High viscosity-reducing polycarboxylate water reducer for ultra-high performance concrete and preparation method thereof

Abstract

The application discloses a high viscosity-reducing polycarboxylic water reducing agent for ultra-high performance concrete and a preparation method thereof, and comprises the following steps: adding a metered amount of deionized water into a reaction container, and then adding a methyl allyl polyoxyethylene ether, sodium methallyl sulfonate, an alkyl acrylate, and styrene into the reaction container, stirring, and heating; adding a metered amount of hydrogen peroxide, and simultaneously dropping a mixed aqueous solution of acrylic acid AA and methoxy polyethylene glycol methacrylate MAA-MPEG and a mixed aqueous solution of mercaptoacetic acid and ascorbic acid; and after dropping, keeping warm. The prepared polycarboxylic water reducing agent can improve the dispersibility of the polycarboxylic water reducing agent, reduce the hydrophilicity of the whole polycarboxylic molecule, and obviously reduce the viscosity of concrete; under the premise that the concrete has good workability, the viscosity of high-grade concrete can be obviously reduced; the polycarboxylic water reducing agent has good adaptability to different types of cement, avoids the need to seek different types and structures of water reducing agents for different types of cement, and is beneficial to practical engineering application.

Description

Technical Field

[0001] This invention relates to the field of concrete additives, specifically to a high-viscosity-reducing polycarboxylate superplasticizer for ultra-high performance concrete and its preparation method. Background Technology

[0002] In recent years, with the expansion of infrastructure construction in my country, high-strength concrete (≥C60) and ultra-high-strength concrete (≥C100) are gradually entering the construction market due to their high strength, good integrity, and low self-weight, especially in bridge engineering. Because of the large amount of cementitious materials and low water-cement ratio, high-strength concrete has problems with high viscosity and slow flow rate, often requiring the use of large amounts of polycarboxylate superplasticizers to increase the fluidity of fresh concrete. However, this often leads to segregation and bleeding. Currently, compound viscosity modifier technology is one of the main methods to solve the segregation and bleeding problems associated with high-volume polycarboxylate superplasticizers. However, this technology has limited effectiveness in solving these problems and comes at the cost of sacrificing concrete workability. It also masks the root cause of the concrete viscosity problem, hindering the development of concrete admixture technology. In addition, polycarboxylic acid superplasticizers compounded with viscosity modifiers are prone to compatibility issues, and precipitation and stratification occur after standing (the precipitate is the viscosity modifier, and the upper layer is the polycarboxylic acid superplasticizer), which will increase the cost accordingly.

[0003] D. Hamada et al. (Pursuance of Workability Retention by NewSuperplasticizer) have developed a novel multi-branched polymer (NHBP type) that better controls the rheological properties of concrete than traditional polycarboxylate superplasticizers. This new polymer has more grafted chains than traditional polycarboxylate superplasticizers, resulting in strong adsorption capacity and high adsorption density on the surface of cement particles, thus promoting better rheological properties and easier-to-work viscosity in mortar or concrete. However, current preparation methods for such superplasticizers lack designability at the molecular structure level, involve complex steps, and use large amounts of toxic organic solvents, posing environmental pollution and safety risks.

[0004] The China Building Materials Academy has applied for a patent (CN103553413A) for a viscosity-adjusting polycarboxylate superplasticizer. The preparation method involves mixing 2-10 wt% unsaturated acid monomers, 18-45 wt% unsaturated polyoxyethylene macromonomers, 1-5 wt% viscosity-adjusting monomers, and the remainder water in a reactor. An initiator solution is then added dropwise at 70-90°C to initiate polymerization over 2-4 hours. The reaction is continued at 70-90°C for 1-3 hours, followed by natural cooling to 45°C and adjustment of the pH to 6.0-8.0, yielding the viscosity-adjusting polycarboxylate superplasticizer. This viscosity-adjusting polycarboxylate superplasticizer exhibits stable performance, and the dosage of each raw material component can be adjusted as needed to meet the fluidity and viscosity requirements of construction concrete, solving the problems of bleeding and segregation in fresh concrete. It possesses advantages such as readily available raw materials, simple preparation process, cleanliness and safety, and ease of industrial production, showing broad prospects for industrial application.

