An early-strength and shrinkage-reducing polycarboxylate water reducer and its preparation method

Abstract

This application relates to the technical field of cement mortar admixtures, and specifically discloses an early-strength and shrinkage-reducing polycarboxylate water reducer and a preparation method thereof. An early-strength and shrinkage-reducing polycarboxylate water reducer includes a base material, Material A, and Material B. The base material includes water, methallyl polyoxyethylene ether, 2-acrylamide-2-methylpropanesulfonic acid, sodium hypophosphite, and an initiator; Material A includes water, sodium formaldehyde sulfoxylate, and a regulator; Material B includes water, acrylic acid, and a shrinkage-reducing monomer. The regulator is obtained by esterifying maleic anhydride and mercaptoethanol in a molar ratio of 1:(1-1.05) to obtain an esterification product, and diluting the esterification product; the preparation method is as follows: S1. Weighing; S2. Reacting. The early-strength and shrinkage-reducing polycarboxylate water reducer of this application can be used as an admixture for cement mortar, ensuring the strength of the cement mortar while improving the shrinkage problem of the cement mortar.

Description

Technical Field

[0001] The present application relates to the technical field of cement mortar admixtures, and more specifically, to an early-strength and shrinkage-reducing polycarboxylate water reducer and a preparation method thereof. Background Art

[0002] Polycarboxylate water reducer is a high-performance cement mortar admixture, and its main function is to reduce the amount of mixing water used and change the rheological properties and construction properties of cement mortar, etc. Polycarboxylate high-performance water reducer is a macromolecular compound composed of functional groups such as sulfonic acid groups, carboxyl groups, amino groups, and polyoxyethylene side chains, and is usually a polymeric surfactant with a comb structure synthesized in an aqueous solution through the principle of free radical copolymerization.

[0003] After adding polycarboxylate water reducer to cement mortar, the amount of mixing water used can be reduced, and the rheological and construction properties of cement mortar can be improved. However, the shrinkage problem of cement mortar still exists. The cracking of cement mortar caused by shrinkage will greatly reduce the strength and durability of cement mortar, thereby shortening the service life of cement mortar. At present, the shrinkage problem of cement mortar is generally improved by adding shrinkage-reducing agents. The shrinkage-reducing agent reduces the surface tension of water in the capillary pores of cement mortar and the shrinkage force during the water evaporation process to achieve the purpose of reducing cracks in cement mortar. However, the shrinkage-reducing agent affects the strength of cement mortar. Therefore, it is of great significance to improve the structural properties of cement mortar by ensuring the early strength of cement mortar while improving the shrinkage problem of cement mortar. Summary of the Invention

[0004] In order to improve the shrinkage problem of cement mortar while ensuring the early strength of cement mortar, the present application provides an early-strength and shrinkage-reducing polycarboxylate water reducer and a preparation method thereof.

[0005] In the first aspect, the present application provides an early-strength and shrinkage-reducing polycarboxylate water reducer, adopting the following technical solution:

[0006] An early-strength and shrinkage-reducing polycarboxylate water reducer, comprising a base material, material A, and material B. The base material includes water, methallyl polyoxyethylene ether, 2-acrylamide-2-methylpropanesulfonic acid, sodium hypophosphite, and an initiator;

[0007] Material A includes water, sodium formaldehyde sulfoxylate, and a regulator;

[0008] Material B includes water, acrylic acid, and a shrinkage-reducing monomer;

[0009] The regulator is obtained by esterifying maleic anhydride and mercaptoethanol in a molar ratio of 1:(1 - 1.05) to obtain an esterification product, and diluting the esterification product.

[0010] By adopting the above technical solution, allyl methyl polyoxyethylene ether is used as the macromonomer, and 2-acrylamide-2-methylpropanesulfonic acid, sodium hypophosphite, acrylic acid, and shrinkage-reducing monomer are used as the small monomers, so that the obtained polycarboxylate water reducer molecules contain strong cationic and anionic groups such as sulfonic acid groups, amide groups, and phosphate groups at the same time, producing a good synergistic early-strength effect; grafting the shrinkage-reducing monomer on the main chain of the polycarboxylate water reducer to provide a hydrophobic group for the main chain, reducing the surface tension of water, thereby reducing the cracking of cement mortar, achieving the improvement of the shrinkage problem of cement mortar while ensuring the early strength of cement mortar.

