A cement admixture and its preparation method and application

Abstract

The present invention discloses a cement admixture and a preparation method and application thereof, belonging to the technical field of cement admixtures. The preparation method comprises the following steps: 1) esterification of polyhydroxy organic amine: after mixing polyhydroxy organic amine with unsaturated carboxylic acid, adding a catalyst for catalytic reaction to obtain esterified polyhydroxy organic amine; 2) free radical polymerization: preparing the esterified polyhydroxy organic amine as an esterified polyhydroxy organic amine aqueous solution, and then dripping anionic polymerization monomer solution, cationic polymerization monomer solution, initiator solution and chain transfer agent solution in sequence, and after reaction, obtaining the cement admixture. The present invention also discloses the cement admixture prepared by the above preparation method and its application in improving the adaptability of cement. The present invention reassembles the alcoholamine molecules to synthesize a star-shaped amphoteric polymer, which can not only enhance the grinding aid performance of cement, but also promote the dispersion of cement particles and improve the adaptability of cement.

Description

Technical Field

[0001] The invention belongs to the technical field of cement admixtures, and in particular relates to a cement admixture and a preparation method and application thereof. Background Art

[0002] Cement admixtures have become an essential and important component in the production, preparation and application of cement. Among them, cement grinding aids are an admixture added in the production process of cement. They have the functions of reducing particle agglomeration, improving grinding efficiency, and enhancing cement strength development, and play an important role in energy conservation and carbon reduction in the cement industry. The active ingredient in cement grinding aids is amines, which usually show good grinding aid and strengthening effects. However, these substances can complex calcium ions, thereby increasing the hydration rate of cement in the early stage of hydration, which has an adverse effect on the adaptability of cement.

[0003] Therefore, how to provide an admixture that does not affect the hydration rate of cement in the early stage of hydration is a technical problem that those skilled in the art urgently need to solve. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a cement admixture and a preparation method and application thereof.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A method for preparing a cement admixture comprises the following steps:

[0007] 1) Esterification of polyhydroxy organic amine: after mixing polyhydroxy organic amine with unsaturated carboxylic acid, adding a catalyst to carry out catalytic reaction to obtain esterified polyhydroxy organic amine;

[0008] 2) Free radical polymerization: the esterified polyhydroxy organic amine is prepared as an esterified polyhydroxy organic amine aqueous solution, and then an anionic polymerization monomer solution, a cationic polymerization monomer solution, an initiator solution and a chain transfer agent solution are sequentially added dropwise, and after reaction, the cement admixture is obtained, and the cement admixture has a star structure.

[0009] More preferably, the structure of the cement admixture is as shown in formula (I):

[0010]

[0011] Wherein, R1 and R2 are independently selected from and / or

[0012] The R3 is an anionic monomer polymerization unit, and the structure is shown in formula (II):

[0013]

[0014] Wherein, a, b and c in formula (II) are not equal to 0 at the same time;

[0015] The R4 is an anionic monomer polymerization unit, and its structure is shown in formula (III):

[0016]

[0017] Wherein, d and e in formula (III) are not equal to 0 at the same time.

[0018] Beneficial effects: The present invention reassembles the olamine molecules to synthesize an amphoteric polymer with a star-shaped molecular structure, which can not only achieve the grinding aid and enhancement performance of cement, but also promote the dispersion of cement particles and improve the adaptability of cement.

[0019] Preferably, the polyhydroxy organic amine in step (1) comprises one of triethanolamine, diethanol monoisopropanolamine, monoethanol diisopropanolamine and triisopropanolamine;

[0020] The unsaturated carboxylic acid includes one of acrylic acid and α-methacrylic acid;

[0021] The catalyst is concentrated sulfuric acid.

[0022] Beneficial effects: The above technical solution is beneficial to achieving enhanced performance of cement and providing unsaturated bonds for subsequent free radical polymerization.

[0023] Preferably, the molar ratio of the polyhydroxy organic amine to the unsaturated carboxylic acid in step (1) is 1:3-1:2;

[0024] The added amount of the catalyst is 0.5-2.0% of the total mass of the polyhydroxy organic amine and the unsaturated carboxylic acid.