[0005] Jiangsu Aolaite New Materials Co., Ltd. has applied for a patent (CN104262550A) for a viscosity-reducing polycarboxylate superplasticizer. The preparation method is as follows: First, an anhydride monomer containing unsaturated double bonds and diamine organic small molecules are stirred at a certain temperature to generate unsaturated primary amine small monomers. Then, organic small molecules containing epoxy groups and halogen-containing groups are added to the above-generated unsaturated primary amine small monomer reaction system, and stirring is continued for 5-72 hours to obtain quaternary ammonium salt unsaturated small monomers. Next, the quaternary ammonium salt unsaturated small monomers, unsaturated ester small monomers, unsaturated acid small monomers, and unsaturated polyester macromonomers undergo an aqueous free radical polymerization reaction under the action of an initiator and a chain transfer agent. After the reaction is completed, the pH value is adjusted, and water is added to obtain the viscosity-reducing polycarboxylate superplasticizer. The viscosity-reducing polycarboxylate superplasticizer prepared by this invention has the advantages of simple reaction, easy control, and low cost. Simultaneously, it can reduce concrete viscosity and improve slump retention.

[0006] Although there are many reports on viscosity-reducing polycarboxylate superplasticizers, improvements are still needed in viscosity reduction, and good adaptability to different types of concrete is also a goal to be pursued. Summary of the Invention

[0007] In view of the shortcomings and needs of existing technologies, the purpose of this invention is to provide a high-viscosity-reducing polycarboxylate superplasticizer for ultra-high performance concrete and its preparation method. By designing the reactants and the structure of the polycarboxylate superplasticizer, the high performance of the polycarboxylate superplasticizer is achieved by controlling the degree of polymerization of the main chain, the density of the side chains, and the types of functional groups. The polycarboxylate superplasticizer prepared by this invention has good dispersibility and slump retention, as well as excellent viscosity-reducing properties, which can better improve the overall performance of ultra-high performance concrete and has high adaptability to different types of concrete.

[0008] To solve the above-mentioned technical problems, one of the technical solutions adopted by the present invention is:

[0009] A method for preparing a high-viscosity-reducing polycarboxylate superplasticizer for ultra-high performance concrete includes the following steps:

[0010] (1) Add a measured amount of deionized water to the reaction vessel, then add methyl allyl polyoxyethylene ether (TPEG), sodium methacrylate (SMAS), alkyl acrylate, and styrene, respectively, stir and heat to 60-65°C. (2) Add a measured amount of 30wt% hydrogen peroxide, and simultaneously add a mixed aqueous solution of AA acrylic acid, methoxy polyethylene glycol methacrylate (MAA-MPEG), and a mixed aqueous solution of mercaptoacetic acid and ascorbic acid dropwise. The dropwise addition time is 2-3 hours, and the temperature is maintained for 1-2 hours after the addition is completed.

[0011] (3) After the heat preservation is completed and the temperature is reduced to 40-45℃, add a metered 32wt% sodium hydroxide solution while stirring, adjust the pH value to 6-8, and add a certain amount of deionized water to obtain the viscosity-reducing polycarboxylate superplasticizer.

[0012] Furthermore, the alkyl acrylate is selected from octadecyl acrylate SA.

[0013] Further, the molar ratio of the methyl allyl polyoxyethylene ether (TPEG), sodium methacrylate (SMAS), alkyl acrylate, styrene, AA acrylate, and methoxy polyethylene glycol methacrylate (MAA-MPEG) is 1.0:(0.45-0.55):(1.1-1.2):(0.5-0.6):(6-8):(1.2-1.4).

[0014] Furthermore, the molar ratio of the methyl allyl polyoxyethylene ether (TPEG), sodium methacrylate (SMAS), alkyl acrylate, styrene, AA acrylate, and methoxy polyethylene glycol methacrylate (MAA-MPEG) is 1.0:0.5:1.2:0.6:7:1.3.

[0015] Further, the molar ratio of deionized water to methyl allyl polyoxyethylene ether measured in step (1) is (15-20):1.

[0016] Furthermore, in step (2), the molar ratio of hydrogen peroxide to methyl allyl polyoxyethylene ether is (0.04~0.05):1.

[0017] Furthermore, in step (2), the molar ratio of mercaptoacetic acid: ascorbic acid: methyl allyl polyoxyethylene ether is (0.02~0.05):(0.01~0.02):1.

[0018] The second technical solution adopted in this invention is: a high-viscosity-reducing polycarboxylate superplasticizer for ultra-high performance concrete, prepared by the above steps (1) to (3), and its general structural formula is:

[0019]

[0020] Where a, b, c, d, e, f, m, n, and k are the degree of aggregation and are all positive integers, a = 5 to 15, b = 3 to 10, c = 30 to 50, d = 2 to 5, e = 2 to 3, f = 1 to 2, m = 150 to 200, n = 50 to 60, and k = 16.

