A concrete reducing agent and preparation method thereof

Abstract

The present invention discloses a concrete collapse reducing agent and a preparation method thereof. Acrylic acid and maltose syrup are esterified under mild activator conditions, the generation of monoesters can be well controlled, and the appropriate introduction of an inhibitor can prevent highly active acrylic acid from self-polymerization without affecting the esterification rate and its conversion rate. The β-cyclodextrin structure shell has a dense hydroxyl group, the inner core is a hydrophobic cavity, and the hydrophilic hydroxyl group of the shell has a significant steric hindrance effect, which improves the dispersibility of cement, and the hydrophobic cavity can load a hydrophobic long chain, which is slowly released during the contact process with cement, adsorbed on the surface of cement particles, and prevents the hydration of cement. The present invention reduces the amount of concrete collapse reducing agent, which not only solves the problem of high amount of collapse reducing agent, but also reduces the cost of concrete admixtures.

Description

Technical Field

[0001] The invention relates to the field of concrete admixtures, in particular to a concrete additive and a preparation method thereof. Background Art

[0002] Concrete collapse reducing agent, as the name suggests, is an admixture that can reduce the amount of concrete collapse reducing agent.

[0003] In recent years, polycarboxylate water reducers have been used more and more widely in my country, but many problems have arisen along with it. One of the most common and main difficulties is how to control the slump loss of concrete. It is generally believed that the reasons for the serious loss of concrete slump over time are: (1) Commercial concrete requires an external transportation process, and traffic congestion and blockage occur frequently in my country. Therefore, the slump loss requirements for concrete are relatively high, and the slump of concrete must be kept small over a long period of time; (2) With the shortage of concrete raw materials, the adsorption rate and amount of high-mud sand and gravel on water reducers, especially polycarboxylic acid water reducers, are faster and larger than those of cementitious materials systems. Compared with natural sand, machine-made sand has poor grading, large fineness modulus, and rough surface, which will increase the flow resistance of concrete after mixing, resulting in poor fluidity and poor slump retention of concrete; (3) The compatibility problem between cementitious materials and water reducers. The large amount of superfine particles in cement and admixtures adsorb on water reducers causes the slump loss of concrete; (4) Water reducers fail at high temperatures, water evaporates quickly, and bubbles overflow, causing rapid slump loss. There are many methods to solve the slump of concrete after adding water reducers. The common methods in construction are: (1) increasing the amount of retarder to reduce the initial hydration rate of cement, but there is a risk of setting time; (2) using the post-addition method, adding water reducers after a certain period of time after the concrete is mixed, but this method is difficult to control the amount of water reducers and is prone to concrete quality accidents; (3) using high-performance slump retaining agents and water reducers for reuse.

[0004] In recent years, domestic and foreign scholars have focused on the research of concrete slump-reducing agents, using molecular structure design to improve cement dispersibility by increasing the charge density in the molecular chain, and solving the slump loss of concrete by combining long chains and short chains. The design concept of slump-reducing agents is almost the same as that of water reducers. Polycarboxylic acid slump-reducing agents can also be called polycarboxylic acid water reducers with special functional groups. Their molecular weight is as high as hundreds of thousands. They use a large number of strong polar or non-polar groups with high molecular weight to adsorb on the surface of cement particles, improve the dispersion of cement, and delay the physical coagulation of cement, thereby prolonging the loss of concrete. At present, polycarboxylic acid slump-reducing agents and polycarboxylic acid water reducers are widely used in concrete. They can reduce the hydration rate of cement, reduce the slump loss of concrete, and greatly ensure the working performance of concrete. However, with the shortage of sand and gravel materials and the decline in cement quality, the amount of slump-reducing agents in admixtures is getting higher and higher, even exceeding the amount of water reducers, but still cannot prolong the retention of concrete. In addition, excessive use of slump-preventing agent is not conducive to the workability and reaction speed of concrete, and cannot adapt to changes in materials. It is easy to cause reverse increase and segregation, resulting in difficulty in pumping and concrete quality problems. In addition, polycarboxylic acid slump-preventing agent and polyether macromonomer are raw materials. With the tight supply of raw materials such as ethylene oxide, the production cost of polycarboxylic acid slump-preventing agent has also been pushed up. Summary of the invention

