A viscosity-reducing and fast-dispersing polycarboxylic acid water reducer for high-strength concrete and a preparation method thereof

Abstract

The application discloses a high-strength-concrete viscosity-reducing fast-dispersing polycarboxylic acid water reducing agent and a preparation method thereof, and relates to the technical field of polycarboxylic acid water reducing agents; the high-strength-concrete viscosity-reducing fast-dispersing polycarboxylic acid water reducing agent comprises the following components in parts by weight: 400 parts of unsaturated polyether macromonomer, 20-40 parts of unsaturated acid monomer and 10-20 parts of unsaturated functional monomer; and the application further provides a preparation method of the polycarboxylic acid water reducing agent. The water reducing agent can reduce the viscosity of high-strength concrete, improve the dispersing performance of the concrete, reduce the mixing time, and thus solve the problems of high plastic viscosity of the concrete and the like without reducing the strength and other performances of the concrete.

Description

Technical Field

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

[0002] With the development of the construction industry, the demand for high-strength concrete is increasing, but its viscosity and dispersion time remain key challenges. High-strength concrete has a low water-cement ratio and high cement content per cubic meter, resulting in a high viscosity system. Reasonable viscosity control is crucial for ensuring the workability and quality of concrete projects. Excessive viscosity makes concrete construction difficult, affects pumping and pouring efficiency, and can even lead to segregation, bleeding, and reduced strength and durability. Rapid dispersibility refers to the ability of concrete to disperse quickly and evenly during mixing or pumping, without agglomeration or clumping. This is particularly important for high-strength concrete because it uses a large amount of binder, has high viscosity, and is prone to agglomeration. Good rapid dispersibility ensures smooth pumping, reduces pipeline friction, lowers pump losses, and improves construction efficiency. Furthermore, rapid dispersibility helps concrete quickly reach a homogeneous state after pouring, improving its density and strength.

[0003] Therefore, controlling the viscosity and rapid dispersibility of high-strength concrete is one of the important measures to ensure the quality of concrete projects and improve construction efficiency. Through reasonable mix design, selection of viscosity-reducing and rapid-dispersing admixtures, and strict construction control, the viscosity and rapid dispersibility of high-strength concrete can be effectively controlled, ensuring the smooth progress of concrete projects and the steady improvement of project quality. Summary of the Invention

[0004] To address the aforementioned technical problems, the present invention aims to provide a viscosity-reducing and fast-dispersing polycarboxylate superplasticizer for high-strength concrete and its preparation method. This superplasticizer can reduce the viscosity of high-strength concrete, while improving the dispersion performance of concrete and reducing mixing time, thereby solving the problem of high plastic viscosity of concrete without reducing concrete strength or other properties.

[0005] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: a high-strength concrete viscosity-reducing and fast-dispersing polycarboxylate superplasticizer is provided, comprising the following components by weight: 400 parts of unsaturated polyether macromonomer, 20-40 parts of unsaturated acid monomer, and 10-20 parts of unsaturated functional monomer.

[0006] High-strength concrete viscosity-reducing fast-dispersing polycarboxylate superplasticizer also includes chain transfer agent, reducing agent and oxidizing agent, which account for 0.1-0.3%, 0.05-0.2% and 0.15-0.3% of the total mass of polycarboxylate superplasticizer, respectively.

[0007] Furthermore, the high-strength concrete viscosity-reducing and fast-dispersing polycarboxylate superplasticizer comprises the following components by weight: 400 parts of unsaturated polyether macromonomer, 24 parts of unsaturated acid monomer, and 15 parts of unsaturated functional monomer.

[0008] Furthermore, the unsaturated polyether macromonomer is at least one of isopentenyl polyoxyethylene ether, isobutylene polyethylene glycol ether, and isoethylene glycol monovinyl polyoxyethylene ether.

[0009] Furthermore, the molecular weight of the unsaturated polyether macromonomer is 1100-2400.

[0010] Furthermore, the unsaturated acid monomer is at least one of acrylic acid, methacrylic acid, maleic anhydride, and itaconic acid.

[0011] Furthermore, the unsaturated functional monomer is at least one of methyl pyrene acrylate, ethyl pyrene acrylate, and methyl 2-methacrylate.