[0021] Furthermore, the molecular weight of the high viscosity-reducing polycarboxylate superplasticizer is 50,000 to 90,000.

[0022] To obtain high-grade fresh concrete with good plasticity, low viscosity, and good workability, and to achieve self-leveling and self-compacting effects in areas with dense reinforcement, while simultaneously addressing the segregation and bleeding problems caused by high polycarboxylate superplasticizer dosage in high-grade concrete, this experiment started from the root cause of concrete viscosity problems. Considering the complementary advantages of ester and ether-based polycarboxylate superplasticizers, hydrogen peroxide-vitamin C was used as an initiator, mercaptoacetic acid as a chain transfer agent, and two macromonomers, methoxy polyethylene glycol methacrylate and methyl allyl polyoxyethylene ether, were selected to copolymerize with acrylic acid, sodium methacrylate sulfonate, and styrene. Furthermore, dodecyl acrylate or octadecyl acrylate was selected as the viscosity-reducing functional monomer for styrene through comparative analysis. A co-functional polycarboxylate superplasticizer with ether-ester copolymer viscosity-reducing properties was successfully prepared.

[0023] The applicant conducted extensive preliminary experiments, including a single-factor variable study on monomer dosage. The results showed that with increasing octadecyl acrylate dosage, the initial dispersibility of the prepared polycarboxylate superplasticizer in cement paste first increased and then decreased, while the plastic viscosity first decreased and then increased. This is because as the acrylate dosage increases, the interaction between the lipophilic long alkyl ester side chains and the hydrophilic long polyoxyethylene side chains in the polycarboxylate molecule lowers the hydrophilic-lipophilic balance value of the polycarboxylate, making the polyoxyethylene side chains more extended and increasing steric hindrance, thus enhancing the initial dispersibility of the cement paste. When the octadecyl acrylate dosage increased to 1.2%, the hydrophilic-lipophilic interaction reached equilibrium, the extension degree of the alkyl ester side chains and the polyoxyethylene side chains reached equilibrium, and the dispersing ability of the superplasticizer reached its optimal level. Further increasing the octadecyl acrylate dosage resulted in a relatively reduced proportion of carboxylate groups in the polycarboxylate molecule, which could not effectively adsorb onto the surface of cement particles, and the steric hindrance could not be fully utilized, leading to a decrease in initial dispersibility. Therefore, the optimal dosage of octadecyl acrylate was determined to be 1.1–1.2%.

[0024] As the amount of acrylic acid increases, the initial dispersibility of polycarboxylate superplasticizer in cement paste first increases and then decreases, while the plastic viscosity first decreases and then increases. This is mainly because when the proportion of carboxylate groups in the polycarboxylate molecule is low, its adsorption capacity is poor. Although the branch density on the main chain is high, it cannot be effectively adsorbed onto the surface of cement particles, and the steric hindrance cannot be fully utilized, resulting in poor initial dispersibility. When the proportion of carboxylate groups gradually increases, the adsorption of superplasticizer molecules onto cement particles increases, leading to an increase in the anionic charge density on the surface of cement particles and an increase in electrostatic repulsion, thus improving the dispersion performance. However, when the proportion of carboxylate groups in the polycarboxylate molecule is high, its adsorption capacity is enhanced, but the branch density on its main chain will relatively decrease. After adsorption, the number of branches per unit area on the surface of cement particles will also decrease, resulting in the steric hindrance not only not being enhanced but also weakened to some extent, thus reducing its initial dispersibility. Therefore, the optimal amount of acrylic acid is determined to be 6–8%.

[0025] With increasing SMAS dosage, the initial dispersibility of the synthesized polycarboxylate superplasticizer in cement paste initially increases and then decreases, while the plastic viscosity initially decreases and then increases. When the SMAS dosage reaches 0.5%, further increases in dosage lead to a rapid decrease in the initial dispersibility of the cement paste. This is mainly because sulfonate adsorption capacity is stronger than carboxylate adsorption capacity. As the SMAS dosage increases, the sulfonate content increases, enhancing adsorption and facilitating adsorption on the surface of cement particles, resulting in a gradual increase in the initial dispersibility of the cement paste. However, when the SMAS dosage is too high, the chain transfer effect of SMAS broadens the molecular weight distribution of polycarboxylate molecules, significantly reducing the main component responsible for dispersing the cement paste, thus greatly decreasing the initial dispersibility of the cement paste. Therefore, the optimal SMAS dosage is determined to be 0.45–0.55%. Similarly, the optimal styrene dosage is 0.5–0.6%.

