A concrete water reducing agent and preparation method thereof

Abstract

The invention discloses a concrete water reducer and a preparation method thereof, and belongs to the technical field of water reducers. First, the concrete water reducer provided by the invention comprises the following raw materials by weight: 72-78 parts of aliphatic water reducer, 12-14 parts of slump retaining agent, 2-3 parts of hydroxypropyl methyl cellulose ether and 4-5 parts of retarder. The invention adds the self-made slump retaining agent of the invention to the aliphatic water reducer, and the concrete water reducer finally prepared exhibits excellent slump retaining performance. The principle is as follows: the slump retaining agent prepared by the invention has abundant phosphate groups, ester groups and nitrogen atoms, and the slump retaining agent itself is a macromolecular segment structure, which plays a key role in improving the slump retaining performance of the finally prepared aliphatic water reducer.

Description

Technical Field

[0001] The invention belongs to the technical field of water reducing agents, and in particular relates to a concrete water reducing agent and a preparation method thereof. Background Art

[0002] As one of the indispensable admixtures in concrete, water reducer is second only to water, cement, sand and other aggregates in importance. The addition of water reducer can not only significantly reduce the mixing water consumption of concrete, but also effectively improve the fluidity of concrete and enhance its mechanical properties. In modern construction projects, the use of water reducer has become one of the key technologies to improve the performance of concrete.

[0003] Aliphatic water reducer is a new type of high-efficiency water reducer, which has been widely studied and applied in recent years. This type of water reducer mainly uses carbonyl compounds as raw materials, such as acetone, butanone, cyclohexanone, etc., and introduces hydrophilic sulfonic acid groups through sulfonation reaction. Then under alkaline conditions, these groups react with formaldehyde to form aliphatic polymer chains with moderate molecular weight, giving the molecules surface activity. The water reduction rate of aliphatic water reducer can usually reach more than 20%, has good adaptability to different types of cement, and has good water retention performance, which can effectively improve the workability of fresh concrete.

[0004] Although aliphatic water reducers have many advantages, their molecular structure is linear and they act on concrete particles mainly through electrostatic repulsion, lacking steric hindrance effect. The linear molecular structure of aliphatic water reducers leads to poor slump retention performance, that is, during the concrete construction process, the slump loss is large, making it difficult to meet the requirements of high-performance concrete for maintaining good workability for a long time. Summary of the invention

[0005] The object of the present invention is to provide a concrete water reducing agent and a preparation method thereof, so as to solve the technical problem that the aliphatic water reducing agent has poor slump retention performance.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A concrete water reducing agent, comprising the following raw materials in parts by weight:

[0008] Aliphatic water reducing agent 72-78 parts;

[0009] 12-14 parts of collapse-preventing agent;

[0010] 2-3 parts of hydroxypropyl methylcellulose ether;

[0011] 4-5 parts of retarder;

[0012] The collapse-preserving aid is prepared by the following steps:

[0013] S1. Add 2-carboxyphenyl phosphate, N-methylethanolamine and p-toluenesulfonic acid to toluene with stirring. After the addition is completed, the system is heated to 85-90° C. and stirred at a constant temperature for 5-6 hours. After the reaction is completed, the system is cooled to room temperature and then the toluene is removed by rotary evaporation to obtain an intermediate 1. During the preparation of the intermediate 1, 2-carboxyphenyl phosphate containing a terminal carboxyl group and N-methylethanolamine containing a terminal hydroxyl group undergo an esterification reaction under the catalysis of p-toluenesulfonic acid. The reaction process is as follows:

[0014] ;

[0015] S2. Under a nitrogen atmosphere, add intermediate 1 to methanol with stirring, stir at room temperature for 20 to 30 minutes, then add methyl acrylate with stirring, heat the system to 35 to 40° C., and stir at constant temperature for 5 to 6 hours. After the reaction is completed, remove methanol by rotary evaporation to obtain intermediate 2. In the preparation process of intermediate 2, intermediate 1 containing a secondary amine group and methyl acrylate containing an unsaturated double bond undergo Michael addition reaction. The reaction process is shown as follows:

[0016] ;

[0017] S3, take the intermediate dimethylolpropane, trimethylolpropane and p-toluenesulfonic acid and stir and mix for 10 minutes, then heat the system to 120-130°C, stir and react at constant temperature for 4-5 hours, after the reaction is completed, discharge the material, cool to room temperature, and obtain a collapse-preserving aid. In the preparation process of the collapse-preserving aid, the intermediate dimethylolpropane and trimethylolpropane undergo ester exchange reaction under the catalysis of p-toluenesulfonic acid. The reaction process is as follows:

[0018] ;

[0019] Furthermore, the usage ratio of toluene, 2-carboxyphenyl phosphate, N-methylethanolamine and p-toluenesulfonic acid in S1 is 1L:1mol:1.0-1.1mol:2.5-3.0g.

