Preparation method and application of rust-resistant polycarboxylate water reducer

Abstract

The present invention discloses a preparation method and application of a rust-resistant polycarboxylate water reducer, including an imidazoline derivative preparation step: mixing alkyl N-hydroxyethyl imidazoline with allyl chloride and adding it to a reactor, and adding sodium hydroxide, sequentially performing substitution and dehydration reactions to obtain an imidazoline derivative; a p-isopropenylphenol polyalkoxy ether preparation step: taking p-isopropenylphenol into an autoclave, under high pressure conditions, raising the reaction temperature, adding ethylene oxide and propylene oxide to obtain p-isopropenylphenol polyalkoxy ether; a rust-resistant polycarboxylate water reducer preparation step: mixing p-isopropenylphenol polyalkoxy ether, an imidazoline derivative and deionized water and adding them to a reaction device, heating and stirring to generate a polyether monomer, then adding acrylic acid and an oxidant, and finally sequentially adding a reducing agent, an initiator, and a chain transfer agent, and neutralizing to obtain a rust-resistant polycarboxylate water reducer. The rust-resistant polycarboxylate water reducer prepared by the present invention has good rust-resistant performance and water-reducing performance.

Description

Technical Field

[0001] The invention belongs to the technical field of concrete admixtures, and in particular relates to a preparation method and application of a rust-resistant polycarboxylate water-reducing agent. Background Art

[0002] In recent years, with the acceleration of my country's urbanization and the vigorous development of infrastructure such as high-speed railways, airports, skyscrapers, coal mines, nuclear power plants, and dams, cement production has maintained a steady growth trend. At the same time, the quality requirements for concrete have become more stringent. To improve the performance of cement-based materials, various admixtures are often added during the preparation of cement concrete.

[0003] Currently, the most commonly used admixture in concrete is polycarboxylate superplasticizer, which offers advantages such as high water reduction, minimal slump loss, and environmental friendliness. However, in concrete applications for marine projects and foundation structures in salt lake areas, rust inhibitors are required to prevent corrosion of steel bars by seawater and concrete. Therefore, during construction, both superplasticizers and rust inhibitors are typically added separately to achieve both rust prevention and water reduction. The addition of additional admixtures can sometimes create antagonistic effects, leading to reduced concrete performance.

[0004] In order to solve the above-mentioned shortcomings, it is necessary to propose a preparation method and application of a rust-resistant polycarboxylate water-reducing agent. Summary of the Invention

[0005] The present invention aims to provide a preparation method and application of a rust-resistant polycarboxylate water-reducing agent, so as to solve the technical problem in the prior art that a rust inhibitor needs to be added to the water-reducing agent to achieve the purpose of water reduction and rust prevention, and that the addition of the rust inhibitor leads to a decrease in concrete performance.

[0006] The first aspect of the present invention provides a rust-resistant polycarboxylate water reducer, the structural formula of the rust-resistant polycarboxylate water reducer is:

[0007]

[0008] Among them, m is 50-80, n is 0-5, x is 1-6, y is 1-60, and z is 1-5.

[0009] A second aspect of the present invention provides a method for preparing a rust-resistant polycarboxylate water reducer, comprising the steps of preparing an imidazoline derivative, mixing alkyl N-hydroxyethyl imidazoline with allyl chloride, adding the mixture to a reactor, adding sodium hydroxide, and sequentially performing a substitution reaction and a dehydration reaction at a reaction temperature to obtain an imidazoline derivative; preparing a p-isopropenylphenol polyalkoxy ether, adding p-isopropenylphenol and potassium hydroxide to an autoclave, raising the temperature of the autoclave to the reaction temperature under high pressure, adding ethylene oxide and propylene oxide, and aging and degassing to obtain the p-isopropenylphenol polyalkoxy ether; and preparing a rust-resistant polycarboxylate water reducer, mixing p-isopropenylphenol polyalkoxy ether, an imidazoline derivative, and deionized water, adding the mixture to a reaction apparatus, heating and stirring the mixture to generate a polyether monomer, stirring the polyether monomer until dissolved, adding acrylic acid and an oxidant to the reaction apparatus, adding acrylic acid dropwise again after stirring, and finally sequentially adding a reducing agent, an initiator, and a chain transfer agent, followed by neutralization with a neutralizer to obtain the rust-resistant polycarboxylate water reducer.

