A water-hardening cementitious material slurry anti-segregation agent and a preparation method thereof

Abstract

The present application relates to a kind of hydraulic cementitious material slurry anti-segregation agent and its preparation method, the preparation raw material of the anti-segregation agent includes: workability adjusting monomer 7-9 parts;Alkyl ether sulfate 3-4 parts;Unsaturated ester monomer 4-6 parts;Surfactant 3-5 parts;Unsaturated acid monomer 8-12 parts;Unsaturated amide 25-45 parts;2-acrylamide-2-methylpropane sulfonic acid 3-10 parts;Reducing agent 0.9-1.4 parts;Oxidizing agent 1.0-2.0 parts;And water;The present application can form hydrogen bond network by introducing workability adjusting monomer, increase the viscosity of concrete mixture moderately, prevent aggregate sinking and cement slurry 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] The present application relates to the technical field of concrete admixtures, in particular to a water-hardening cementitious material slurry anti-segregation agent and a preparation method thereof. BACKGROUND

[0002] Concrete admixtures are currently the most widely researched and applied concrete additives. In the case of maintaining the workability of concrete, the addition of water reducing agents can effectively save cement consumption, reduce water consumption, and improve the strength of concrete. Polycarboxylate superplasticizer is widely used in various construction projects due to its low dosage, good slump retention, strong molecular structure controllability, and green and environmentally friendly production process. However, with the rapid development of the construction industry, a large amount of cement and aggregate is consumed in a large number of engineering construction, exacerbating the shortage of aggregate resources. The natural sand and stone resources in many parts of the country are becoming increasingly scarce, and the supply of aggregate materials is insufficient, resulting in unstable quality of aggregate materials and high and unstable clay content of aggregate materials. These factors, combined with the differences in raw materials and environment, result in insufficient or rapid loss of fresh concrete fluidity, or cause concrete segregation and bleeding, increasing the difficulty of controlling concrete production.

[0003] Traditional anti-segregation measures such as adjusting the mix proportion, optimizing the mixing process, and controlling the slump have limitations and cannot fundamentally solve the problem. In recent years, the development of efficient anti-segregation agents has become a key way to improve the uniformity and stability of concrete. An ideal anti-segregation agent should have good dispersibility, appropriate viscosity adjustment, excellent water retention, and be environmentally friendly and economical. However, existing anti-segregation agents still have deficiencies in terms of application scope, compatibility, and long-term performance. Therefore, there is an urgent need to develop a water-hardening cementitious material slurry anti-segregation agent that is suitable for various types of concrete, compatible with various admixtures, can improve the long-term performance of concrete, and is environmentally friendly and economical, in order to improve the quality and performance of concrete and promote the sustainable development of the building materials industry. SUMMARY

[0004] Therefore, it is necessary to provide a water-hardening cementitious material slurry anti-segregation agent and a preparation method thereof, aiming to solve the technical problems existing in the prior art.

[0005] To achieve the above-mentioned purpose, the present application provides a technical solution:

[0006] A water-hardening cementitious material slurry anti-segregation agent, the preparation raw materials of the anti-segregation agent include, in terms of weight fraction:

[0007]

[0008] The structure formula of the workability adjusting monomer is as follows:

[0009] wherein n is an integer from 1 to 25, and m is an integer from 1 to 50.

[0010] In some embodiments, the raw material for preparing the workability adjusting monomer comprises an unsaturated ether, an acyl chloride compound, and an alkylene oxide.

[0011] In some embodiments, the alkylene oxide comprises ethylene oxide and propylene oxide.

[0012] In some embodiments, the step of preparing the workability adjusting monomer comprises:

[0013] S110, dissolving the unsaturated ether in a first organic solvent to obtain an unsaturated ether solution;

[0014] S120, dissolving the acyl chloride compound in a second organic solvent to obtain an acyl chloride compound solution;

[0015] S130, adding the acyl chloride compound solution dropwise into the unsaturated ether solution to react, and obtaining a functional monomer after the reaction is completed.

[0016] S140, under alkaline conditions, introducing ethylene oxide and propylene oxide into the hydrophobic functional monomer to obtain the workability adjusting monomer.

[0017] In some embodiments, the concentration of the unsaturated ether solution is 0.25 mol / L to 0.30 mol / L.

[0018] In some embodiments, the concentration of the acyl chloride compound solution is 0.35 mol / L to 0.4 mol / L.

