Concrete anti-segregation agent and preparation method thereof

Abstract

The invention relates to a concrete anti-segregation agent and a preparation method thereof, and the anti-segregation agent is prepared from the following raw materials in parts by weight: 7-9 parts of a workability adjusting monomer; 3-4 parts of alkyl ether sulfate; 4-6 parts of an unsaturated ester monomer; 3-5 parts of a surfactant; 8-12 parts of an unsaturated acid monomer; 25 to 45 parts of unsaturated amide; 3-10 parts of an unsaturated sulfonate monomer; 0.9 to 1.4 parts of a reducing agent; 1.0 to 2.0 parts of an oxidizing agent; and water; by introducing the workability adjusting monomer, a hydrogen bond network can be formed by the workability adjusting monomer and water molecules, the viscosity of a concrete mixture is moderately increased, aggregate sinking and cement paste floating are prevented, and therefore segregation is effectively inhibited; and the fluidity of the concrete can be maintained, so that the concrete has good operability in the construction processes of pumping, vibrating and the like. Due to the balanced viscosity adjusting capability, the concrete is not too sticky or too thin, so that the construction efficiency is improved.

Description

Technical Field

[0001] The invention relates to the technical field of concrete admixtures, in particular to a concrete anti-segregation agent and a preparation method thereof. Background Art

[0002] As a widely used building material, concrete often undergoes segregation during mixing, transportation and pouring, which means uneven distribution of coarse and fine aggregates, cementitious materials and water. This segregation not only leads to reduced concrete strength, reduced 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 ratio, optimizing mixing process and controlling slump have limitations and are difficult to fundamentally solve the problem. For example, increasing the sand ratio or reducing water consumption can improve workability, but may lead to shrinkage cracks or insufficient fluidity, and excessive mixing may accelerate cement hydration reaction and affect the final performance. Summary of the invention

[0004] Based on this, it is necessary to provide a concrete anti-segregation agent and a preparation method thereof, aiming to solve the technical problems existing in the prior art.

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

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

[0007]

[0008] as well as

[0009] water;

[0010] Among them, the structural formula of the workability regulating monomer is as follows:

[0011]

[0012] One of the following, wherein n is an integer from 1 to 25, and m is an integer from 1 to 50.

[0013] The present invention fundamentally solves the segregation problem of concrete in the mixing, transportation and pouring process in the prior art by introducing efficient functional additives (such as rhamnolipids) and optimizing molecular structures through molecular shearing technology. This innovative solution not only improves the strength, durability and surface quality of concrete, but also improves the quality and efficiency of the project. At the same time, the environmental protection characteristics of the present invention also meet the requirements of the modern construction industry for sustainable development and has broad application prospects.

[0014] In some of the embodiments, the raw materials for preparing the workability-adjusting monomer include unsaturated terminal olefin alcohols, acyl chloride compounds, and alkylene oxides.

[0015] In some embodiments, the alkylene oxide includes ethylene oxide and propylene oxide.

[0016] In some embodiments, the preparation step of the workability adjusting monomer comprises:

[0017] S110, dissolving an unsaturated terminal alkenol in a first organic solvent to obtain an unsaturated terminal alkenol solution;

[0018] S120, dissolving the acyl chloride compound in a second organic solvent to obtain an acyl chloride compound solution;

[0019] S130, adding the acyl chloride compound solution dropwise to the unsaturated terminal olefin alcohol solution for reaction, and completing the reaction to obtain a functional monomer;

[0020] S140, introducing alkylene oxide into the hydrophobic functional monomer under alkaline conditions to obtain the workability adjusting monomer.

[0021] In some embodiments, the concentration of the unsaturated terminal ene alcohol solution is 0.25 mol / L to 0.30 mol / L.

[0022] In some embodiments, the concentration of the acyl chloride compound solution is 0.35 mol / L to 0.4 mol / L.

[0023] In some embodiments, in step S110, an acid binding agent is added to the unsaturated terminal alkenyl alcohol solution. This is because when the unsaturated terminal alkenyl alcohol reacts with the acyl chloride compound, hydrogen chloride is released. The acid binding agent neutralizes the hydrogen chloride to prevent the acidic byproduct from affecting the reaction efficiency and product quality. Preferably, the acid binding agent is triethylamine.