[0010] Alternatively, in the step of preparing the imidazoline derivative, the molar ratio of alkyl N-hydroxyethyl imidazoline, allyl chloride and sodium hydroxide is 1:1.1-1.3:1.1-1.3.

[0011] Alternatively, in the p-isopropenylphenol polyalkoxy ether preparation step, the molar ratio of p-isopropenylphenol, ethylene oxide and propylene oxide is 1:60-70:0-1.

[0012] Alternatively, in the step of preparing the rust-resistant polycarboxylate water-reducing agent, the molar ratio of the imidazoline derivative, the p-isopropenylphenol polyalkoxy ether and the acrylic acid is 2:1:6.

[0013] Optionally, in the step of preparing the rust-resistant polycarboxylate water-reducing agent, the mass ratio of the initiator, the chain transfer agent, the oxidant, and the reducing agent is 0.5-3:0.5-0.8:0.3-3:0.1-0.5.

[0014] Optionally, in the step of preparing the rust-resistant polycarboxylate water-reducing agent, the masses of the initiator, chain transfer agent, oxidant and reducing agent are 0.3%-0.7%, 0.5%-0.8%, 0.3%-2% and 0.1%-0.5% of the total mass of the polyether monomer, respectively.

[0015] Optionally, in the preparation step of the rust-resistant polycarboxylate water-reducing agent, the initiator is any one or more of ammonium persulfate, hydrogen peroxide or L-ascorbic acid; the chain transfer agent is mercaptopropionic acid; the oxidant is hydrogen peroxide; the reducing agent is vitamin C and ferrous sulfate, and the mass ratio of vitamin C to ferrous sulfate is 1:1; and the neutralizing agent is 30% liquid alkali.

[0016] A third aspect of the present invention provides an application of a rust-resistant polycarboxylate water-reducing agent. Reference cement, standard sand, and water are mixed evenly to obtain concrete. The rust-resistant polycarboxylate water-reducing agent is then mixed and stirred evenly. The concrete is vibrated until the slurry is formed. A steel bar test rod is then inserted to perform a potential test and a net slurry fluidity test.

[0017] Optionally, the amount of the rust-resistant polycarboxylate water-reducing agent added is 0.5%-2% of the mass of the concrete.

[0018] The present invention provides a method for preparing a rust-resistant polycarboxylate water-reducing agent, which obtains a rust-resistant polycarboxylate water-reducing agent having both good rust-resistant and water-reducing properties. The long-chain alkyl group and the imidazoline ring in the structure of the rust-resistant polycarboxylate water-reducing agent play a double-layer protection role, effectively preventing chloride ions from damaging the passivation film on the surface of the steel bar. The alkoxy chain segment plays the role of air entrainment, dispersion, and stabilization. The introduction of the carboxyl group plays the role of water reduction, slowing setting, and preventing collapse. The benzene ring itself also has the advantages of a naphthalene-based water-reducing agent, enhances compatibility with other concrete admixtures, and improves the workability of concrete. Therefore, the rust-resistant polycarboxylate water-reducing agent of the present invention has good rust-resistant and water-reducing properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The above and other objects, features and advantages of the exemplary embodiments of the present invention will become readily understood by reading the detailed description below with reference to the accompanying drawings. In the accompanying drawings, several embodiments of the present invention are shown in an exemplary and non-limiting manner, and the same or corresponding reference numerals represent the same or corresponding parts, wherein:

[0020] Figure 1 Schematic diagram of the structural formula of the rust-resistant polycarboxylate water-reducing agent of the present invention;

[0021] Figure 2 This is the infrared spectrum of the rust-resistant polycarboxylate water-reducing agent of the present invention. DETAILED DESCRIPTION

[0022] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art.

