Monosilane methacrylate, preparation method of monosilane methacrylate, compound water reducer and preparation method of compound water reducer

Abstract

The invention relates to the field of compound synthesis, in particular to methacrylic acid monosilane ester and a preparation method thereof, and a compound water reducer and a preparation method thereof. According to the invention, (methyl) acrylic acid and alcoholic hydroxyl modified silicone oil are subjected to an esterification reaction under the action of a catalyst and a polymerization inhibitor to prepare methacrylic acid monosilane ester. According to the method, the characteristics that micromolecular silicone oil is a linear polymer and is hydrophobic are utilized, micromolecular hydroxyl-terminated silicone oil and (methyl) acrylic acid in unsaturated carboxylic acid are selected as raw materials, and monosilane methacrylate is generated through esterification reaction, so that the hydrophilicity of the monosilane methacrylate is improved. The generated methacrylic acid monosilane ester and unsaturated carboxylic acid are subjected to a copolymerization reaction to synthesize the water reducing agent taking a Si-O bond as a core, and the characteristics of easy film formation and high rigidity of a siloxane long chain are retained. The methacrylic acid monosilane ester is suitable for gypsum-based self-leveling mortar, has excellent water absorption, impermeable pressure and compressive strength, and has waterproof and reinforcing effects in the gypsum-based mortar.

Description

Technical Field

[0001] The invention relates to the field of compound preparation, and in particular to monosilane methacrylate and a preparation method thereof, a composite water reducing agent and a preparation method thereof. Background Art

[0002] Gypsum-based self-leveling mortar is widely used in indoor floor heating pads, exterior wall decoration, etc. because of its advantages such as light weight, fire resistance, sound insulation and heat preservation, and fast hardening speed.

[0003] However, gypsum-based self-leveling mortar has many capillary pores on its surface and a low softening coefficient, so it is easily softened by absorbing water and moisture. At the same time, the gypsum base dries quickly, resulting in poor volume stability. After the gypsum-based self-leveling mortar is formed, the compressive strength is low after it comes into contact with water or absorbs water, which affects the quality of the project and its promotion and use.

[0004] In the process of mixing gypsum-based self-leveling mortar, appropriate amounts of cement and water reducing agent are added to improve the working performance of the mortar, compensate for the shrinkage of the mortar after strengthening, and improve the water resistance and structural density of the hardened gypsum body. However, adding cement will reduce the color of the gypsum mortar base surface. The water reducing agent currently added to gypsum-based self-leveling mortar is a water reducing agent designed to solve concrete construction problems. Its carrier is cement, which has different physical and chemical properties from gypsum-based rapid hardening materials, resulting in many problems in the application of gypsum-based mortar.

[0005] Silane ester is an organic silicon compound, usually used as a surface modifier, coupling agent or cross-linking agent, and is widely used in the fields of plastics, rubber, coatings, adhesives and composite materials. However, the existing silane ester water reducer has high water absorption, poor water-proof (resistance) effect, low anti-seepage pressure and water-resistant compressive strength when used in gypsum-based self-leveling mortar.

[0006] In the prior art, how to prepare a water reducing agent suitable for gypsum-based self-leveling mortar with low water absorption, excellent anti-seepage pressure and compressive strength is a difficult problem that technicians in this field need to solve. Summary of the invention

[0007] The invention aims to solve the problems that the silane ester water reducing agent in the existing gypsum-based self-leveling mortar has poor water resistance (waterproofing) effect, low anti-seepage pressure and low compressive strength.

[0008] The present invention provides a monosilyl methacrylate as described in general formula I: (I) Wherein, R is an alkyl group, a silane group or a cycloalkyl group, R1 is hydrogen or a methyl group, R2 is an amino group, a benzene ring or hydrogen, n is 1-5, and m is 1-3.

[0009] The monosilyl methacrylate provided by the present invention is a small molecule with a homopolymer molecular weight of 270-660, and a hydroxyl group is retained at one end. Since the hydroxyl group is a low-viscosity linear group, the synthesized monosilyl methacrylate is polar, and the molecule is in an asymmetric polar long chain. The asymmetric molecular configuration leads to mutual twisting in molecular motion. When applied to a water reducer, the surface film-forming effect of the water reducer on the gypsum-based mortar can be improved, and the fluidity of the gypsum-based mortar can be improved by using an appropriate amount of the water reducer.

