Early-strength polycarboxylate superplasticizer and preparation method thereof

Abstract

The invention relates to the field of building admixtures, in particular to an early-strength polycarboxylate superplasticizer and a preparation method thereof. The preparation method comprises the following steps: adding a polyether monomer, an accelerant, ferrous sulfate, an oxidant and water into a reactor, stirring and dissolving uniformly to obtain a backing material; the preparation method comprises the following steps: adding acrylic acid and a chain transfer agent into water, and uniformly dissolving to obtain a solution A; dropwise adding the solution A and the reducing agent aqueous solution into the base material at the same time for reaction, and after dropwise adding is completed, performing heat preservation reaction to obtain the polycarboxylate superplasticizer; and dropwise adding the modified calcium nitrate aqueous solution and the modified sodium silicate aqueous solution into the polycarboxylate superplasticizer at the same time, and fully reacting to obtain the early-strength polycarboxylate superplasticizer. The early-strength polycarboxylate superplasticizer is dispersed more uniformly in the concrete stirring process, cement hydration is induced through sodium silicate, the hydration process is accelerated, the early strength of concrete is improved, the later strength of the concrete is guaranteed, meanwhile, operation is easy, and the early-strength polycarboxylate superplasticizer has higher popularization value.

Description

Technical Field

[0001] The invention relates to the field of building admixtures, and in particular to an early-strength polycarboxylate water-reducing agent and a preparation method thereof. Background Art

[0002] The dosage of traditional early strength agent is high during use, the concrete has low strength in the later stage, and it is highly chemically corrosive. In addition, the dosage of traditional early strength polycarboxylate water reducer is high and unstable. Currently, the commonly used early strength admixtures are mainly organic compounds, such as calcium formate, etc. Although they can improve the early strength, they have an adverse effect on the later strength of concrete, and excessive admixture may lead to the stability and durability of the concrete structure.

[0003] During the cement hydration process, water reducers can induce the hydration reaction to occur quickly, but the existing induction method is mainly solid powder admixtures, which cannot achieve rapid dispersion during the concrete mixing process, resulting in uneven dispersion and uneven strength distribution.

[0004] Therefore, how to prepare a water reducing agent that carries hydration-inducing groups, releases them quickly in concrete, improves the early strength of concrete and ensures the later strength is a technical problem that technical personnel in this field urgently need to solve. Summary of the invention

[0005] In order to solve the problem of how to prepare a kind of hydration-inducing group, which can be quickly released in concrete and A water reducer for improving the early strength of concrete and ensuring the later strength. The present invention provides a method for preparing an early strength polycarboxylate water reducer, comprising the following steps: S1. Add polyether monomer, accelerator, ferrous sulfate, oxidant and water into the reactor and stir to dissolve Add acrylic acid and chain transfer agent into water and dissolve them uniformly to obtain liquid A; S2, adding liquid A and the reducing agent aqueous solution to the bottom material at the same time, reacting, and after the addition is completed, heat preservation reaction is carried out to obtain a polycarboxylate water reducer; S3, adding modified calcium nitrate aqueous solution and modified sodium silicate aqueous solution to the polycarboxylate water-reducing agent at the same time, and after sufficient reaction, an early strength polycarboxylate water-reducing agent is obtained; The preparation method of the modified calcium nitrate aqueous solution and the modified sodium silicate aqueous solution is as follows: Calcium nitrate tetrahydrate is dissolved in a quaternary ammonium salt aqueous solution, heated and fully stirred, after the reaction is completed, filtered and dried to obtain modified calcium nitrate, and the modified calcium nitrate is dissolved in water to obtain a modified calcium nitrate aqueous solution; sodium silicate nonahydrate is dissolved in a quaternary ammonium salt aqueous solution, heated and fully stirred, after the reaction is completed, filtered and dried to obtain modified sodium silicate, and the modified sodium silicate is dissolved in water to obtain a modified sodium silicate aqueous solution.