[0023] It should be noted that, unless otherwise specified, the technical or scientific terms used in the present invention should have the ordinary meaning understood by those skilled in the art to which the present invention belongs. The terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, the elements defined by the phrase "comprising..." do not exclude the presence of other identical elements in the process, method, article, or device comprising the elements.

[0024] This embodiment provides a rust-resistant polycarboxylate water-reducing agent, the structural formula of which is:

[0025]

[0026] Among them, m is 50-80, n is 0-5, x is 1-6, y is 1-60, and z is 1-5.

[0027] For example, in the structural formula of the rust-resistant polycarboxylate water-reducing agent in this embodiment, m is 60-70, n is 0 or 1, x is 2-6, y is 6-18, and z is 1-3.

[0028] In the above structural formula, m is the degree of polymerization of the ethoxylated molecules. The number of ethoxylated molecules can ensure the solubility of the molecules in water. It is similar to the number of ethoxylated molecules in the common polycarboxylate water-reducing agent macromonomers on the market, which can ensure that the addition will not have a significant impact on the physical and chemical properties of concrete.

[0029] In the above structural formula, n is the degree of polymerization of the propoxylated molecules. The addition of propoxylated molecules can reduce the viscosity and shrinkage of the molecules and increase the fluidity of the molecules. Whether to add propoxylated molecules can be determined according to different needs and actual application conditions.

[0030] In the above structural formula, x is the degree of polymerization of the imidazoline derivative molecules. The addition of the imidazoline derivative molecules can effectively prevent the damage of chloride ions and the like on the passive film on the surface of the steel bar test bar.

[0031] In the above structural formula, y is the degree of polymerization of acrylic acid molecules. The addition of acrylic acid molecules can improve the effects of water reduction, retarding setting and slump retention.

[0032] In the above structural formula, z is the degree of polymerization of the benzene ring derivative molecules. The addition of the benzene ring derivative molecules combines the characteristics of the naphthalene series water reducer, enhances the compatibility with other concrete admixtures, and improves the workability of the concrete.

[0033] In one possible embodiment, the steps for preparing an imidazoline derivative include: mixing alkyl N-hydroxyethyl imidazoline and allyl chloride, adding the mixture to a reactor, adding sodium hydroxide, and sequentially carrying out a substitution reaction and a dehydration reaction at a reaction temperature to obtain an imidazoline derivative. The steps for preparing a p-isopropenylphenol polyalkoxy ether include: adding p-isopropenylphenol and potassium hydroxide to an autoclave, raising the temperature of the autoclave to the reaction temperature under high pressure, adding ethylene oxide and propylene oxide, and aging and degassing to obtain the p-isopropenylphenol polyalkoxy ether. The steps for preparing a rust-resistant polycarboxylate water reducer include: mixing p-isopropenylphenol polyalkoxy ether, an imidazoline derivative, and deionized water, adding the mixture to a reaction apparatus, heating and stirring to generate a polyether monomer, stirring the polyether monomer until dissolved, adding acrylic acid and an oxidant to the reaction apparatus, adding acrylic acid dropwise again after stirring, and finally adding a reducing agent, an initiator, and a chain transfer agent in sequence, followed by neutralization with a neutralizer to obtain the rust-resistant polycarboxylate water reducer.

[0034] The infrared spectrum of the rust-resistant polycarboxylate water-reducing agent in this embodiment is as follows: Figure 2 As shown, specifically, the infrared spectrum analysis is: at 3030cm -1 There are two weaker peaks nearby, which are the absorption peaks of benzene ring -CH; at 1700cm -1 The strong absorption peak near is the C=O characteristic absorption peak of carboxyl group; at 1513cm -1 Nearby and 1406cm -1 Nearby are the characteristic absorption peaks of imidazoline ring C=N and CN; at 1288cm -1 The stretching vibration absorption peak of the polyether long chain COC near 722cm -1 Nearby (CH2) n In-plane rocking vibration absorption peak at 1660 cm -1 The disappearance of the C=C peak indicates that the monomers have been polymerized. Therefore, it can be determined that the rust-resistant polycarboxylate water-reducing agent is synthesized and obtained by the preparation method of the rust-resistant polycarboxylate water-reducing agent of this embodiment.

