High water-reducing rate pure water-reducing water-reducing agent and preparation method thereof

Abstract

The application discloses a high water-reducing rate pure water-reducing type water-reducing agent and a preparation method thereof, and belongs to the field of concrete admixtures. The water-reducing agent comprises the following components in parts by weight: 65-80 parts of ethylene glycol monovinyl polyethylene glycol ether, 10-20 parts of acrylic acid, 2-6 parts of 2-acrylamide-2-methylpropane sulfonic acid, 2-3 parts of vinyl phosphonic acid, 0.1-0.5 parts of mercaptoacetic acid, 0.8-1.5 parts of an oxidizing agent, 0.5-0.7 parts of vitamin C and 115-135 parts of deionized water. The application further discloses a preparation method of the water-reducing agent. The water-reducing agent has outstanding comprehensive advantages in water-reducing rate, mud resistance, low viscosity and workability maintenance, can meet the strict requirements of super-high-strength, low water-binder ratio concrete in major projects such as high-speed railways, sea-crossing bridges and super-high-rise buildings, and has definite engineering practical value and popularization prospect.

Description

Technical Field

[0001] This invention belongs to the field of concrete admixtures, and more specifically, relates to a high water-reducing rate pure water-reducing agent and its preparation method. Background Technology

[0002] Polycarboxylate superplasticizers, as third-generation high-performance superplasticizers, are widely used in high-speed railways, cross-sea bridges, and super high-rise buildings due to their unique comb-like molecular structure. The main chain contains adsorption groups such as carboxylate groups, and the side chains are long polyether chains, which provide steric hindrance, effectively dispersing cement particles. In recent years, with the continuous improvement of concrete grades and the reduction of water-cement ratios to below 0.25 or even lower, higher requirements have been placed on the water reduction rate of superplasticizers. Existing polycarboxylate superplasticizers are mainly divided into slump-retaining and water-reducing types. Traditional high-water-reducing superplasticizers typically use HPEG or TPEG macromonomers with molecular weights generally between 2400 and 3000. The water reduction rate is improved by increasing the side chain density or adjusting the acid-ether ratio, but many technical bottlenecks still exist under low water-cement ratio conditions. In terms of water reduction rate, the water reduction rate of water-reducing agents synthesized by conventional processes is usually only 25% to 35%. This level is difficult to meet the dual requirements of low viscosity and high fluidity of concrete at extremely low water-cement ratios, thus limiting the preparation of ultra-high strength concrete.

[0003] In terms of adsorption behavior, traditional polycarboxylate superplasticizers mainly adsorb onto the surface of cement particles through carboxylate groups on the main chain. However, in sand and gravel aggregates with high mud content, clay minerals preferentially adsorb the polyether side chains of the superplasticizer through intercalation, resulting in a large amount of ineffective consumption of the superplasticizer, a sharp drop in effective adsorption, and a significant deterioration in water reduction effect.

[0004] In addition, there is an inherent contradiction in molecular weight design: in order to improve the water reduction rate, it is usually necessary to increase the molecular weight of the water-reducing agent, but an excessively high molecular weight will significantly increase the viscosity of concrete, resulting in high pumping resistance and construction difficulties, making it difficult to achieve both high water reduction rate and good construction performance.

[0005] Therefore, there is an urgent need to develop a pure water-reducing agent that has both extremely high water reduction rate and can maintain low viscosity at low water-cement ratio, and is not sensitive to clay. Summary of the Invention

[0006] One of the objectives of this invention is to provide a high water reduction rate pure water-reducing agent that exhibits outstanding comprehensive advantages in terms of water reduction rate, mud resistance, low viscosity, and workability retention. It can simultaneously solve the problems of insufficient water reduction rate under low water-cement ratio conditions, ineffective consumption of water-reducing agent in high mud content environments, and the inherent contradiction between high water reduction rate and high viscosity.

[0007] The second objective of this invention is to provide a method for preparing the high water reduction rate pure water-reducing agent.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The first aspect of this invention provides a high water-reducing rate pure water-reducing agent, which comprises the following components in parts by weight: 65-80 parts of ethylene glycol monovinyl polyethylene glycol ether, 10-20 parts of acrylic acid, 2-6 parts of 2-acrylamide-2-methylpropanesulfonic acid, 2-3 parts of vinylphosphonic acid, 0.1-0.5 parts of mercaptoacetic acid, 0.8-1.5 parts of oxidant, 0.5-0.7 parts of vitamin C, and 115-135 parts of deionized water.