[0011] Maleic anhydride and mercaptoethanol are esterified to synthesize a regulator. The regulator acts as a chain transfer agent. The regulator in this application not only has the function of regulating the molecular weight but also can participate in the polymerization reaction, making the obtained polycarboxylate water reducer have an increased charge density, promoting cement hydration, and having dual functions of early strength and shrinkage reduction. At the same time, sodium hypophosphite in the base material also has a certain regulatory effect, and cooperating with the regulator is beneficial to further improving the strength of concrete.

[0012] Preferably, in the preparation of the regulator, the esterification product is diluted to a volume concentration of 65-75%.

[0013] By adopting the above technical solution, controlling the concentration of the regulator enables the regulator to fully contact and react with the reactants, giving full play to its regulatory effect.

[0014] Preferably, the reaction temperature of the esterification reaction of maleic anhydride and mercaptoethanol is 50-60 °C, and the reaction time is 2-2.5 h.

[0015] Preferably, the molecular weight of the allyl methyl polyoxyethylene ether is 4000.

[0016] By adopting the above technical solution, using the allyl methyl polyoxyethylene ether monomer with a molecular weight of 4000, the higher molecular weight can improve the promotion effect of the polycarboxylate water reducer on the early strength of cement mortar and ensure the early strength of cement mortar.

[0017] Preferably, by weight, the base material includes 2800-2900 parts of water, 3250-3350 parts of allyl methyl polyoxyethylene ether, 38-42 parts of 2-acrylamide-2-methylpropanesulfonic acid, 50-60 parts of sodium hypophosphite, and 30-35 parts of initiator;

[0018] The material A includes 540-560 parts of water, 10-12 parts of sodium formaldehyde sulfoxylate, and 20-28 parts of regulator;

[0019] The material B includes 210-230 parts of water, 345-365 parts of acrylic acid, and 38-45 parts of shrinkage-reducing monomer.

[0020] By adopting the above technical solution, the ratio of each raw material is regulated, so that the synergistic effect between the functional groups of the synthesized polycarboxylate superplasticizer molecules can be exerted to a greater extent, making the polycarboxylate superplasticizer have good water-reducing property while also having the effects of resisting the shrinkage of cement mortar and improving the early strength of cement mortar.

[0021] Preferably, the initiator includes ammonium persulfate and hydrogen peroxide with a weight ratio of 1:(0.9 - 1.1).

[0022] By adopting the above technical solution, ammonium persulfate and hydrogen peroxide are used as initiators to jointly form an initiation system, which has a fast reaction rate and the synthesized polycarboxylate superplasticizer molecules have high stability.

[0023] Preferably, the preparation method of the shrinkage-reducing monomer is as follows:

[0024] 1) Mix heptafluorobutyric anhydride and amino polyethylene glycol in methanol, and carry out a chemical reaction in the presence of a catalyst, and obtain fluorinated polyethylene glycol after purification;

[0025] 2) Carry out a chemical reaction between the fluorinated polyethylene glycol obtained in step 1) and acrylic acid in the presence of an inhibitor to obtain a reaction product, and dilute the reaction product to obtain a shrinkage-reducing monomer.

[0026] By adopting the above technical solution, first react heptafluorobutyric anhydride with amino polyethylene glycol. The heptafluorobutyric anhydride undergoes an acylation reaction with the amino group on the amino polyethylene glycol to obtain fluorinated polyethylene glycol, grafting a fluorine-containing group onto the polyethylene glycol. Then, the fluorinated polyethylene glycol undergoes an esterification reaction with acrylic acid to obtain a fluorine-containing shrinkage-reducing monomer, thereby introducing a fluorine-containing group onto the polycarboxylate superplasticizer molecule. The carbon-fluorine bond in the polycarboxylate superplasticizer molecule is short, strong, has low polarity and is not easily broken. Fluorine atoms have the characteristic of enriching on the surface. The carbon-fluorine bond can extend into the air and occupy the interface between the polymer and the air, thereby reducing the surface energy. Compared with the carbon-hydrogen chain, the carbon-fluorine chain has a larger molecular volume and stronger rigidity, so it has a stronger hydrophobic effect, making the carbon-fluorine surfactant have higher surface activity, which can significantly reduce the surface tension of the solution. When added to cement mortar, it can not only reduce the surface tension of the pore solution, but also reduce the evaporation rate of the pore solution, reduce the drying shrinkage and autogenous shrinkage of cement-based materials. The fluorine-containing superplasticizer makes the cement paste have a higher initial fluidity and better fluidity retention, and promotes the formation of calcium hydroxide and ettringite in the 3d hydration products, which is beneficial to improving the early strength of cement mortar.