[0020] Furthermore, the usage ratio of methanol, intermediate 1 and methyl acrylate in S2 is 1L:275.5-276.0g:1mol.

[0021] Furthermore, the usage ratio of the intermediate dimethylolpropane, trimethylolpropane and p-toluenesulfonic acid in S3 is 325.2-326.0 g: 0.3 mol: 2.5-3.0 g.

[0022] Furthermore, the aliphatic water reducing agent is prepared by the following steps:

[0023] Sodium sulfite is added to pure water with stirring, the system is heated to 45-50°C, and stirred at a constant temperature until the solid component is completely dissolved. Cyclohexanone is then added thereto with stirring, and sulfonation is continued for 40-50 minutes with constant temperature stirring. After completion, a formaldehyde solution with a mass fraction of 37% is added dropwise. After the addition is completed, the system is heated to 80-90°C, and the reaction is stirred at a constant temperature for 1-2 hours. After completion, it is cooled to room temperature to obtain an aliphatic water reducer.

[0024] Furthermore, the usage ratio of the pure water, sodium sulfite, cyclohexanone and 37% formaldehyde solution is 200mL: 7-10g: 15-20g: 80-100mL.

[0025] Furthermore, a method for preparing a concrete water reducing agent comprises the following steps:

[0026] The aliphatic water reducing agent, the slump retaining agent, the hydroxypropyl methyl cellulose ether and the retarder are weighed in parts by mass, and then the aliphatic water reducing agent, the slump retaining agent, the hydroxypropyl methyl cellulose ether and the retarder are stirred and mixed for 20 to 30 minutes. After completion, a concrete water reducing agent is obtained.

[0027] Furthermore, the retarder is one of citric acid, malic acid and tartaric acid.

[0028] Beneficial effects of the present invention:

[0029] The present invention adds the self-made collapse-preserving aid of the present invention to the aliphatic water reducer, and the concrete water reducer finally prepared exhibits excellent collapse-preserving performance. The principle is as follows: the collapse-preserving aid prepared by the present invention has abundant phosphate groups, ester groups and nitrogen atoms, and the collapse-preserving aid itself is a macromolecular chain segment structure, which all play a key role in improving the collapse-preserving performance of the finally prepared aliphatic water reducer.

[0030] First, the phosphate group has a strong adsorption capacity. In the concrete hydration environment, the phosphate group can react with the calcium ions on the surface of the concrete particles to form a stable complex. This complex reaction can make the concrete particles carry the same charge and generate electrostatic repulsion, so that the concrete particles are dispersed in the liquid phase, reducing the yield stress and plastic viscosity of the concrete slurry, achieving the initial dispersion effect, that is, achieving the slump-preserving effect. At the same time, this complexing action can make the water-reducing agent prepared by the present invention firmly adsorbed on the surface of the concrete particles, and form a layer of "protective film" on the surface of the concrete particles. In the process of concrete particle hydration, the "protective film" can maintain the electrostatic repulsion and steric hindrance effect between the concrete particles, thereby maintaining the slump of the concrete.

[0031] Then, the ester group can enhance the hydrophilicity and steric hindrance effect of the prepared water-reducing agent molecules. The hydrophilicity helps the water-reducing agent to maintain a good dispersion state in the concrete paste, while the steric hindrance effect can effectively prevent the agglomeration of concrete particles.

[0032] Then, nitrogen atoms also participate in the adsorption on the surface of concrete particles. Nitrogen atoms bind to the surface of concrete particles through interactions such as hydrogen bonds, further enhancing the adsorption stability of the prepared water-reducing agent molecules on the surface of concrete particles.