[0026] As the ester-ether ratio increases, the initial dispersibility of polycarboxylate superplasticizer in cement paste first increases and then decreases, while the plastic viscosity first decreases and then increases. This is mainly because as the ester-ether ratio increases, the polyoxyethylene ester side chain component in the polycarboxylate molecule increases, both increasing steric hindrance and enhancing the dispersing ability of the superplasticizer. When the ester-ether ratio increases to a certain value, the steric hindrance effect of the side chains reaches its maximum. Further increasing the ester-ether ratio reduces the proportion of carboxylate groups in the polycarboxylate molecule, preventing effective adsorption onto the cement particle surface. The steric hindrance is not fully utilized, leading to a decrease in initial dispersibility. Therefore, the optimal ester-ether ratio is determined to be 1.2–1.4.

[0027] The synthetic route of the high viscosity-reducing polycarboxylate superplasticizer of this application is shown in the following reaction formula:

[0028]

[0029] Compared with the prior art, the present invention has the following advantages:

[0030] (1) The polycarboxylate superplasticizer prepared by introducing alkyl acrylate viscosity-reducing monomers and styrene monomers with high steric hindrance has a significant effect on reducing the viscosity of high-grade concrete compared with ordinary products. It can improve the dispersibility of polycarboxylate superplasticizer and reduce the hydrophilicity of the entire polycarboxylate molecule. The longer the alkyl side chain of alkyl acrylate, the more obvious the effect of polycarboxylate superplasticizer on reducing concrete viscosity. Dodecyl acrylate and octadecyl acrylate have the best effect.

[0031] (2) Under the premise that the concrete has good workability, the viscosity-reducing polycarboxylate superplasticizer prepared in this experiment can significantly reduce the viscosity of high-grade concrete, and its performance is superior to similar products on the market. (3) The ether ester copolymer viscosity-reducing polycarboxylate superplasticizer provided in this application has good adaptability to different types of cement, avoiding the need to seek different types and structures of superplasticizers for different types of cement, which is beneficial to practical engineering applications.

[0032] (4) The preparation method of the ether ester copolymer viscosity-reducing polycarboxylate superplasticizer provided in this application is simple and the conditions are easy to control, and it can be widely used in production. Attached Figure Description

[0033] Figure 1 The curves show the effect of different types of alkyl acrylates on the performance of water-reducing agents.

[0034] Figure 2 The results show the adaptability evaluation of the water-reducing agent prepared in Example 1. Detailed Implementation

[0035] To better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the embodiments.

[0036] Example 1

[0037] A method for preparing a high-viscosity-reducing polycarboxylate superplasticizer for ultra-high performance concrete includes the following steps:

[0038] (1) Add measured amounts of deionized water to the reaction vessel, then add methyl allyl polyoxyethylene ether (TPEG), sodium methacrylate (SMAS), alkyl acrylate, and styrene, respectively, stir and heat to 65°C.

[0039] (2) Add a measured amount of 30wt% hydrogen peroxide, and simultaneously add a mixed aqueous solution of AA acrylic acid, methoxy polyethylene glycol methacrylate (MAA-MPEG) and a mixed aqueous solution of mercaptoacetic acid and ascorbic acid. The addition time is 3h for each, and the temperature is kept warm for 1.5h after the addition is complete.

[0040] (3) After the heat preservation is completed and the temperature is reduced to 45°C, add a metered 32wt.% sodium hydroxide solution while stirring, adjust the pH value to about 7, and add a certain amount of deionized water to obtain the viscosity-reducing polycarboxylate superplasticizer.

[0041] Specifically, the alkyl acrylate is selected from octadecyl acrylate (SA). The molar ratio of each component is as follows: methyl allyl polyoxyethylene ether (TPEG), sodium methacrylate sulfonate (SMAS), alkyl acrylate, styrene, acrylic acid (AA), and methoxy polyethylene glycol methacrylate (MAA-MPEG) is 1.0:0.5:1.2:0.5:7:1.3; the molar ratio of deionized water to methyl allyl polyoxyethylene ether in step (1) is 20:1; the molar ratio of hydrogen peroxide to methyl allyl polyoxyethylene ether in step (2) is 0.045:1; and the molar ratio of mercaptoacetic acid to ascorbic acid to methyl allyl polyoxyethylene ether in step (2) is 0.03:0.02:1.