[0027] Preferably, the inhibitor includes hydroquinone, phenothiazine, and methylhydroquinone with a weight ratio of 1:1:(2 - 3).

[0028] In a second aspect, the present application provides a preparation method of an early-strength and shrinkage-reducing polycarboxylate superplasticizer, adopting the following technical solution:

[0029] A preparation method of an early-strength and shrinkage-reducing polycarboxylate water reducer, comprising the following steps:

[0030] S1. Batching

[0031] Mix the raw materials of material A to obtain material A, and mix the raw materials of material B to obtain material B;

[0032] S2. Reaction

[0033] At 25 - 27 °C, mix the water, methyl allyl polyoxyethylene ether, 2-acrylamide-2-methylpropanesulfonic acid, and sodium hypophosphite in the base material. After the methyl allyl polyoxyethylene ether is dissolved, add the initiator, and then simultaneously dropwise add material A and material B. Both material A and material B are added dropwise within 2 hours, and then keep the temperature for reaction to obtain the early-strength and shrinkage-reducing polycarboxylate water reducer.

[0034] By adopting the above technical solution, the synthesis of the polycarboxylate water reducer in this application is carried out at room temperature without heating, the reaction conditions are mild, and the preparation method is simple and convenient, without special requirements for equipment, and is suitable for industrial production.

[0035] In summary, this application has the following beneficial effects:

[0036] 1. Since this application uses methyl allyl polyoxyethylene ether as the macromonomer, 2-acrylamide-2-methylpropanesulfonic acid, sodium hypophosphite, acrylic acid, and shrinkage-reducing monomer as the small monomers, and the esterification product of maleic anhydride and mercaptoethanol as the regulator to synthesize the polycarboxylate water reducer, the 3d compressive strength of the cement mortar prepared with the synthesized polycarboxylate water reducer can reach 15.7 - 17.7 Mpa, the 7d compressive strength can reach 21.1 - 28.8 Mpa, and the 28d compressive strength can reach 35.9 - 37.3 Mpa; the 3d drying shrinkage rate can reach 0.17 - 0.26%, the 7d drying shrinkage rate can reach 0.19 - 0.28%, and the 28d drying shrinkage rate can reach 0.19 - 0.26%, ensuring the strength of the cement mortar while improving the shrinkage problem of the cement mortar.

[0037] 2. In this application, a fluorine-containing shrinkage-reducing monomer is preferably used, which can reduce the surface tension of the pore solution, reduce the evaporation rate of the pore solution, reduce the drying shrinkage and autogenous shrinkage of the cement-based material; promote the formation of hydration products calcium hydroxide and ettringite, which is beneficial to improving the early strength of the cement mortar. Specific embodiments

[0038] The following further describes this application in detail with reference to embodiments.

[0039] Preparation examples of raw materials and intermediates

[0040] Raw materials

[0041] The raw materials in the embodiments of the present application can all be obtained commercially;

[0042] Methyl allyl polyoxyethylene ether: Oct 804 monomer with a molecular weight of 4000; Oct 501 monomer with a molecular weight of 2400; Oct 609 monomer with a molecular weight of 3000;

[0043] Amino polyethylene glycol with a molecular weight of 2000.

[0044] Preparation Example

[0045] Preparation Example I-1

[0046] A shrinkage reducing monomer, and its preparation method is as follows:

[0047] 1) Dissolve 45 kg of heptafluorobutyric anhydride and 400 kg of amino polyethylene glycol in 10 l of methanol and mix. Add 100 ml of triethylamine as a catalyst to the mixed solution and react at 25 °C for 48 hours. Then, dialyze the reaction solution with pure water for 4 days. The molecular weight cut-off for dialysis is 1000. After dialysis, filter once with a 220 nm pore size filter membrane and vacuum dry for 48 hours to obtain fluorinated polyethylene glycol;

[0048] 2) Put 7050 kg of the fluorinated polyethylene glycol obtained in step 1) into an esterification reaction kettle, then add 4 kg of inhibitor, and then add 740 kg of acrylic acid for a chemical reaction. Heat up to 80 °C and add 45 kg of sulfuric acid. Pass nitrogen at 120 °C to remove water. React for 4 hours. After the reaction is completed, dilute with water to a volume concentration of 70% to obtain the shrinkage reducing monomer;

[0049] The inhibitor is hydroquinone.