[0009] In some embodiments of the present invention, the water-reducing agent comprises the following components in parts by weight: The product contains the following components in parts by weight: 72 parts ethylene glycol monovinyl polyethylene glycol ether, 15 parts acrylic acid, 4 parts 2-acrylamide-2-methylpropanesulfonic acid, 2.5 parts vinylphosphonic acid, 0.3 parts mercaptoacetic acid, 1.2 parts oxidant, 0.6 parts vitamin C, and 125 parts deionized water. Alternatively, the water-reducing agent may contain the following components in parts by weight: 65 parts ethylene glycol monovinyl polyethylene glycol ether, 10 parts acrylic acid, 2 parts 2-acrylamide-2-methylpropanesulfonic acid, 2 parts vinylphosphonic acid, 0.1 parts mercaptoacetic acid, 0.8 parts oxidant, 0.5 parts vitamin C, and 115 parts deionized water. Alternatively, the water-reducing agent may contain the following components in parts by weight: 80 parts ethylene glycol monovinyl polyethylene glycol ether, 20 parts acrylic acid, 6 parts 2-acrylamide-2-methylpropanesulfonic acid, 3 parts vinylphosphonic acid, 0.5 parts mercaptoacetic acid, 1.5 parts oxidant, 0.7 parts vitamin C, and 135 parts deionized water.

[0010] In some embodiments of the present invention, the oxidant includes hydrogen peroxide.

[0011] In some embodiments of the present invention, the molecular weight of the ethylene glycol monovinyl polyethylene glycol ether is 4000-5000.

[0012] In this invention, a pure water-reducing agent refers to a water-reducing agent that is substantially composed of water-reducing components and does not contain intentionally added retarders and / or air-entraining agents.

[0013] A second aspect of the present invention provides a method for preparing the above-mentioned high water-reducing rate pure water-reducing agent, which includes the following steps: S1. Prepare the base solution, drop solution A, and drop solution B separately; Ethylene glycol monovinyl polyethylene glycol ether was placed in a reaction vessel, and water was added and stirred until homogeneous to obtain the bottom liquid. Acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid, vinylphosphonic acid, and mercaptoacetic acid were dissolved in water to prepare dropwise solution A. Vitamin C was dissolved in water to prepare a 2 wt% solution, which was then used to prepare dropwise solution B. S2. Reaction: Under a protective atmosphere, an oxidant is added to the liquid at the bottom of the reaction vessel, and then the temperature is raised while dropping solution A and dropping solution B are added dropwise; after the addition is complete, the reaction is maintained at the temperature. S3. Post-treatment: After the reaction is complete, the temperature is lowered, and the pH of the system is adjusted from weakly acidic to neutral to obtain a high water-reducing rate pure water-reducing agent. In some embodiments of the present invention, ethylene glycol monovinyl polyethylene glycol ether is placed in a reaction vessel, and 45-50 parts of water are added and stirred evenly to obtain a base liquid; preferably, the mixture is stirred evenly at 30-40°C.

[0014] In some embodiments of the present invention, acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid, vinylphosphonic acid, and mercaptoacetic acid are dissolved in 45-50 parts of water to prepare dropwise solution A.

[0015] Preferably, the dripping time is 2 to 4 hours.

[0016] In some embodiments of the present invention, in step S3, the protective atmosphere gas includes nitrogen.

[0017] In some embodiments of the present invention, in step S3, the temperature is raised to 30~60°C, and then dropping solution A and dropping solution B are added dropwise simultaneously.

[0018] In some embodiments of the present invention, the heat preservation reaction is carried out for 1 to 2 hours.

[0019] In some embodiments of the present invention, after the reaction is complete, the temperature is lowered and an alkaline solution is added to adjust the pH value.

[0020] Preferably, an alkaline solution is added to adjust the pH value to 6-7.

[0021] Preferably, the alkaline solution comprises a sodium hydroxide solution with a concentration of 30wt%-35wt%.

[0022] Compared with the prior art, the present invention has the following beneficial effects: This invention is scientifically designed and ingeniously conceived, capable of simultaneously resolving the issues of insufficient water reduction rate under low water-cement ratio conditions, ineffective consumption of water-reducing agents in high mud content environments, and the inherent contradiction between high water reduction rate and high viscosity. It exhibits outstanding comprehensive advantages in terms of water reduction rate, mud resistance, low viscosity, and workability retention, and can meet the stringent requirements for ultra-high strength, low water-cement ratio concrete in major projects such as high-speed railways, cross-sea bridges, and super high-rise buildings. It has clear engineering practical value and promising prospects for promotion.