[0010] In addition, the monosilyl methacrylate has Si-O bonds as its core skeleton. Compared with the conventional PCE water reducer with -CC bonds as its skeleton, it retains the film-forming, high rigidity and hydrophobic properties of the long chain of siloxane. After mixing and acting with gypsum-based materials, its aqueous solution penetrates into the mortar structure and is brought into the gaps inside the gypsum-based mortar, where it undergoes a chelating reaction with the calcium ions in the gypsum base to form water-insoluble microcrystalline particles with Si-O as the core. The crystals are formed from sparse to dense in the gaps of the gypsum-based mortar, so that a dense anti-seepage area is gradually formed from the surface of the gypsum-based mortar structure to the depth, thereby rapidly improving the strength of the gypsum-based mortar.

[0011] As the water molecules evaporate, the gypsum hardens quickly, and the long hydrophobic silane chains in the monosilyl methacrylate remain in the pores of the gypsum mortar, overlapping and interlacing to form a rigid hydrophobic film between the mortar pores, sealing the tiny pores of the gypsum-based board, preventing foreign water molecules from gathering on the surface and penetrating into the interior of the gypsum-based board, and effectively improving the water resistance of the gypsum-based self-leveling mortar surface.

[0012] The present invention also provides a method for preparing monosilyl methacrylate, comprising the following steps: The (meth)acrylic acid of the general formula II and the alcohol hydroxyl-modified silicone oil of the general formula III are subjected to an esterification reaction under the action of a catalyst and a polymerization inhibitor, and monosilane methacrylate is obtained after separation; (II) (III) Wherein, R in general formula II is hydrogen or methyl, R in general formula III is alkyl, silane or cycloalkyl, R2 is hydrogen or methyl, R3 is amino, benzene ring or hydrogen, n is 1-5, and m is 1-3.

[0013] The method for preparing monosilyl methacrylate provided by the present invention utilizes the characteristics of organic silicone oil as a linear polymer, which is hydrophobic and is commonly used as a waterproofing agent for materials such as building materials, textiles, and paper, and selects small molecular hydroxyl-terminated silicone oil and unsaturated carboxylic acid as raw materials, and generates silane esters through esterification reaction. Then, the silane esters are copolymerized with unsaturated carboxylic acids to obtain a PCE-type water reducer with Si-O bonds as the core skeleton, which retains the film-forming properties of the long chain of siloxane (Si-O bond energy is 100KJ / mol higher than CC bond energy), high rigidity, and hydrophobic properties, and the chelation effect of unsaturated carboxylic acid groups and calcium ions, and is used in gypsum-based mortar to enhance waterproofing. The prepared monosilyl methacrylate has certain hydrophobic properties, which enable the mortar to form a waterproof film when it contacts water, reduce the absorption and penetration of water, and effectively improve the waterproof performance of gypsum-based mortar.

[0014] At the same time, the prepared terminal hydroxyl silane ester has active hydroxyl groups and has a proper retarding effect. To a certain extent, it can delay the rapid hardening of anhydrous gypsum and maintain the working performance of gypsum-based mortar.

[0015] Preferably, the catalyst is one or more of stannous sulfate, stannous chloride, stannous pyrophosphate, cuprous chloride and phosphoric acid.

[0016] The catalyst is not only an esterification catalyst, but also a hydroxyl protective agent to prevent the terminal hydroxyl group from being oxidized; in addition, the catalyst can also inhibit the production of diester products (by-products), and can control the diester products in the esterification product within a certain range. During the reaction, the catalyst is dissolved in an acidic solution. As the esterification reaction of the system proceeds, the free acid is consumed, the acid radical (pH) concentration in the system gradually decreases, the dissolution effect of the stannous salt in the catalyst decreases, and it slowly precipitates to form microparticles. The concentration of stannous ions in the catalyst decreases rapidly, which naturally delays the esterification reaction. Even if the system temperature is increased within a certain range and the system reaction time is extended, the diesterization rate will not increase, and the proportion of diester products (by-products) is maintained at about 3%-11%.