[0042] The water-reducing agent obtained in Specific Example 1 is referred to as PC-SA.

[0043] To test the effect of alkyl acrylate monomers on carboxylic acid water-reducing agents, the applicant also selected butyl acrylate and dodecyl acrylate for comparison.

[0044] Comparative Example 1

[0045] The preparation steps for Comparative Example 1 are the same as those for Example 1, except that butyl acrylate is replaced with alkyl acrylate. The water-reducing agent obtained in Comparative Example 1 is referred to as PC-BA.

[0046] Comparative Example 2

[0047] The preparation steps for Comparative Example 2 were the same as those for Example 1, except that the alkyl acrylate was replaced with dodecyl acrylate. The water-reducing agent obtained in Comparative Example 2 is referred to as PC-LA.

[0048] The fluidity and plastic viscosity of cement paste in Example 1 and Comparative Examples 1-2 were tested according to the experimental methods described above.

[0049] from Figure 1The results show that polycarboxylate superplasticizers prepared from different types of alkyl acrylates all reduce the plastic viscosity of cement paste. However, the degree of reduction in plastic viscosity increases with the increase of alkyl ester chain length. The polycarboxylate superplasticizer synthesized from octadecyl acrylate exhibits the highest degree of reduction in plastic viscosity and also demonstrates good slump retention. This is mainly because, in alkyl acrylates, the longer the alkyl ester chain, the greater the shift in the hydrophilic-lipophilic balance value of the polycarboxylate superplasticizer towards the lipophilic direction. This leads to a higher degree of hydrogen bond disruption between polycarboxylate molecules, a more ordered arrangement of polyoxyethylene side chains, greater spread, improved dispersibility, and a reduction in the plastic viscosity of the paste. Therefore, this experiment preferentially selects octadecyl acrylate (SA) as the viscosity-reducing monomer.

[0050] from Figure 1 The results show that the polycarboxylate superplasticizer prepared in Example 1 of this application has a plastic viscosity of less than 1000 mPa·s and a flowability of about 150 mm.

[0051] Compatibility test of viscosity-reducing polycarboxylate superplasticizer with cement

[0052] To investigate the adaptability of viscosity-reducing polycarboxylate superplasticizers to different types of cement, silicate cement (P.Ⅱ42.5), ordinary silicate cement (P.O42.5), and fly ash silicate cement (P.F42.5) from different manufacturers were selected. Polycarboxylate superplasticizer PC-SA prepared with the optimal mix ratio was used as the test material. The flowability and plastic viscosity of the cement paste were tested. The experimental results are as follows: Figure 2 As shown. The water-reducing agent dosage is 0.12%.

[0053] Depend on Figure 2 It can be seen that although the fluidity and plastic viscosity of different types of cement paste vary, the overall trend is consistent, and the dispersion retention is good. This indicates that the viscosity-reducing water-reducing agent has good adaptability to different types of cement. The main reason is that the polycarboxylate water-reducing agent molecule has both ether and ester long-branched structures, and the benzene ring structure greatly increases steric hindrance, giving it the advantages of high dispersibility and dispersion retention of ether-based polycarboxylate water-reducing agents and the advantages of strong adaptability of ester-based polycarboxylate water-reducing agents.

[0054] Example 2

[0055] A method for preparing a high-viscosity-reducing polycarboxylate superplasticizer for ultra-high performance concrete includes the following steps:

[0056] (1) Add measured amounts of deionized water to the reaction vessel, then add methyl allyl polyoxyethylene ether (TPEG), sodium methacrylate (SMAS), alkyl acrylate, and styrene, respectively, stir and heat to 60°C.

[0057] (2) Add a measured amount of 30wt% hydrogen peroxide, and simultaneously add a mixed aqueous solution of AA acrylic acid, methoxy polyethylene glycol methacrylate (MAA-MPEG) and a mixed aqueous solution of mercaptoacetic acid and ascorbic acid. The addition time is 2.5h for each addition, and keep warm for 1.5h after the addition is complete.

[0058] (3) After the heat preservation is completed and the temperature is reduced to 40°C, add a metered 32wt% sodium hydroxide solution while stirring, adjust the pH value to about 7, and add a certain amount of deionized water to obtain the viscosity-reducing polycarboxylate superplasticizer.