[0023] Firstly, regarding water-reducing performance, the pure water-reducing polycarboxylate superplasticizer of this invention can achieve a cement paste fluidity of over 320 mm at a dosage of only 0.3% (converted to solids). Its measured water reduction rate in concrete reaches 41.35%~42.17%, far exceeding the typical 25%~35% water reduction rate of traditional polycarboxylate superplasticizers, and significantly surpassing the GB8076 standard requirement of no less than 25% for high-performance water-reducing agents. This superior water-reducing capacity allows the water-cement ratio to be stably controlled below 0.25, even as low as 0.20, thus providing crucial technical support for the preparation of ultra-high-strength concrete.

[0024] Secondly, in terms of resistance to clay interference, even under harsh conditions where the mud content of sand and gravel aggregate is as high as 7%, the water-reducing agent of this invention can still maintain minimal loss of concrete spread over time, and the construction performance does not show significant deterioration. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0026] Example 1 This embodiment discloses the composition and preparation method of the high water reduction rate pure water-reducing agent of the present invention.

[0027] The water-reducing agent of this embodiment contains the following components in parts by weight: 72 parts of ethylene glycol monovinyl polyethylene glycol ether with a molecular weight of 4500, 15 parts of acrylic acid, 4 parts of 2-acrylamide-2-methylpropanesulfonic acid, 2.5 parts of vinylphosphonic acid, 0.3 parts of mercaptoacetic acid, 1.2 parts of hydrogen peroxide, 0.6 parts of vitamin C, and 125 parts of deionized water.

[0028] Its preparation method is as follows: Step (1) Prepare the base solution, add solution A and add solution B respectively.

[0029] The preparation method of the drop solution B is as follows: dissolve vitamin C in water to prepare a solution with a concentration of 2wt%, which is the drop solution B; The preparation method of the base solution is as follows: Place ethylene glycol monovinyl polyethylene glycol ether in a reaction vessel, add 47.5 parts of water, stir evenly at 30-40℃ to obtain the base solution; The preparation method of the dropping solution A is as follows: dissolve acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid, vinylphosphonic acid, and mercaptoacetic acid in 47.5 parts of water to obtain dropping solution A.

[0030] Step (2) reaction Under a nitrogen protective atmosphere, hydrogen peroxide, an oxidant, was added to the liquid at the bottom of the reactor. The temperature was then raised to 45°C. While stirring, droplets A and B were added dropwise at the same time, with the addition time controlled at 2.5 hours. After the addition was completed, the reaction was kept at this temperature for 1.5 hours. Post-processing in step (3) After the reaction, the temperature is lowered to below 30°C, and a 35wt% sodium hydroxide solution is added to adjust the pH value to 6-7, thus obtaining a high water reduction rate pure water-reducing agent.

[0031] Example 2 This embodiment discloses the composition and preparation method of the high water reduction rate pure water-reducing agent of the present invention.

[0032] The water-reducing agent of this embodiment contains the following components in parts by weight: 65 parts of ethylene glycol monovinyl polyethylene glycol ether with a molecular weight of 4000, 10 parts of acrylic acid, 2 parts of 2-acrylamide-2-methylpropanesulfonic acid, 2 parts of vinylphosphonic acid, 0.1 parts of mercaptoacetic acid, 0.8 parts of hydrogen peroxide, 0.5 parts of vitamin C, and 115 parts of deionized water.

[0033] Its preparation method is as follows: Step (1) Prepare the base solution, add solution A and add solution B respectively.

[0034] The preparation method of the drop solution B is as follows: dissolve vitamin C in water to prepare a solution with a concentration of 2wt%, which is the drop solution B; The preparation method of the base solution is as follows: Place ethylene glycol monovinyl polyethylene glycol ether in a reaction vessel, add 45 parts water, stir evenly at 30-40℃ to obtain the base solution; The preparation method of the drop solution A is as follows: dissolve acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid, vinylphosphonic acid, and mercaptoacetic acid in 45 parts of water to obtain drop solution A; the amount of water added is the amount of water remaining after preparing drop solution B and the base solution.

[0035] Step (2) reaction Under a nitrogen protective atmosphere, hydrogen peroxide, an oxidant, is added to the liquid at the bottom of the reactor. The temperature is then raised to 45°C. While stirring, droplets A and B are added dropwise at the same time, with the addition time controlled at 2 hours. After the addition is completed, the reaction is kept at the temperature for 1.5 hours. Post-processing in step (3) After the reaction, the temperature is lowered to below 30°C, and a 30wt% sodium hydroxide solution is added to adjust the pH value to 6-7, thus obtaining a high water reduction rate pure water-reducing agent.

