environmentally friendly concrete water-reducing agent in this comparative example includes the following raw materials in parts by weight: 25 parts polycarboxylate superplasticizer mother liquor, 2.5 parts early strength agent, 0.1 parts defoamer, 6 parts water-retaining agent, 1.5 parts dispersant, 0.4 parts air-entraining agent, and 5 parts retarder; The retarder in this comparative example is lignin sulfonate.

[0064] The accelerator in this comparative example is sodium citrate. All other parameters remain the same as in Example 1.

[0065] Comparative Example 2 The difference between this comparative example and Example 1 is that the environmentally friendly concrete water-reducing agent in this comparative example includes the following raw materials in parts by weight: In this comparative example, an equal amount of lignin sulfonate (specifically sodium lignin sulfonate) was used instead of the retarder in Example 1.

[0066] The modified early-strength agent in this comparative example was prepared by the method of Preparation Example 4. All other parameters remained the same as in Example 1.

[0067] Comparative Example 3 The difference between this comparative example and Example 1 is that the environmentally friendly concrete water-reducing agent in this comparative example includes the following raw materials in parts by weight: The retarder in this comparative example was prepared by the method of Preparation Example 1.

[0068] In this comparative example, an equal amount of sodium citrate was used instead of the modified early-strength agent in Example 1. All other parameters remained the same as in Example 1.

[0069] Experimental testing According to GB / 8076-2008 "Concrete Admixtures" and GBT / 50082-2009 "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete", relevant performance tests were conducted on concretes containing water-reducing agents from Examples 1-8 and Comparative Examples 1-3 (with an admixture dosage of 0.5% of the total weight of the concrete). The test results are shown in Table 1 (the concrete mix ratio was: m(cement):m(sand):m(aggregate):m(water) = 330:673:1000:140. The cement was ordinary Portland cement (PO 42.5R).

[0070] Table 1 - Performance Test Results of Concrete As shown in Table 1, the environmentally friendly concrete water-reducing agent provided in this application, when added to concrete, can extend the setting time of concrete and improve its compressive strength and workability. Compared with the unmodified water-reducing agent, the modified retarder and composite early-strength agent can simultaneously improve the setting time and compressive strength of concrete.

[0071] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. An environmentally friendly concrete water-reducing agent, characterized in that, The water-reducing agent comprises the following raw materials by weight: 25-60 parts of polycarboxylate superplasticizer mother liquor, 1.5-3 parts of modified early strength agent, 0.1-0.6 parts of defoamer, 6-15 parts of water-retaining agent, 1.5-3.5 parts of dispersant, 0.4-1.2 parts of air-entraining agent, and 3-6 parts of retarder; The retarder is an oxidized modified lignin sulfonate, and its preparation method includes the following steps: The modified lignin sulfonate is prepared by dissolving lignin sulfonate in water, adjusting the pH to 9-11, adding hydrogen peroxide, reacting at 60-65℃ for 2-4 hours, and drying. The amount of hydrogen peroxide used is 5-10% of the weight of lignin sulfonate. The modified early strength agent includes sodium citrate, nano-silica, and silane coupling agent in a weight ratio of (3-5):1:(0.08-0.12).

2. The environmentally friendly concrete water-reducing agent according to claim 1, characterized in that, The preparation method of the modified early strength agent includes the following steps: mixing sodium citrate and nano silica in a weight ratio to obtain a mixture, adding a silane coupling agent to the mixture, ball milling, and drying to obtain the modified early strength agent.

3. The environmentally friendly concrete water-reducing agent according to claim 1, characterized in that, The average particle size of the nano-silica is 10-50 nm; the ball milling parameters are as follows: ball milling at 50-70℃ for 2-4 hours.

4. The environmentally friendly concrete water-reducing agent according to claim 1, characterized in that, The weight ratio of the retarder to the modified early strength agent is 1.5-2.5:

1.

5. The environmentally friendly concrete water-reducing agent according to claim 1, characterized in that, The air-entraining agent is a triterpenoid saponin; the water-retaining agent includes hydroxypropyl starch ether.

6. The environmentally friendly concrete water-reducing agent according to claim 1, characterized in that, The polycarboxylate superplasticizer mother liquor is a water-reducing polycarboxylate superplasticizer mother liquor.

7. The environmentally friendly concrete water-reducing agent according to claim 1, characterized in that, The defoamer is an organosilicone defoamer.

8. The environmentally friendly concrete water-reducing agent according to claim 1, characterized in that, The dispersant is sodium polyacrylate.

9. A method for preparing the environmentally friendly concrete water-reducing agent according to claim 1, characterized in that, The preparation method includes the following steps: S1. Mix the polycarboxylate superplasticizer mother liquor with water and stir at 40-50℃ for 10-15 minutes; S2. Add the modified early strength agent, retarder, water-retaining agent and dispersant in sequence, stir at 35-45℃ for 20-30 minutes, then add the remaining ingredients, homogenize and stir for 5-10 minutes, cool, filter and package to obtain the water-reducing agent.

10. The preparation method of the environmentally friendly concrete water-reducing agent according to claim 9, characterized in that, The mixing ratio of the polycarboxylate superplasticizer mother liquor to water in step S1 is 1:(1.2-2.5).

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