[0035] In a possible embodiment, in the step of preparing the imidazoline derivative, the molar ratio of alkyl N-hydroxyethyl imidazoline, allyl chloride and sodium hydroxide is 1:1.1-1.3:1.1-1.3.

[0036] In a possible embodiment, in the step of preparing p-isopropenylphenol polyalkoxy ether, the molar ratio of p-isopropenylphenol, ethylene oxide and propylene oxide is 1:60-70:0-1.

[0037] In a possible embodiment, in the step of preparing the rust-resistant polycarboxylate water-reducing agent, the molar ratio of the imidazoline derivative, the p-isopropenylphenol polyalkoxy ether, and the acrylic acid is 2:1:6.

[0038] In a possible embodiment, in the step of preparing the rust-resistant polycarboxylate water-reducing agent, the mass ratio of the initiator, the chain transfer agent, the oxidant, and the reducing agent is 0.5-3:0.5-0.8:0.3-3:0.1-0.5.

[0039] In a possible embodiment, in the step of preparing the rust-resistant polycarboxylate water-reducing agent, the masses of the initiator, chain transfer agent, oxidant, and reducing agent are 0.3%-0.7%, 0.5%-0.8%, 0.3%-2%, and 0.1%-0.5% of the total mass of the polyether monomer, respectively.

[0040] In a possible embodiment, in the step of preparing the rust-resistant polycarboxylate water-reducing agent, the initiator is any one or more of ammonium persulfate, hydrogen peroxide, or L-ascorbic acid; the chain transfer agent is mercaptopropionic acid; the oxidant is hydrogen peroxide; the reducing agent is vitamin C and ferrous sulfate, and the mass ratio of vitamin C to ferrous sulfate is 1:1; and the neutralizing agent is 30% liquid caustic soda.

[0041] This embodiment also provides an application of a rust-resistant polycarboxylate water-reducing agent. Reference cement, standard sand, and water are mixed evenly to obtain concrete. The rust-resistant polycarboxylate water-reducing agent is then mixed and stirred evenly. The concrete is vibrated until the slurry is formed, and then a steel bar test rod is inserted to perform a potential test and a net slurry fluidity test.

[0042] In a possible embodiment, the amount of the rust-resistant polycarboxylate water-reducing agent added is 0.5%-2% of the mass of the concrete.

[0043] Example 1

[0044] (1) 1 mol (350.59 g) of alkyl N-hydroxyethyl imidazoline and 1.2 mol (91.82 g) of allyl chloride were mixed and added to a reaction kettle. 1.1 mol (44 g) of NaOH was added as a catalyst. Substitution and dehydration reactions were carried out at 40°C to obtain imidazoline derivatives.

[0045] (2) 1 mol (134.18 g) of p-isopropenylphenol and 0.13 g of potassium hydroxide were placed in an autoclave. The temperature was raised to 125-130° C. under a high pressure of 0.3-0.5 MPa. 60 mol (2643 g) of ethylene oxide was added. After aging and degassing, p-isopropenylphenol polyalkoxy ether was obtained.

[0046] (3) Take the total mass of 2 mol (781.32 g) of imidazoline derivative and 1 mol (2777.36 g) of p-isopropenylphenol polyalkoxy ether and mix them with deionized water in a mass ratio of 1:1, add them to the reaction device, heat to 25 ° C and stir until the polyether monomer is fully dissolved; first add 1 mol (72.06 g) of acrylic acid and 11.97 g of oxidant to the reaction device, stir thoroughly for 30 minutes, start to dropwise add the remaining 5 mol (360.3 g) of acrylic acid, and then add 11.97 g of initiator, 19.96 g of chain transfer agent, and 4 g of reducing agent in sequence, and then neutralize with 30% liquid alkali to obtain a rust-resistant polycarboxylic acid water reducer.

