Viscosity-reducing fast-dispersing polycarboxylate superplasticizer for high-strength concrete and preparation method thereof

Abstract

The invention discloses a viscosity-reducing fast-dispersing polycarboxylate superplasticizer for high-strength concrete and a preparation method thereof, and relates to the technical field of polycarboxylate superplasticizers. The viscosity-reducing fast-dispersing polycarboxylic acid water reducer for the high-strength concrete 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. The invention also provides a preparation method of the polycarboxylate superplasticizer. The water reducer can reduce the viscosity of high-strength concrete, improve the dispersing performance of the concrete and shorten the mixing time, so that the problems of high plastic viscosity and the like of the concrete are solved under the condition of not reducing other performances such as the strength of the concrete.

Description

Technical Field

[0001] The invention relates to the technical field of polycarboxylate water reducers, and in particular to a viscosity-reducing and fast-dispersing polycarboxylate water reducer for high-strength concrete and a preparation method thereof. Background Art

[0002] With the development of the construction industry, the demand for high-strength concrete is increasing, but its viscosity and dispersion time have always been the key issues that are difficult to solve. Due to the low water-binder ratio and high cement content in a single cubic meter of concrete, high viscosity of the concrete system is caused. Reasonable viscosity control is crucial to ensure the working performance and engineering quality of concrete. Excessive viscosity will make concrete construction difficult, affect the pumping and pouring effects of concrete, and even cause stratification and water seepage in concrete, reducing the strength and durability of concrete. Fast dispersion refers to the ability of concrete to disperse quickly and evenly during mixing or pumping without agglomeration or caking. This is especially important for high-strength concrete, because it uses a large amount of adhesive, has a high viscosity, and is easy to agglomerate. Good fast dispersion can ensure that the concrete is smooth and unobstructed during pumping, reduce pipeline friction, reduce pump loss, and improve construction efficiency; at the same time, fast dispersion also helps the concrete quickly reach a uniform state after pouring, and improves the density and strength of the concrete.

[0003] Therefore, the control of viscosity and rapid dispersion in 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 dispersion admixtures and strict construction control, the viscosity and rapid dispersion of high-strength concrete can be effectively controlled to ensure the smooth progress of concrete projects and the steady improvement of project quality. Summary of the invention

[0004] In order to solve the above technical problems, the purpose of the present invention is to provide a high-strength concrete viscosity-reducing fast-dispersing polycarboxylic acid water-reducing agent and a preparation method thereof, which 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 other properties such as concrete strength.

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

[0006] The viscosity-reducing and fast-dispersing polycarboxylate water-reducing agent for high-strength concrete also includes a chain transfer agent, a reducing agent and an oxidizing agent, wherein the chain transfer agent, the reducing agent and the oxidizing agent account for 0.1-0.3%, 0.05-0.2% and 0.15-0.3% of the total mass of the polycarboxylate water-reducing agent respectively.

[0007] Furthermore, the viscosity-reducing and fast-dispersing polycarboxylic acid water-reducing agent for high-strength concrete includes the following components in parts 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 isopentanol 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 pyrene methyl acrylate, pyrene ethyl acrylate and 2-methyl methacrylate.

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

[0013]

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

[0015] (1) mixing an unsaturated acid monomer, an unsaturated functional monomer and a chain transfer agent, and then adding water to obtain a mixed solution A; mixing a reducing agent and water to obtain a mixed solution B;

[0016] (2) dissolving the unsaturated polyether macromonomer in water at room temperature, adding an oxidant, and then respectively adding the mixed solution A and the mixed solution B obtained in step (1) dropwise, stirring for reaction, keeping the temperature, cooling to room temperature, and diluting with water to a solid content of 45-50%, thereby obtaining a viscosity-reducing fast-dispersing polycarboxylic acid water-reducing agent for high-strength concrete.

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

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

[0019]

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

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

[0022] Furthermore, in step (2), the reaction is stirred and then kept at 35° C. for 0.5-2 h.

[0023] Furthermore, in step (2), the dropwise addition time of mixed solution A and mixed solution B is 1-3 h and 1.5-3.5 h, respectively.

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

[0025] 1. The present invention provides effective hydrophobicity for water reducer molecules by introducing unsaturated polyether macromonomers, ensures the adsorption of cement particles by the water reducer, and provides sufficient water reducing performance; the introduction of unsaturated acid monomers introduces negatively charged carboxyl groups into the water reducer molecular chain, exerts electrostatic repulsion, further disperses particles, and provides greater water reducing performance; the introduction of unsaturated functional monomers introduces pyrene ring structures into the water reducer, increases the hydrophobicity of the water reducer molecules, and provides certain water reducing performance. At the same time, as an ester, it will hydrolyze in an alkaline environment, thereby providing certain collapse retention performance for the water reducer.

