Powder slow-release water reducing agent and preparation method thereof

Abstract

The invention discloses a powder slow-release water reducing agent and a preparation method thereof, and the powder slow-release water reducing agent comprises ethylene glycol monoethylene glycol ether, acrylic acid, 2-acrylamide-2-methylpropane sulfonic acid, hydroxyethyl acrylate, sodium p-styrenesulfonate, a chain transfer agent, a reducing agent, an oxidizing agent, an initiator, a neutralizer and deionized water. The rigid functional monomer is introduced into the structure of the polycarboxylate superplasticizer, so that the slump loss of concrete can be reduced, the glass transition temperature of the polycarboxylate superplasticizer is increased, and the polycarboxylate superplasticizer can be dried into powder through spray drying.

Description

Technical Field

[0001] This invention relates to the technical field of concrete admixtures, and particularly to a powder slow-release water-reducing agent and its preparation method. Background Technology

[0002] Currently, concrete, as the most important building material, plays a vital role in various engineering projects. Modern construction places increasingly higher demands on the performance of concrete. The fluidity of concrete must meet the requirements of pumping construction, while also maintaining a certain degree of fluidity retention. This is because there is a certain distance between the mixing plant and the construction site, and the transportation process takes time.

[0003] Polycarboxylate superplasticizers have the characteristics of high water reduction rate, low slump loss and strong molecular structure design, which can improve various problems encountered in the construction of concrete.

[0004] Currently, the main solutions for addressing concrete fluidity loss on construction sites include increasing water usage, increasing the dosage of water-reducing agents, and adding retarders. Indiscriminately increasing water usage leads to a higher water-cement ratio, lower concrete strength, and exacerbates bleeding and segregation. Increasing the dosage of polycarboxylate superplasticizers may cause segregation or delayed bleeding. The use of some retarders can significantly extend the construction period; others are temperature-sensitive and have poor compatibility with concrete, potentially reducing the later-stage strength of the concrete. To address these issues, slow-release water-reducing agents have emerged.

[0005] However, existing technologies have the following shortcomings:

[0006] Liquid slow-release water-reducing agents: have high transportation costs, their storage stability is easily affected by temperature, and their slow-release performance is also significantly affected by ambient temperature.

[0007] Powder water-reducing agents: Currently, powder water-reducing agents obtained by conventional spray drying are only a physical transformation of some liquid products. Their dispersion and retention properties are consistent with their liquid products, and they do not have a sustained-release function. However, if liquid sustained-release water-reducing agents are directly spray dried, the liquid sustained-release water-reducing agents often undergo hydrolysis due to the instability of ester bonds and other components at high drying temperatures, resulting in the failure of the sustained-release function. Summary of the Invention

[0008] The main technical problem solved by this invention is to provide a powdered slow-release water-reducing agent that has good dispersibility, significant slow-release effect, excellent storage stability and is easy to transport over long distances.

[0009] To solve the above-mentioned technical problems, one technical solution adopted by the present invention is: a powdered slow-release water-reducing agent, comprising: ethylene glycol monoethylene polyethylene glycol ether, acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid, hydroxyethyl acrylate, sodium p-styrene sulfonate, chain transfer agent, reducing agent, oxidizing agent, initiator, neutralizing agent, and deionized water. The raw materials, by weight, are: 300-350 parts ethylene glycol monoethylene polyethylene glycol, 30-50 parts acrylic acid, 10-20 parts acrylamide-2-methylpropanesulfonic acid, 15-30 parts hydroxyethyl acrylate, 3-5 parts p-styrene sulfonic acid, 1-3 parts chain transfer agent, 0.3-0.6 parts reducing agent, 3.3-5 parts oxidizing agent, 0.1-0.3 parts initiator, 20-30 parts neutralizing agent, and 570-600 parts deionized water.

[0010] In a specific embodiment of the present invention, the chain transfer agent is mercaptopropionic acid.

[0011] In a specific embodiment of the present invention, the reducing agent is ascorbic acid.

[0012] In a specific embodiment of the present invention, the oxidant is hydrogen peroxide.

[0013] In a specific embodiment of the present invention, the initiator is ferrous sulfate.

[0014] In a specific embodiment of the present invention, the neutralizing agent is sodium hydroxide.

[0015] In another embodiment of the present invention, a method for preparing a powder-based slow-release water-reducing agent is disclosed, comprising the following steps:

[0016] S1. Add ethylene glycol monoethylene polyethylene glycol ether and deionized water to the reaction vessel and stir evenly. After 5 minutes, add hydrogen peroxide and ferrous sulfate.

[0017] S2. Dissolve acrylic acid, ascorbic acid, and mercaptopropionic acid in a portion of water to form solution A; dissolve hydroxyethyl acrylate in a portion of water to form solution B; dissolve sodium p-styrene sulfonate in a portion of water to form solution C; add solutions A, B, and C dropwise to the reaction vessel to carry out the reaction, controlling the reaction temperature at 15-32℃.

[0018] S3. After the addition is complete, add 200g of water and keep warm for 1 hour. Add sodium hydroxide to neutralize to a weakly alkaline state and then spray dry to obtain the water-reducing agent.