[0012] Furthermore, methyl pyrene acrylate is obtained by esterification of acrylic acid and pyrene methanol, and ethyl pyrene acrylate is obtained by esterification of acrylic acid and pyrene ethanol; the structural formula of methyl pyrene acrylate is:

[0013]

[0014] This invention also provides a method for preparing the above-mentioned high-strength concrete viscosity-reducing and fast-dispersing polycarboxylate superplasticizer, comprising the following steps:

[0015] (1) Mix unsaturated acid monomers, unsaturated functional monomers and chain transfer agents and add water to obtain mixed solution A; mix reducing agent and water to obtain mixed solution B;

[0016] (2) Dissolve the unsaturated polyether macromonomer in water at room temperature, add an oxidant, and then add the mixed solution A and mixed solution B obtained in step (1) dropwise. After stirring and reacting, keep warm, cool to room temperature, and dilute with water to a solid content of 45-50% to obtain a high-strength concrete viscosity-reducing fast-dispersing polycarboxylate superplasticizer.

[0017] Furthermore, in step (1), when the unsaturated functional monomers are methyl pyrene acrylate and ethyl pyrene acrylate, they are dissolved in tetrahydrofuran before being added.

[0018] When the unsaturated functional monomer is methyl pyrene acrylate, the preparation process is as follows:

[0019]

[0020] Where a = 0-20, b = 0-100, c = 0-15, n = 20-70, and a, b, c, and n are all positive integers.

[0021] Furthermore, the chain transfer agent is at least one of mercaptoacetic acid, mercaptopropionic acid, and mercaptoethanol, and its dosage is 0.1-0.3% of the total mass of the polycarboxylate superplasticizer; the reducing agent is at least one of L-ascorbic acid, isoascorbic acid, ferrous sulfate, and sodium bisulfite, and its dosage is 0.05-0.2% of the total mass of the polycarboxylate superplasticizer; the oxidizing agent is at least one of ammonium persulfate, hydrogen peroxide, and potassium persulfate, and its dosage is 0.15-0.3% of the total mass of the polycarboxylate superplasticizer.

[0022] Furthermore, in step (2), after stirring the reaction, the mixture is kept at 35°C for 0.5-2 hours.

[0023] Furthermore, in step (2), the dripping times for mixed solution A and mixed solution B are 1-3h and 1.5-3.5h, respectively.

[0024] The present invention has the following beneficial effects:

[0025] 1. This invention introduces unsaturated polyether macromonomers to provide effective hydrophobicity to the water-reducing agent molecules, ensuring the adsorption of cement particles by the water-reducing agent and providing sufficient water-reducing performance. The introduction of unsaturated acid monomers introduces negatively charged carboxyl groups into the water-reducing agent molecular chain, exerting electrostatic repulsion to further disperse particles and provide greater water-reducing performance. The introduction of unsaturated functional monomers introduces a pyrene ring structure into the water-reducing agent, increasing the hydrophobicity of the water-reducing agent molecules and providing certain water-reducing performance. At the same time, as an ester, it will hydrolyze in an alkaline environment, thereby providing certain slump-retaining properties for the water-reducing agent.

[0026] 2. This invention uses polyether macromonomers with a low molecular weight of 1100-2400, which have shorter side chains, resulting in greater steric hindrance in their molecular structure. This allows for more effective dispersion of cement particles, improving water-reducing performance, and shortening the dispersion time of cement, thus achieving rapid dispersion.

[0027] 3. The pyrene ring structure of the unsaturated functional monomer of the present invention has a plate-like structure, which can improve the workability of concrete and reduce its viscosity. At the same time, its esterification structure can continuously play a re-adsorption-dispersion role on the surface of cement hydration products, effectively improving the loss and gas stabilization effect of concrete, thereby continuously playing a viscosity-reducing role and achieving the overall effect of reducing concrete viscosity.

[0028] 4. When the unsaturated functional monomers of the present invention are methyl pyrene acrylate and ethyl pyrene acrylate, the specific methyl pyrene acrylate / ethyl acrylate is obtained by esterification reaction of acrylic acid and methyl pyrene acrylate / ethanol, which gives it certain hydrolytic properties. In the alkaline environment provided by cement, there is a later hydrolysis, which provides a certain slump retention effect for polycarboxylate superplasticizer, and also improves its later viscosity reduction effect. Detailed Implementation

[0029] The principles and features of this invention are described below. The examples given are for illustrative purposes only and are not intended to limit the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer should be followed. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0030] Example 1

[0031] A fast-dispersing polycarboxylate superplasticizer for high-strength concrete, comprising the following steps:

[0032] (1) Mix 15 parts acrylic acid, 5 parts maleic anhydride, 10 parts methyl pyrene acrylate (dissolved in 1 part tetrahydrofuran), 1.5 parts mercaptoethanol and 32 parts deionized water to obtain mixed solution A; mix 0.7 parts L-ascorbic acid and 56 parts deionized water to obtain mixed solution B.