[0005] In order to solve the above-mentioned deficiencies and defects in the prior art, the inventors have developed and designed a concrete slump reducing agent and a preparation method thereof, which reduces the amount of concrete slump reducing agent, solves the problem of high amount of slump reducing agent, and reduces the cost of concrete admixtures. Specifically, the present invention is as follows:

[0006] A method for preparing a concrete insurance reduction agent comprises the following steps:

[0007] Step S1, mixing acrylic acid and maltose syrup in a mass ratio of 1:0.08-1.12, adding an activator and an inhibitor after stirring evenly, and heating to react to obtain liquid A;

[0008] Step S2, mixing acrylic acid and β-cyclodextrin in a mass ratio of 1:0.06-0.1, adding an activator and an inhibitor after stirring evenly, and heating to react to obtain liquid B;

[0009] Step S3, dissolving liquid B, β-cyclodextrin and a long hydrophobic chain in an ethanol solution to obtain a solid-containing mixed solution, and then dripping the mixed solution dropwise into a stirred aqueous solution, stirring to obtain a liquid C with a solid content of 20 to 30%;

[0010] Step S4, mixing maleic anhydride and an alcohol amine compound in a mass ratio of 1:0.4-1, stirring evenly and heating to react to obtain a D solution;

[0011] Step S5, mixing maleic anhydride and polyethylene glycol monomethyl ether in a mass ratio of 1:5-11, stirring evenly, and then heating to obtain liquid E;

[0012] Step S6, according to the mass ratio, 100-225 parts of liquid C, 30-68 parts of liquid D, 40-60 parts of liquid E, and 260-320 parts of water are stirred and mixed, 156-175 parts of liquid A are mixed to form a solution as material 1, and 8.7-14.2 parts of initiator are configured into a solution as material 2; after heating, material 1 and material 2 are added dropwise at the same time, and the temperature is lowered after the addition is completed to obtain a concrete reduction agent.

[0013] Another aspect of the present invention provides a concrete insurance reduction agent, which is prepared by the above-mentioned preparation method of the concrete insurance reduction agent; its structural formula is:

[0014]

[0015] Wherein, M1=H, CH3; M2=H, C6H5, CH3, CH2CH2OH, CH2CH2(CH3)OH; M3=H, CH3. n=16.4~33.

[0016] The working principle of the present invention is introduced: there are few reports on maltose syrup as a component of concrete admixture. Maltose syrup is a polyhydroxy compound. It can improve the workability of concrete when mixed, but the dosage is limited. Acrylic acid and maltose syrup are esterified under mild activator conditions, which can well control the generation of monoesters. The appropriate introduction of inhibitors can avoid the self-polymerization of highly active acrylic acid without affecting the esterification rate and its conversion rate. The shell of the β-cyclodextrin structure has dense hydroxyl groups, the core is a hydrophobic cavity, and the hydrophilic hydroxyl groups of the shell have a significant steric hindrance effect, which improves the dispersibility of cement, while the hydrophobic cavity can load hydrophobic long chains, which are slowly released during the contact process of cement and adsorbed on the surface of cement particles to prevent the hydration of cement. The reactivity of alcohol amine compounds and polyethylene glycol monomethyl ether is difficult to control with acrylic acid, so maleic anhydride with mild activity is selected for esterification. Alcohol amine compounds are generally used as early strength agents, which have a negative impact on the dispersibility of cement, and their molecular structure can be changed after modification. Polyethylene glycol monomethyl ether has good hydrophilic properties, and the long polymer chain greatly increases the steric hindrance and reduces the probability of inserting into the clay layered structure. Four structures with different structures are formed into oligomers with a molecular weight of 6800 to 10200 through redox polymerization. The synthesized reduction agent has a smaller molecular weight than the polycarboxylic acid collapse agent. Different from the collapse mechanism of the polycarboxylic acid collapse agent, the reduction agent can also be called a self-sacrificing agent, which protects the polycarboxylic acid collapse agent at the cost of its own loss. The low molecular weight of the reduction agent determines that it can be adsorbed on the surface of cement particles, soil particles, and ultrafine powder before the polycarboxylic acid collapse agent, and then use its steric hindrance effect to disperse the cement particles. At the same time, the hydrophobic long chain in the hydrophobic cavity of β-cyclodextrin is slowly released, and the hydrophobic group can be adsorbed on the surface of cement particles to inhibit the hydration of cement particles. The function of the polycarboxylic acid collapse agent needs to be exerted only after the ester group of the reduction agent is hydrolyzed and the hydrophobic cavity is slowly released.