[0059] Specifically, the alkyl acrylate is selected from octadecyl acrylate (SA). The molar ratio of each component is as follows: methyl allyl polyoxyethylene ether (TPEG), sodium methacrylate sulfonate (SMAS), alkyl acrylate, styrene, acrylic acid (AA), and methoxy polyethylene glycol methacrylate (MAA-MPEG) is 1.0:0.45:1.1:0.6:6:1.4; the molar ratio of deionized water to methyl allyl polyoxyethylene ether in step (1) is 15:1; the molar ratio of hydrogen peroxide to methyl allyl polyoxyethylene ether in step (2) is 0.04:1; the molar ratio of mercaptoacetic acid to ascorbic acid to methyl allyl polyoxyethylene ether in step (2) is 0.02:0.01:1.

[0060] Comparative Example 3

[0061] The specific preparation steps of Comparative Example 3 are the same as those of Example 2, except that styrene is not added.

[0062] Concrete tests were conducted on the water-reducing agents obtained in Examples 1-2 and Comparative Examples 1-3 to compare their effects on concrete performance. The experimental results are shown in Table 1.

[0063] Table 1. Concrete test results of polycarboxylate superplasticizer

[0064]

[0065]

[0066] As shown in Table 1, the water reduction rates of the aforementioned viscosity-reducing polycarboxylate products are basically equivalent. Under the premise of ensuring good workability of concrete, the flow-through time of concrete prepared with the experimentally synthesized viscosity-reducing polycarboxylate water-reducing agent is 15s and 16s, which is significantly lower than the flow-through time of 25s for the water-reducing agent prepared in Comparative Example 3, and also lower than the flow-through time of the water-reducing agent prepared in Comparative Example 3. According to the comparison between Example 2 and Comparative Example 3, the presence of styrene monomer can shorten the flow-through time of the water-reducing agent, indicating that the water-reducing agent prepared in the presence of both octadecyl acrylate and styrene can significantly shorten the flow-through time, that is, it can reduce viscosity to a greater extent.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a high viscosity-reducing polycarboxylate superplasticizer for ultra-high performance concrete, characterized by: It comprises the following steps: (1) adding a metered amount of deionized water into a reaction vessel, then adding methyl allyl polyoxyethylene ether, sodium methallyl sulfonate and alkyl acrylate and styrene respectively, stirring and heating to 60-65℃; (2) adding a metered amount of 30wt% concentration hydrogen peroxide, while dropping a mixed aqueous solution of acrylic acid, methoxy polyethylene glycol methacrylate and a mixed aqueous solution of mercaptoacetic acid and ascorbic acid, the dropping time is 2-3h, and after dropping, keeping warm for 1-2h; (3) after keeping warm, cooling to 40-45℃, adding a metered amount of 32wt% concentration sodium hydroxide solution while stirring, adjusting the pH value to 6-8, and adding a certain amount of deionized water, to obtain a viscosity-reducing polycarboxylic acid water reducer; The alkyl acrylate is selected from octadecyl acrylate SA; In step (1), the molar ratio of metered deionized water to methyl allyl polyoxyethylene ether is (15-20):1; In step (2), the molar ratio of hydrogen peroxide to methyl allyl polyoxyethylene ether is (0.04-0.05):1; In step (2), the molar ratio of mercaptoacetic acid to ascorbic acid to methyl allyl polyoxyethylene ether is (0.02-0.05):(0.01-0.02):1; The molar ratio of methyl allyl polyoxyethylene ether TPEG, sodium methallyl sulfonate SMAS, alkyl acrylate, styrene, acrylic acid AA, and methoxy polyethylene glycol methacrylate MAA-MPEG is 1.0:(0.45-0.55):(1.1-1.2):(0.5-0.6):(6-8):(1.2-1.4).

2. The preparation method of high slump-reducing polycarboxylate superplasticizer for ultra-high performance concrete according to claim 1, characterized in that: The molar ratio of methyl allyl polyoxyethylene ether TPEG, sodium methallyl sulfonate SMAS, alkyl acrylate, styrene, acrylic acid AA, and methoxy polyethylene glycol methacrylate MAA-MPEG is 1.0:0.5:1.2:0.6:7:1.

3.

3. The high slump-reducing polycarboxylate superplasticizer for ultra-high performance concrete prepared by the method of any one of claims 1-2, characterized in that: The general structure of the high viscosity-reducing polycarboxylic acid water reducer is: ； Wherein, a, b, c, d, e, f, m, n, k are the polymerization degree and are all positive integers, a=5-15, b=3-10, c=30-50, d=2-5, e=2-3, f=1-2, m=150-200, n=50-60, k=16; The molecular weight of the high viscosity-reducing polycarboxylic acid water reducer is 50000-90000.

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