[0047] (4) The prepared saturated Ca(OH)2 solution containing 1.15% NaCl was poured into three ground-mouth glass bottles. 0.5% of the above-mentioned rust-resistant polycarboxylate water reducer was added. A steel bar test rod was placed in the solution and completely immersed in the solution. The bottle caps were tightly closed. The natural potential of the steel bar test rod was measured using a voltmeter at 1 day, 3 days, 5 days, and 7 days, and compared with a blank. The test results are summarized in Table 1. The obtained rust-resistant polycarboxylate water reducer was added to concrete and stirred evenly. The net paste fluidity test was performed. The amount of rust-resistant polycarboxylate water reducer was 0.5% of the concrete mass. The test results are summarized in Table 5.

[0048] Example 2

[0049] (1) 1 mol (350.59 g) of alkyl N-hydroxyethyl imidazoline and 1.1 mol (84.17 g) of allyl chloride were mixed and added to a reaction kettle. 1.1 mol (44 g) of NaOH was added as a catalyst. Substitution and dehydration reactions were carried out at 40°C to obtain imidazoline derivatives.

[0050] (2) 1 mol (134.18 g) of p-isopropenylphenol and 0.13 g of potassium hydroxide were placed in an autoclave. The temperature was raised to 125-130° C. under a high pressure of 0.3-0.5 MPa. 63 mol (2775.15 g) of ethylene oxide and 1 mol (58.08 g) of propylene oxide were added. After aging and degassing, p-isopropenylphenol polyalkoxy ether was obtained.

[0051] (3) Take the total mass of 3 mol (1171.98 g) of imidazoline derivative and 1.5 mol (4451.4 g) of p-isopropenylphenol polyalkoxy ether and mix them with deionized water in a mass ratio of 1:1, add them to the reaction device, heat to 25 ° C and stir until the polyether monomer is fully dissolved; first add part of 1.5 mol (108.09 g) of acrylic acid and 50.18 g of oxidant to the reaction device, stir well for 30 minutes, start to dropwise add the remaining 6.5 mol (540.45 g) of acrylic acid, and add 28.22 g of initiator, 37.63 g of chain transfer agent, and 15.05 g of reducing agent in sequence, and then neutralize with 30% liquid alkali to obtain a rust-resistant polycarboxylic acid water reducer.

[0052] (4) The prepared saturated Ca(OH)2 solution containing 1.15% NaCl was poured into three ground-mouth glass bottles. 1% of the above-mentioned rust-resistant polycarboxylate water reducer was added, and a steel bar test rod was placed in the solution. The entire rod was immersed in the solution, and the bottle caps were tightly closed. The natural potential of the steel bar test rod was measured using a voltmeter at 1 day, 3 days, 5 days, and 7 days, and compared with a blank. The test results are summarized in Table 2. The obtained rust-resistant polycarboxylate water reducer was added to concrete and stirred evenly. The net paste fluidity test was performed. The amount of rust-resistant polycarboxylate water reducer was 1% of the concrete mass. The test results are summarized in Table 5.

[0053] Example 3

[0054] (1) 1 mol (350.59 g) of alkyl N-hydroxyethyl imidazoline and 1.3 mol (99.48 g) of allyl chloride were mixed and added to a reaction kettle. 1.2 mol (48 g) of NaOH was added as a catalyst. Substitution and dehydration reactions were carried out at 40°C to obtain imidazoline derivatives.

[0055] (2) 1 mol (134.18 g) of p-isopropenylphenol and 0.13 g of potassium hydroxide were placed in an autoclave. The temperature was raised to 125-130° C. under a high pressure of 0.3-0.5 MPa. 66 mol (2907.3 g) of ethylene oxide and 1 mol (58.08 g) of propylene oxide were added. After aging and degassing, p-isopropenylphenol polyalkoxy ether was obtained.