[0033] Finally, the collapse-preserving agent prepared by the present invention itself is a macromolecular segment structure. Adding the collapse-preserving agent prepared by the present invention to the aliphatic concrete water reducer can increase the steric hindrance of the finally prepared water reducer, and finally achieve the purpose of improving the dispersibility of concrete particles. DETAILED DESCRIPTION

[0034] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only 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] Example 1

[0036] Preparation of aliphatic water reducer:

[0037] Pure water was added to the reactor, and sodium sulfite (AR; 97%; purchased from Sinopharm Chemical Reagent Co., Ltd.) was added to the pure water with stirring. The reactor was heated to 45°C and stirred at a constant temperature until the solid component was completely dissolved. Cyclohexanone (AR; 99.5%; purchased from Sinopharm Chemical Reagent Co., Ltd.) was added to the reactor with stirring, and sulfonation was continued at a constant temperature with stirring for 40 minutes. After completion, a formaldehyde solution with a mass fraction of 37% (purchased from Sinopharm Chemical Reagent Co., Ltd.) was added dropwise to the reactor. After the addition was completed, the system was heated to 80°C and stirred at a constant temperature for 1 hour. After completion, it was cooled to room temperature to obtain an aliphatic water reducer, wherein the amount ratio of pure water, sodium sulfite, cyclohexanone and formaldehyde solution with a mass fraction of 37% was 200mL:7g:15g:80mL.

[0038] Example 2

[0039] Preparation of aliphatic water reducer:

[0040] Pure water was added to the reactor, and sodium sulfite (AR; 97%; purchased from Sinopharm Chemical Reagent Co., Ltd.) was added to the pure water with stirring. The reactor was heated to 50°C and stirred at a constant temperature until the solid component was completely dissolved. Cyclohexanone (AR; 99.5%; purchased from Sinopharm Chemical Reagent Co., Ltd.) was added to the reactor with stirring, and sulfonation was continued for 50 minutes with constant temperature stirring. After completion, a formaldehyde solution with a mass fraction of 37% (purchased from Sinopharm Chemical Reagent Co., Ltd.) was added dropwise to the reactor. After the addition was completed, the system was heated to 85°C and stirred at a constant temperature for 2 hours. After completion, it was cooled to room temperature to obtain an aliphatic water reducer, wherein the amount ratio of pure water, sodium sulfite, cyclohexanone and formaldehyde solution with a mass fraction of 37% was 200mL:8g:20g:100mL.

[0041] Example 3

[0042] Preparation of aliphatic water reducer:

[0043] Pure water was added to the reactor, and sodium sulfite (AR; 97%; purchased from Sinopharm Chemical Reagent Co., Ltd.) was added to the pure water with stirring. The reactor was heated to 50°C and stirred at a constant temperature until the solid component was completely dissolved. Cyclohexanone (AR; 99.5%; purchased from Sinopharm Chemical Reagent Co., Ltd.) was added to the reactor with stirring, and sulfonation was continued at a constant temperature with stirring for 50 minutes. After completion, a formaldehyde solution with a mass fraction of 37% (purchased from Sinopharm Chemical Reagent Co., Ltd.) was added dropwise to the reactor. After the addition was completed, the system was heated to 90°C and stirred at a constant temperature for 2 hours. After completion, it was cooled to room temperature to obtain an aliphatic water reducer, wherein the amount ratio of pure water, sodium sulfite, cyclohexanone and formaldehyde solution with a mass fraction of 37% was 200mL:10g:20g:100mL.

[0044] Example 4

[0045] Preparation of collapse-preserving additives:

[0046] S1. Take 1L of toluene (AR; 99.5%; purchased from Sinopharm Chemical Reagent Co., Ltd.), add 1mol of 2-carboxyphenyl phosphate (98%; purchased from Sinopharm Chemical Reagent Co., Ltd.), 1.0mol of N-methylethanolamine (99%; purchased from Shanghai Yuanye Biotechnology Co., Ltd.) and 2.5g of p-toluenesulfonic acid (99%; purchased from Sinopharm Chemical Reagent Co., Ltd.) thereto with stirring. After the addition is completed, the system is heated to 85°C and stirred at a constant temperature for 5h. After the reaction is completed, it is cooled to room temperature and then the toluene is removed by rotary evaporation to obtain intermediate 1.

