A concrete anti-segregation agent and a preparation method thereof

Abstract

The present application relates to a kind of concrete anti-segregation agent and its preparation method, and the preparation raw materials of the anti-segregation agent include: workability adjusting monomer 7-9 parts by weight;Alkyl ether sulfate 3-4 parts by weight;Unsaturated ester monomer 4-6 parts by weight;Surfactant 3-5 parts by weight;Unsaturated acid monomer 8-12 parts by weight;Unsaturated amide 25-45 parts by weight;2-acrylamide-2-methylpropane sulfonic acid 3-10 parts by weight;Reducing agent 0.9-1.4 parts by weight;Oxidizing agent 1.0-2.0 parts by weight;And water;The present application can form hydrogen bond network by introducing workability adjusting monomer, increase the viscosity of concrete mixture moderately, prevent aggregate from sinking and cement paste from floating, thereby effectively inhibit segregation;They can also maintain the fluidity of concrete, ensure its good operability in pumping, vibrating and other construction processes. This balanced viscosity regulating capacity makes concrete neither too thick nor too thin, thereby improving construction efficiency.

Description

Technical Field

[0001] This invention relates to the field of concrete admixture technology, specifically to a concrete anti-segregation agent and its preparation method. Background Technology

[0002] Concrete, as a widely used building material, often experiences segregation during mixing, transportation, and pouring, which is the uneven distribution of coarse and fine aggregates, cementitious materials, and moisture. This segregation not only leads to reduced concrete strength, decreased durability, and poor surface quality, but also increases construction difficulty and affects project quality and efficiency.

[0003] Traditional anti-segregation measures, such as adjusting mix proportions, optimizing mixing processes, and controlling slump, have limitations and cannot fundamentally solve the problem. For example, increasing the sand ratio or reducing the water content can improve workability, but may lead to drying shrinkage cracks or insufficient fluidity. Over-mixing may accelerate the cement hydration reaction and affect the final performance. Summary of the Invention

[0004] Therefore, it is necessary to provide a concrete anti-segregation agent and its preparation method, in order to solve the technical problems existing in the prior art.

[0005] To achieve the above objectives, the present invention provides a technical solution:

[0006] A concrete anti-segregation agent, wherein the raw materials for preparing the anti-segregation agent, by weight, include:

[0007]

[0008]

[0009] The structural formula of the ease-regulating monomer is as follows:

[0010]

[0011] One of them, where n is an integer from 1 to 25 and m is an integer from 1 to 50.

[0012] This invention, through molecular shearing technology, introduces highly efficient functional additives (such as rhamnose glycolipids) and optimizes the molecular structure, fundamentally solving the segregation problem that occurs in concrete during mixing, transportation, and pouring in existing technologies. This innovative solution not only improves the strength, durability, and surface quality of concrete, enhancing project quality and efficiency, but also aligns with the environmentally friendly characteristics of this invention, meeting the requirements of sustainable development in the modern construction industry and possessing broad application prospects.

[0013] In some embodiments, the raw materials for preparing the ease-adjusting monomer include unsaturated terminal enols, acyl chlorides, and epoxides.

[0014] In some of these embodiments, the alkyl oxides include ethylene oxide and propylene oxide.

[0015] In some embodiments, the preparation steps of the ease-adjusting monomer include:

[0016] S110. Dissolve the unsaturated terminal enol in the first organic solvent to obtain an unsaturated terminal enol solution;

[0017] S120. Dissolve the acyl chloride compound in a second organic solvent to obtain an acyl chloride compound solution;

[0018] S130. Add the acyl chloride compound solution dropwise to the unsaturated terminal enol solution and react. After the reaction is completed, the functional monomer is obtained.

[0019] S140. Under alkaline conditions, an epoxide is introduced into the hydrophobic functional monomer to obtain the ease-adjusting monomer.

[0020] In some embodiments, the concentration of the unsaturated terminal enol solution is 0.25 mol / L to 0.30 mol / L.

[0021] In some embodiments, the concentration of the acyl chloride compound solution is 0.35 mol / L to 0.4 mol / L.