[0056] (3) Take the total mass of 1.67 mol (652.4 g) of imidazoline derivative and 0.83 mol (2572.8 g) of p-isopropenylphenol polyalkoxy ether and mix them with deionized water in a mass ratio of 1:1, add them to the reaction device, heat to 25 ° C and stir until the polyether monomer is fully dissolved; first add part of 2 mol (144.12 g) of acrylic acid and 50.19 g of oxidant to the reaction device, stir well for 30 minutes, start to dropwise add the remaining 3 mol (216.18 g) of acrylic acid, and add 19.72 g of initiator, 25.1 g of chain transfer agent, and 12.91 g of reducing agent in sequence, and then neutralize with 30% liquid alkali to obtain a rust-resistant polycarboxylic acid water reducer.

[0057] (4) The prepared saturated Ca(OH)2 solution containing 1.15% NaCl was poured into three ground-mouth glass bottles. 1.5% of the above-mentioned rust-resistant polycarboxylate water reducer was added. A steel bar test rod was placed in the solution and completely immersed in the solution. The bottle caps were tightly closed. A voltmeter was used to measure the potential of the steel bar test rod at 1 day, 3 days, 5 days, and 7 days, and compared with a blank. The test results are summarized in Table 3. The obtained rust-resistant polycarboxylate water reducer was added to concrete and stirred evenly. The net paste fluidity test was performed. The amount of rust-resistant polycarboxylate water reducer was 1.5% of the concrete mass. The test results are summarized in Table 5.

[0058] Example 4

[0059] (1) 1 mol (350.59 g) of alkyl N-hydroxyethyl imidazoline and 1.2 mol (91.82 g) of allyl chloride were mixed and added to a reaction kettle. 1.3 mol (52 g) of NaOH was added as a catalyst. Substitution and dehydration reactions were carried out at 40°C to obtain imidazoline derivatives.

[0060] (2) 1 mol (134.18 g) of p-isopropenylphenol and 0.13 g of potassium hydroxide were placed in an autoclave. The temperature was raised to 125-130° C. under a high pressure of 0.3-0.5 MPa. 70 mol (3083.5 g) of ethylene oxide and 1 mol (58.08 g) of propylene oxide were added. After aging and degassing, p-isopropenylphenol polyalkoxy ether was obtained.

[0061] (3) Take the total mass of 2 mol (781.32 g) of imidazoline derivative and 1 mol (3275.97 g) of p-isopropenylphenol polyalkoxy ether and mix them with deionized water in a mass ratio of 1:1, add them to the reaction device, heat to 25 ° C and stir until the polyether monomer is fully dissolved; first add part of 2.5 mol (180.15 g) of acrylic acid and 89.79 g of oxidant to the reaction device, stir well for 30 minutes, start to dropwise add the remaining 3.5 mol (252.21 g) of acrylic acid, and add 31.43 g of initiator, 35.92 g of chain transfer agent, and 22.45 g of reducing agent in sequence, and then neutralize with 30% liquid alkali to obtain a rust-resistant polycarboxylic acid water reducer.

[0062] (4) The prepared saturated Ca(OH)2 solution containing 1.15% NaCl was poured into three ground-mouth glass bottles. 2% of the above-mentioned rust-resistant polycarboxylate water reducer was added, and a steel bar test rod was placed in it. The entire rod was immersed in the solution and the bottle caps were tightly closed. The natural potential of the steel bar test rod was measured using a voltmeter at 1 day, 3 days, 5 days, and 7 days, and compared with a blank. The test results are summarized in Table 4. The obtained rust-resistant polycarboxylate water reducer was added to concrete and stirred evenly. The net paste fluidity test was performed. The amount of rust-resistant polycarboxylate water reducer was 2% of the concrete mass. The test results are summarized in Table 5.