[0047] S2. Take 1L of methanol (AR; 99.5%; purchased from Sinopharm Chemical Reagent Co., Ltd.), add 275.5g of intermediate 1 thereto under nitrogen atmosphere, stir at room temperature for 20min, then add 1mol of methyl acrylate (AR; 99%; purchased from Sinopharm Chemical Reagent Co., Ltd.) thereto, heat the system to 35°C, stir at constant temperature for 5h, after the reaction is complete, remove methanol by rotary evaporation, and obtain intermediate 2;

[0048] S3, take 325.2g of intermediate 2, 0.3mol of trimethylolpropane (98%; purchased from Sinopharm Chemical Reagent Co., Ltd.) and 2.5g of p-toluenesulfonic acid (99%; purchased from Sinopharm Chemical Reagent Co., Ltd.), stir and mix for 10min, then heat the system to 120°C, stir and react at constant temperature for 4h, after the reaction is completed, discharge the material, cool to room temperature, and obtain a collapse-preserving aid.

[0049] Example 5

[0050] Preparation of collapse-preserving additives:

[0051] S1. Take 1L of toluene (AR; 99.5%; purchased from Sinopharm Chemical Reagent Co., Ltd.), add 1mol of 2-carboxyphenyl phosphate (98%; purchased from Sinopharm Chemical Reagent Co., Ltd.), 1.1mol of N-methylethanolamine (99%; purchased from Shanghai Yuanye Biotechnology Co., Ltd.) and 2.8g of p-toluenesulfonic acid (99%; purchased from Sinopharm Chemical Reagent Co., Ltd.) thereto with stirring. After the addition is completed, the system is heated to 88°C and stirred at a constant temperature for 6h. After the reaction is completed, it is cooled to room temperature and then the toluene is removed by rotary evaporation to obtain intermediate 1.

[0052] S2. Take 1L of methanol (AR; 99.5%; purchased from Sinopharm Chemical Reagent Co., Ltd.), add 276.0g of intermediate 1 thereto under nitrogen atmosphere, stir at room temperature for 30min, then add 1mol of methyl acrylate (AR; 99%; purchased from Sinopharm Chemical Reagent Co., Ltd.) thereto, heat the system to 38°C, stir at constant temperature for 6h, after the reaction is complete, remove methanol by rotary evaporation, and obtain intermediate 2;

[0053] S3, take 325.5g of intermediate 2, 0.3mol of trimethylolpropane (98%; purchased from Sinopharm Chemical Reagent Co., Ltd.) and 3.0g of p-toluenesulfonic acid (99%; purchased from Sinopharm Chemical Reagent Co., Ltd.), stir and mix for 10 minutes, then heat the system to 125°C, stir and react at constant temperature for 5 hours, after the reaction is completed, discharge the material, cool to room temperature, and obtain a collapse-preserving aid.

[0054] Example 6

[0055] Preparation of collapse-preserving additives:

[0056] S1. Take 1L of toluene (AR; 99.5%; purchased from Sinopharm Chemical Reagent Co., Ltd.), add 1mol of 2-carboxyphenyl phosphate (98%; purchased from Sinopharm Chemical Reagent Co., Ltd.), 1.1mol of N-methylethanolamine (99%; purchased from Shanghai Yuanye Biotechnology Co., Ltd.) and 3.0g of p-toluenesulfonic acid (99%; purchased from Sinopharm Chemical Reagent Co., Ltd.) thereto with stirring. After the addition is completed, the system is heated to 90°C and stirred at a constant temperature for 6h. After the reaction is completed, it is cooled to room temperature and then the toluene is removed by rotary evaporation to obtain intermediate 1.

[0057] S2. Take 1L of methanol (AR; 99.5%; purchased from Sinopharm Chemical Reagent Co., Ltd.), add 276.0g of intermediate 1 thereto under nitrogen atmosphere, stir at room temperature for 30min, then add 1mol of methyl acrylate (AR; 99%; purchased from Sinopharm Chemical Reagent Co., Ltd.) thereto, heat the system to 40°C, stir at constant temperature for 6h, after the reaction is complete, remove methanol by rotary evaporation, and obtain intermediate 2;

[0058] S3, take 326.0g of intermediate 2, 0.3mol of trimethylolpropane (98%; purchased from Sinopharm Chemical Reagent Co., Ltd.) and 3.0g of p-toluenesulfonic acid (99%; purchased from Sinopharm Chemical Reagent Co., Ltd.), stir and mix for 10min, then heat the system to 130°C, stir and react at constant temperature for 5h, after the reaction is completed, discharge the material, cool to room temperature, and obtain a collapse-preserving aid.