[0050] Preparation Example I-2

[0051] The difference from Preparation Example I-1 is that the inhibitor in Preparation Example I-2 includes hydroquinone, phenothiazine, and methyl hydroquinone with a weight ratio of 1:1:2.

[0052] Preparation Example I-3

[0053] A shrinkage reducing monomer, and its preparation method is as follows:

[0054] Put 7000 kg of polyethylene glycol into an esterification reaction kettle, then add 4 kg of inhibitor, and then add 740 kg of acrylic acid for a chemical reaction. Heat up to 80 °C and add 45 kg of sulfuric acid. Pass nitrogen at 120 °C to remove water. React for 4 hours. After the reaction is completed, dilute with water to a volume concentration of 70% to obtain the shrinkage reducing monomer;

[0055] The inhibitor is hydroquinone.

[0056] Preparation Example II-1

[0057] A regulator, and its preparation method is as follows:

[0058] Add 98 kg of maleic anhydride and 78 kg of mercaptoethanol into a reaction kettle, heat to 55 °C, keep the temperature for reaction for 2 hours, and after the reaction, add water to dilute to a volume concentration of 70%.

[0059] Example

[0060] Examples 1 - 3

[0061] An early-strength and shrinkage-reducing polycarboxylate water reducer, and its preparation method is as follows:

[0062] S1. Batching

[0063] According to the raw material ratio in Table 1, mix the water, sodium formaldehyde sulfoxylate, and regulator of Material A to obtain Material A, and mix the water, acrylic acid, and shrinkage-reducing monomer of Material B to obtain Material B;

[0064] S2. Reaction

[0065] At 25 °C, according to the raw material ratio in Table 1, mix the water, methallyl polyoxyethylene ether, 2-acrylamide-2-methylpropanesulfonic acid, and sodium hypophosphite in the base material. After the methallyl polyoxyethylene ether is dissolved, add the initiator, and then simultaneously drip-feed Material A and Material B. Both Material A and Material B are drip-fed within 2 hours, and then keep the temperature for reaction for 1.5 hours to obtain the early-strength and shrinkage-reducing polycarboxylate water reducer.

[0066] Table 1 Raw material ratio table for Examples 1 - 3 (kg)

[0067]

[0068] Among them, the methallyl polyoxyethylene ether in the base material is Oct 804 monomer, and the initiator is ammonium persulfate; the regulator in Material A comes from Preparation Example II-1; the shrinkage-reducing monomer in Material B comes from Preparation Example I-1.

[0069] Example 4

[0070] The difference from Example 2 is that the shrinkage-reducing monomer in Material B of Example 4 comes from Preparation Example I-2.

[0071] Example 5

[0072] The difference from Example 2 is that the shrinkage-reducing monomer in Material B of Example 5 comes from Preparation Example I-3.

[0073] Example 6

[0074] The difference from Example 4 is that the methallyl polyoxyethylene ether in the base material of Example 6 is Oct 501 monomer.

[0075] Example 7

[0076] Different from Example 4, the methyl allyl polyoxyethylene ether in the base material of Example 7 is Oct 609 monomer.

[0077] Example 8

[0078] Different from Example 4, the initiator in Example 8 is ammonium persulfate and hydrogen peroxide with a weight ratio of 1:1.

[0079] Comparative Example

[0080] Comparative Example 1

[0081] Different from Example 1, the base material in Comparative Example 1 does not contain sodium hypophosphite.

[0082] Comparative Example 2

[0083] Different from Example 1, the material A in Comparative Example 2 does not contain sodium formaldehyde sulfoxylate.

[0084] Comparative Example 3

[0085] Different from Example 1, the regulator in Comparative Example 3 is mercaptoethanol.

[0086] Comparative Example 4

[0087] Different from Example 1, the regulator in Comparative Example 4 is maleic anhydride and mercaptoethanol with a weight ratio of 1:1.