[0022] In some embodiments, in step S110, an acid-binding agent is added to the unsaturated terminal enol solution. This is because the reaction between unsaturated terminal enols and acyl chloride compounds releases hydrogen chloride, and the acid-binding agent neutralizes the hydrogen chloride, preventing acidic byproducts from affecting reaction efficiency and product quality. Preferably, the acid-binding agent is triethylamine.

[0023] In some embodiments, the unsaturated terminal enol includes one of 1-allyloxyprop-1-ol and 4-(allyloxy)-1-butanol.

[0024] In some embodiments, the acyl chloride compound includes at least one of acryloyl chloride, methacryloyl chloride, and maleic chloride.

[0025] In some of these embodiments, the first solvent includes at least one of acetone, dichloromethane, trichloromethane, acetonitrile, and toluene.

[0026] In some of these embodiments, the second solvent includes at least one of acetone, dichloromethane, chloroform, acetonitrile, and toluene.

[0027] In some embodiments, the reaction temperature in step S130 is 50°C to 70°C.

[0028] In some embodiments, the reaction time in step S130 is 12h to 14h.

[0029] In some embodiments, in step S130, the functional monomer may be purified through the following steps:

[0030] First, the salts produced during the reaction are removed by vacuum filtration, the solvent is removed by rotary evaporator, then extracted with diethyl ether, and finally dried under vacuum at room temperature to obtain the purified functional monomer.

[0031] In some embodiments, step S140 specifically includes the following steps:

[0032] The functional monomer was slowly heated to 110℃~130℃ and dehydrated under reduced pressure to 0.1+0.2MPa. After dehydration, sodium hydroxide was added, followed by nitrogen gas to remove excess oxygen. After degassing, ethylene oxide was introduced, and the reaction was allowed to proceed until the pressure remained constant. Then, propylene oxide was introduced, and the reaction was allowed to proceed until the reaction was complete. The reaction system was then cooled to 70℃~90℃, neutralized with acetic acid, and then filtered to obtain the workability-adjusting monomer.

[0033] In some embodiments, the molar ratio of the unsaturated terminal enol to the acyl chloride compound is (5-7):(7-8);

[0034] In some embodiments, in step S410, the mass ratio of the functional monomer, ethylene oxide, and propylene oxide is (100-120):(400-800):(130-170).

[0035] In some embodiments, the unsaturated amide includes acrylamide.

[0036] In some embodiments, the reaction temperature in step S140 is 110°C to 130°C.

[0037] In some embodiments, the reaction pressure in step S140 is 0.1 MPa to 0.3 MPa.

[0038] In some embodiments, the unsaturated ester monomer is rhamnolipid, and the structural formula of the rhamnolipid is as follows:

[0039]

[0040] One of them.

[0041] In some embodiments, the general structural formula of the alkyl ether sulfate is as follows:

[0042] RO-(CH2 CH2O) n -SO3Na;

[0043] Where R is an alkyl chain of C8 to C18, and n is a positive integer from 1 to 4.

[0044] In some embodiments, the surfactant includes one of methacryloyloxyethyl dimethylhexadecyl ammonium chloride, methacryloyloxyethyl dimethyl octadecyl ammonium chloride, methacryloyloxyethyl dimethyl dodecyl ammonium chloride, and acryloyloxyethyl dimethyl hexadecyl ammonium chloride.

[0045] In some embodiments, the unsaturated acid monomer includes at least one of acrylic acid and methacrylic acid.

[0046] In some embodiments, the reducing agent includes at least one of ascorbic acid, sodium formaldehyde sulfoxylate, sodium sulfite, sodium formaldehyde sulfoxylate, sodium bisulfite, and sodium hypophosphite.

[0047] In some embodiments, the oxidant includes at least one of potassium persulfate and ammonium persulfate.

[0048] This invention also provides a method for preparing a concrete anti-segregation agent, the method comprising the following steps:

[0049] S210, mix the workability adjusting monomer, alkyl ether sulfate, unsaturated acid monomer, unsaturated amide, 2-acrylamide-2-methylpropanesulfonic acid, surfactant, and water to prepare a base material;

[0050] S220. Adjust the pH value of the substrate to 7.0-8.0, add solution A and solution B dropwise to the substrate to start the reaction, and after the addition is completed, keep the reaction at a constant temperature for 1-3 hours to obtain the concrete anti-segregation agent.