[0025] Beneficial effect: The above ratio is conducive to achieving full esterification of polyhydroxy organic amines.

[0026] Preferably, the catalytic reaction temperature in step (1) is 80-100° C. and the reaction time is 4-6 hours.

[0027] Beneficial effects: The above conditions are conducive to the full esterification of polyhydroxy organic amines.

[0028] Preferably, the anionic polymerizable monomer in step (2) includes one or two of 2-acrylamide-2-methylpropanesulfonic acid, α-methylacrylic acid, sodium vinyl sulfonate, and 2-methacryloyloxyethyl phosphate;

[0029] The cationic polymerization monomer includes one or two of methacryloylpropyltrimethylammonium chloride and allyltrimethylammonium chloride;

[0030] The initiator is one of acetyl cyclohexanesulfonyl peroxide, dicyclohexyl peroxydicarbonate, and diisobutyl peroxydicarbonate;

[0031] The chain transfer agent is one of dodecyl mercaptan, 3-mercaptopropionic acid butyl ester, and 1-mercapto-2-propanol;

[0032] Beneficial effects: The anionic polymerizable monomers in the present invention are beneficial to adsorb on the surface of cement minerals (C3A and C4AF) and disperse cement particles, while the cationic polymerizable monomers are beneficial to adsorb on the surface of cement minerals (C3S and C2S) and further disperse cement particles.

[0033] Preferably, the mass concentration of the anionic polymerization monomer solution in step (2) is 50%;

[0034] The mass concentration of the cationic polymerization monomer solution is 50%;

[0035] The mass concentration of the initiator solution is 1%;

[0036] The mass concentration of the chain transfer agent solution is 1%.

[0037] Beneficial effects: The above conditions are conducive to forming a target product of fully dispersed cement particles.

[0038] Preferably, the mass ratio of the esterified polyhydroxy organic amine, the anionic polymerizable monomer and the cationic polymerizable monomer in step (2) is (70-85): (15-20): (5-10);

[0039] The added amount of the initiator is 0.1%-1% of the total mass of the esterified polyhydroxy organic amine, the anionic polymerization monomer and the cationic polymerization monomer;

[0040] The added amount of the chain transfer agent is 1%-5% of the total mass of the esterified polyhydroxy organic amine, the anionic polymerizable monomer and the cationic polymerizable monomer.

[0041] Beneficial effects: The above conditions are conducive to the formation of a target product with both enhancement and dispersion functions.

[0042] Preferably, the concentration of the esterified polyhydroxy organic amine aqueous solution in step (2) is 50%-80%.

[0043] The reaction temperature is 25-60°C and the reaction time is 4-6h;

[0044] The total time of the dropwise addition is 2-4 h.

[0045] Beneficial effects: The above conditions are conducive to controlling the degree of polymerization and molecular weight.

[0046] A cement admixture prepared by a method for preparing a cement admixture.

[0047] Beneficial effects: The cement admixture provided by the present invention can not only realize the strengthening effect of traditional alcohol amines on cement, but also improve the dispersibility of cement particles through electrostatic repulsion and steric hindrance by adsorbing cationic and anionic functional groups on the surface of cement minerals with different charges, thereby improving the adaptability of cement.

[0048] The invention discloses an application of a cement admixture in improving the adaptability of cement, wherein the addition amount of the cement admixture is 0.01%-0.10% of the cement mass.

[0049] The present invention provides a cement admixture and a preparation method and application thereof. The present invention polymerizes anionic / cationic functional groups into the molecular structure of polyhydroxy organic amines, which can be adsorbed on the four mineral surfaces of cement, disperse cement particles through electrostatic repulsion and steric hindrance, and improve the adaptability of cement. In addition, the present invention also introduces functional functional groups into the molecular structure of polyhydroxy organic amines, and changes the structure and morphology of hydration products by complexing with metal ions, which is conducive to forming a more compact cement matrix structure and improving the mechanical properties of cement. When the cement admixture provided by the present invention is used in cement technology, the dosage is only 0.01 to 0.1% of the mass of cement. The small dosage has a good effect on improving the early and late strength of cement, and can significantly increase the compatibility of cement. DETAILED DESCRIPTION

[0050] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0051] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below in conjunction with specific implementation methods.