[0017] The beneficial effects of the present invention are introduced as follows:

[0018] 1. The raw materials of the concrete insurance reduction agent prepared by the present invention are abundant, each step has been industrialized, and the method is mature.

[0019] 2. The concrete retaining agent prepared by the present invention can partially replace the collapse retaining agent to extend the retention of concrete. Different from the collapse retaining mechanism of the polycarboxylic acid collapse retaining agent, it utilizes the preferential adsorption of low molecular weight polymers to ensure the normal construction of concrete at the expense of itself.

[0020] 3. The concrete collapse reducing agent prepared by the present invention can reduce the dosage of the collapse preventing agent. When the replacement amount does not exceed 30 kg, 1 kg of the collapse reducing agent can replace 3 to 5 kg of the polycarboxylic acid collapse preventing agent. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail. It should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present invention. In addition, in the following description, the description of known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0022] Embodiment 1: A method for preparing a concrete protection reducing agent, comprising the following steps:

[0023] (1) Add acrylic acid and maltose syrup in a mass ratio of 1:0.08-1.12 into a three-necked flask, stir evenly, then add 4% of the total amount of acrylic acid and maltose syrup and of polymerization inhibitor, raise the temperature to 82-87°C and react for 4-6 hours to obtain liquid A.

[0024] Its structural reaction formula is:

[0025]

[0026] Wherein, M=H, CH2OH(CHOH)4CHO or CH2OH(CHOH)4CHO-CH2OH(CHOH)4CHO.

[0027] Preferably, the maltose syrup is tested according to GB / T 20883-2017 "Maltose", and its main components are maltobiose, glucose and maltotriose, wherein the content of maltobiose is 57.4-61.2%, the content of glucose is 10.3-12.1%, and the content of maltotriose is 7.45-9.2%.

[0028] Preferably, the activator comprises one or more of copper sulfate, tin oxide, zinc oxide, aluminum oxide, zinc acetate, manganese acetate, p-toluenesulfonic acid, phosphoric acid, boric acid, and concentrated sulfuric acid.

[0029] Preferably, the polymerization inhibitor includes one or more of p-hydroxyanisole, 2-tert-butylhydroquinone, 1,4-hydroquinone, phenothiazine, and dibutyl copper dithiocarbamate.

[0030] (2) Add acrylic acid and β-cyclodextrin in a mass ratio of 1:0.06-0.1 into a three-necked flask, stir evenly, and then add 5% of the total amount of acrylic acid and β-cyclodextrin activator and The polymerization inhibitor is heated to 110-120℃ and reacted for 4-6 hours to obtain liquid B. Its structural reaction formula is:

[0031]

[0032] (3) Solution B and 3-6% by weight of the hydrophobic long chain of β-cyclodextrin cyclodextrin are dissolved in an ethanol solution to obtain a 50% solid content mixed solution, and then the mixed solution is dripped into the stirred aqueous solution and stirred for 2 hours to obtain a solution C with a solid content of 20-30%.

[0033] Preferably, the hydrophobic long chain includes one or more of dodecanedioic acid, undecanoic acid, tridecanedioic acid, methyl dodecanoate, heptadecanoic acid, cycloalkane acid, methyl tetradecanoate, and tridecanol.

[0034] (4) Maleic anhydride and alcohol amine compound are added into a three-necked flask at a mass ratio of 1:0.4-1, stirred evenly, and then heated to 90-110°C for reaction for 4-6 hours to obtain liquid D. Its structural reaction formula is:

[0035]

[0036] Among them, M1=H, CH3; M2=H, C6H5, CH3, CH2CH2OH, CH2CH2(CH3)OH; M3=H, CH3.

[0037] Preferably, the alcoholamine compound includes one or more of diethanolamine, triethanolamine, triisopropanolamine, diethanol monoisopropanolamine, N,N-di(2-hydroxypropyl)aniline, and methyldiethanolamine.

[0038] (5) Maleic anhydride and polyethylene glycol monomethyl ether are added into a three-necked flask at a mass ratio of 1:5-11, stirred evenly, and then heated to 90-110°C for reaction for 4-6 hours to obtain liquid E. Its structural reaction formula is:

[0039]

[0040] Among them, n=16.4~33.