[0019] In a specific embodiment of the present invention, in S2, liquids A, B, and C are added to the reaction vessel for a reaction time of 50-60 minutes.

[0020] In a specific embodiment of the present invention, the pH value of the solution after neutralization with sodium hydroxide is 7-8.

[0021] The beneficial effects of this invention are as follows: introducing functional monomers containing carbon-carbon double bonds and hydroxyl groups into the structure of polycarboxylate superplasticizer can reduce concrete slump loss; by adjusting the molecular structure, the superplasticizer mother liquor can be powdered, improving storage stability and reducing transportation costs; introducing rigid functional monomers into the structure of polycarboxylate superplasticizer increases the glass transition temperature of polycarboxylate superplasticizer, enabling it to be powdered by spray drying, exhibiting good slow-release properties and improving the workability of concrete. Detailed Implementation

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] This invention relates to a powder-based slow-release water-reducing agent, comprising: ethylene glycol monoethylene polyethylene glycol ether, acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid, hydroxyethyl acrylate, sodium p-styrene sulfonate, chain transfer agent, initiator, neutralizer, and deionized water. The raw materials, by weight, are: 300-350 parts ethylene glycol monoethylene polyethylene glycol, 30-50 parts acrylic acid, 10-20 parts acrylamide-2-methylpropanesulfonic acid, 15-30 parts hydroxyethyl acrylate, 3-5 parts p-styrene sulfonic acid, 1-3 parts chain transfer agent, 0.3-0.6 parts reducing agent, 3.3-5 parts oxidizing agent, 3-6 parts initiator, 20-30 parts neutralizer, and 570-600 parts deionized water.

[0024] Specifically, the chain transfer agent is mercaptopropionic acid, the reducing agent is ascorbic acid, the oxidizing agent is hydrogen peroxide, the initiator is ferrous sulfate, and the neutralizing agent is sodium hydroxide.

[0025] A method for preparing a powder-based slow-release water-reducing agent includes the following steps:

[0026] S1. Add ethylene glycol monoethylene polyethylene glycol ether and deionized water to a reaction vessel and stir until homogeneous, wherein the deionized water accounts for 60% of the total water volume;

[0027] S2. Dissolve acrylic acid, ascorbic acid, and mercaptopropionic acid in a portion of water to form solution A. Dissolve hydroxyethyl acrylate in a portion of water to form solution B. Dissolve sodium p-styrene sulfonate in a portion of water to form solution C. Add solutions A, B, and C dropwise to the reaction vessel for reaction. The reaction time is 50-60 minutes, and the reaction temperature is controlled at 15-32℃.

[0028] S3. After the addition is complete, add 200g of water and keep warm for 1 hour. Add sodium hydroxide to neutralize to a weakly alkaline state with a pH of 7-8. Spray dry to obtain the water-reducing agent.

[0029] Example 1

[0030] 300g of ethylene glycol monoethylene polyethylene glycol ether, 250g of water, 10g of 2-acrylamide-2-methylpropanesulfonic acid (AMPS), 3g of hydrogen peroxide, and 0.01g of ferrous sulfate were fully dissolved. Additive A was prepared by dissolving 30g of acrylic acid, 0.5g of ascorbic acid, 1.2g of mercaptopropionic acid, and 40g of water. Additive B consisted of 15g of hydroxyethyl acrylate and 40g of water. Additive C consisted of 3g of sodium p-styrene sulfonate and 40g of water. Additives A and C were added dropwise over 50 minutes, and additive B over 60 minutes, controlling the reaction temperature at 15-32℃. After the reaction was complete, 200g of water was added and the mixture was kept at this temperature for 1 hour. Sodium hydroxide was added to neutralize to a weakly alkaline state (pH=7-8), and then the mixture was spray-dried to obtain white water-reducing agent A.

[0031] Example 2

[0032] 300g of ethylene glycol monoethylene polyethylene glycol ether, 250g of water, 10g of 2-acrylamide-2-methylpropanesulfonic acid (AMPS), 3g of hydrogen peroxide, and 0.01g of ferrous sulfate were fully dissolved. Additive A was prepared by dissolving 40g of acrylic acid, 0.5g of ascorbic acid, 1.2g of mercaptopropionic acid, and 40g of water. Additive B consisted of 15g of hydroxyethyl acrylate and 40g of water. Additive C consisted of 3g of sodium p-styrene sulfonate and 40g of water. Additives A and C were added dropwise for 50 minutes, and additive B for 60 minutes, controlling the reaction temperature at 15-32℃. After the reaction was complete, 200g of water was added and the mixture was kept at this temperature for 1 hour. Sodium hydroxide was added to neutralize to a weakly alkaline state (pH=7-8), and then the mixture was spray-dried to obtain white water-reducing agent B.