[0059] Example 7

[0060] Preparation of concrete water reducing agent:

[0061] First, concrete water reducing agent includes the following raw materials by weight:

[0062] 72 parts of the aliphatic water reducing agent prepared in Example 1;

[0063] 12 parts of the collapse-preserving aid prepared in Example 4;

[0064] 2 parts of hydroxypropyl methylcellulose ether;

[0065] 4 parts of retarder;

[0066] Then, the concrete water reducing agent is prepared by the following steps:

[0067] The aliphatic water reducer prepared in Example 1, the slump retaining agent prepared in Example 4, hydroxypropyl methyl cellulose ether (model HD6100; viscosity at 25°C is 100000 mPa·s; purchased from Shandong Heda Co., Ltd.) and the retarder were weighed by mass, wherein the retarder was citric acid (98%; purchased from Sinopharm Chemical Reagent Co., Ltd.), and the aliphatic water reducer prepared in Example 1, the slump retaining agent prepared in Example 4, hydroxypropyl methyl cellulose ether and citric acid were placed in a stirrer and stirred and mixed at a speed of 60 r / min for 20 min. After completion, a concrete water reducer was obtained.

[0068] Example 8

[0069] Preparation of concrete water reducing agent:

[0070] First, concrete water reducing agent includes the following raw materials by weight:

[0071] 75 parts of the aliphatic water reducing agent prepared in Example 2;

[0072] 14 parts of the collapse-preserving aid prepared in Example 5;

[0073] 2 parts of hydroxypropyl methylcellulose ether;

[0074] 4 parts of retarder;

[0075] Then, the concrete water reducing agent is prepared by the following steps:

[0076] The aliphatic water reducer prepared in Example 2, the slump retaining agent prepared in Example 5, hydroxypropyl methyl cellulose ether (model HD6100; viscosity at 25°C is 100000 mPa·s; purchased from Shandong Heda Co., Ltd.) and the retarder were weighed by mass, wherein the retarder was malic acid (D-malic acid; 99.5%; purchased from Sinopharm Chemical Reagent Co., Ltd.), and the aliphatic water reducer prepared in Example 2, the slump retaining agent prepared in Example 5, hydroxypropyl methyl cellulose ether and malic acid were placed in a stirrer and stirred and mixed at a speed of 80 r / min for 30 min. After completion, a concrete water reducer was obtained.

[0077] Example 9

[0078] Preparation of concrete water reducing agent:

[0079] First, concrete water reducing agent includes the following raw materials by weight:

[0080] 78 parts of the aliphatic water reducing agent prepared in Example 3;

[0081] 14 parts of the collapse-preserving aid prepared in Example 6;

[0082] 3 parts of hydroxypropyl methylcellulose ether;

[0083] 5 parts of retarder;

[0084] Then, the concrete water reducing agent is prepared by the following steps:

[0085] The aliphatic water reducer prepared in Example 3, the slump retaining agent prepared in Example 6, hydroxypropyl methyl cellulose ether (model HD6100; viscosity at 25°C is 100000 mPa·s; purchased from Shandong Heda Co., Ltd.) and the retarder were weighed by mass, wherein the retarder was tartaric acid (L(+)-tartaric acid; AR; 99.5%; purchased from Sinopharm Chemical Reagent Co., Ltd.), and the aliphatic water reducer prepared in Example 3, the slump retaining agent prepared in Example 6, hydroxypropyl methyl cellulose ether and tartaric acid were placed in a stirrer and stirred and mixed at a speed of 80 r / min for 30 min. After completion, a concrete water reducer was obtained.

[0086] Comparative Example 1

[0087] Comparative Example 1 is the control group of Example 8, in which the collapse-preserving agent prepared by Example 5 of the raw materials in Example 8 is removed, and the remaining raw materials, raw material amounts and preparation methods are kept the same as those in Example 8, and finally a concrete water reducer is obtained.