[0033] (2) 400 parts of isobutylene-based polyethylene glycol ether with a molecular weight of 2400 and 360 parts of deionized water were stirred until fully dissolved. 1.5 parts of ammonium persulfate were added. Mixed solution B was added dropwise first, and mixed solution A was added dropwise after 2 minutes. Mixed solution A was added dropwise for 150 minutes, and mixed solution B was added dropwise for 180 minutes. After stirring and reacting, the mixture was kept at 35°C for 1 hour, cooled to room temperature, and diluted with water to a solid content of 45% to obtain a high-strength concrete viscosity-reducing fast-dispersing polycarboxylate superplasticizer.

[0034] Example 2

[0035] A fast-dispersing polycarboxylate superplasticizer for high-strength concrete, comprising the following steps:

[0036] (1) Mix 20 parts acrylic acid, 4 parts methacrylic acid, 15 parts methyl pyrene acrylate (dissolved in 1 part tetrahydrofuran), 1.5 parts mercaptopropionic acid and 32 parts deionized water to obtain mixed solution A; mix 0.7 parts isoascorbic acid and 56 parts deionized water to obtain mixed solution B;

[0037] (2) 400 parts of isopentenyl alcohol polyoxyethylene ether with a molecular weight of 2400 and 360 parts of deionized water were stirred until fully dissolved. 1.6 parts of hydrogen peroxide were added. Mixed solution B was added dropwise first, and mixed solution A was added dropwise after 2 minutes. Mixed solution A was added dropwise for 120 minutes, and mixed solution B was added dropwise for 150 minutes. After stirring and reacting, the mixture was kept at 35°C for 1 hour, cooled to room temperature, and diluted with water to a solid content of 45% to obtain a high-strength concrete viscosity-reducing fast-dispersing polycarboxylate superplasticizer.

[0038] Example 3

[0039] A fast-dispersing polycarboxylate superplasticizer for high-strength concrete, comprising the following steps:

[0040] (1) Mix 20 parts acrylic acid, 10 parts itaconic acid, 8 parts methyl pyrene acrylate (dissolved in 1 part tetrahydrofuran), 10 parts ethyl pyrene acrylate, 1.3 parts mercaptoacetic acid and 32 parts deionized water to obtain mixed solution A; mix 0.1 parts ferrous sulfate, 0.5 parts L-ascorbic acid and 56 parts deionized water to obtain mixed solution B;

[0041] (2) 400 parts of isoethylene glycol monovinyl polyoxyethylene ether with a molecular weight of 2400 and 360 parts of deionized water were stirred until fully dissolved. 1.5 parts of hydrogen peroxide were added. Mixed solution B was added dropwise first, and mixed solution A was added dropwise after 2 minutes. Mixed solution A was added dropwise for 60 minutes, and mixed solution B was added dropwise for 80 minutes. After stirring and reacting, the mixture was kept at 35°C for 1 hour, cooled to room temperature, and diluted with water to a solid content of 45% to obtain a high-strength concrete viscosity-reducing fast-dispersing polycarboxylate superplasticizer.

[0042] Example 4

[0043] A fast-dispersing polycarboxylate superplasticizer for high-strength concrete, comprising the following steps:

[0044] (1) Mix 20 parts acrylic acid, 4 parts maleic anhydride, 4 parts itaconic acid, 12 parts methyl methacrylate (dissolved in 1 part tetrahydrofuran), 2 parts mercaptoethanol and 32 parts deionized water to obtain mixed solution A; mix 0.5 parts L-ascorbic acid, 0.2 parts ferrous sulfate and 56 parts deionized water to obtain mixed solution B;

[0045] (2) 400 parts of isoethylene glycol monovinyl polyoxyethylene ether with a molecular weight of 2400 and 360 parts of deionized water were stirred until fully dissolved. 2 parts of hydrogen peroxide were added. Mixed solution B was added dropwise first, and mixed solution A was added dropwise after 2 minutes. Mixed solution A was added dropwise for 60 minutes, and mixed solution B was added dropwise for 80 minutes. After stirring and reacting, the mixture was kept at 35°C for 1 hour, cooled to room temperature, and diluted with water to a solid content of 45% to obtain a high-strength concrete viscosity-reducing fast-dispersing polycarboxylate superplasticizer.