[0024] In some embodiments, the unsaturated terminal olefinic alcohol includes one of 1-allyloxypropan-1-ol and 4-(allyloxy)-1-butanol.

[0025] In some embodiments, the acyl chloride compound includes at least one of acryloyl chloride, methacryloyl chloride and maleoyl chloride.

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

[0027] In some embodiments, the second solvent includes at least one of acetone, dichloromethane, chloroform, acetonitrile and toluene.

[0028] In some embodiments, in step S130, the reaction temperature is 50°C to 70°C.

[0029] In some embodiments, in step S130, the reaction time is 12 hours to 14 hours.

[0030] In some embodiments, in step S130, the functional monomer can be purified by the following steps:

[0031] The salts generated during the reaction are first removed by suction filtration, the solvent is removed by a rotary evaporator, and then extracted with ether and vacuum dried at room temperature to finally obtain the purified functional monomer.

[0032] In some embodiments, in step S140, the specific steps are as follows:

[0033] The functional monomer is slowly heated to 110°C to 130°C, and the pressure is reduced to 0.1+0.2MPa for dehydration; after the dehydration is completed, sodium hydroxide is added, and then nitrogen is introduced to remove excess oxygen; after the degassing is completed, ethylene oxide is introduced, and after the reaction is completed until the pressure remains unchanged, propylene oxide is introduced, and after the reaction is completed, the reaction system is cooled to 70°C to 90°C, acetic acid is added for neutralization, and then filtered to obtain the workability adjusting monomer.

[0034] In some embodiments, the molar ratio of the unsaturated terminal olefinic alcohol and the acyl chloride compound is (5-7):(7-8);

[0035] In some of the embodiments, in step S410, the mass ratio of the functional monomer, ethylene oxide, and propylene oxide is (100-120):(400-800):(130-170).

[0036] In some embodiments, the unsaturated amide includes acrylamide.

[0037] In some embodiments, in step S140, the reaction temperature is 110°C to 130°C.

[0038] In some embodiments, in step S140, the reaction pressure is 0.1 MPa to 0.3 MPa.

[0039] In some embodiments, the unsaturated ester monomer is rhamnolipid, and the rhamnolipid has the following structural formula:

[0040]

[0041] One of them.

[0042] In some embodiments, the surfactant is an alkyl ether sulfate, and its general structural formula is as follows:

[0043] RO-(CH2 CH2O) n -SO3Na;

[0044] Wherein, R is a C8-C18 alkyl chain, and n is a positive integer of 1-4.

[0045] In some embodiments, the surfactant includes one of methacryloyloxyethyl dimethyl hexadecyl ammonium chloride, methacryloyloxyethyl dimethyl octadecyl ammonium chloride, methacryloyloxyethyl dimethyl dodecyl ammonium chloride, and acryloyloxyethyl dimethyl hexadecyl ammonium chloride.

[0046] In some embodiments, the unsaturated acid monomer includes at least one of acrylic acid and methacrylic acid.

[0047] In some embodiments, the unsaturated sulfonate monomer includes 2-acrylamide-2-methylpropane sulfonic acid.

[0048] In some embodiments, the reducing agent includes at least one of ascorbic acid, sodium formaldehyde sulfoxylate, sodium sulfite, bleaching powder, sodium bisulfite and sodium hypophosphite.

[0049] In some embodiments, the oxidant includes at least one of potassium persulfate and ammonium persulfate.

[0050] The present invention also provides a method for preparing a concrete anti-segregation agent, the preparation method comprising the steps of:

[0051] S210, mixing workability adjustment monomers, alkyl ether sulfate, unsaturated acid monomers, unsaturated amides, unsaturated sulfonate monomers, surfactants, and water to prepare a base material;

[0052] S220, adjusting the pH value of the base material to 7.0-8.0, dripping solution A and solution B into the base material to start the reaction, and after the dripping is completed, heat-insulating the reaction for 1-3 hours to obtain a concrete anti-segregation agent.