[0006] On the basis of the above scheme, further, in the base material, the polyether monomer is 200 parts, the accelerator is 3-5 parts, the ferrous sulfate is 0.01-0.05 parts, the oxidant is 1-3 parts, and the water is 100-200 parts; in liquid A, the acrylic acid is 5-20 parts, the chain transfer agent is 0.3-0.8 parts, and the water is 15 parts; The reducing agent aqueous solution is 0.3-0.5 parts of the reducing agent dissolved in 10 parts of water.

[0007] On the basis of the above scheme, further, in the preparation process of the modified calcium nitrate aqueous solution and the modified sodium silicate aqueous solution, the calcium nitrate tetrahydrate is 10-50 parts, the sodium silicate nonahydrate is 10-50 parts, and the quaternary ammonium salt aqueous solution is 50-60 parts; the quaternary ammonium salt aqueous solution is a quaternary ammonium salt dissolved in water, the mass ratio of the quaternary ammonium salt to water is 1-10:10, and the pH value of the quaternary ammonium salt aqueous solution is 2-5; in the modified calcium nitrate aqueous solution, the mass ratio of modified calcium nitrate to water is 1-5:15; the modified calcium nitrate aqueous solution is 15-20 parts, wherein the mass ratio of modified calcium nitrate to water is 5:10-15; the modified sodium silicate aqueous solution is 15-20 parts, wherein the mass ratio of modified sodium silicate to water is 5:10-15.

[0008] On the basis of the above scheme, further, in step S2, the dropping time is 1-3h, the reaction temperature is 20-70°C, the insulation temperature is 20-70°C, and the insulation reaction time is 1-3h; In step S3, the dropping time is 0.5-3 hours, and the stirring is 1-2 hours after the dropping is completed.

[0009] On the basis of the above scheme, further, during the preparation process of the modified calcium nitrate aqueous solution and the modified sodium silicate aqueous solution, the heating temperature is 30-80° C. and the stirring time is 2-6 hours.

[0010] On the basis of the above scheme, further, the polyether monomer is one or more combinations of methyl allyl polyoxyethylene ether, isopentenyl polyoxyethylene ether, isobutylene ether polyoxyethylene ether, isobutylene polyethylene glycol ether or isopentenyl polyethylene glycol ether; the molecular weight of the polyether monomer is 3000-6000.

[0011] On the basis of the above scheme, further, the accelerator is hydroxyethyl acrylate; the chain transfer agent is one or more combinations of mercaptopropionic acid, thioglycolic acid, sodium methacrylic acid or sodium propylene sulfonate; and the oxidant is hydrogen peroxide.

[0012] On the basis of the above scheme, further, the reducing agent is one or more combinations of sodium bisulfite, vitamin C and sodium hypophosphite.

[0013] On the basis of the above scheme, further, the quaternary ammonium salt is one or more combinations of hexadecyltrimethylammonium bromide, octadecyltrimethylammonium bromide, Gemini quaternary ammonium salt or hydroxyethyldimethylalkylammonium bromide.

[0014] The present invention also provides an early-strength polycarboxylate water-reducing agent prepared according to the preparation method of the early-strength polycarboxylate water-reducing agent as described above.