[0019] In some embodiments, in step S110, an acid binding agent is further added into the unsaturated ether solution, because the reaction between the unsaturated ether and the acyl chloride compound releases hydrogen chloride, and the acid binding agent neutralizes the hydrogen chloride to prevent the acidic byproduct from affecting the reaction efficiency and the product quality. As a preferred embodiment, the acid binding agent is triethylamine.

[0020] In some embodiments, the unsaturated ether comprises at least one of ethylene glycol monovinyl ether, 4-hydroxybutyl vinyl ether, and diethylene glycol monovinyl ether.

[0021] In some embodiments, the acyl chloride compound comprises at least one of acryloyl chloride, methacryloyl chloride, and maleoyl chloride.

[0022] In some embodiments, the first solvent comprises at least one of acetone, dichloromethane, trichloromethane, acetonitrile, and toluene.

[0023] In some embodiments, the second solvent includes at least one of acetone, dichloromethane, trichloromethane, acetonitrile and toluene.

[0024] In some embodiments, the reaction temperature in step S130 is 50-70°C.

[0025] In some embodiments, the reaction time in step S130 is 12-14h.

[0026] In some embodiments, the functional monomer in step S130 can be purified by the following steps:

[0027] The salts generated in the reaction process are removed by filtration, the solvent is removed by a rotary evaporator, and then the functional monomer is extracted by diethyl ether and dried under vacuum at room temperature.

[0028] In some embodiments, the specific steps in step S140 are as follows:

[0029] The functional monomer is slowly heated to 110-130°C, and dehydrated under reduced pressure to 0.1-0.2 MPa; after dehydration, sodium hydroxide is added, and then nitrogen is passed to remove excess oxygen; after degassing, ethylene oxide is introduced, and after the pressure remains unchanged, propylene oxide is introduced, and after the reaction is completed, the reaction system is cooled to 70-90°C, acetic acid is added for neutralization, and then filtered to obtain the workability adjusting monomer.

[0030] In some embodiments, the molar ratio of the unsaturated ether and the acyl chloride compound is (5-7):(7-8).

[0031] In some embodiments, the mass ratio of the functional monomer, ethylene oxide and propylene oxide in step S410 is (100-120):(400-800):(130-170).

[0032] In some embodiments, the unsaturated amide includes at least one of acrylamide, N-phenyl acrylamide, N-isobutyl acrylamide, N-hydroxy acrylamide and N-p-hydroxyphenyl acrylamide, and preferably acrylamide.

[0033] In some embodiments, the reaction temperature in step S140 is 110-130°C.

[0034] In some embodiments, the reaction pressure in step S140 is 0.1-0.3 MPa.

[0035] In some embodiments, the unsaturated ester monomer is rhamnolipid, and the structure of the rhamnolipid is as follows:

[0036] one of Claims 1-6.

[0037] Specifically, in the rhamnolipid, the hydrophilic rhamnose group improves the workability and uniformity of the concrete by reducing the surface tension, dispersing particles and improving water retention; while the hydrophobic fatty acid chain group enhances the durability and segregation resistance of the concrete by emulsifying, stabilizing the foam and optimizing the interface transition zone, and the synergistic effect between the two makes the rhamnolipid a high-efficiency concrete segregation resistance agent.

[0038] In some embodiments, the alkyl ether sulfate has the following general structure:

[0039] RO-(CH2 CH2O) n -SO3Na;

[0040] wherein R is an alkyl chain of C8-C18, and n is a positive integer of 1-4.

[0041] 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.

[0042] In some embodiments, the unsaturated acid monomer includes at least one of acrylic acid and methacrylic acid.

[0043] In some embodiments, the reducing agent includes at least one of ascorbic acid, sodium formaldehyde sulfoxylate, sodium sulfite, sodium bisulfite, sodium bisulfite, and sodium hypophosphite.

[0044] In some embodiments, the oxidizing agent includes at least one of potassium persulfate and ammonium persulfate.

[0045] The present application also provides a preparation method of the water-hardening cementitious material slurry segregation resistance agent, and the preparation method includes the following steps:

[0046] S210, mixing the workability adjusting monomer, the alkyl ether sulfate, the unsaturated acid monomer, the unsaturated amide, 2-acrylamide-2-methylpropane sulfonic acid, the surfactant, and water to prepare a base material;

[0047] S220, adjusting the pH value of the base material to 7.0-8.0, adding solution A and solution B into the base material to start the reaction, and after the addition is completed, the reaction is kept for 1-3 hours to obtain the water-hardening cementitious material slurry segregation resistance agent.