[0036] Example 3 This embodiment discloses the composition and preparation method of the high water reduction rate pure water-reducing agent of the present invention.

[0037] The water-reducing agent of this embodiment contains the following components in parts by weight: 80 parts of ethylene glycol monovinyl polyethylene glycol ether with a molecular weight of 5000, 20 parts of acrylic acid, 6 parts of 2-acrylamide-2-methylpropanesulfonic acid, 3 parts of vinylphosphonic acid, 0.5 parts of mercaptoacetic acid, 1.5 parts of hydrogen peroxide, 0.7 parts of vitamin C, and 135 parts of deionized water.

[0038] Its preparation method is as follows: Step (1) Prepare the base solution, add solution A and add solution B respectively.

[0039] The preparation method of the drop solution B is as follows: dissolve vitamin C in water to prepare a solution with a concentration of 2wt%, which is the drop solution B; The preparation method of the base solution is as follows: Place ethylene glycol monovinyl polyethylene glycol ether in a reaction vessel, add 50 parts water, stir evenly at 30-40℃ to obtain the base solution; The preparation method of the drop solution A is as follows: dissolve acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid, vinylphosphonic acid, and mercaptoacetic acid in 50 parts of water to obtain drop solution A; the amount of water added is the amount of water remaining after preparing drop solution B and the base solution.

[0040] Step (2) reaction Under a nitrogen protective atmosphere, hydrogen peroxide, an oxidant, is added to the liquid at the bottom of the reactor. The temperature is then raised to 45°C. While stirring, droplets A and B are added dropwise at the same time, with the addition time controlled at 4 hours. After the addition is completed, the reaction is kept at the temperature for 1.5 hours. Post-processing in step (3) After the reaction, the temperature is lowered to below 30°C, and a 35wt% sodium hydroxide solution is added to adjust the pH value to 6-7, thus obtaining a high water reduction rate pure water-reducing agent.

[0041] Comparative Example 1 This comparative example is identical to Example 1 except that it does not contain vinylphosphonic acid, and all other conditions are the same.

[0042] Comparative Example 2 This comparative example differs from Example 1 in that it does not contain 2-acrylamide-2-methylpropanesulfonic acid and vinylphosphonic acid, while all other conditions are the same.

[0043] Comparative Example 3 This comparative example is identical to Example 1 except that it does not contain 2-acrylamide-2-methylpropanesulfonic acid.

[0044] Comparative Example 4 Compared with Example 1, this comparative example replaces vinylphosphonic acid with diethyl vinylphosphonate, while the remaining conditions are the same.

[0045] Comparative Example 5 Compared with Example 1, this comparative example replaces 2-acrylamide-2-methylpropanesulfonic acid with sodium allyl sulfonate, while the remaining conditions are the same.

[0046] Experimental Example 1 This experiment tested the performance of the water-reducing agents prepared in Examples 1-3 and Comparative Example 1. The specific test items and methods are as follows: 1. Flowability of cement paste The test was conducted in accordance with GB / T 8077-2012 "Test Method for Homogeneity of Concrete Admixtures".

[0047] 2. Concrete water reduction rate and pouring time According to GB 8076-2008 standard, the mix proportion of C80 concrete (cementing material dosage 550 kg / m³) is as follows: 3 The test was conducted at a water-to-binder ratio of 0.22.

[0048] 3. Loss of spread over time under manufactured sand conditions with 7% mud content. Using manufactured sand with a mud content of 7%, the spread loss of concrete mixture after standing for 60 minutes was tested.

[0049] The results of the above tests are shown in Table 1.

[0050] Table 1. Performance test results of water-reducing agents in Examples 1-3 and Comparative Examples 1-5

[0051] As can be seen from Table 1, the fluidity of the neat paste and the water reduction rate of the concrete in Examples 1-3 of this application are significantly higher than those in Comparative Examples 1-5, while the concrete pouring time and the loss of spread (60 min) at a mud content of 7% are significantly lower than those in Comparative Examples 1-5. This indicates that the water-reducing agent of the present invention has better dispersibility, water reduction effect and workability, and is suitable for more stringent construction conditions.