[0015] Compared with the prior art, the early-strength polycarboxylate water-reducing agent and the preparation method thereof provided by the present invention modify calcium nitrate and sodium silicate by means of quaternary ammonium salt, wherein the cations in the quaternary ammonium salt can undergo ion exchange reaction with the anions in the sodium silicate or calcium silicate, thereby changing the charge properties and surface properties of the materials, and obtaining modified calcium nitrate and modified sodium silicate. The modified calcium nitrate and modified sodium silicate are added dropwise to the polycarboxylate water-reducing agent, and the cations carried by the modified calcium nitrate and the modified sodium silicate attract each other through electrostatic interaction with the anions of the polycarboxylic acid, and no new chemical bonds are formed at the same time, and the modified calcium nitrate and the modified sodium silicate are attached to the polycarboxylic acid molecular chain to form an early-strength polycarboxylate water-reducing agent. The early-strength polycarboxylate water-reducing agent synthesized by the method can better improve the early strength of concrete by physically inducing cement to undergo hydration reaction by introducing calcium silicate particles into concrete, while taking into account the later strength of concrete, and greatly reducing the influence of organic additives on the durability and stability of concrete. During use, the advantages of low dosage and high strength can be achieved. In addition, the preparation method provided by the present invention is simple to operate and low in cost, and can achieve good social benefits. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0017] Example 1 Preparation of modified calcium nitrate and modified sodium silicate: Dissolve 10 parts of calcium nitrate tetrahydrate and 10 parts of sodium silicate nonahydrate in 50 parts of hexadecyltrimethylammonium bromide aqueous solution, heat to 35°C, and stir at constant temperature for 3 hours. After the reaction is completed, filter and dry to obtain modified calcium nitrate and modified sodium silicate; Wherein, the mass ratio of hexadecyltrimethylammonium bromide:water is 1:10, and the pH value of the hexadecyltrimethylammonium bromide aqueous solution is 4.

[0018] Preparation of early strength polycarboxylate water reducer: S1: 200 parts of 3000 molecular weight methyl allyl polyoxyethylene ether, 2 parts of hydrogen peroxide, 3 parts of hydroxyethyl acrylate, 0.01 parts of ferrous sulfate and 170 parts of water are added into a reactor and stirred to dissolve uniformly to obtain a base material; 6 parts of acrylic acid, 0.5 parts of thioglycolic acid and 15 parts of water are mixed to obtain liquid A; 0.3 parts of vitamin C are added into 10 parts of water and stirred to obtain a reducing agent aqueous solution; S2: Liquid A and the reducing agent aqueous solution are simultaneously added dropwise to the base material at a temperature of 20°C for 1 hour. After the addition is completed, the mixture is kept at 20°C for 1 hour to obtain a polycarboxylate water-reducing agent. S3: Take 5 parts of modified calcium nitrate and 5 parts of modified sodium silicate, dissolve them in 15 parts of water respectively, and prepare modified calcium nitrate aqueous solution and modified sodium silicate aqueous solution. Add the modified calcium nitrate aqueous solution and modified sodium silicate aqueous solution into the polycarboxylate water reducer at the same time. The adding time is 1 hour. After the adding is completed, stir for 1 hour to obtain an early-strength polycarboxylate water reducer with a solid content of 40%.

[0019] Example 2 Preparation of modified calcium nitrate and modified sodium silicate: Dissolve 10 parts of calcium nitrate tetrahydrate and 10 parts of sodium silicate nonahydrate in 50 parts of octadecyltrimethylammonium bromide aqueous solution, heat to 40°C, and stir at constant temperature for 2.5 hours. After the reaction is completed, filter and dry to obtain modified calcium nitrate and modified sodium silicate; Wherein, the mass ratio of octadecyltrimethylammonium bromide:water is 1:10, and the pH value of the octadecyltrimethylammonium bromide aqueous solution is 5.

[0020] Preparation of early strength polycarboxylate water reducer: S1: 200 parts of 5000 molecular weight isobutylene polyethylene glycol ether, 1.5 parts of hydrogen peroxide, 3 parts of hydroxyethyl acrylate, 0.01 parts of ferrous sulfate and 180 parts of water are added into a reactor and stirred to dissolve uniformly to obtain a base material; 6 parts of acrylic acid, 0.5 parts of thioglycolic acid and 15 parts of water are mixed to obtain liquid A; 0.5 parts of sodium bisulfate are added into 10 parts of water and stirred to obtain a reducing agent aqueous solution; S2: Liquid A and the reducing agent aqueous solution are simultaneously added dropwise to the base material at a temperature of 30°C for 1.5 hours. After the addition is completed, the mixture is kept at 30°C for 1 hour to obtain a polycarboxylate water-reducing agent. S3: Take 5 parts of modified calcium nitrate and 5 parts of modified sodium silicate, dissolve them in 10 parts of water respectively, and prepare modified calcium nitrate aqueous solution and modified sodium silicate aqueous solution. Add the modified calcium nitrate aqueous solution and modified sodium silicate aqueous solution into the polycarboxylate water reducer at the same time. The adding time is 2 hours. After the adding is completed, stir for 1 hour to obtain an early-strength polycarboxylate water reducer with a solid content of 30%.