[0048] The solution A is an aqueous solution of unsaturated acid monomer, unsaturated ester monomer and reducing agent; specifically, in the preparation method, the unsaturated acid monomers are added twice, the first time is added in the mother liquor to adjust the pH of the mother liquor, and the second time is added dropwise into the mother liquor from the solution A to participate in the reaction, and the mass ratio of the unsaturated acid monomers in the mother liquor to the unsaturated acid monomers in the solution A is 1: (1-2).

[0049] The solution B is an aqueous solution of an oxidizing agent.

[0050] In some embodiments, the initial reaction temperature in step S220 is 30-45 DEG C.

[0051] In some embodiments, the dropping time of the solution A is 1-2 hours.

[0052] In some embodiments, the dropping time of the solution B is 1-2 hours.

[0053] The beneficial effects of the present application are as follows:

[0054] 1. The present application can react with cement hydration products (such as Ca (OH) 2) to form stable complexes or covalent bonds by introducing and adjusting the monomer, thereby improving the interface transition zone between the cement paste and the aggregate. And it can form a hydrogen bond network with water molecules, moderately increase the viscosity of the concrete mixture, prevent the sinking of the aggregate and the floating of the cement paste, thereby effectively inhibiting segregation. At the same time, they can also maintain the fluidity of the concrete, ensuring its good operability in the construction process such as pumping and vibrating. This balanced viscosity adjustment capability makes the concrete neither too thick nor too thin, thereby improving the construction efficiency.

[0055] 2. The anti-segregation agent prepared by the present application can continuously and slowly release free water to supplement the free water consumed in the hydration process through the hydrolysis effect of the amide group, meeting the demand for the fluidity of the concrete time-dependent viscosity retention agent.

[0056] 3. The preparation method of the present application introduces sulfonic acid groups, carboxylate groups and ester groups into the polymer molecular structure. Among them, the ester groups continuously hydrolyze in the cement hydration process, continue to react with the cement hydration products, inhibit the growth of Ca (OH) 2 and AFt crystal nucleus, slow down the hydration speed, and prolong the cement hydration induction period, thereby playing a role in improving the retention. The sulfonic acid group can react with calcium ions in cement to form a network structure with adhesion, further improving the slump retention of concrete and being able to be adsorbed on the surface of cement particles, so that the surface of cement particles has a negative charge, thereby reducing the repulsion between cement particles, playing a dispersion and adsorption role.

[0057] 4. The anti-segregation agent prepared by the method has the advantages of anti-segregation, viscosity adjustment and good workability, can significantly reduce the viscosity of the concrete, and improve the workability of the concrete. DETAILED DESCRIPTION

[0058] For the purpose, technical solution and advantages of the present application, the present application will be further described below in combination with specific examples.

[0059] In the examples, the test methods used are conventional methods unless otherwise specified, and the materials, reagents, etc. used are commercially available unless otherwise specified.

[0060] I. Preparation of workability adjusting monomer

[0061] 1. Workability adjusting monomer A:

[0062] S110, accurately weigh 0.25 mol of ethylene glycol monovinyl ether and 0.10 mol of triethylamine dissolved in dichloromethane, and add to a three-necked flask with a circulating cooling reflux device to obtain an unsaturated ether solution;

[0063] S120, dissolve 0.35 mol of acryloyl chloride in dichloromethane to obtain an acyl chloride compound solution;

[0064] S130, add the acyl chloride compound solution dropwise into the three-necked flask, and react at a temperature of 50℃ for 14 hours to obtain functional monomer A.

[0065] Then, the salts generated during the reaction process are removed by suction filtration, the solvent is removed using a rotary evaporator, and then extracted with diethyl ether and vacuum dried at room temperature for 24 hours to obtain pure functional monomer A.

[0066] S140, add 100 parts of functional monomer to the reaction vessel, slowly heat to 110℃, and dehydrate under reduced pressure to 0.1 MPa; after dehydrating, add 5 parts of sodium hydroxide, then pass nitrogen gas into the reaction kettle to remove excess oxygen; after degassing, pass in 400 parts of ethylene oxide, and after the pressure remains unchanged, pass in 300 parts of propylene oxide; after the reaction is complete, the reaction system is cooled to 70℃, 3 parts of acetic acid is added for neutralization, and then filtered to obtain the workability adjusting monomer A.