[0017] Preferably, the added amount of the catalyst is 0.02%-0.2% of the total mass of (meth)acrylic acid and alcohol hydroxyl modified silicone oil.

[0018] Preferably, the polymerization inhibitor is one or more of hydroquinone or phenothiazine, and its function is to prevent the self-polymerization of (meth)acrylic acid in the system at high temperature through free radical reaction, or to prevent the unsaturated double bonds of the esterification product from being oxidized and losing their reactivity during storage.

[0019] Preferably, the addition amount of the polymerization inhibitor is 0.02%-0.4% of the total mass of (meth)acrylic acid and alcohol hydroxyl modified silicone oil.

[0020] Preferably, the molar ratio of the (meth) acrylic acid to the alcohol hydroxyl modified silicone oil is 1.6-2.0%. Preferably, the alcohol hydroxyl-modified silicone oil is terminal hydroxyl amino-modified silicone oil, double terminal hydroxyl amino-modified silicone oil or terminal hydroxyl hydrogenated heterocyclic silicone oil.

[0021] Preferably, the alcohol hydroxyl-modified silicone oil is a double-terminal hydroxyl amino-modified silicone oil.

[0022] Preferably, the homopolymer molecular weight of the alcohol hydroxyl modified silicone oil is 100-3000.

[0023] Preferably, the homopolymer molecular weight of the alcohol hydroxyl modified silicone oil is 200-600 or 800-1200.

[0024] Preferably, the esterification reaction is carried out under nitrogen protection, stirred at a temperature of 60-100° C. for 40-120 min, and the silane ester esterification liquid is obtained after cooling. Preferably, the silane ester esterification liquid is separated by extraction to obtain the methacrylic acid monosilane ester described in Formula I; specifically, the extraction process is: Dissolve the silane esterification liquid in a saturated sodium chloride solution, stir and disperse it completely, and let it stand for extraction. The upper oily liquid is disilane ester and silicone oil. Keep the lower aqueous solution, filter it with an RO (reverse osmosis) membrane, wash it with pure water, and collect the components gathered in the RO membrane tube diameter, which is methacrylate monosilane ester.

[0025] Preferably, the temperature of the esterification reaction is 75-85°C.

[0026] The present invention also provides a composite water reducing agent, characterized in that: The components A and B are mixed for preparation; The component A comprises 80% to 91% by weight of monosilyl methacrylate, 3% to 11% of disilyl methacrylate, 0.3% to 7% of (meth)acrylic acid and 0.1% to 10% of alcohol hydroxyl modified silicone oil; The component B is any one of a polycarboxylate water reducer and a melamine water reducer; The mass ratio of component A to component B is (3-9):(1-2).

[0027] The composite water-reducing agent provided by the present invention combines the hydrophobic and lipophilic properties, longer chains and good superimposed film-forming effect of disilane esters with the small molecular weight, easy film-forming and high rigidity of monosilane esters. It has good molecular film-forming effect and is applied in gypsum-based mortar with excellent waterproof effect and compressive strength.

[0028] In addition, the silane ester esterification liquid produced in the preparation process of the present invention has disilane ester and monosilane ester in the required ratio without separation and ratio, and can directly reach a weight ratio of 80%-91% of monosilane methacrylate, 3%-11% of disilane methacrylate, 0.3%-7% of (meth)acrylic acid and 0.1%-10% of alcohol hydroxyl modified silicone oil. The above silicone oil ester mixed liquid is directly copolymerized with acrylic acid to obtain a silane ester water reducer.

[0029] Preferably, when the homopolymer molecular weight of the alcohol hydroxyl modified silicone oil is 800-1200, the ratio of monosilyl methacrylate to disilyl methacrylate is 100:7-13, and the molecular film-forming effect is the best, and the waterproof effect is the best when used in gypsum-based self-leveling mortar.

[0030] Preferably, when the homopolymer molecular weight of the alcohol hydroxyl modified silicone oil is 200-600, the ratio of monosilyl methacrylate to disilyl methacrylate is 100:3-9, which has the defoaming effect of silane ester and the microbead effect of Si-O, and has a good viscosity reduction effect on high-grade concrete.