[0088] Performance Detection Test

[0089] Detection Method / Test Method Specimen Preparation: Weigh 450 g of cement, 1350 g of standard sand, with a water-cement ratio of 0.5, and a water reducer dosage of 0.2% to prepare a cement mortar specimen, and then conduct the following detections:

[0090] Cement Mortar Strength Detection: Refer to GB / T 17671-2021 "Test Method for Cement Mortar Strength (ISO Method)" to detect the compressive strength of the cement mortar at 3d, 7d, and 28d. The detection results are shown in Table 2.

[0091] Cement Mortar Drying Shrinkage Rate Detection: According to JC / T 603-2004 "Test Method for Dry Shrinkage of Cement Mortar", detect the drying shrinkage rate of the cement mortar at 3d, 7d, and 28d. The detection results are shown in Table 3.

[0092] Table 2 Detection Results of Cement Mortar Strength Performance (MPa)

[0093]

[0094]

[0095] Table 3 Detection of Cement Mortar Drying Shrinkage Rate (%)

[0096] 3d 7d 28d Example 1 0.22 0.25 0.25 Example 2 0.21 0.23 0.23 Example 3 0.22 0.24 0.24 Example 4 0.19 0.20 0.21 Example 5 0.26 0.28 0.26 Example 6 0.24 0.26 0.24 Example 7 0.24 0.25 0.25 Example 8 0.17 0.19 0.19 Comparative Example 1 0.27 0.32 0.35 Comparative Example 2 0.29 0.35 0.38 Comparative Example 3 0.35 0.43 0.48 Comparative Example 4 0.33 0.41 0.45

[0097] Combined with Examples 1-8 and Comparative Examples 1-4, and combined with Table 2 and Table 3, it can be seen that the polycarboxylate water reducer prepared in Examples 1-8 is applied to the cement mortar, and the strength of the prepared cement mortar is higher than that of Comparative Examples 1-4, and the drying shrinkage rate is lower than that of Comparative Examples 1-4. This shows that the polycarboxylate water reducer prepared in this application performs better in improving the strength of cement mortar and improving the shrinkage of cement mortar, and has higher practical value and economic value.

[0098] Combined with Example 1 and Comparative Examples 1-2, and combined with Table 2 and Table 3, it can be seen that sodium hypophosphite is not contained in Comparative Example 1, and sodium formaldehyde sulfoxylate is not contained in Comparative Example 2. Then, compared with Example 1, the strength of the cement mortar prepared by the polycarboxylate water reducer in Comparative Examples 1 and 2 is significantly reduced, and the drying shrinkage rate is significantly increased. This shows that the functional groups of the polycarboxylate water reducer synthesized from the raw materials of this application cooperate with each other and have a good effect of improving strength and reducing shrinkage.

[0099] Combined with Example 1 and Comparative Examples 3-4, and combined with Table 2 and Table 3, it can be seen that the regulator in Example 1 is the reaction product of mercaptoethanol and maleic anhydride, the regulator in Comparative Example 3 is mercaptoethanol, and the regulator in Comparative Example 4 is a mixture of mercaptoethanol and maleic anhydride. Then, compared with Example 1, the strength of the cement mortar prepared by the polycarboxylate water reducer in Comparative Examples 3 and 4 is significantly reduced, and the drying shrinkage rate is significantly increased. This shows that using the reaction product of mercaptoethanol and maleic anhydride as a regulator can improve strength and reduce shrinkage. This may be because maleic anhydride and mercaptoethanol undergo an esterification reaction to synthesize the regulator, and the regulator acts as a chain transfer agent. Moreover, the regulator not only has the function of adjusting the molecular weight but also can participate in the polymerization reaction, making the obtained polycarboxylate water reducer have an increased charge density, promoting cement hydration, and having the dual effects of early strength and shrinkage reduction.

[0100] Combining Example 2 with Example 4-5, and combining Table 2 with Table 3, it can be seen that compared with Example 2 and Example 4, the strength of the cement mortar prepared by the polycarboxylate water-reducing agent in Example 5 is significantly reduced and the drying shrinkage rate is significantly increased, which shows that the shrinkage-reducing monomers in Example 2 and Example 4 have a better promoting effect on improving the strength of the mortar and slowing down the shrinkage. This may be because the fluorine-containing group is introduced into the polycarboxylate water-reducing agent molecule. The carbon-fluorine bond in the polycarboxylate water-reducing agent molecule is short, strong, low in polarity, and not easy to break. The fluorine atom has the characteristic of enriching on the surface. The carbon-fluorine bond can extend into the air and occupy the interface between the polymer and the air, thereby reducing the surface energy. The carbon-fluorine chain has a large molecular volume and strong rigidity, so it has a stronger hydrophobic effect, so that the carbon-fluorine surfactant has a higher surface activity and can significantly reduce the surface tension of the solution. Adding it to the cement mortar can not only reduce the surface tension of the pore solution, but also reduce the evaporation rate of the pore solution, and reduce the drying shrinkage and self-shrinkage of the cement-based material. Fluorine-containing water-reducing agent makes cement paste have higher initial fluidity and better fluidity retention, and promotes the formation of hydration products calcium hydroxide and ettringite, which is beneficial to improve the early strength of cement mortar.