[0067] 2. Workability adjusting monomer B:

[0068] S110, accurately weigh 0.25 mol of 4-hydroxybutyl vinyl ether and 0.10 mol of triethylamine dissolved in dichloromethane, and add to a three-necked flask with a circulating cooling reflux device to obtain an unsaturated ether solution;

[0069] S120, 0.35 mol of acryloyl chloride is dissolved in dichloromethane to obtain an acyl chloride compound solution;

[0070] S130, the acyl chloride compound solution is added dropwise into a three-necked flask, and reacted at 50°C for 14 hours to obtain functional monomer B.

[0071] Then, the salts generated in the reaction process are removed by suction filtration, the solvent is removed using a rotary evaporator, and then extracted with diethyl ether, and vacuum dried at room temperature for 24 hours to obtain pure functional monomer B.

[0072] S140, 100 parts of functional monomer are added to the reaction vessel, slowly heated to 110°C, and dehydrated under reduced pressure to 0.1 MPa; after dehydration, 5 parts of sodium hydroxide are added, then nitrogen is introduced into the reaction kettle to remove excess oxygen; after degassing, 400 parts of ethylene oxide are introduced, and after the pressure remains unchanged, 300 parts of propylene oxide are introduced, and 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.

[0073] 2. Workability adjusting monomer C:

[0074] S110, 0.25 mol of diethylene glycol monovinyl ether and 0.10 mol of triethylamine are accurately weighed and dissolved in dichloromethane, and then added to a three-necked flask with a circulating cooling reflux device to obtain an unsaturated ether solution;

[0075] S120, 0.35 mol of acryloyl chloride is dissolved in dichloromethane to obtain an acyl chloride compound solution;

[0076] S130, the acyl chloride compound solution is added dropwise into a three-necked flask, and reacted at 50°C for 14 hours to obtain functional monomer C.

[0077] Then, the salts generated in the reaction process are removed by suction filtration, the solvent is removed using a rotary evaporator, and then extracted with diethyl ether, and vacuum dried at room temperature for 24 hours to obtain pure functional monomer C.

[0078] S140, 100 parts of functional monomer are added to the reaction vessel, slowly heated to 110°C, and dehydrated under reduced pressure to 0.1 MPa;

[0079] After dehydration, 5 parts of sodium hydroxide are added, then nitrogen is introduced into the reaction kettle to remove excess oxygen; after degassing, 400 parts of ethylene oxide are introduced, and after the pressure remains unchanged, 300 parts of propylene oxide are introduced, and 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 C.

[0080] II. Preparation of water-hardening cement paste segregation resistance agent

[0081] Example 1:

[0082] S210, 5 parts of acrylic acid, 30 parts of acrylamide, 6 parts of 2-acrylamido-2-methylpropane sulfonic acid, 8 parts of a workability adjusting monomer, 3 parts of an alkyl ether sulfate, and 2 parts of a surfactant are mixed with an aqueous solution to prepare a base solution, and a sodium hydroxide solution is added to the base solution to adjust the pH value of the base solution to 7.0-8.0;

[0083] S220, wherein the initial reaction temperature is 35°C, the dropping time of solution A and solution B is 2h, and the apparent viscosity of the cement paste is measured after the dropping is completed and the solution is aged for 3h.

[0084] Solution A is prepared by mixing 5 parts of acrylic acid, 4 parts of rhamnolipid, and 1.3 parts of sodium hypophosphite with water;

[0085] Solution B is prepared by mixing 1.1 parts of potassium persulfate with water;

[0086] The experimental procedures 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, as shown in Table 1 for the raw material ratios of Examples and Table 2 for the raw material ratios of Comparative Examples.

[0087] Table 1 Raw material ratio table of Examples

[0088]

[0089]

[0090] Table 2 Raw material ratio table of Comparative Examples

[0091]

[0092] The polycarboxylic acid water reducing agent samples obtained by synthesizing Examples 1-4 and Comparative Examples 1-4 are subjected to neat paste apparent viscosity test to evaluate the viscosity reducing performance of the water reducing agent synthesized in the Examples.

[0093] The cement used in the mortar test is reference P·O 42.5 cement, and the water-cement ratio is kept at 0.29. Three parallel tests are performed for each water reducing agent sample. By adjusting the water reducing agent dosage, the initial fluidity of each sample is ensured to be within the range of 280±10mm. The RheolabQC rotary rheometer produced by Anton Par Company in Germany is used to test the apparent viscosity of each paste sample, and the test data are shown in Table 3.

[0094] Table 3 Test results of neat paste apparent viscosity

[0095]

[0096] From Table 3, it can be seen that the apparent viscosity of the anti-segregation agent prepared in the embodiment of the present application and the addition of the comparative examples can effectively adjust the viscosity of the slurry, adjust the workability of the slurry, and the viscosity variation of the embodiment is larger than that of the comparative examples, which can effectively increase the viscosity of the slurry.