[0053] Wherein, solution A is an aqueous solution of unsaturated acid monomer, unsaturated ester monomer and reducing agent; specifically, in the preparation method of the present invention, the unsaturated acid monomer is added in two times, the first time it is added to the mother liquor for the purpose of adjusting the pH of the mother liquor, and the second time it is added dropwise to the mother liquor in liquid A for participating in the reaction, and the mass ratio of the unsaturated acid monomer in the mother liquor to the unsaturated acid monomer used in liquid A is 1:(1-2).

[0054] Solution B is an aqueous solution of an oxidizing agent.

[0055] In some embodiments, in step S220, the initial reaction temperature is 30-45°C.

[0056] In some embodiments, the solution A is added dropwise for 1 h to 2 h.

[0057] In some embodiments, the solution B is added dropwise for 1 h to 2 h.

[0058] Beneficial effects of the present invention:

[0059] 1. The present invention can chemically react with cement hydration products (such as Ca(OH)2) to form stable complexes or covalent bonds by introducing workability regulating monomers, thereby improving the interface transition zone between cement paste and aggregate. In addition, by forming a hydrogen bond network with water molecules, the viscosity of the concrete mixture can be appropriately increased to prevent aggregates from sinking and cement paste from floating, thereby effectively inhibiting segregation. At the same time, they can also maintain the fluidity of concrete, ensuring that it has good operability during construction processes such as pumping and vibrating. This balanced viscosity regulation ability ensures that the concrete is neither too viscous nor too thin, thereby improving construction efficiency.

[0060] 2. The anti-segregation agent prepared by the present invention continuously and slowly releases free water during the hydration process of cement through the hydrolysis effect of the amide group to replenish the free water consumed in the hydration process, thereby meeting the fluidity requirements of the concrete time-dependent thickening and water-retaining agent.

[0061] 3. The preparation method of the present invention introduces sulfonic acid groups, carboxylic acid radicals, and ester groups into the polymer molecular structure. The ester groups are continuously hydrolyzed during the cement hydration process, and continue to react with cement hydration products, inhibiting the growth of Ca(OH)2 and AFt crystal nuclei, slowing down the hydration rate, and extending the cement hydration induction period, thereby improving the retention. The sulfonic acid groups can react with calcium ions in cement to generate a cohesive network structure, further improving the collapse retention of concrete and being able to be adsorbed on the surface of cement particles, so that the surface of cement particles carries a negative charge, thereby reducing the repulsion between cement particles, and playing a role in dispersion and adsorption.

[0062] 4. The anti-segregation agent prepared by the method of the present invention has the advantages of anti-segregation, viscosity adjustment and good workability, and can significantly reduce the viscosity of concrete and improve the workability of concrete. DETAILED DESCRIPTION

[0063] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0064] In the examples, the test methods used are conventional methods unless otherwise specified, and the materials, reagents, etc. used are all commercially available unless otherwise specified.

[0065] 1. Preparation of monomers for workability adjustment

[0066] 1. Workability adjustment monomer A:

[0067] S110, accurately weigh 0.25 mol of 1-allyloxypropan-1-ol and 0.10 mol of triethylamine, dissolve them in dichloromethane, and add them into a three-necked flask with a circulating cooling reflux device to obtain an unsaturated terminal enol solution;

[0068] S120, dissolving 0.35 mol of acryloyl chloride in dichloromethane to obtain an acyl chloride compound solution;

[0069] S130, dropwise add the acyl chloride compound solution into a three-necked flask, react at 50° C. for 14 hours, and obtain a functional monomer A.

[0070] Next, the salts produced during the reaction were removed by suction filtration, the solvent was removed by a rotary evaporator, and then extracted with ether and vacuum dried at room temperature for 24 hours to finally obtain pure functional monomer A.

[0071] S140, adding 100 parts of functional monomers into a reaction vessel, slowly heating to 110°C, and decompressing to 0.1MPa for dehydration; after dehydration, adding 5 parts of sodium hydroxide, and then passing nitrogen into the reactor to remove excess oxygen; after degassing, passing 400 parts of ethylene oxide, reacting until the pressure remains unchanged, and then passing 300 parts of propylene oxide, after the reaction is completed, the reaction system is cooled to 70°C, 3 parts of acetic acid are added for neutralization, and then filtered to obtain the workability adjusting monomer A.