[0101] Combining Example 4 with Examples 6-7 and Table 2, it can be seen that the molecular weight of the methyl allyl polyoxyethylene ether in Examples 6-7 is relatively low, and the strength of the obtained cement mortar is relatively low, which indicates that higher molecular weight methyl allyl polyoxyethylene ether helps to improve the strength of cement mortar.

[0102] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. An early strength and shrinkage reducing polycarboxylic acid water reducer, comprising a base material, an A material, and a B material. It is characterized in that The base material comprises water, methyl allyl polyoxyethylene ether, 2-acrylamide-2-methylpropane sulfonic acid, sodium hypophosphite, and an initiator; The material A includes water, bleaching agent and a conditioning agent; The material B includes water, acrylic acid, and shrinkage-reducing monomer; The regulator is obtained by esterifying maleic anhydride and mercaptoethanol in a molar ratio of 1: (1-1.05) to obtain an esterification product, and diluting the esterification product; the reaction temperature of the esterification reaction of maleic anhydride and mercaptoethanol is 50-60°C, and the reaction time is 2-2.5h; The preparation method of the shrinkage-reducing monomer is as follows: 1) Dissolving heptafluorobutyric anhydride and aminopolyethylene glycol in methanol, carrying out chemical reaction in the presence of a catalyst, and obtaining fluorinated polyethylene glycol after purification; 2) chemically reacting the fluorinated polyethylene glycol obtained in step 1) with acrylic acid in the presence of a polymerization inhibitor to obtain a reaction product, and diluting the reaction product to obtain a shrinkage-reducing monomer.

2. The early strength and shrinkage reducing polycarboxylate water reducer according to claim 1, Features: In the preparation of the regulator, the esterification product is diluted to a volume concentration of 65-75%.

3. The early strength and shrinkage reducing polycarboxylate water reducer according to claim 1, Features: The molecular weight of the methyl allyl polyoxyethylene ether is 4000.

4. The early strength and shrinkage reducing polycarboxylate water reducer according to claim 1, Features: In parts by weight, the base material includes 2800-2900 parts of water, 3250-3350 parts of methyl allyl polyoxyethylene ether, 38-42 parts of 2-acrylamide-2-methylpropane sulfonic acid, 50-60 parts of sodium hypophosphite, and 30-35 parts of initiator; The material A includes 540-560 parts of water, 10-12 parts of bleaching powder, and 20-28 parts of conditioning agent; The material B comprises 210-230 parts of water, 345-365 parts of acrylic acid, and 38-45 parts of shrinkage-reducing monomer.

5. The early strength and shrinkage reducing polycarboxylate water reducer according to claim 1, Features: The initiator includes ammonium persulfate and hydrogen peroxide in a weight ratio of 1: (0.9-1.1).

6. The early strength and shrinkage reducing polycarboxylate water reducer according to claim 1, Features: The polymerization inhibitor comprises hydroquinone, phenothiazine and methyl hydroquinone in a weight ratio of 1:1:(2-3).

7. A method for preparing the early strength and shrinkage reducing polycarboxylate water reducer according to any one of claims 1 to 6, It is characterized in that The following steps are involved: S1. Ingredients The raw materials of material A are mixed to obtain material A, and the raw materials of material B are mixed to obtain material B; S2. Reaction At 25-27°C, mix the water, methyl allyl polyoxyethylene ether, 2-acrylamide-2-methylpropane sulfonic acid and sodium hypophosphite in the base material, add the initiator after the methyl allyl polyoxyethylene ether is dissolved, and then add material A and material B dropwise at the same time. Both material A and material B are added dropwise within 2 hours, and then heat-retained for reaction to obtain an early strength and shrinkage-reducing polycarboxylic acid water-reducing agent.

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