[0097] In order to effectively evaluate the application effect of the anti-segregation agent in concrete, the optimized C30 mixing proportion is used in the present study, and the cementitious material and sand ratio are adjusted.

[0098] Specifically, the cementitious material per cubic meter of concrete is reduced by 30 kg, and the sand ratio is reduced by 2% to 4% while keeping other ingredients unchanged. This adjustment aims to simulate the segregation problem that may occur in actual construction, that is, the initial expansion degree of concrete is controlled between 550 mm and 650 mm, and there should be obvious stone separation, accumulation and bleeding or slurry bleeding phenomenon after initial state or standing.

[0099] The concrete mixing proportion used in the experiment is as follows:

[0100]

[0101]

[0102] The formulation of the admixture is as follows:

[0103]

[0104] Table 4: Concrete test data table

[0105]

[0106] As can be seen from Table 4, the comparative example 1 without adding workability adjusting monomer and the comparative example 2 without adding rhamnolipid have slight bleeding phenomenon over time, and the workability is poor. The anti-segregation agents prepared in Examples 1-4 have lower dosage, and the performance of 0h and 2.0h concrete is better, and the influence on fluidity is small.

[0107] It should be noted that the specific parameters or some reagents in the above embodiments are specific embodiments or preferred embodiments under the concept of the present application, but not a limitation; those skilled in the art can make adaptive adjustments within the concept and protection scope of the present application.

Claims

1. A water-hardening cementitious material slurry anti-separating agent, characterized by, The preparation raw materials of the anti-segregation agent include, in parts by weight: The structure formula of the workability adjusting monomer is as follows: One of the above compounds wherein n is an integer from 1 to 25 and m is an integer from 1 to 50. The surfactant includes one of methyl methacryloyloxyethyl dimethyl hexadecyl ammonium chloride, methyl methacryloyloxyethyl dimethyl octadecyl ammonium chloride, methyl methacryloyloxyethyl dimethyl dodecyl ammonium chloride, and acryloyloxyethyl dimethyl hexadecyl ammonium chloride. The unsaturated ester monomer is rhamnolipid.

2. The set retarding admixture for hydraulic cementitious material slurry according to claim 1, characterized in that, The preparation raw materials of the workability adjusting monomer include unsaturated ether, acyl chloride compound, and alkylene oxide.

3. The set retarding admixture for hydraulic cementitious material slurry according to claim 2, characterized in that, The preparation steps of the workability adjusting monomer include: dissolving the unsaturated ether in a first organic solvent to obtain an unsaturated ether solution; dissolving the acyl chloride compound in a second organic solvent to obtain an acyl chloride compound solution; adding the acyl chloride compound solution dropwise into the unsaturated ether solution to react, and obtaining the functional monomer after the reaction; under alkaline conditions, introducing the alkylene oxide into the functional monomer to obtain the workability adjusting monomer.

4. The set retarding admixture for hydraulic cementitious material slurry according to claim 2, wherein The unsaturated ether includes at least one of ethylene glycol monovinyl ether, 4-hydroxybutyl vinyl ether, and diethylene glycol monovinyl ether.

5. The set retarding admixture for hydraulic cementitious material slurry according to claim 2, wherein The acyl chloride compound includes at least one of acryloyl chloride, methacryloyl chloride, and maleoyl chloride.

6. The set retarding admixture for hydraulic cementitious slurry of claim 1, wherein, The structure formula of the rhamnolipid is as follows: one of the following:

7. The set retarding admixture for hydraulic cementitious material slurry of claim 1, wherein, The general structure formula of the alkyl ether sulfate is as follows: RO-(CH2CH2O) n -SO3Na; wherein, R is an alkyl chain of C8-C18, and n is a positive integer of 1-4.

8. A method for the production of a setting time retarder for a hydraulic cementitious material slurry according to any one of claims 1 to 7, characterized in that The method includes the steps of: mixing the workability adjusting monomer, the alkyl ether sulfate, the unsaturated acid monomer, the unsaturated amide, 2-acrylamide-2-methylpropane sulfonic acid, the surfactant, and water to prepare a base material; adjusting the pH value of the base material to 7.0-8.0, adding solution A and solution B into the base material to start the reaction, and obtaining the hydraulic cementitious material slurry anti-segregation agent after the addition is completed and the reaction is maintained for 1-3 hours.

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