[0033] Example 3

[0034] 300g of ethylene glycol monoethylene polyethylene glycol ether, 250g of water, 10g of 2-acrylamide-2-methylpropanesulfonic acid (AMPS), 3g of hydrogen peroxide, and 0.01g of ferrous sulfate were fully dissolved. Additive A was prepared by dissolving 40g of acrylic acid, 0.5g of ascorbic acid, 1.2g of mercaptopropionic acid, and 40g of water; Additive B was prepared by dissolving 25g of hydroxyethyl acrylate and 40g of water; Additive C was prepared by dissolving 3g of sodium p-styrene sulfonate and 40g of water. Additives A and C were added dropwise for 50 minutes, and Additive B for 60 minutes, controlling the reaction temperature at 15-32℃. After the reaction was complete, 200g of water was added and the mixture was kept at this temperature for 1 hour. Sodium hydroxide was added to neutralize to a weakly alkaline state (pH=7-8), and then the mixture was spray-dried to obtain white water-reducing agent C.

[0035] Mortar test results

[0036] The mortar mix ratio is: 450g of 425 cement and 1350g of manufactured sand.

[0037]

[0038] The mortar test results show that the powder water-reducing agent synthesized in this invention has excellent slow-release properties, especially Example 3, which has obvious performance advantages.

[0039] Concrete test results

[0040] The concrete mix proportions are: 3.6 kg of 425 cement, 8.4 kg of sand, 10.2 kg of aggregate, and 1.75 kg of water.

[0041] The concrete test results were consistent with the mortar test results, indicating that the powder water-reducing agent synthesized in this invention exhibits excellent dispersion and slow-release properties.

[0042] The slow-release water-reducing agent prepared by this invention introduces functional monomers containing carbon-carbon double bonds and hydroxyl groups into the structure of polycarboxylate water-reducing agent, which can reduce the slump loss of concrete. By adjusting the molecular structure, the water-reducing agent mother liquor can be powdered, which improves storage stability and reduces transportation costs. Introducing rigid functional monomers into the structure of polycarboxylate water-reducing agent increases the glass transition temperature of polycarboxylate water-reducing agent, enabling it to be powdered by spray drying, and giving it good slow-release performance, which can improve the workability of concrete.

[0043] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A powder type water reducing agent having a slow release, characterized in that, It comprises: Glycol monovinyl polyethylene glycol ether, acrylic acid, 2-acrylamide-2-methyl propane sulfonic acid, hydroxyethyl acrylate, sodium p-styrene sulfonate, chain transfer agent, initiator, neutralizing agent and deionized water, each raw material is calculated by weight parts: glycol monovinyl polyethylene glycol 300-350 parts, acrylic acid 30-50 parts, acrylamide-2-methyl propane sulfonic acid 10-20 parts, hydroxyethyl acrylate 15-30 parts, p-styrene sulfonate 3-5 parts, chain transfer agent 1-3 parts, reducing agent 0.3-0.6 parts, oxidizing agent 3.3-5 parts, initiator 0.1-0.3 parts, neutralizing agent 20-30 parts, deionized water 570-600 parts.

2. The powder type water reducing agent according to claim 1, characterized in that, The chain transfer agent is mercaptopropanoic acid.

3. The powder slow-release water-reducing agent according to claim 1, characterized in that, The reducing agent is at least one of ascorbic acid, sodium hypophosphite or sodium sulfite.

4. The powder slow-release water-reducing agent according to claim 1, characterized in that, The oxidizing agent is at least one of hydrogen peroxide or ammonium persulfate.

5. The powder type water reducing agent according to claim 1, wherein the powder type water reducing agent is characterized by comprising 0.1 to 10 mass% of the water reducing agent and 90 to 99.9 mass% of the powder carrier. The initiator is ferrous sulfate.

6. The powder type water reducing agent according to claim 1, wherein The neutralizing agent is sodium hydroxide.

7. A method for preparing a powder-based slow-release water-reducing agent, characterized in that, It comprises the following steps: S1, glycol monovinyl polyethylene glycol ether and deionized water are added into the reaction kettle and stirred uniformly, and after 5 minutes, the oxidizing agent and the initiator are added; S2, acrylic acid, reducing agent and chain transfer agent are dissolved in part of water as A liquid, hydroxyethyl acrylate is dissolved in part of water as B liquid, and sodium p-styrene sulfonate is dissolved in part of water as C liquid, A, B and C liquids are added dropwise into the reaction kettle for reaction, and the appropriate reaction temperature is controlled; S3, after the dropwise addition is completed, 200g of water is added and kept for 1h, sodium hydroxide is added to neutralize to weak alkaline, and then spray drying is carried out to obtain the water reducing agent.

8. The method according to claim 7, wherein the powder type slow release water reducing agent is prepared by the following steps: 1) mixing the water reducing agent, the powder carrier and the water to form a mixture; 2) drying the mixture to obtain a powder type slow release water reducing agent. In S2, the time for A, B and C liquids to be added dropwise into the reaction kettle for reaction is 50-60 minutes.

9. The method for preparing a powder-based slow-release water-reducing agent according to claim 7, characterized in that, In S2, the reaction temperature when A, B and C liquids are added dropwise into the reaction kettle is 15-32℃.

10. The method for preparing a powder-based slow-release water-reducing agent according to claim 7, characterized in that, In S3, the pH value of the solution after neutralization with sodium hydroxide is 7-8.

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