[0031] The present invention also provides a method for preparing a composite water reducing agent, which is characterized by: The preparation method of component A is: The (meth)acrylic acid of the general formula II and the alcohol hydroxyl-modified silicone oil of the general formula III are subjected to an esterification reaction under the action of a catalyst and a polymerization inhibitor to obtain component A; (II) (III) Wherein, R in the general formula II is hydrogen or methyl, R in the general formula III is alkyl, silyl or cycloalkyl, R2 is amino, benzene ring or hydrogen, n is 1-5, and m is 1-3; The component B is any one of a polycarboxylate water reducer and a melamine water reducer; The prepared component A and component B are mixed evenly in a mass ratio of (3-9): (1-2) to obtain the composite water reducer.

[0032] Preferably, the polycarboxylate water reducer is an ether-type polycarboxylate water reducer or an ester-type polycarboxylate water reducer. Aqueous solution.

[0033] Compared with the prior art, the composite water reducing agent provided by the present invention is more suitable for gypsum-based self-leveling mortar, and has excellent water-proof (resistance) effect, anti-seepage pressure and compressive strength. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. 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.

[0035] The present invention provides the following embodiments: Embodiment 1: In a flask, add 306g of bihydroxy-terminated amino silicone oil with a homopolymer molecular weight of 200 and 247.63g of methacrylic acid, start heating and stirring, add 0.42g of hydroquinone, 1.47g of stannous sulfate and 0.24g of phenothiazine, introduce nitrogen, stir at 76-85°C for 40-90min. Cool down to room temperature to obtain aminosilane methacrylate liquid.

[0036] In the aminosilane methacrylate esterification liquid, monosilyl methacrylate accounts for 90.63%, disilyl methacrylate accounts for 3.74%, free methacrylic acid accounts for 0.37%, free terminal hydroxyl amino silicone oil accounts for 2.68%, and the rest is a small amount of methyl silicone oil entrained in the raw material terminal hydroxyl silicone oil, residual methacrylic acid self-polymer and water in the esterification product.

[0037] The aminosilane methacrylate liquid and the ether type polycarboxylic acid water reducer are prepared in a mass ratio of 9:1 to obtain a 1# water reducer.

[0038] The formulation of ether type polycarboxylic acid water reducer is shown in Table 1 below: Table 1 Proportions of ether-based polycarboxylic acid water reducer

[0039] Embodiment 2: Add 338g of 600 homopolymer molecular weight bishydroxy hydrogenated benzene ring modified silicone oil and 80.48g of acrylic acid into a flask, start stirring, add 0.38g of hydroquinone, 1.24g of stannous chloride and 0.27g of phenothiazine, introduce nitrogen, heat to 68-75℃, keep stirring for 60-120min. Cool down to obtain hydroxyl-terminated hydrogenated benzene ring silicone oil acrylate liquid.

[0040] In the acrylated liquid of terminal hydroxyl hydrogenated benzene ring silicone oil, monosilane acrylate accounts for 89.39%, hydrogenated silicone oil diester acrylate accounts for 4.91%, free acrylic acid accounts for 1.08%, free dihydroxy hydrogenated benzene ring modified silicone oil accounts for 1.98%, and the rest is a small amount of methyl silicone oil entrained in the raw material dihydroxy hydrogenated benzene ring silicone oil, residual acrylic acid self-polymer and water in the esterification product.

[0041] The hydroxyl-terminated hydrogenated silicone oil acrylate liquid and melamine-type water reducer are prepared in a mass ratio of 3:2 to obtain 2# water reducer. The formulation of melamine type water reducer is shown in Table 1 below: Table 1 Ratio of melamine water reducer

[0042] Embodiment 3: Add 298g of bishydroxyamino silicone oil with a homopolymer molecular weight of 800 and 61.02g of methacrylic acid into a flask, start stirring, add 0.42g of hydroquinone, 0.87g of cuprous chloride and 0.48g of stannous chloride, introduce nitrogen, raise the temperature to 82-88°C, keep stirring for 60-80 minutes. Cool down to obtain hydroxyl-terminated amino silicone oil methacrylate liquid In the methacrylated liquid of terminal hydroxyl silicone oil, monosilyl methacrylate accounts for 81.63%, disilyl dimethacrylate accounts for 6.74%, free methacrylic acid accounts for 0.89%, free dihydroxy silicone oil accounts for 9.37%, and the rest is a small amount of methyl silicone oil entrained in the raw terminal hydroxyl silicone oil, methacrylic acid self-polymer and water remaining in the esterification product.