[0051] In this invention, solution A is an aqueous solution of unsaturated acid monomers, unsaturated ester monomers, and reducing agent. Specifically, in the preparation method of this invention, the unsaturated acid monomers are added in two parts. The first part is added to the mother liquor to adjust the pH of the mother liquor. The second part is added dropwise to solution A to participate in the reaction. The mass ratio of the unsaturated acid monomers in the mother liquor to the unsaturated acid monomers used in solution A is 1:(1-2).

[0052] Solution B is an aqueous solution of the oxidizing agent.

[0053] In some embodiments, the initial reaction temperature in step S220 is 30–45°C.

[0054] In some embodiments, the solution A is added over a period of 1 to 2 hours.

[0055] In some embodiments, the solution B is added over a period of 1 to 2 hours.

[0056] The beneficial effects of this invention are:

[0057] 1. This invention introduces workability-adjusting monomers that can chemically react with cement hydration products (such as Ca(OH)2) to form stable complexes or covalent bonds, thereby improving the interfacial transition zone between cement paste and aggregates. Furthermore, by forming a hydrogen bond network with water molecules, they moderately increase the viscosity of the concrete mixture, preventing aggregate settling and cement paste floating, thus effectively suppressing segregation. Simultaneously, they maintain the fluidity of the concrete, ensuring good workability during pumping, vibration, and other construction processes. This balanced viscosity-adjusting capability ensures that the concrete is neither too viscous nor too thin, thereby improving construction efficiency.

[0058] 2. The anti-segregation agent prepared by this invention continuously and slowly releases free water to replenish the free water consumed during the hydration process of cement through the hydrolysis effect of the amide groups, thereby meeting the fluidity requirements of concrete thickening and water-retaining agents over time.

[0059] 3. The preparation method of this invention introduces sulfonic acid groups, carboxylate groups, and ester groups into the polymer molecular structure. Simultaneously, the ester groups continuously hydrolyze during cement hydration, continuing to react with cement hydration products, inhibiting the growth of Ca(OH)₂ and AFt crystal nuclei, slowing down the hydration rate, and prolonging the cement hydration induction period, thereby improving slump retention. The sulfonic acid groups can react with calcium ions in cement to generate a cohesive network structure, further improving the slump retention of concrete and adsorbing onto the surface of cement particles, giving the cement particle surface a negative charge, thereby reducing the repulsive force between cement particles and playing a role in dispersion and adsorption.

[0060] 4. The anti-segregation agent prepared by the method of the present invention has the advantages of anti-segregation, good viscosity adjustment and workability, and can significantly reduce the viscosity of concrete and improve the workability of concrete. Detailed Implementation

[0061] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0062] In the embodiments, unless otherwise specified, the experimental methods used are conventional methods, and the materials and reagents used are commercially available unless otherwise specified.

[0063] I. Preparation of monomers with adjustable workability

[0064] 1. Monomer A, which regulates workability:

[0065] S110. Accurately weigh 0.25 mol of 1-allyloxyprop-1-ol and 0.10 mol of triethylamine, dissolve them in dichloromethane, and add them to a three-necked flask equipped with a circulating cooling reflux device to obtain an unsaturated terminal enol solution.

[0066] S120. 0.35 mol of acryloyl chloride is dissolved in dichloromethane to obtain a solution of acryl chloride compounds;

[0067] S130. Add an acyl chloride compound solution dropwise to a three-necked flask and react at 50°C for 14 hours to obtain functional monomer A.

[0068] Next, the salts produced during the reaction were removed by vacuum filtration, the solvent was removed by rotary evaporator, and then extracted with diethyl ether. Finally, the product was vacuum dried at room temperature for 24 hours to obtain pure functional monomer A.

[0069] S140. Add 100 parts of the functional monomer to the reaction vessel, slowly heat to 110°C, and depressurize to 0.1 MPa for dehydration. After dehydration, add 5 parts of sodium hydroxide, and then purge the reaction vessel with nitrogen to remove excess oxygen. After degassing, purge with 400 parts of ethylene oxide. After the reaction reaches a constant pressure, purge with 300 parts of propylene oxide. After the reaction is complete, cool the reaction system to 70°C, add 3 parts of acetic acid for neutralization, and then filter to obtain the solubility-adjusting monomer A.