[0026] 2. The present invention uses a polyether macromonomer with a low molecular weight of 1100-2400, which has a shorter side chain, so that its molecular structure has a greater steric hindrance, thereby more effectively dispersing cement particles, improving water reduction performance, and shortening the dispersion time of cement, thereby achieving a fast dispersion effect.

[0027] 3. The pyrene ring structure of the unsaturated functional monomer of the present invention has a flaky structure, which can improve the workability of concrete while reducing the viscosity of concrete. At the same time, its esterified 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 effect of reducing the overall viscosity of concrete.

[0028] 4. When the unsaturated functional monomer of the present invention is pyrene methyl acrylate or pyrene ethyl acrylate, the specific pyrene methyl / ethyl acrylate is obtained by esterification reaction of acrylic acid and pyrene methyl / ethanol, so that it has certain hydrolysis performance and there is late hydrolysis in the alkaline environment provided by cement, that is, it provides a certain slump retention effect for the polycarboxylic acid water reducer, so that its late viscosity reduction effect is also improved. DETAILED DESCRIPTION

[0029] The principles and features of the present invention are described below, and the examples are only used to explain the present invention and are not used to limit the scope of the present invention. If no specific conditions are specified in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially.

[0030] Example 1

[0031] A viscosity-reducing and fast-dispersing polycarboxylate water-reducing agent for high-strength concrete, the preparation method of which comprises the following steps:

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

[0033] (2) 400 parts of isobutylene 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, and mixed solution B was first added dropwise, and then mixed solution A was added dropwise 2 minutes later. Mixed solution A was added dropwise for 150 minutes, and mixed solution B was added dropwise for 180 minutes. After stirring for reaction, the mixture was kept warm at 35° C. for 1 hour, cooled to room temperature, and diluted with water to a solid content of 45%, thereby obtaining a viscosity-reducing and fast-dispersing polycarboxylate water-reducing agent for high-strength concrete.

[0034] Example 2

[0035] A viscosity-reducing and fast-dispersing polycarboxylate water-reducing agent for high-strength concrete, the preparation method of which comprises the following steps:

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

[0037] (2) 400 parts of isopentanol 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, and mixed solution B was first added dropwise, and then mixed solution A was added dropwise 2 minutes later. Mixed solution A was added dropwise for 120 minutes, and mixed solution B was added dropwise for 150 minutes. After stirring for reaction, the mixture was kept warm at 35° C. for 1 hour, cooled to room temperature, and diluted with water to a solid content of 45%, thereby obtaining a viscosity-reducing and fast-dispersing polycarboxylic acid water-reducing agent for high-strength concrete.

[0038] Example 3

[0039] A viscosity-reducing and fast-dispersing polycarboxylate water-reducing agent for high-strength concrete, the preparation method of which comprises the following steps:

[0040] (1) 20 parts of acrylic acid, 10 parts of itaconic acid, 8 parts of methyl acrylate (dissolved in 1 part of tetrahydrofuran), 10 parts of ethyl acrylate, 1.3 parts of thioglycolic acid and 32 parts of deionized water were mixed to obtain a mixed solution A; 0.1 parts of ferrous sulfate, 0.5 parts of L-ascorbic acid and 56 parts of deionized water were mixed to obtain a 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, and mixed solution B was first added dropwise, and then mixed solution A was added dropwise 2 minutes later. Mixed solution A was added dropwise for 60 minutes and mixed solution B was added dropwise for 80 minutes. After stirring for reaction, the mixture was kept warm at 35° C. for 1 hour, cooled to room temperature, and diluted with water to a solid content of 45%, thereby obtaining a viscosity-reducing and fast-dispersing polycarboxylic acid water-reducing agent for high-strength concrete.