[0043] The terminal hydroxyl silicone oil methacrylate esterified liquid and the ester type polycarboxylic acid water reducer are prepared in a mass ratio of 7:1 to obtain a 3# water reducer.

[0044] Embodiment 4: Add 360g of bishydroxyphenyl modified silicone oil with a homopolymer molecular weight of 1200 and 40.54g of acrylic acid into a flask, start stirring, add 0.40g of hydroquinone, 1.28g of stannous pyrophosphate, 0.23g of phosphoric acid and 0.24g of phenothiazine, introduce nitrogen, heat to 85-98°C, keep stirring for 40-70min. Cool down to obtain hydroxyl phenyl modified silicone oil acrylate liquid.

[0045] In the terminal hydroxyphenyl modified silicone oil acrylate liquid, terminal hydroxyphenyl modified silicone oil acrylate monoester accounts for 80.38%, diacrylate silane accounts for 10.84%, free acrylic acid accounts for 6.37%, free dihydroxyphenyl modified silicone oil accounts for 0.13%, and the rest is a small amount of methyl silicone oil entrained in the raw material terminal hydroxyphenyl modified silicone oil, residual acrylic acid self-polymer and water in the esterification product.

[0046] The hydroxy-terminated phenyl silicone oil acrylate liquid is copolymerized with acrylic acid, and then neutralized with liquid alkali to obtain a 4# water reducing agent.

[0047] Comparative Example 1: It is an ether-type polycarboxylic acid water reducer, and the specific formulation is shown in Table 1 above.

[0048] Comparative Example 2: It is a melamine water reducer, and the specific formula is shown in Table 2 above.

[0049] Comparative Example 3: It is an ester polycarboxylic acid water reducer, and the specific formula is shown in Table 3 below.

[0050] Table 3 Proportions of ester polycarboxylate water reducer

[0051] Comparative Example 4: Comparative Example 4: In Comparative Example 4, the aminosilane methacrylate esterification liquid in Example 1 was replaced with methacrylate 3-(trimethoxysilyl)propyl ester esterification liquid, and the rest was the same as Example 1.

[0052] Add 306g of 3-(trimethoxysilyl)propanol and 247.63g of methacrylic acid into a flask, start heating and stirring, add 0.42g of hydroquinone, 1.47g of stannous sulfate and 0.24g of phenothiazine, introduce nitrogen, stir at 76-85°C for 40-90min. Cool down to room temperature to obtain methacrylate-3-(trimethoxysilyl)propyl ester ester liquid.

[0053] In the esterification liquid of 3-(trimethoxysilyl)propyl methacrylate, 3-(trimethoxysilyl)propyl methacrylate accounts for 88.96%, free methacrylic acid accounts for 6.91%, free 3-(trimethoxysilyl)propanol accounts for 2.47%, and the rest are impurities in the raw materials and a small amount of water.

[0054] In order to reflect that the water reducer provided by the present invention has outstanding technical effects compared with the existing water reducers, the present invention will combine the above embodiments and comparative examples, test reference standards JC / T 1023-2021 gypsum-based self-leveling mortar, JG / T 230-2007 premixed mortar, JGJ / T 70-2009 basic performance test method of building mortar, take two gypsum-based mortar substrates (a-semihydrate gypsum, ß-semihydrate gypsum) on the market, compare the water reducers prepared in Examples 1-4 and Comparative Examples 1-4 to perform gypsum-based self-leveling mortar performance tests, and evaluate from the initial fluidity, 30min fluidity, water absorption, impermeability pressure and compressive strength.