[0088] Test Example 1

[0089] The concrete water reducing agents prepared in Examples 7 to 9 and Comparative Example 1 were subjected to performance tests. The test process is as follows. The test results are shown in Table 1:

[0090] Cement paste fluidity: Refer to GB / T 8077-2012 "Test method for homogeneity of concrete admixtures" to test the fluidity of cement paste (cement + water + water reducer), where P.042.5 cement is used, the water-cement mass ratio is 0.29, and the amount of concrete water reducer is 1% of the cement mass. The initial paste fluidity of the cement paste and the paste fluidity after standing for 60 minutes are tested;

[0091] Slump: refer to the test standard in 3.1 Slump and slump spread method in GB / T 50080-2002 "Standard for Test Methods for Performance of Ordinary Concrete Mixtures" to conduct slump test on cement paste (cement + water + water reducer), where P.042.5 cement is used, the water-cement mass ratio is 0.29, the amount of concrete water reducer is 1% of the cement mass, and the initial slump of the cement paste and the slump after standing for 60 minutes are tested.

[0092] Table 1 Test results

[0093] ;

[0094] It can be seen from Table 1 that the concrete water reducing agent added with the collapse-preserving additive prepared by the present invention has excellent collapse-preserving performance.

[0095] It should be noted that, in this article, terms such as "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or equipment that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or equipment.

[0096] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A concrete water reducing agent, characterized in that: Including the following raw materials by weight: Aliphatic water reducing agent 72-78 parts; 12-14 parts of collapse-preventing agent; 2-3 parts of hydroxypropyl methylcellulose ether; 4-5 parts of retarder; The collapse-preserving aid is prepared by the following steps: S1. Add 2-carboxyphenyl phosphate, N-methylethanolamine and p-toluenesulfonic acid to toluene with stirring. After the addition is completed, the system is heated to 85-90° C. and stirred at a constant temperature for 5-6 hours. After the reaction is completed, the system is cooled to room temperature and the toluene is removed by rotary evaporation to obtain an intermediate 1. S2. In a nitrogen atmosphere, add intermediate 1 to methanol with stirring, stir at room temperature for 20 to 30 minutes, then add methyl acrylate with stirring, heat the system to 35 to 40° C., stir at constant temperature for 5 to 6 hours, and after the reaction is completed, remove methanol by rotary evaporation to obtain intermediate 2; S3, taking the intermediate dimethylolpropane and trimethylolpropane and p-toluenesulfonic acid, stirring and mixing for 10 minutes, then heating the system to 120-130° C., stirring and reacting at a constant temperature for 4-5 hours, after the reaction is completed, discharging the material, cooling to room temperature, and obtaining a collapse-preserving aid.

2. A concrete water reducing agent according to claim 1, characterized in that: The usage ratio of toluene, 2-carboxyphenyl phosphate, N-methylethanolamine and p-toluenesulfonic acid in S1 is 1L:1mol:1.0-1.1mol:2.5-3.0g.

3. A concrete water reducing agent according to claim 1, characterized in that: The usage ratio of methanol, intermediate 1 and methyl acrylate in S2 is 1L:275.5-276.0g:1mol.

4. A concrete water reducing agent according to claim 1, characterized in that: The usage ratio of the intermediate di-trimethylolpropane and p-toluenesulfonic acid in S3 is 325.2-326.0 g: 0.3 mol: 2.5-3.0 g.

5. A concrete water reducing agent according to claim 1, characterized in that: The aliphatic water reducer is prepared by the following steps: adding sodium sulfite to pure water with stirring, heating the system to 45-50° C., stirring at a constant temperature until the solid component is completely dissolved, adding cyclohexanone thereto with stirring, continuing to stir at a constant temperature for sulfonation for 40-50 minutes, and then dripping a formaldehyde solution with a mass fraction of 37% thereto. After the dripping is completed, heating the system to 80-90° C., stirring at a constant temperature for reaction for 1-2 hours, and then cooling to room temperature to obtain the aliphatic water reducer.

6. A concrete water reducing agent according to claim 5, characterized in that: The usage ratio of the pure water, sodium sulfite, cyclohexanone and the formaldehyde solution with a mass fraction of 37% is 200mL: 7-10g: 15-20g: 80-100mL.

7. A method for preparing a concrete water reducing agent according to any one of claims 1 to 6, characterized in that: The method comprises the following steps: weighing aliphatic water reducing agent, slump retaining agent, hydroxypropyl methyl cellulose ether and retarder according to mass parts, stirring and mixing the aliphatic water reducing agent, slump retaining agent, hydroxypropyl methyl cellulose ether and retarder for 20 to 30 minutes, and obtaining a concrete water reducing agent after completion.

8. The method for preparing a concrete water reducing agent according to claim 7, characterized in that: The retarder is one of citric acid, malic acid and tartaric acid.