[0041] Preferably, the polyethylene glycol monomethyl ether includes one or more of polyethylene glycol monomethyl ether with a molecular weight of 350 (MPEG-350), polyethylene glycol monomethyl ether with a molecular weight of 450 (MPEG-450), polyethylene glycol monomethyl ether with a molecular weight of 500 (MPEG-500), and polyethylene glycol monomethyl ether with a molecular weight of 1000 (MPEG-1000).

[0042] (6) At room temperature, 100-225 parts of liquid C, 30-68 parts of liquid D, 40-60 parts of liquid E, and 260-320 parts of water were added to a stirred three-necked flask, 156-175 parts of liquid A were mixed to form a 50% solution as material 1, and 8.7-14.2 parts of initiator were prepared into a 10% solution as material 2. The temperature of the three-necked flask was raised to 70-80°C, and then material 1 and material 2 were added dropwise at the same time, with the addition time being 1.5-3h and 2-3h respectively. After the addition was completed, the temperature was lowered to 60-65°C and kept warm for 4h. After the temperature was lowered, the concrete reduction agent was obtained.

[0043] Preferably, the initiator includes one or more of sodium persulfate, ammonium persulfate, potassium persulfate, tert-butyl hydroperoxide, hydrogen peroxide, and sodium sulfite.

[0044]

[0045] Wherein, M1=H, CH3; M2=H, C6H5, CH3, CH2CH2OH, CH2CH2(CH3)OH; M3=H, CH3. n=16.4~33.

[0046] Experimental Example 1:

[0047] (1) Add acrylic acid and maltose syrup in a mass ratio of 1:0.08 into a three-necked flask, stir evenly, then add 2% copper sulfate, 2% p-toluenesulfonic acid, Add p-hydroxyanisole, heat to 82°C and react for 6 hours to obtain solution A.

[0048] (2) Add acrylic acid and β-cyclodextrin in a mass ratio of 1:0.1 into a three-necked flask, stir evenly, and then add 2% tin oxide, 3% zinc acetate and Add 2-tert-butylhydroquinone, heat to 110℃ and react for 5h to obtain solution B.

[0049] (3) Solution B and 6% dodecanedioic acid by weight of β-cyclodextrin cyclodextrin were dissolved in an ethanol solution to obtain a 50% solid content mixed solution, and then the mixed solution was dripped into the stirred aqueous solution and stirred for 2 h to obtain a solution C with a solid content of 25%.

[0050] (4) Maleic anhydride, diethanolamine, and diethanol monoisopropanolamine were added into a three-necked flask in a mass ratio of 1:0.2:0.2, stirred evenly, and then heated to 90°C for 6 hours to obtain solution D.

[0051] (5) Maleic anhydride and MPEG-1000 were added into a three-necked flask at a mass ratio of 1:11, stirred evenly, and then heated to 110°C for 4 hours to obtain liquid E.

[0052] (6) At room temperature, 160 parts of liquid C, 50 parts of liquid D, 60 parts of liquid E, and 276 parts of water were placed in a stirred three-necked flask, 156 parts of liquid A were mixed to form a 50% solution as material 1, and 14.2 parts of sodium persulfate were prepared to form a 10% solution as material 2. The temperature of the three-necked flask was raised to 70°C, and then material 1 and material 2 were added dropwise at the same time, with the addition time being 2h and 2.5h respectively. After the addition was completed, the temperature was lowered to 60°C and kept warm for 4h. After the temperature was lowered, the concrete reduction agent was obtained.

[0053] Experimental Example 2

[0054] (1) Add acrylic acid and maltose syrup in a three-necked flask at a mass ratio of 1:1.12, stir evenly, then add 4% concentrated sulfuric acid and Add 1,4-hydroquinone and heat to 87℃ for 4h to obtain liquid A.

[0055] (2) Add acrylic acid and β-cyclodextrin in a mass ratio of 1:0.06 into a three-necked flask, stir evenly, and then add 2% manganese acetate, 3% phosphoric acid, The dibutyl dithiocarbamate copper was heated to 120°C and reacted for 4 hours to obtain liquid B. Liquid B and 1.5% undecanoic acid and 1.5% tridecanol by mass of β-cyclodextrin were dissolved in ethanol solution to obtain a 50% solid content mixed solution, and then the mixed solution was dripped into the stirred aqueous solution drop by drop and stirred for 2 hours to obtain liquid C with a solid content of 20%.