[0063] This example provides a performance test of a rust-resistant polycarboxylate water-reducing agent:

[0064] (1) The salt water immersion test was evaluated in accordance with the industry standard YB / T9231-2009 "Technical Specifications for the Application of Rebar Rust Inhibitors". The steel bars selected for the experiment were polished step by step with sandpaper. After being processed, they were placed in a container. The prepared corrosion solution was poured into the container to a height of about 40 mm. Two steel bars were placed in each container and all immersed in the solution. The bottle cap was tightly closed until the potential was measured and the cap was opened. During the measurement, one end of the steel bar was exposed to the liquid surface and touched to the positive terminal of the voltmeter, and the negative terminal was connected to the calomel electrode. The potential test of each group of steel bar test bars was measured at 1 day, 3 days, 5 days, and 7 days, and the surface of the steel bar test bars was observed to see if there was any rust.

[0065] (2) Paste fluidity test: The test is conducted in accordance with GB / T 8077-2012 "Test method for homogeneity of concrete admixtures". A certain amount of cement, admixture, and water are added to a cement paste mixer and stirred. The mixed paste is poured into a truncated cone mold. The truncated cone mold is lifted and the maximum diameter of the cement paste flowing freely on a glass surface is measured.

[0066] Table 1 Potential test results of Example 1

[0067] Time (day / d) blank / mv Rust-inhibiting polycarboxylate water reducer / mv 1d -227 -161 3d -242 -167 5d -255 -180 7d -262 -181

[0068] Table 2 Potential test results of Example 2

[0069] Time (day / d) blank / mv Rust-inhibiting polycarboxylate water reducer / mv 1d -227 -141 3d -242 -152 5d -255 -160 7d -262 -161

[0070] Table 3 Potential test results of Example 3

[0071]

[0072]

[0073] Table 4 Potential test results of Example 4

[0074] Time (day / d) blank / mv Rust-inhibiting polycarboxylate water reducer / mv 1d -227 -103 3d -242 -120 5d -255 -127 7d -262 -129

[0075] Combined with the potential test results of Examples 1-4 in Tables 1 to 4, the potential test results of the steel bar after adding the rust-resistant polycarboxylate water-reducing agent were significantly reduced compared with the blank experiment. The N of the imidazoline ring in the structure of the rust-resistant polycarboxylate water-reducing agent in this embodiment can form a coordination bond with the metal Fe to form a protective film, and the presence of long-chain alkyl groups in the rust-resistant polycarboxylate water-reducing agent molecules forms another oil film. The double-layer protection effectively avoids the damage of chloride ions and the like to the passivation film on the surface of the steel bar, so the potential test results are reduced, which plays a role in rust prevention. In addition, comparing the data in Tables 1 to 4, it can be seen that as the amount of rust-resistant polycarboxylate water-reducing agent added increases, the potential test results also gradually decrease, that is, the increase in the amount of rust-resistant polycarboxylate water-reducing agent is conducive to increasing the rust prevention effect.

[0076] Table 5 Test results of the fluidity of the slurry in Examples 1-4

[0077] Example Initial fluidity / mm 60min fluidity / mm Example 1 245 225 Example 2 243 223 Example 3 250 235 Example 4 246 232

[0078] The data in Table 5 show that after adding the rust-resistant polycarboxylate water-reducing agent of this embodiment, the initial slurry fluidity remains above 240 mm, and the slurry fluidity after 60 minutes remains above 220 mm, indicating that the rust-resistant polycarboxylate water-reducing agent of this embodiment has good dispersibility.

[0079] As shown in Tables 1 to 5, the rust-resistant polycarboxylate water-reducing agent prepared in this embodiment has good rust-resistant and water-reducing properties.

[0080] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A rust-resistant polycarboxylate water-reducing agent, characterized in that: The structural formula of rust-resistant polycarboxylate water reducer is: Among them, m is 50-80, n is 0-5, x is 1-6, y is 1-60, and z is 1-5.