[0052] The raw materials in the examples of the present invention are all purchased from commercial sources.

[0053] The instruments and equipment involved in the preparation process and test process of the cement modifier in the embodiments of the present invention and the comparative examples are as follows:

[0054] Changzhou Ronghua Instrument Manufacturing Co., Ltd. produces digital display electric stirrer;

[0055] Tianjin Tianma Hengji Instrument Co., Ltd. produces several balances;

[0056] NJ-160A cement slurry mixer produced by Wuxi Jianyi Instrument Machinery Co., Ltd.;

[0057] JJ-5 cement mortar mixer produced by Wuxi Jianyi Instrument Machinery Co., Ltd.;

[0058] Beijing Road Construction Instrument Technology Co., Ltd. produces ZS-15 cement mortar vibrating table;

[0059] KZJ-500 electric bending test machine produced by Shenyang Changcheng Electromechanical Equipment Factory;

[0060] Beijing Luda Xingwang Construction Machinery Co., Ltd. produces the HYE-300 fully automatic constant stress pressure testing machine.

[0061] Example 1

[0062] A method for preparing a cement admixture comprises the following steps:

[0063] 1) Esterification of polyhydroxy organic amine: triethanolamine and acrylic acid are added into a reaction vessel at a molar ratio of 1:3, and then concentrated sulfuric acid of 3% of the total weight of triethanolamine and acrylic acid is added thereto, and the temperature is raised to 80° C. for catalytic reaction for 6 hours to obtain esterified triethanolamine;

[0064] 2) Free radical polymerization: water is added to the esterified triethanolamine obtained in step 1) to prepare an esterified triethanolamine aqueous solution with a mass concentration of 60%, and then the temperature is raised to 50° C., and 2-acrylamide-2-methylpropanesulfonic acid solution (50% mass concentration), allyltrimethylammonium chloride solution (50% mass concentration), acetyl cyclohexanesulfonyl peroxide solution (1% mass concentration) and 1-mercapto-2-propanol solution (1%) are added dropwise for 2 hours. After the addition is completed, the reaction is carried out for 4 hours to obtain a cement admixture.

[0065] Among them, the mass ratio of esterified triethanolamine, 2-acrylamide-2-methylpropane sulfonic acid and allyltrimethylammonium chloride is 80:15:5, the added amount of acetyl cyclohexanesulfonyl peroxide is 0.4% of the total mass of esterified triethanolamine, 2-acrylamide-2-methylpropane sulfonic acid and allyltrimethylammonium chloride, and the added amount of 1-mercapto-2-propanol is 1% of the total mass of esterified triethanolamine, 2-acrylamide-2-methylpropane sulfonic acid and allyltrimethylammonium chloride.

[0066] Example 2

[0067] A method for preparing a cement admixture comprises the following steps:

[0068] 1) Esterification of polyhydroxy organic amine: diethanol monoisopropanolamine and α-methacrylic acid are added into a reaction vessel at a molar ratio of 1:2, and then concentrated sulfuric acid with a total weight of triethanolamine and acrylic acid of 0.5% is added thereto, and the temperature is raised to 100° C. for catalytic reaction for 4 hours to obtain esterified diethanol monoisopropanolamine;

[0069] 2) Free radical polymerization: add water to the esterified diethanol monoisopropanolamine obtained in step 1) to prepare an esterified diethanol monoisopropanolamine aqueous solution with a mass concentration of 40%, then heat to 25° C., dropwise add sodium vinyl sulfonate solution (50% mass concentration), methacryloylpropyltrimethylammonium chloride solution (50% mass concentration), dicyclohexyl peroxydicarbonate solution (1% mass concentration) and dodecyl mercaptan solution (1%), the dropping time is 4 hours, and the reaction is carried out for 5 hours after the dropping is completed to obtain a cement admixture.