[0042] Example 4

[0043] A viscosity-reducing and fast-dispersing polycarboxylate water-reducing agent for high-strength concrete, the preparation method of which comprises the following steps:

[0044] (1) 20 parts of acrylic acid, 4 parts of maleic anhydride, 4 parts of itaconic acid, 12 parts of methyl pyrene acrylate (dissolved in 1 part of tetrahydrofuran), 2 parts of mercaptoethanol and 32 parts of deionized water were mixed to obtain a mixed solution A; 0.5 parts of L-ascorbic acid, 0.2 parts of ferrous sulfate and 56 parts of deionized water were mixed to obtain a 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, and the mixed solution B was first added dropwise, and then the mixed solution A was added dropwise 2 minutes later. The mixed solution A was added dropwise for 60 minutes and the mixed solution B was added dropwise for 80 minutes. After stirring for reaction, the mixture was kept warm at 35° C. for 1 hour, cooled to room temperature, and diluted with water to a solid content of 45%, thereby obtaining a viscosity-reducing and fast-dispersing polycarboxylic acid water-reducing agent for high-strength concrete.

[0046] Comparative Example 1

[0047] A polycarboxylic acid water-reducing agent, the preparation method of which is different from that of Example 4 in that no unsaturated functional monomer is added, and other conditions remain unchanged.

[0048] Comparative Example 2

[0049] A polycarboxylate water-reducing agent, the preparation method of which is different from that of Example 2 in that no unsaturated functional monomer is added, and other conditions remain unchanged.

[0050] Comparative Example 3

[0051] A polycarboxylic acid water reducer, the preparation method of which is different from that of Example 4 in that the molecular weight of isoethylene glycol monovinyl polyoxyethylene ether is adjusted to 3000, and the other conditions remain unchanged.

[0052] Comparative Example 4

[0053] Commercially available viscosity-reducing and slump-retaining polycarboxylic acid water-reducing agent (BASF 416).

[0054] Comparative Example 5

[0055] Commercially available high-efficiency polycarboxylate water reducer (Subot Polycarboxylic acid highly adaptable water reducer).

[0056] Test example

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

[0058] Table 1 Test table of pure slurry fluidity under room temperature

[0059]

[0060] As can be seen from Table 1, by comparing Example 4 with Comparative Example 1, and Example 2 with Comparative Example 2, it can be seen that the use of pyrene methyl / ethyl acrylate can effectively reduce the cement dispersion time and play a role in rapid dispersion; by comparing Examples 1-4, it can be seen that the increase in the amount of pyrene methyl / ethyl acrylate can effectively improve the dispersion retention and the slump retention performance of the polycarboxylic acid water-reducing agent. At the same time, it can be seen that the use of different types of polyether macromonomers and the molecular weight of the polyether macromonomer have a certain effect on the cement dispersion time; by comparing Example 4 with Comparative Example 3, it can be seen that the use of polyether macromonomers with different molecular weights has a significant effect on the water-reducing performance, the slump retention performance and the cement dispersion time. The lower the molecular weight, the greater the steric hindrance and the faster the dispersion time; by comparing Example 4 with Comparative Example 4 and Comparative Example 5, it can be clearly seen that the polycarboxylic acid water-reducing agent prepared using pyrene methyl acrylate has obvious advantages in the fluidity of the slurry and the dispersion time of the cement compared to commercially available viscosity-reducing products and ordinary products.

[0061] 2. The polycarboxylate water-reducing agents obtained in Examples 1-4 and Comparative Examples 1-5 were applied to C60 concrete using the same admixture formula (see Table 2) to compare the concrete's fluidity and collapse time over time (the viscosity of the concrete was tested by the inverted slump cone test. The shorter the time it took for the concrete to flow out of the inverted slump cone, the smaller the viscosity of the concrete). The cement was Esheng Cement P·O 42.5, and the fineness modulus of the machine-made sand was 2.6; the crushed stone was a continuously graded crushed stone with a particle size of 5-20 mm, the mineral powder was S95 grade mineral powder, and the polycarboxylate water-reducing agent was added in an amount of 2.1 wt%. The test method was based on GB / T50080-2016 "Standard for Test Methods 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", and the test results are shown in Tables 3 and 4.

[0062] Table 2C60 concrete mix ratio (kg / m 3 )

[0063] Label cement Fly ash Mineral powder Machine-made sand 5-20 stones water C60 420 50 60 810 910 150

[0064] Table 3 C60 concrete test table at room temperature

[0065]

[0066] Table 4 C60 concrete strength record under room temperature

[0067]