[0056] (4) Maleic anhydride, triethanolamine and amine were added into a three-necked flask in a mass ratio of 1:0.6:0.4, stirred evenly and heated to 110°C for 4 hours to obtain solution D.

[0057] (5) Maleic anhydride and MPEG-500 were added into a three-necked flask at a mass ratio of 1:7, stirred evenly, and then heated to 90°C for 6 hours to obtain liquid E.

[0058] (6) At room temperature, 225 parts of liquid C, 30 parts of liquid D, 40 parts of liquid E, and 286 parts of water were placed in a stirred three-necked flask, 166 parts of liquid A were mixed to form a 50% solution as material 1, and 5.7 parts of hydrogen peroxide and 3 parts of sodium sulfite were mixed to form a 10% solution as material 2. The temperature of the three-necked flask was raised to 75°C, and then material 1 and material 2 were added dropwise at the same time, with the addition time being 3 hours and 3 hours respectively. After the addition was completed, the temperature was lowered to 60°C and kept warm for 4 hours. After the temperature was lowered, the concrete reduction agent was obtained.

[0059] Experimental Example 3

[0060] (1) Add acrylic acid and maltose syrup in a mass ratio of 1:0.6 into a three-necked flask, stir evenly, then add 3% zinc oxide, 1% boric acid, The temperature of phenothiazine was raised to 85℃ and reacted for 5h to obtain solution A.

[0061] (2) Add acrylic acid and β-cyclodextrin in a mass ratio of 1:0.08 into a three-necked flask, stir evenly, and then add 3% zinc acetate, 2% concentrated sulfuric acid, The temperature of phenothiazine was raised to 115℃ and reacted for 6h to obtain solution B.

[0062] (3) Solution B and 2.5% of tridecanedioic acid and 2.5% of methyl dodecanoate by mass of β-cyclodextrin were dissolved in an ethanol solution to obtain a 50% solid content mixed solution, and then the mixed solution was dripped into the stirred aqueous solution and stirred for 2 h to obtain a solution C with a solid content of 30%.

[0063] (4) Maleic anhydride, triisopropanolamine and N,N-di(2-hydroxypropyl)aniline were added into a three-necked flask in a mass ratio of 1:0.5:0.2, stirred evenly and heated to 100°C for reaction for 5 hours to obtain solution D.

[0064] (5) Maleic anhydride and MPEG-350 were added into a three-necked flask at a mass ratio of 1:5, stirred evenly, and then heated to 100°C for reaction for 5 hours to obtain liquid E.

[0065] (6) At room temperature, 100 parts of liquid C, 68 parts of liquid D, 40 parts of liquid E, and 328 parts of water were placed in a stirred three-necked flask. 175 parts of liquid A were mixed to form a 50% solution as material 1, and 10 parts of ammonium persulfate and 1.45 parts of potassium persulfate were mixed to form a 10% solution as material 2. The temperature of the three-necked flask was raised to 80°C, and then material 1 and material 2 were added dropwise at the same time, with the addition time being 1.5 hours and 2 hours respectively. After the addition was completed, the temperature was lowered to 65°C and kept warm for 4 hours. After the temperature was lowered, the concrete reduction agent was obtained.

[0066] Experimental Example 4

[0067] (1) Add acrylic acid and maltose syrup in a mass ratio of 1:0.2 into a three-necked flask, stir evenly, then add 3% alumina, 1% p-toluenesulfonic acid, Add p-hydroxyanisole, heat to 82°C and react for 4 hours to obtain solution A.

[0068] (2) Add acrylic acid and β-cyclodextrin in a mass ratio of 1:0.06 into a three-necked flask, stir evenly, and then add 5% of the total amount of acrylic acid and β-cyclodextrin, aluminum oxide and Add 2-tert-butylhydroquinone, heat to 110℃ and react for 6h to obtain solution B.

[0069] (3) Dissolve liquid B and β-cyclodextrin, 1% heptadecanoic acid, 1.5% cycloalkanoic acid, and 1.5% methyl tetradecanoate by mass in an ethanol solution to obtain a 50% solid content mixed solution, then add the above mixed solution dropwise into the stirred aqueous solution and stir for 2 hours to obtain liquid C with a solid content of 20%.