[0055] The water rate of the initial fluidity of the above-mentioned Examples 1-4 and Comparative Examples 1-4 is 22.4%, and the amount of water reducer added is 1.6-2.0% of the amount of the base material in the gypsum-based mortar to ensure the initial fluidity of the self-leveling mortar and maintain the operability of the gypsum-based mortar for about 40 minutes. The test results are shown in Table 4 below: Table 4 Performance test results of gypsum-based self-leveling mortars described in Examples 1-4 and Comparative Examples 1-4

[0056] Compared with the water reducers of comparative examples 1-4, the water reducers prepared in the embodiments of the present invention can effectively improve the water resistance, anti-seepage pressure and compressive strength of the gypsum-based self-leveling mortar, indicating that the silane ester prepared by the present invention is applied to the gypsum-based self-leveling mortar, has a good waterproof effect, and can effectively improve the strength of the gypsum-based self-leveling mortar.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A monosilyl methacrylate, as described in general formula I, characterized in that: （I） Wherein, R is an alkyl group, a silane group or a cycloalkyl group, R1 is hydrogen or a methyl group, R2 is an amino group, a benzene ring or a methyl group, n is 1-5, and m is 1-3.

2. A method for preparing monosilyl methacrylate, characterized in that: The (meth)acrylic acid of the general formula II and the alcohol hydroxyl-modified silicone oil of the general formula III are subjected to an esterification reaction under the action of a catalyst and a polymerization inhibitor, and monosilane methacrylate is obtained after separation; (II) (III) Wherein, R in general formula II is hydrogen or methyl, R in general formula III is alkyl, silane or cycloalkyl, R2 is amino, benzene ring or hydrogen, n is 1-5, and m is 1-3.

3. The method for preparing monosilyl methacrylate according to claim 2, characterized in that: The catalyst is one or more of stannous sulfate, stannous chloride, stannous pyrophosphate, cuprous chloride and phosphoric acid, and the added amount of the catalyst is 0.02%-0.2% of the total mass of (meth)acrylic acid and alcohol hydroxyl modified silicone oil.

4. The method for preparing monosilyl methacrylate according to claim 2, characterized in that: The polymerization inhibitor is one or more of hydroquinone or phenothiazine, and the addition amount of the polymerization inhibitor is 0.02%-0.4% of the total mass of (meth) acrylic acid and alcohol hydroxyl modified silicone oil.

5. The method for preparing monosilyl methacrylate according to claim 2, characterized in that: The molar ratio of the (meth) acrylic acid to the alcohol hydroxyl modified silicone oil is 1.6-2.

0.

6. The method for preparing monosilyl methacrylate according to claim 2, characterized in that: The alcohol hydroxyl modified silicone oil is terminal hydroxyl amino modified silicone oil, double terminal hydroxyl amino modified silicone oil or terminal hydroxyl hydrogenated heterocyclic silicone oil.

7. The method for preparing monosilyl methacrylate according to claim 2, characterized in that: The homopolymer molecular weight of the alcohol hydroxyl modified silicone oil is 100-3000.

8. The method for preparing monosilyl methacrylate according to claim 2, characterized in that: The esterification reaction is carried out under nitrogen protection and stirred at a temperature of 60-100° C. for 40-120 min.

9. A composite water reducing agent, characterized in that: The components A and B are mixed for preparation; The component A comprises 80% to 91% by weight of monosilyl methacrylate, 3% to 11% of disilyl methacrylate, 0.3% to 7% of (meth)acrylic acid and 0.1% to 10% of alcohol hydroxyl modified silicone oil; The component B is any one of a polycarboxylate water reducer and a melamine water reducer; The mass ratio of component A to component B is (3-9):(1-2).

10. A method for preparing a composite water reducing agent according to claim 9, characterized in that: The preparation method of component A is: The (meth) acrylic acid of the general formula II and the alcohol hydroxyl modified silicone oil of the general formula III are subjected to an esterification reaction under the action of a catalyst and a polymerization inhibitor to obtain component A; (II) (III) Wherein, R in the general formula II is hydrogen or methyl, R in the general formula III is alkyl, silyl or cycloalkyl, R2 is amino, benzene ring or hydrogen, n is 1-5, and m is 1-3; The component B is any one of a polycarboxylate water reducer and a melamine water reducer; The prepared component A and component B are mixed evenly in a mass ratio of (3-9): (1-2) to obtain the composite water reducing agent.

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