[0021] Example 3 Preparation of modified calcium nitrate and modified sodium silicate: Dissolve 10 parts of calcium nitrate tetrahydrate and 10 parts of sodium silicate nonahydrate in 60 parts of hydroxyethyl dimethyl alkyl ammonium bromide aqueous solution, heat to 60°C, and stir at constant temperature for 3 hours. After the reaction is completed, filter and dry to obtain modified calcium nitrate and modified sodium silicate; Wherein, the mass ratio of hydroxyethyldimethylalkylammonium bromide: water is 1:10, and the pH value of the hydroxyethyldimethylalkylammonium bromide aqueous solution is 5.

[0022] Preparation of early strength polycarboxylate water reducer: S1: 150 parts of 3000 molecular weight methyl allyl polyoxyethylene ether, 50 parts of 5000 molecular weight isobutylene ether polyoxyethylene ether, 2.2 parts of hydrogen peroxide, 3 parts of hydroxyethyl acrylate, 0.01 parts of ferrous sulfate and 170 parts of water are added into a reactor and stirred to dissolve uniformly to obtain a base material; 6 parts of acrylic acid, 0.2 parts of thioglycolic acid, 0.3 parts of sodium propylene sulfonate and 15 parts of water are mixed to obtain liquid A; 0.1 parts of sodium hypophosphite and 0.3 parts of sodium bisulfite are added into 10 parts of water and stirred to obtain a reducing agent aqueous solution; S2: Liquid A and the reducing agent aqueous solution are simultaneously added dropwise to the base material at a temperature of 20°C for 1 hour. After the addition is completed, the mixture is kept at 20°C for 1 hour to obtain a polycarboxylate water-reducing agent. S3: Take 5 parts of modified calcium nitrate and 5 parts of modified sodium silicate, dissolve them in 10 parts of water respectively, and prepare modified calcium nitrate aqueous solution and modified sodium silicate aqueous solution. Add the modified calcium nitrate aqueous solution and modified sodium silicate aqueous solution into the polycarboxylate water reducer at the same time, and add the solution for 30 minutes. After the addition is completed, stir for 2 hours to obtain an early-strength polycarboxylate water reducer with a solid content of 50%.

[0023] Example 4 The difference between Example 4 and Example 1 is that in the preparation process of modified calcium nitrate and modified sodium silicate, the raw material portions of calcium nitrate tetrahydrate and sodium silicate nonahydrate are different, specifically: Dissolve 10 parts of calcium nitrate tetrahydrate and 30 parts of sodium silicate nonahydrate in 50 parts of hexadecyltrimethylammonium bromide aqueous solution, heat to 35°C, and stir at constant temperature for 3 hours. After the reaction is completed, filter and dry to obtain modified calcium nitrate and modified sodium silicate; The remaining raw material components and preparation process are the same as those in Example 1.

[0024] Example 5 The difference between Example 5 and Example 2 is that in the preparation process of modified calcium nitrate and modified sodium silicate, the raw material portions of calcium nitrate tetrahydrate and sodium silicate nonahydrate are different, specifically: Dissolve 10 parts of calcium nitrate tetrahydrate and 50 parts of sodium silicate nonahydrate in 50 parts of octadecyltrimethylammonium bromide aqueous solution, heat to 40°C, and stir at constant temperature for 2.5 hours. After the reaction is completed, filter and dry to obtain modified calcium nitrate and modified sodium silicate; The remaining raw material components and preparation process are the same as those in Example 2.