[0046] Comparative Example 1

[0047] A polycarboxylate superplasticizer is prepared in a manner different from that in Example 4, but without the addition of unsaturated functional monomers, while all other conditions remain the same.

[0048] Comparative Example 2

[0049] A polycarboxylate superplasticizer is prepared in a manner different from that in Example 2, but without the addition of unsaturated functional monomers, while all other conditions remain the same.

[0050] Comparative Example 3

[0051] A polycarboxylate superplasticizer is prepared in a manner different from that in Example 4, wherein the molecular weight of isoethylene glycol monovinyl polyoxyethylene ether is adjusted to 3000, while the other conditions remain unchanged.

[0052] Comparative Example 4

[0053] Commercially available viscosity-reducing and slump-preserving polycarboxylate superplasticizer (BASF 416).

[0054] Comparative Example 5

[0055] Commercially available high-efficiency polycarboxylate superplasticizers (Subote) Polycarboxylate superplasticizer.

[0056] Test case

[0057] 1. Using Esheng Cement P·O 42.5, the water-reducing agents obtained in Examples 1-4 and Comparative Examples 1-5 were compared with cement paste with a water-cement ratio of 0.2. The change in the fluidity of the cement paste within 0-1h and the initial cement dispersion time were tested. The test results are shown in Table 1.

[0058] Table 1. Test results of paste fluidity at room temperature.

[0059]

[0060] Table 1 shows that, comparing Example 4 with Comparative Example 1 and Example 2 with Comparative Example 2, it can be seen that using methyl pyrene acrylate / ethyl acrylate can effectively reduce cement dispersion time and achieve rapid dispersion. Comparing Examples 1-4 shows that increasing the amount of methyl pyrene acrylate / ethyl acrylate can effectively improve dispersion retention and slump retention performance of the polycarboxylate superplasticizer. It can also be seen that the use of different types of polyether macromonomers and their molecular weights have a certain impact on cement dispersion time. Comparing Example 4 with Comparative Example 3 shows that using polyether macromonomers with different molecular weights has a significant impact on water-reducing performance, slump retention performance, and cement dispersion time; the lower the molecular weight, the greater the steric hindrance and the faster the dispersion time. Furthermore, comparing Example 4 with Comparative Examples 4 and 5, it is clear that the polycarboxylate superplasticizer prepared using methyl pyrene acrylate has significant advantages over commercially available viscosity-reducing products and ordinary products in terms of paste fluidity and cement dispersion time.

[0061] 2. The polycarboxylate superplasticizers obtained in Examples 1-4 and Comparative Examples 1-5 were applied to C60 concrete using the same admixture formulation (see Table 2). The flowability and slump time of the concrete were compared (the viscosity of the concrete was tested using the inverted slump cone method; the shorter the time it took for the concrete to flow out of the inverted slump cone, the lower the viscosity of the concrete). The cement used was Esheng cement P·O 42.5, the fineness modulus of the manufactured sand was 2.6, the crushed stone was continuously graded with a particle size of 5-20mm, the mineral powder was S95 grade mineral powder, and the polycarboxylate superplasticizer dosage was 2.1wt%. The test methods were in accordance with GB / T50080-2016 "Standard for Test Methods of Performance of Ordinary Concrete Mixtures", GB / T50080-2016 "Standard Specification for Air Content of Concrete", and GB / T50081-2002 "Standard for Test Methods of Mechanical Properties of Ordinary Concrete". The test results are shown in Tables 3 and 4.

[0062] Table 2. C60 Concrete Mix Proportion (kg / m³) 3 )

[0063] label cement fly ash Mineral powder Manufactured sand 5-20 stones water C60 420 50 60 810 910 150

[0064] Table 3. Test results for C60 concrete at room temperature.