[0072] 2. Workability adjustment monomer B:

[0073] S110, accurately weigh 0.25 mol of 4-(allyloxy)-1-butanol and 0.10 mol of triethylamine, dissolve them in dichloromethane, and add them into a three-necked flask with a circulating cooling reflux device to obtain an unsaturated terminal enol solution;

[0074] S120, dissolving 0.35 mol of acryloyl chloride in dichloromethane to obtain an acyl chloride compound solution;

[0075] S130, dropwise add the acyl chloride compound solution into a three-necked flask, react at 50° C. for 14 hours, and obtain a functional monomer B.

[0076] Next, the salts produced during the reaction were removed by suction filtration, the solvent was removed by a rotary evaporator, and then extracted with ether and vacuum dried at room temperature for 24 hours to finally obtain pure functional monomer B.

[0077] S140, adding 100 parts of functional monomers into a reaction vessel, slowly heating to 110°C, and decompressing to 0.1MPa for dehydration; after dehydration, adding 5 parts of sodium hydroxide, and then passing nitrogen into the reactor to remove excess oxygen; after degassing, passing 400 parts of ethylene oxide, reacting until the pressure remains unchanged, and then passing 300 parts of propylene oxide, after the reaction is completed, the reaction system is cooled to 70°C, 3 parts of acetic acid are added for neutralization, and then filtered to obtain the workability adjusting monomer B.

[0078] 2. Preparation of Concrete Anti-segregation Agent

[0079] Embodiment 1:

[0080] S210, 5 parts of acrylic acid, 30 parts of acrylamide, 6 parts of 2-acrylamide-2-methylpropanesulfonic acid, 8 parts of workability adjusting monomer, 3 parts of alkyl ether sulfate, 2 parts of surfactant and aqueous solution are mixed to prepare a base material, sodium hydroxide solution is added to the base material, and the pH value of the base liquid is adjusted to 7.0-8.0;

[0081] S220, wherein the initial reaction temperature is 35°C, the dripping time of solution A and solution B is 2 hours, and after the dripping is completed, the mixture is aged at a constant temperature for 3 hours to obtain an anti-segregation agent.

[0082] Among them, 5 parts of acrylic acid, 4 parts of rhamnolipid, 1.3 parts of sodium hypophosphite and water are prepared into solution A;

[0083] Prepare solution B by mixing 1.1 parts of potassium persulfate with water;

[0084] The experimental steps of Examples 2 to 4 and Comparative Examples 1 to 3 are the same as those of Example 1, except that the raw material ratios of Examples 2 to 4 and Comparative Examples 1 to 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.

[0085] Table 1 Example Raw Materials Ratio Table

[0086]

[0087]

[0088] Table 2 Comparative Example Raw Material Ratio

[0089]

[0090] The polycarboxylate water-reducing agent samples synthesized in Examples 1 to 4 and Comparative Examples 1 to 4 were subjected to a pure slurry apparent viscosity test to evaluate the viscosity reducing performance of the water-reducing agent synthesized in the examples of the present invention.

[0091] The cement used in the mortar test was the benchmark P·O 42.5 cement, and the water-cement ratio was kept at 0.29. Three parallel tests were performed for each water reducer sample. The water reducer dosage was adjusted to ensure that the initial fluidity of each sample was within the range of 280±10mm. The apparent viscosity of each slurry sample was tested using the RheolabQC rotational rheometer produced by Anton Par, Germany. The test data are listed in Table 3.

[0092] Table 3 Test results of apparent viscosity of pure slurry

[0093]

[0094] As can be seen from Table 3, the apparent viscosity of the anti-segregation agent prepared in the embodiment of the present invention and the addition of the comparative example can effectively adjust the viscosity of the slurry and adjust the workability of the slurry. In addition, the embodiment adds a smaller amount of admixture, which can effectively increase the slurry viscosity, while the comparative example adds a larger amount of admixture, and the adjustment range is smaller than that of the embodiment.