[0068] It can be seen from Table 3-4 that the high-strength concrete obtained in Examples 1-4 can significantly reduce the dosage of concrete and reduce the collapse time of concrete, that is, reduce the viscosity of concrete. Comparing Example 4 with Comparative Example 1, Example 2 with Comparative Example 2, it can be seen that the use of pyrene methyl / ethyl acrylate can effectively reduce the collapse time of concrete and reduce the viscosity of concrete. At the same time, it can effectively reduce the dispersion time of concrete and play a role in quick dispersion; from Comparative Examples 1-4, it can be seen that the increase in the amount of pyrene methyl / ethyl acrylate can effectively improve the dispersion retention of concrete and improve the collapse protection performance of polycarboxylic acid water reducer. At the same time, it can be seen that the use of different types of polyether macromonomers and the molecular weight of polyether macromonomers have a certain effect on the viscosity and dispersion time of concrete; from Comparative Example 4 with Comparative Example 3, it can be seen that the use of polyether macromonomers with different molecular weights has a significant effect on water reduction performance, collapse protection 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; at the same time, by comparing Example 4 with Comparative Example 4 and Comparative Example 5, it can be clearly seen that the polycarboxylic acid water reducer prepared using pyrene methyl acrylate has a significant improvement in dosage, concrete viscosity, and dispersion time of concrete compared to commercially available viscosity reduction 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 principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A high-strength concrete viscosity-reducing and fast-dispersing polycarboxylate water-reducing agent, characterized in that: The invention 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.

2. The high-strength concrete viscosity-reducing and fast-dispersing polycarboxylate water-reducing agent according to claim 1, characterized in that: The invention comprises the following components in parts by weight: 400 parts of unsaturated polyether macromonomer, 24 parts of unsaturated acid monomer and 15 parts of unsaturated functional monomer.

3. The viscosity-reducing and fast-dispersing polycarboxylate water-reducing agent for high-strength concrete according to claim 1 or 2, characterized in that: The unsaturated polyether macromonomer is at least one of isopentanol polyoxyethylene ether, isobutylene polyethylene glycol ether and isoethylene glycol monovinyl polyoxyethylene ether.

4. The viscosity-reducing and fast-dispersing polycarboxylate water-reducing agent for high-strength concrete according to claim 1 or 2, characterized in that: The molecular weight of the unsaturated polyether macromonomer is 1100-2400.

5. The viscosity-reducing and fast-dispersing polycarboxylate water-reducing agent for high-strength concrete according to 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.

6. The viscosity-reducing and fast-dispersing polycarboxylate water-reducing agent for high-strength concrete according to claim 1 or 2, characterized in that: The unsaturated functional monomer is at least one of pyrene methyl acrylate, pyrene ethyl acrylate and 2-methyl methacrylate.

7. The method for preparing the viscosity-reducing and fast-dispersing polycarboxylate water-reducing agent for high-strength concrete according to any one of claims 1 to 6, characterized in that: The following steps are involved: (1) mixing an unsaturated acid monomer, an unsaturated functional monomer and a chain transfer agent, and then adding water to obtain a mixed solution A; mixing a reducing agent and water to obtain a mixed solution B; (2) dissolving the unsaturated polyether macromonomer in water at room temperature, adding an oxidant, and then respectively adding the mixed solution A and the mixed solution B obtained in step (1) dropwise, stirring for reaction, keeping the temperature, cooling to room temperature, and diluting with water to a solid content of 45-50%, thereby obtaining a viscosity-reducing fast-dispersing polycarboxylic acid water-reducing agent for high-strength concrete.

8. The method for preparing the viscosity-reducing and fast-dispersing polycarboxylate water-reducing agent for high-strength concrete according to claim 7, characterized in that: The chain transfer agent is at least one of mercaptoacetic acid, mercaptopropionic acid and mercaptoethanol, and its usage is 0.1-0.3% of the total mass of the polycarboxylate water reducer; the reducing agent is at least one of L-ascorbic acid, isoascorbic acid, ferrous sulfate and sodium bisulfite, and its usage is 0.05-0.2% of the total mass of the polycarboxylate water reducer; the oxidant is at least one of ammonium persulfate, hydrogen peroxide and potassium persulfate, and its usage is 0.15-0.3% of the total mass of the polycarboxylate water reducer.

9. The method for preparing the viscosity-reducing and fast-dispersing polycarboxylate water-reducing agent for high-strength concrete according to claim 7, characterized in that: In step (2), the reaction is stirred and then kept at 35° C. for 0.5-2 h.

10. The method for preparing the viscosity-reducing and fast-dispersing polycarboxylate water-reducing agent for high-strength concrete according to claim 7, characterized in that: In step (2), the dropwise addition time of mixed solution A and mixed solution B is 1-3 h and 1.5-3.5 h respectively.

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