2. A method for preparing the rust-resistant polycarboxylate water-reducing agent according to claim 1, characterized in that: include: The preparation steps of the imidazoline derivative are as follows: alkyl N-hydroxyethyl imidazoline and allyl chloride are mixed and added to a reaction kettle, and sodium hydroxide is added, and substitution reaction and dehydration reaction are carried out in sequence at the reaction temperature to obtain the imidazoline derivative; The preparation steps of p-isopropenylphenol polyalkoxy ether are as follows: p-isopropenylphenol and potassium hydroxide are placed in an autoclave, the temperature of the autoclave is raised to the reaction temperature under high pressure, ethylene oxide and propylene oxide are added, and p-isopropenylphenol polyalkoxy ether is obtained after aging and degassing. The preparation steps of the rust-resistant polycarboxylate water reducer are as follows: p-isopropenylphenol polyalkoxy ether, imidazoline derivative and deionized water are mixed and added to a reaction device, heated and stirred to generate a polyether monomer, and then the polyether monomer is stirred until dissolved, and then acrylic acid and an oxidant are added to the reaction device. After stirring, acrylic acid is added dropwise again, and finally a reducing agent, an initiator and a chain transfer agent are added in sequence, and then neutralized with a neutralizer to obtain the rust-resistant polycarboxylate water reducer.

3. The method for preparing the rust-resistant polycarboxylate water-reducing agent according to claim 2, wherein: In the step of preparing the imidazoline derivative, the molar ratio of alkyl N-hydroxyethyl imidazoline, allyl chloride and sodium hydroxide is 1:1.1-1.3:1.1-1.

3.

4. The method for preparing the rust-resistant polycarboxylate water-reducing agent according to claim 2, wherein: In the preparation step of p-isopropenylphenol polyalkoxy ether, the molar ratio of p-isopropenylphenol, ethylene oxide and propylene oxide is 1:60-70:0-1.

5. The method for preparing the rust-resistant polycarboxylate water-reducing agent according to claim 2, wherein: In the preparation step of the rust-resistant polycarboxylate water-reducing agent, the molar ratio of the imidazoline derivative, the p-isopropenylphenol polyalkoxy ether and the acrylic acid is 2:1:

6.

6. The method for preparing the rust-resistant polycarboxylate water-reducing agent according to claim 2, wherein: In the preparation step of the rust-resistant polycarboxylate water-reducing agent, the mass ratio of the initiator, the chain transfer agent, the oxidant, and the reducing agent is 0.5-3:0.5-0.8:0.3-3:0.1-0.

5.

7. The method for preparing the rust-resistant polycarboxylate water-reducing agent according to claim 2, wherein: In the preparation step of the rust-resistant polycarboxylate water-reducing agent, the masses of the initiator, chain transfer agent, oxidant and reducing agent are 0.3%-0.7%, 0.5%-0.8%, 0.3%-2% and 0.1%-0.5% of the total mass of the polyether monomer respectively.

8. The method for preparing the rust-resistant polycarboxylate water-reducing agent according to claim 2, wherein: In the preparation steps of the rust-resistant polycarboxylate water-reducing agent, The initiator is any one or more of ammonium persulfate, hydrogen peroxide or L-ascorbic acid; The chain transfer agent is mercaptopropionic acid; The oxidizing agent is hydrogen peroxide; The reducing agents are vitamin C and ferrous sulfate, and the mass ratio of vitamin C to ferrous sulfate is 1:1; The neutralizing agent is 30% liquid alkali.

9. A use of the rust-resistant polycarboxylate water-reducing agent according to claim 1, characterized in that: Mix the reference cement, standard sand and water evenly to obtain concrete, then add the rust-resistant polycarboxylate water-reducing agent and mix evenly, vibrate until the slurry is reversed, and then insert the steel bar test rod to conduct potential test and net slurry fluidity test.

10. The use of the rust-resistant polycarboxylate water-reducing agent according to claim 9, characterized in that: The addition amount of rust-resistant polycarboxylate water-reducing agent is 0.5%-2% of the concrete mass.

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