[0070] Among them, the mass ratio of esterified diethanol monoisopropanolamine: sodium vinyl sulfonate: methacryloylpropyltrimethylammonium chloride is 75:15:10, and the added amounts of acetyl cyclohexanesulfonyl peroxide and 1-mercapto-2-propanol are 0.1% and 3% of the total mass of esterified diethanol monoisopropanolamine, sodium vinyl sulfonate and methacryloylpropyltrimethylammonium chloride, respectively.

[0071] Example 3

[0072] A method for preparing a cement admixture comprises the following steps:

[0073] 1) Esterification of polyhydroxy organic amine: triisopropanolamine and acrylic acid are added into a reaction vessel at a molar ratio of 1:3, and then concentrated sulfuric acid of 1% of the total mass of triethanolamine and acrylic acid is added thereto, and the temperature is raised to 90° C. for catalytic reaction for 5 hours to obtain esterified triisopropanolamine;

[0074] 2) Free radical polymerization: add water to the esterified triisopropanolamine obtained in step 1) to prepare an esterified triisopropanolamine aqueous solution with a mass concentration of 60%, then heat to 40° C., dropwise add sodium vinyl sulfonate solution (50% mass concentration), allyltrimethylammonium chloride solution (50% mass concentration), diisobutyl peroxydicarbonate solution (1% mass concentration) and 3-butyl mercaptopropionate solution (1%), the dropping time is 3 hours, and the reaction is carried out for 6 hours after the dropping is completed to obtain a cement admixture.

[0075] The mass ratio of esterified triisopropanolamine: sodium vinyl sulfonate: allyltrimethylammonium chloride is 85:10:5, and the added amounts of diisobutyl dicarbonate and butyl 3-mercaptopropionate are 0.5% and 5% of the total mass of esterified triisopropanolamine, sodium vinyl sulfonate and allyltrimethylammonium chloride, respectively.

[0076] Example 4

[0077] A method for preparing a cement admixture comprises the following steps:

[0078] 1) Esterification of polyhydroxy organic amine: triethanolamine and α-methacrylic acid are added into a reaction vessel at a molar ratio of 1:3, and then concentrated sulfuric acid with a total weight of 1.5% of triethanolamine and acrylic acid is added thereto, and the temperature is raised to 95° C. for catalytic reaction for 4.5 hours to obtain esterified triethanolamine;

[0079] 2) Free radical polymerization: add water to the esterified triethanolamine obtained in step 1) to prepare an esterified triethanolamine aqueous solution with a mass concentration of 60%, then heat to 45°C, dropwise add anionic monomer solution (sodium vinyl sulfonate, α-methacrylic acid) (50% mass concentration, mass ratio of 1:1) and cationic monomer solution (methacryloylpropyltrimethylammonium chloride, allyltrimethylammonium chloride) (50% mass concentration, mass ratio of 2:3), dicyclohexyl peroxydicarbonate solution (1% mass concentration) and 1-mercapto-2-propanol solution (1%), the dropwise addition time is 3h, and the reaction is carried out for 5.5h after the dropwise addition is completed to obtain a cement admixture.

[0080] The mass ratio of esterified triethanolamine: anionic monomer: cationic monomer is 78:13:9, and the added amounts of dicyclohexyl peroxydicarbonate and 1-mercapto-2-propanol are 0.8% and 2% of the total mass of esterified triethanolamine, anionic monomer and cationic monomer, respectively.

[0081] Technical effect:

[0082] The polymer products obtained in Examples 1-4 were added to cement, and the fluidity test and mechanical property test were carried out according to GB / T 8077 and GB / T 17671, wherein the fluidity control group used polycarboxylate water-reducing agent to adjust the initial fluidity of cement paste to 200±5mm, and the amount of polycarboxylate water-reducing agent added to the test control group and the experimental group was the same. The experimental results are shown in Table 1.