[0025] Example 6 The difference between Example 6 and Example 3 is that in the preparation process of modified calcium nitrate and modified sodium silicate, the raw material portions of calcium nitrate tetrahydrate and sodium silicate nonahydrate are different, specifically: Dissolve 30 parts of calcium nitrate tetrahydrate and 10 parts of sodium silicate nonahydrate in 60 parts of hydroxyethyl dimethyl alkyl ammonium bromide aqueous solution, heat to 60°C, and stir at constant temperature for 3 hours. After the reaction is completed, filter and dry to obtain modified calcium nitrate and modified sodium silicate; The remaining raw material components and preparation process are the same as those in Example 3.

[0026] Example 7 The difference between Example 7 and Example 1 is that in the preparation process of modified calcium nitrate and modified sodium silicate, the raw material portions of calcium nitrate tetrahydrate and sodium silicate nonahydrate are different, specifically: Dissolve 50 parts of calcium nitrate tetrahydrate and 10 parts of sodium silicate nonahydrate in 50 parts of hexadecyltrimethylammonium bromide aqueous solution respectively, heat to 35°C, stir at constant temperature for 3 hours, and after the reaction is completed, filter and dry to obtain modified calcium nitrate and modified sodium silicate; The remaining raw material components and preparation process are the same as those in Example 1.

[0027] Comparative Example 1 In strict accordance with Example 1, calcium nitrate tetrahydrate and sodium silicate nonahydrate were not modified with quaternary ammonium salts, but were directly added dropwise into the polycarboxylate water-reducing agent. The remaining raw material components and preparation process were the same as those in Example 1.

[0028] Comparative Example 2 Strictly in accordance with Example 2, liquid A, reducing agent aqueous solution, modified calcium nitrate aqueous solution and modified sodium silicate aqueous solution were simultaneously added dropwise into the base material at a temperature of 30°C for 1.5 h. After the addition was completed, the reaction was kept warm for 1 h. The remaining raw material components and preparation process were the same as those in Example 2.

[0029] Comparative Example 3 Strictly follow Example 3, the modification process is carried out at room temperature, and the remaining raw material components and preparation process are the same as Example 3.

[0030] Comparative Example 4 The modification process was strictly in accordance with Example 3. The product was directly added dropwise into the polycarboxylic acid base liquid without filtering and drying. The remaining raw material components and preparation process were the same as those in Example 3.

[0031] Comparative Example 5 Strictly in accordance with Example 3, the polycarboxylate water-reducing agent was synthesized without adding an accelerator, and the remaining raw material components and preparation process were the same as those in Example 3.

[0032] Comparative Example 6 Strictly according to Example 1, 70 parts of calcium nitrate tetrahydrate and 10 parts of sodium silicate nonahydrate were dissolved in 50 parts of hexadecyltrimethylammonium bromide aqueous solution respectively. The other raw material components and preparation process were the same as those in Example 1.

[0033] Comparative Example 7 Strictly according to Example 1, 10 parts of calcium nitrate tetrahydrate and 70 parts of sodium silicate nonahydrate were dissolved in 50 parts of hexadecyltrimethylammonium bromide aqueous solution respectively. The other raw material components and preparation process were the same as those in Example 1.

[0034] Comparative Example 8 Strictly in accordance with Example 1, only the modified calcium nitrate aqueous solution was added during the preparation process, and the modified sodium silicate aqueous solution was not added. The remaining raw material components and the preparation process were the same as those in Example 1.

[0035] Comparative Example 9 Strictly in accordance with Example 1, only the modified sodium silicate aqueous solution was added during the preparation process, and the modified calcium nitrate aqueous solution was not added. The remaining raw material components and the preparation process were the same as those in Example 1.

[0036] Comparative Example 10 Commercially available early-strength polycarboxylate water-reducing agent (mixed with calcium formate).

[0037] Comparative Example 11 Commercially available early-strength polycarboxylate water-reducing agent (mixed with triethanolamine).

[0038] Performance Testing According to GB / T 8077-2012 “Test method for homogeneity of concrete admixtures”, the early-strength polycarboxylate water-reducing agents prepared in the above examples and comparative examples were tested for mortar fluidity and compressive strength.