[0052] The above description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the concept described herein through the above teachings or related technologies or knowledge. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A high water-reducing rate pure water-reducing agent, characterized in that, The components comprise the following parts by mass: 65-80 parts of ethylene glycol monovinyl polyethylene glycol ether, 10-20 parts of acrylic acid, 2-6 parts of 2-acrylamide-2-methylpropanesulfonic acid, 2-3 parts of vinylphosphonic acid, 0.1-0.5 parts of mercaptoacetic acid, 0.8-1.5 parts of oxidant, 0.5-0.7 parts of vitamin C, and 115-135 parts of deionized water.

2. The high water-reducing rate pure water-reducing agent according to claim 1, characterized in that, The product contains the following components in parts by weight: 72 parts ethylene glycol monovinyl polyethylene glycol ether, 15 parts acrylic acid, 4 parts 2-acrylamide-2-methylpropanesulfonic acid, 2.5 parts vinylphosphonic acid, 0.3 parts mercaptoacetic acid, 1.2 parts oxidant, 0.6 parts vitamin C, and 125 parts deionized water. Alternatively, the water-reducing agent may contain the following components in parts by weight: 65 parts ethylene glycol monovinyl polyethylene glycol ether, 10 parts acrylic acid, 2 parts 2-acrylamide-2-methylpropanesulfonic acid, 2 parts vinylphosphonic acid, 0.1 parts mercaptoacetic acid, 0.8 parts oxidant, 0.5 parts vitamin C, and 115 parts deionized water. Alternatively, the water-reducing agent may contain the following components in parts by weight: 80 parts ethylene glycol monovinyl polyethylene glycol ether, 20 parts acrylic acid, 6 parts 2-acrylamide-2-methylpropanesulfonic acid, 3 parts vinylphosphonic acid, 0.5 parts mercaptoacetic acid, 1.5 parts oxidant, 0.7 parts vitamin C, and 135 parts deionized water.

3. A high water-reducing rate pure water-reducing agent according to claim 1 or 2, characterized in that, The oxidizing agent includes hydrogen peroxide.

4. A high water-reducing rate pure water-reducing agent according to claim 1 or 2, characterized in that, The molecular weight of the ethylene glycol monovinyl polyethylene glycol ether is 4000~5000.

5. A high water-reducing rate pure water-reducing agent according to any one of claims 1 to 4, characterized in that, A method for preparing a high water-reducing rate pure water-reducing agent includes the following steps: S1. Prepare the base solution, drop solution A, and drop solution B separately; Ethylene glycol monovinyl polyethylene glycol ether was placed in a reaction vessel, and water was added and stirred until homogeneous to obtain the bottom liquid. Acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid, vinylphosphonic acid, and mercaptoacetic acid were dissolved in water to prepare dropwise solution A. Vitamin C was dissolved in water to prepare a 2 wt% solution, which was then used to prepare dropwise solution B. S2. Reaction: Under a protective atmosphere, an oxidant is added to the liquid at the bottom of the reaction vessel, and then the temperature is raised while dropping solution A and dropping solution B are added dropwise; after the addition is complete, the reaction is maintained at the temperature. S3. Post-treatment: After the reaction is complete, cool down and adjust the pH of the system from weakly acidic to neutral to obtain a pure water-reducing agent with high water reduction rate.

6. The high water-reducing rate pure water-reducing agent according to claim 5, characterized in that, Ethylene glycol monovinyl polyethylene glycol ether is placed in a reaction vessel, and 45-50 parts of water are added and stirred until homogeneous to obtain a base liquid; preferably, it is stirred until homogeneous at 30-40°C. Acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid, vinylphosphonic acid, and mercaptoacetic acid are dissolved in 45-50 parts of water to prepare dropwise solution A.

7. The high water-reducing rate pure water-reducing agent according to claim 5, characterized in that, In step S3, the protective atmosphere gas includes nitrogen.

8. The high water-reducing rate pure water-reducing agent according to claim 5, characterized in that, In step S3, the temperature is raised to 30~60℃, and then dropping solution A and dropping solution B are added dropwise at the same time.

9. A high water-reducing rate pure water-reducing agent according to claim 5, characterized in that, Incubate for 1-2 hours; Preferably, after the reaction is complete, the temperature is lowered and an alkaline solution is added to adjust the pH value.

10. A high water-reducing rate pure water-reducing agent according to claim 5, characterized in that, Adjust the pH to 6-7 by adding alkaline solution; Preferably, the alkaline solution comprises a sodium hydroxide solution; the concentration of the alkaline solution is 30wt%-35wt%.

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