[0070] 2. Monomer B, which regulates workability:

[0071] S110. Accurately weigh 0.25 mol of 4-(allyloxy)-1-butanol and 0.10 mol of triethylamine, dissolve them in dichloromethane, and add them to a three-necked flask equipped with a circulating cooling reflux device to obtain an unsaturated terminal enol solution.

[0072] S120. 0.35 mol of acryloyl chloride is dissolved in dichloromethane to obtain a solution of acryl chloride compounds;

[0073] S130. Add an acyl chloride compound solution dropwise to a three-necked flask and react at 50°C for 14 hours to obtain functional monomer B.

[0074] Next, the salts produced during the reaction were removed by filtration, the solvent was removed by rotary evaporator, and then extracted with diethyl ether. Finally, the product was vacuum dried at room temperature for 24 hours to obtain pure functional monomer B.

[0075] S140. Add 100 parts of the functional monomer to the reaction vessel, slowly heat to 110°C, and depressurize to 0.1 MPa for dehydration. After dehydration, add 5 parts of sodium hydroxide, and then purge the reaction vessel with nitrogen to remove excess oxygen. After degassing, purge with 400 parts of ethylene oxide. After the reaction reaches a constant pressure, purge with 300 parts of propylene oxide. After the reaction is complete, cool the reaction system to 70°C, add 3 parts of acetic acid for neutralization, and then filter to obtain the workability-adjusting monomer B.

[0076] II. Preparation of Concrete Anti-Segregation Agent

[0077] Example 1:

[0078] S210, 5 parts acrylic acid, 30 parts acrylamide, 6 parts 2-acrylamide-2-methylpropanesulfonic acid, 8 parts workability adjusting monomer, 3 parts alkyl ether sulfate, 2 parts surfactant are mixed with an aqueous solution to prepare a base material. Sodium hydroxide solution is added to the base material to adjust the pH value of the base solution to 7.0-8.0.

[0079] S220, wherein the initial reaction temperature is 35℃, the dropwise addition time of solution A and solution B is 2h, and after the dropwise addition is completed, it is kept at a constant temperature for 3h to obtain the anti-segregation agent.

[0080] Solution A is prepared by mixing 5 parts acrylic acid, 4 parts rhamnolipid, 1.3 parts sodium hypophosphite, and water.

[0081] Prepare solution B by mixing 1.1 parts of potassium persulfate with water;

[0082] The experimental steps of Examples 2-4 and Comparative Examples 1-3 are the same as those of Example 1, except that the raw material ratios of Examples 2-4 and Comparative Examples 1-3 are changed. The raw material ratios of the examples are shown in Table 1, and the raw material ratios of the comparative examples are shown in Table 2.

[0083] Table 1. Raw material ratio table for the embodiment

[0084]

[0085]

[0086] Table 2 Comparative Example Raw Material Ratio Table

[0087]

[0088] The polycarboxylate superplasticizer samples synthesized in Examples 1-4 and Comparative Examples 1-4 were evaluated for viscosity reduction performance by means of a paste apparent viscosity test.

[0089] The cement used in the mortar tests was the reference P·O 42.5 cement, maintaining a water-cement ratio of 0.29. Three parallel tests were performed for each water-reducing agent sample. By adjusting the dosage of the water-reducing agent, the initial flowability of each sample was ensured to be within the range of 280±10 mm. The apparent viscosity of each slurry sample was tested using a RheolabQC rotational rheometer manufactured by AntonPar GmbH, Germany. The test data are listed in Table 3.

[0090] Table 3. Results of apparent viscosity test for neat paste

[0091]

[0092] As shown in Table 3, the apparent viscosity of the antisegregation agent prepared in the embodiments of the present invention and the addition of the comparative example can effectively adjust the viscosity and workability of the slurry. Furthermore, the embodiments show that adding a smaller amount of the agent effectively increases the slurry viscosity, while the comparative example, with a larger amount added, shows a smaller change in viscosity compared to the embodiments.