[0039] According to GB / T 50080 2016 "Standard for Test Methods for Properties of Ordinary Concrete Mixtures", the early-strength polycarboxylate water-reducing agent prepared in the above examples and comparative examples was added to the concrete to measure the compressive strength of the concrete, and the water-cement ratio was fixed at 0.48; The concrete mix ratio is: water: 175kg, cement (Spring Pool Cement P.052.5R): 360kg, machine-made sand (mud content 5%): 790kg, stone: 1060kg.

[0040] The test results are shown in Table 1.

[0041] Table 1

[0042] As can be seen from Table 1, compared with Comparative Example 1 in which calcium nitrate tetrahydrate and sodium silicate nonahydrate are not modified with quaternary ammonium salts, Comparative Example 8 in which only modified calcium nitrate is added, and Comparative Example 9 in which only modified sodium silicate is added, the early-strength polycarboxylate water-reducing agent of Examples 1-7 not only improves the initial paste fluidity of cement and the paste fluidity of 1h and 2h, but also accelerates the cement hydration process and improves the compressive strength of cement mortar. In addition, the early strength of concrete is significantly increased, and the later strength of concrete is guaranteed; compared with Comparative Examples 2-4 in which the reaction conditions and the order of reactant addition of the examples are changed, Comparative Example 5 in which no accelerator is added, and Comparative Examples 6-7 in which the ratio of calcium nitrate tetrahydrate and sodium silicate nonahydrate is changed, the early-strength polycarboxylate water-reducing agent of Examples 1-7 has significantly improved initial paste fluidity of cement and the paste fluidity of 1h and 2h, the compressive strength of cement mortar, and the early and late strength of concrete; Comparative Examples 9 and 10 are commercially available polycarboxylate water-reducing agents, which cannot guarantee the later strength of concrete, resulting in reduced durability of concrete.

[0043] In summary, the present invention adopts cations in quaternary ammonium salt to react with anions in sodium silicate or calcium silicate by ion exchange reaction, and sodium silicate and calcium silicate are in a specific ratio, thereby changing the charge property and surface property of the material, obtaining modified calcium nitrate and modified sodium silicate, and the cations carried by sodium silicate generated by reaction in polycarboxylate water-reducing agent and the anions of polycarboxylic acid attract each other through electrostatic interaction, and simultaneously no new chemical bonds are formed, and attached to the polycarboxylic acid chain. The concrete is dispersed more evenly during the concrete mixing process, cement hydration is induced by sodium silicate, the hydration process is accelerated, thereby increasing the early strength of concrete, and the operation is simple at the same time, and the concrete has more promotion value.

[0044] Although the terms such as modified calcium nitrate aqueous solution, modified sodium silicate aqueous solution, polycarboxylate water-reducing agent, calcium nitrate tetrahydrate and sodium silicate nonahydrate are used more frequently in this article, the possibility of using other terms is not excluded. The use of these terms is only for more convenient description and explanation of the essence of the present invention; interpreting them as any additional limitation is contrary to the spirit of the present invention.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements 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. A method for preparing an early-strength polycarboxylate water-reducing agent, characterized in that: The process comprises the following steps: S1, adding polyether monomer, accelerator, ferrous sulfate, oxidant and water into a reactor and stirring to dissolve Add acrylic acid and chain transfer agent into water and dissolve them uniformly to obtain liquid A; S2, adding liquid A and the reducing agent aqueous solution to the bottom material at the same time, reacting, and after the addition is completed, heat preservation reaction is carried out to obtain a polycarboxylate water reducer; S3, adding modified calcium nitrate aqueous solution and modified sodium silicate aqueous solution to the polycarboxylate water-reducing agent at the same time, and after sufficient reaction, an early strength polycarboxylate water-reducing agent is obtained; The preparation method of the modified calcium nitrate aqueous solution and the modified sodium silicate aqueous solution is as follows: Calcium nitrate tetrahydrate is dissolved in a quaternary ammonium salt aqueous solution, heated and fully stirred, after the reaction is completed, filtered and dried to obtain modified calcium nitrate, and the modified calcium nitrate is dissolved in water to obtain a modified calcium nitrate aqueous solution; sodium silicate nonahydrate is dissolved in a quaternary ammonium salt aqueous solution, heated and fully stirred, after the reaction is completed, filtered and dried to obtain modified sodium silicate, and the modified sodium silicate is dissolved in water to obtain a modified sodium silicate aqueous solution.