[0095] In order to effectively evaluate the application effect of anti-segregation agent in concrete, this study adopted the optimized C30 mix ratio and adjusted the cementitious material and sand ratio.

[0096] Specifically, while keeping other ingredients unchanged, the cementitious material per cubic meter of concrete is reduced by 30kg and the sand ratio is reduced by 2% to 4%. This adjustment is intended to simulate the segregation problem that may occur in actual construction, that is, the initial expansion of concrete is controlled between 550mm and 650mm, and there should be obvious stone separation, accumulation, and water or slurry in the initial state or after standing.

[0097] The concrete mix used in the experiment is as follows:

[0098]

[0099] The formula of admixture is:

[0100]

[0101] Table 4 Concrete test data

[0102]

[0103] As can be seen from Table 4, Comparative Example 1 without adding workability adjusting monomer and Comparative Example 2 without adding rhamnolipid have slight bleeding over time and poor workability. Comparative Examples 3 and 4 are concretes without adding alkyl ether sulfate and surfactant, and the time-loss slump retention performance is poor. The anti-segregation agent prepared in Examples 1 to 4 has a lower dosage than the comparative example, and has better performance on concrete 0h and 2.0h concrete, and has little effect on fluidity.

[0104] It should be noted that the specific parameters or some reagents in the above embodiments are specific embodiments or preferred embodiments of the present invention, rather than limiting the present invention; those skilled in the art can make adaptive adjustments within the scope of the present invention.

Claims

1. A concrete anti-segregation agent, characterized in that: In parts by weight, the raw materials for preparing the anti-segregation agent include: water; Among them, the structural formula of the workability regulating monomer is as follows: One of the following, wherein n is an integer from 1 to 25, and m is an integer from 1 to 50.

2. The concrete anti-segregation agent according to claim 1, characterized in that: The raw materials for preparing the workability regulating monomer include unsaturated terminal olefin alcohol, acyl chloride compound and alkylene oxide.

3. The concrete anti-segregation agent according to claim 2, characterized in that: The preparation steps of the workability regulating monomer include: dissolving an unsaturated terminal alkenol in a first organic solvent to obtain an unsaturated terminal alkenol solution; dissolving an acyl chloride compound in a second organic solvent to obtain an acyl chloride compound solution; Adding the acyl chloride compound solution dropwise to the unsaturated terminal ene alcohol solution for reaction, and obtaining a functional monomer after the reaction is completed; Under alkaline conditions, alkylene oxide is introduced into the hydrophobic functional monomer to obtain the workability regulating monomer.

4. The concrete anti-segregation agent according to claim 2, characterized in that: The unsaturated terminal olefinic alcohol comprises at least one of 1-allyloxypropan-1-ol and 4-(allyloxy)-1-butanol.

5. The concrete anti-segregation agent according to claim 2, characterized in that: The acyl chloride compound includes at least one of acryloyl chloride, methacryloyl chloride and maleoyl chloride.

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

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

8. The concrete anti-segregation agent according to claim 1, characterized in that: The surfactant includes at least one of methacryloyloxyethyl dimethyl hexadecyl ammonium chloride, methacryloyloxyethyl dimethyl octadecyl ammonium chloride, methacryloyloxyethyl dimethyl dodecyl ammonium chloride, and acryloyloxyethyl dimethyl hexadecyl ammonium chloride.

9. The concrete anti-segregation agent according to claim 1, characterized in that: The unsaturated sulfonate monomer includes 2-acrylamide-2-methylpropanesulfonic acid.

10. A method for preparing the concrete anti-segregation agent according to any one of claims 1 to 9, characterized in that: Includes steps: Mixing workability adjusting monomer, alkyl ether sulfate, unsaturated acid monomer, unsaturated amide, unsaturated sulfonate monomer, surfactant, and water to prepare a base material; The pH value of the base material is adjusted to 7.0-8.0, and solution A and solution B are added dropwise to the base material to start the reaction. After the addition is completed, the reaction is carried out by heat preservation for 1-3 hours to obtain a concrete anti-segregation agent.

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