[0093] To effectively evaluate the application effect of anti-segregation agents in concrete, this study adopted an optimized C30 mix proportion and adjusted the cementitious materials and sand ratio.

[0094] Specifically, while keeping other components constant, the cementitious material per cubic meter of concrete was reduced by 30 kg, and the sand ratio was reduced by 2% to 4%. This adjustment aims to simulate segregation problems that may occur in actual construction, namely, the initial spread of the concrete is controlled between 550 mm and 650 mm, and there should be obvious separation, accumulation, and bleeding or grouting phenomena in the initial state or after standing.

[0095] The concrete mix design used in the experiment is as follows:

[0096]

[0097] The formulation of the admixture is as follows:

[0098]

[0099] Table 4 Concrete Test Data

[0100]

[0101] Table 4 shows that Comparative Example 1 (without workability modifier monomer) and Comparative Example 2 (without rhamnolipid) exhibited slight bleeding over time, indicating poor workability. Comparative Examples 3 and 4, which did not contain alkyl ether sulfates or surfactants, showed poor slump retention over time. The anti-segregation agents prepared in Examples 1-4, compared to the comparative examples, required lower dosages and showed better performance in concrete at 0h and 2.0h, with minimal impact on flowability.

[0102] It should be noted that the specific parameters or reagents in the above embodiments are specific or preferred embodiments under the concept of the present invention, and not limitations thereof; those skilled in the art can make adaptive adjustments within the concept and protection scope of the present invention.

Claims

1. A concrete anti-segregation agent, characterized in that, The raw materials for preparing the anti-segregation agent, by weight, include: The structural formula of the ease-regulating monomer is as follows: One of them, where n is an integer from 1 to 25 and m is an integer from 1 to 50; The unsaturated ester monomer is rhamnolipid; The surfactant includes at least one of methacryloyloxyethyl dimethylhexadecyl ammonium chloride, methacryloyloxyethyl dimethyl octadecyl ammonium chloride, methacryloyloxyethyl dimethyl dodecyl ammonium chloride, and methacryloyloxyethyl dimethyl hexadecyl ammonium chloride.

2. The concrete anti-segregation agent according to claim 1, characterized in that, The raw materials for preparing the ease-adjusting monomer include unsaturated terminal enols, acyl chloride compounds, and epoxides.

3. The concrete anti-segregation agent according to claim 2, characterized in that, The preparation steps of the ease-adjusting monomer include: Unsaturated terminal enols are dissolved in a first organic solvent to obtain an unsaturated terminal enol solution; An acyl chloride compound is dissolved in a second organic solvent to obtain an acyl chloride compound solution; The acyl chloride compound solution was added dropwise to the unsaturated terminal enol solution and reacted. After the reaction was completed, the functional monomer was obtained. Under alkaline conditions, epoxides are introduced into the functional monomer to obtain the ease-adjusting monomer.

4. The concrete anti-segregation agent according to claim 2, characterized in that, The unsaturated terminal enols include at least one of 1-allyloxyprop-1-ol and 4-(allyloxy)-1-butanol.

5. The concrete anti-segregation agent according to claim 2, characterized in that, The acyl chloride compounds include at least one of acryloyl chloride, methacryloyl chloride, and maleic chloride.

6. The concrete anti-segregation agent according to claim 1, characterized in that, The structural formula of the rhamnolipid is as follows: One of them.

7. The concrete anti-segregation agent according to claim 1, characterized in that, The general structural formula of the alkyl ether sulfate is as follows: RO-(CH2 CH2O) n -SO3Na: Where R is an alkyl chain of C8 to C18, and n is a positive integer from 1 to 4.

8. A method for preparing a concrete anti-segregation agent as described in any one of claims 1 to 7, characterized in that, Including the following steps: A base material is prepared by mixing a workability-modifying monomer, an alkyl ether sulfate, an unsaturated acid monomer, an unsaturated amide, 2-acrylamide-2-methylpropanesulfonic acid, a surfactant, and water. Adjust the pH value of the substrate to 7.0-8.0, add solution A and solution B dropwise to the substrate to start the reaction, and after the dropwise addition is completed, keep the reaction at a warm temperature for 1-3 hours to obtain the concrete anti-segregation agent.

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