2. The method for preparing the early-strength polycarboxylate water-reducing agent according to claim 1, characterized in that: In terms of weight, in the base material, the polyether monomer is 200 parts, the accelerator is 3-5 parts, the ferrous sulfate is 0.01-0.05 parts, the oxidant is 1-3 parts, and the water is 100-200 parts; in liquid A, the acrylic acid is 5-20 parts, the chain transfer agent is 0.3-0.8 parts, and the water is 15 parts; The reducing agent aqueous solution is 0.3-0.5 parts of the reducing agent dissolved in 10 parts of water.

3. The method for preparing the early-strength polycarboxylate water-reducing agent according to claim 1, characterized in that: In the preparation process of the modified calcium nitrate aqueous solution and the modified sodium silicate aqueous solution, the calcium nitrate tetrahydrate is 10-50 parts, the sodium silicate nonahydrate is 10-50 parts, and the quaternary ammonium salt aqueous solution is 50-60 parts; the quaternary ammonium salt aqueous solution is a quaternary ammonium salt dissolved in water, the mass ratio of the quaternary ammonium salt to water is 1-10:10, and the pH value of the quaternary ammonium salt aqueous solution is 2-5; in the modified calcium nitrate aqueous solution, the mass ratio of the modified calcium nitrate to water is 1-5:15; the modified calcium nitrate aqueous solution is 15-20 parts, wherein the mass ratio of the modified calcium nitrate to water is 5:10-15; the modified sodium silicate aqueous solution is 15-20 parts, wherein the mass ratio of the modified sodium silicate to water is 5:10-15.

4. The method for preparing the early-strength polycarboxylate water-reducing agent according to claim 1, characterized in that: In the step S2, the dropping time is 1-3h, the reaction temperature is 20-70°C, the insulation temperature is 20-70°C, and the insulation reaction time is 1-3h; In step S3, the dropping time is 0.5-3 hours, and the stirring is 1-2 hours after the dropping is completed.

5. The method for preparing the early-strength polycarboxylate water-reducing agent according to claim 1, characterized in that: During the preparation of the modified calcium nitrate aqueous solution and the modified sodium silicate aqueous solution, the heating temperature is 30-80° C. and the stirring time is 2-6 hours.

6. The method for preparing the early-strength polycarboxylate water-reducing agent according to claim 1, characterized in that: The polyether monomer is one or more combinations of methylallyl polyoxyethylene ether, isopentenyl polyoxyethylene ether, isobutylene ether polyoxyethylene ether, isobutylene polyethylene glycol ether or isopentenyl polyethylene glycol ether; the molecular weight of the polyether monomer is 3000-6000.

7. The method for preparing the early-strength polycarboxylate water-reducing agent according to claim 1, characterized in that: The accelerator is hydroxyethyl acrylate; the chain transfer agent is one or more combinations of mercaptopropionic acid, thioglycolic acid, sodium methacrylic acid or sodium propylene sulfonate; and the oxidant is hydrogen peroxide.

8. The method for preparing the early-strength polycarboxylate water-reducing agent according to claim 2, characterized in that: The reducing agent is one or more combinations of sodium bisulfite, vitamin C and sodium hypophosphite.

9. The method for preparing the early-strength polycarboxylate water-reducing agent according to claim 3, characterized in that: The quaternary ammonium salt is one or more combinations of hexadecyltrimethylammonium bromide, octadecyltrimethylammonium bromide, Gemini quaternary ammonium salt or hydroxyethyldimethylalkylammonium bromide.

10. An early-strength polycarboxylate water-reducing agent prepared according to the method for preparing an early-strength polycarboxylate water-reducing agent according to any one of claims 1 to 9.

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