[0065]

[0066] Table 4. Strength Record of C60 Concrete at Room Temperature

[0067]

[0068] As shown in Tables 3-4, the high-strength concrete viscosity-reducing fast-dispersing polycarboxylate superplasticizers obtained in Examples 1-4 can significantly reduce the dosage of concrete and reduce the concrete slump time, thus reducing the viscosity of the concrete. Comparing Example 4 with Comparative Example 1, and Example 2 with Comparative Example 2, it can be seen that using methyl methacrylate / ethyl acrylate can effectively reduce the concrete slump time and viscosity, and also effectively reduce the concrete dispersion time, resulting in rapid dispersion. Comparing Examples 1-4, it can be seen that increasing the amount of methyl methacrylate / ethyl acrylate can effectively improve the dispersion retention of concrete and enhance the slump retention performance of the polycarboxylate superplasticizer. It can also be seen that the use of different types of polyether macromonomers and their molecular weights have a certain impact on concrete viscosity and dispersion time. Comparing Example 4 with Comparative Example 3, it can be seen that using polyether macromonomers with different molecular weights has a significant impact on water-reducing performance, slump retention performance, concrete viscosity, and dispersion time; the lower the molecular weight, the greater the steric hindrance, the lower the concrete viscosity, and the faster the dispersion time. Furthermore, comparing Example 4 with Comparative Examples 4 and 5, it can be clearly seen that the polycarboxylate superplasticizer prepared using methyl methacrylate has significant improvements in dosage, concrete viscosity, and concrete dispersion time compared to commercially available viscosity-reducing products and ordinary products.

[0069] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A fast-dispersing polycarboxylate superplasticizer for high-strength concrete, characterized in that, The raw materials for preparation include the following parts by weight: 400 parts of unsaturated polyether macromonomer, 20-40 parts of unsaturated acid monomer, and 10-20 parts of unsaturated functional monomer; The unsaturated polyether macromonomer has a molecular weight of 1100-2400; the unsaturated functional monomer is at least one of methyl pyrene acrylate and ethyl pyrene acrylate; the unsaturated polyether macromonomer is at least one of isopentenyl polyoxyethylene ether, isobutylene polyethylene glycol ether and isoethylene glycol monovinyl polyoxyethylene ether.

2. The high-strength concrete viscosity-reducing, fast-dispersing polycarboxylate superplasticizer as described in claim 1, characterized in that, The raw materials for preparation include the following parts by weight: 400 parts of unsaturated polyether macromonomer, 24 parts of unsaturated acid monomer, and 15 parts of unsaturated functional monomer.

3. The high-strength concrete viscosity-reducing, fast-dispersing polycarboxylate superplasticizer as described in claim 1 or 2, characterized in that, The unsaturated acid monomer is at least one of acrylic acid, methacrylic acid, maleic anhydride, and itaconic acid.

4. The preparation method of the high-strength concrete viscosity-reducing fast-dispersing polycarboxylate superplasticizer according to any one of claims 1-3, characterized in that, Includes the following steps: (1) Mix unsaturated acid monomers, unsaturated functional monomers and chain transfer agents and add water to obtain mixed solution A; mix reducing agent and water to obtain mixed solution B; (2) Dissolve the unsaturated polyether macromonomer in water at room temperature, add an oxidant, and then add the mixed solution A and mixed solution B obtained in step (1) dropwise. After stirring and reacting, keep warm, cool to room temperature, and dilute with water to a solid content of 45-50% to obtain a high-strength concrete viscosity-reducing fast-dispersing polycarboxylate superplasticizer.

5. The preparation method of the high-strength concrete viscosity-reducing and fast-dispersing polycarboxylate superplasticizer as described in claim 4, characterized in that, The chain transfer agent is at least one of mercaptoacetic acid, mercaptopropionic acid, and mercaptoethanol, and its dosage is 0.1-0.3% of the total mass of the polycarboxylate superplasticizer; the reducing agent is at least one of L-ascorbic acid, isoascorbic acid, ferrous sulfate, and sodium bisulfite, and its dosage is 0.05-0.2% of the total mass of the polycarboxylate superplasticizer; the oxidizing agent is at least one of ammonium persulfate, hydrogen peroxide, and potassium persulfate, and its dosage is 0.15-0.3% of the total mass of the polycarboxylate superplasticizer.

6. The preparation method of the high-strength concrete viscosity-reducing fast-dispersing polycarboxylate superplasticizer as described in claim 4, characterized in that, In step (2), after stirring the reaction, the mixture is kept at 35°C for 0.5-2 h.

7. The preparation method of the high-strength concrete viscosity-reducing fast-dispersing polycarboxylate superplasticizer as described in claim 4, characterized in that, In step (2), the dripping times for mixed solution A and mixed solution B are 1-3 h and 1.5-3.5 h, respectively.

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