[0083] Table 1 Effects of various grinding aids on cement properties

[0084]

[0085] From the results in Table 1, it can be found that the fluidity of cement paste decreases with time, and when the cement admixtures obtained in Examples 1-4 are added at 0.01-0.10% of the cement mass, the initial fluidity of the cement paste is significantly improved and the loss of fluidity over time is reduced, indicating that the admixtures prepared in Examples 1-4 improve the adaptability of cement. And the strength results show that the admixtures prepared in Examples 1-4 have the effect of improving the early and late mechanical properties of cement.

[0086] The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for preparing a cement admixture, characterized in that: The following steps are involved: (1) Esterification of polyhydroxy organic amine: After mixing the polyhydroxy organic amine with an unsaturated carboxylic acid, a catalyst is added to carry out a catalytic reaction to obtain an esterified polyhydroxy organic amine; (2) free radical polymerization: preparing the esterified polyhydroxy organic amine into an esterified polyhydroxy organic amine aqueous solution, and then sequentially adding dropwise anionic polymerization monomer solution, cationic polymerization monomer solution, initiator solution and chain transfer agent solution, and after reaction, obtaining the cement admixture; The anionic polymerizable monomers in step (2) include one or two of 2-acrylamide-2-methylpropanesulfonic acid, α-methylacrylic acid, sodium vinyl sulfonate, and 2-methacryloyloxyethyl phosphate; The cationic polymerization monomer includes one or two of methacryloylpropyltrimethylammonium chloride and allyltrimethylammonium chloride; The initiator is one of acetyl cyclohexanesulfonyl peroxide, dicyclohexyl peroxydicarbonate, and diisobutyl peroxydicarbonate; The chain transfer agent is one of dodecyl mercaptan, 3-mercaptopropionic acid butyl ester and 1-mercapto-2-propanol.

2. The method for preparing a cement admixture according to claim 1, characterized in that: The polyhydroxy organic amine in step (1) comprises one of triethanolamine, diethanol monoisopropanolamine, monoethanol diisopropanolamine and triisopropanolamine; The unsaturated carboxylic acid includes one of acrylic acid and α-methacrylic acid; The catalyst is concentrated sulfuric acid.

3. The method for preparing a cement admixture according to claim 1, characterized in that: The molar ratio of the polyhydroxy organic amine to the unsaturated carboxylic acid in step (1) is 1:3-1:2; The added amount of the catalyst is 0.5-2.0% of the total mass of the polyhydroxy organic amine and the unsaturated carboxylic acid.

4. The method for preparing a cement admixture according to claim 1, characterized in that: The catalytic reaction temperature in step (1) is 80-100° C. and the reaction time is 4-6 hours.

5. The method for preparing a cement admixture according to claim 1, characterized in that: The mass concentration of the anionic polymerization monomer solution in step (2) is 50%; The mass concentration of the cationic polymerization monomer solution is 50%; The mass concentration of the initiator solution is 1%; The mass concentration of the chain transfer agent solution is 1%.

6. The method for preparing a cement admixture according to claim 1, characterized in that: The mass ratio of the esterified polyhydroxy organic amine, the anionic polymerizable monomer and the cationic polymerizable monomer in step (2) is (70-85): (15-20): (5-10); The added amount of the initiator is 0.1%-1% of the total mass of the esterified polyhydroxy organic amine, the anionic polymerization monomer and the cationic polymerization monomer; The added amount of the chain transfer agent is 1%-5% of the total mass of the esterified polyhydroxy organic amine, the anionic polymerizable monomer and the cationic polymerizable monomer.

7. The method for preparing a cement admixture according to claim 1, characterized in that: The concentration of the esterified polyhydroxy organic amine aqueous solution in step (2) is 50%-80%; The reaction temperature is 25-60°C and the reaction time is 4-6h; The total time of the dropwise addition is 2-4 h.

8. A cement admixture prepared by the method for preparing a cement admixture according to any one of claims 1 to 7.

9. The use of a cement admixture as claimed in claim 8 in improving the adaptability of cement, characterized in that: The cement admixture is added in an amount of 0.01%-0.10% of the cement mass.

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