[0070] (4) Maleic anhydride and triisopropanolamine were added into a three-necked flask at a mass ratio of 1:0.4, stirred evenly, and then heated to 90°C for 4 hours to obtain liquid D.

[0071] (5) Maleic anhydride, MPEG-450 and MPEG-1000 were added into a three-necked flask in a mass ratio of 1:3:3.5, stirred evenly and heated to 90°C for 4 hours to obtain liquid E.

[0072] (6) At room temperature, 160 parts of liquid C, 30 parts of liquid D, 50 parts of liquid E, and 286 parts of water were placed in a stirred three-necked flask, 166 parts of liquid A were mixed to form a 50% solution as material 1, and 14.2 parts of potassium persulfate were prepared to form a 10% solution as material 2. The temperature of the three-necked flask was raised to 75°C, and then material 1 and material 2 were added dropwise at the same time, with the addition time being 2h and 3h respectively. After the addition was completed, the temperature was lowered to 65°C and kept warm for 4h. After the temperature was lowered, the concrete reduction agent was obtained.

[0073] The concrete reduction agent prepared in Experimental Examples 1 to 4 was tested, and the concrete performance test was carried out according to GB / T 50080-2016 "Standard for Performance Test Methods of Ordinary Concrete Mixtures" and GB / T8076-2008 "Concrete Admixtures". The cement used was Dongjun PO 425 ordinary Portland cement, the fineness modulus of machine-made sand was 3.0, the water-cement ratio was 0.5, the sand rate was 52%, and the mud content was ≥5%. The water reducer used was a commercially available polycarboxylate water reducer with a solid content of 50% and a water reduction rate of ≥34%; the slump retainer used was a commercially available polycarboxylate slump retainer with a solid content of 40%; the retarder was Xiwang sodium gluconate (PN).

[0074] Table 1 Compounding of admixtures

[0075] Admixtures Polycarboxylate water reducer / Kg Collapse inhibitor / Kg PN / Kg Insurance reduction agent / Kg Water / Kg 1 100 80 30 0 790 2 100 60 30 4 806 3 100 50 30 6 814 4 100 40 30 8 822

[0076] Table 2 Performance of concrete reduction agent (admixture dosage 2.4%)

[0077]

[0078]

[0079] The data show that the concrete reduction agent prepared by the present invention can reduce the amount of slump-retaining agent in the admixture and has good economic value. Using 1 kg of the reduction agent of Example 1 to Example 4 to replace 5 kg of the polycarboxylic acid slump-retaining agent improves the concrete state (flow rate and slump) while ensuring the strength of the concrete, and does not affect the time loss of the concrete.

[0080] Table 3 Concrete reduction agent replaces different slump retaining agents

[0081]

[0082] The data show that the concrete slump reducing agent prepared by the present invention can replace 5 kg of polycarboxylic acid slump reducing agent, but when the replacement amount exceeds 30 kg, the water reduction of concrete becomes weaker and the retention becomes worse.

[0083] It should be understood that the above specific embodiments of the present invention are only used to illustrate or explain the principles of the present invention, and do not constitute a limitation of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. In addition, the appended claims of the present invention are intended to cover all changes and modifications that fall within the scope and boundaries of the appended claims, or the equivalent forms of such scope and boundaries.

Claims

1. A method for preparing a concrete insurance reduction agent, characterized in that The following steps are involved: Step S1, mixing acrylic acid and maltose syrup in a mass ratio of 1:0.08-1.12, adding an activator and an inhibitor after stirring evenly, and heating to react to obtain liquid A; Step S2, mixing acrylic acid and β-cyclodextrin in a mass ratio of 1:0.06-0.1, adding an activator and an inhibitor after stirring evenly, and heating to react to obtain liquid B; Step S3, dissolving liquid B and 3-6% by weight of a hydrophobic long chain of β-cyclodextrin in an ethanol solution to obtain a 50% solid content mixed solution, then dripping the mixed solution dropwise into the stirred aqueous solution, stirring for 2 hours to obtain liquid C with a solid content of 20-30%; Step S4, mixing maleic anhydride and an alcohol amine compound in a mass ratio of 1:0.4-1, stirring evenly and heating to react to obtain a D solution; Step S5, mixing maleic anhydride and polyethylene glycol monomethyl ether in a mass ratio of 1:5-11, stirring evenly and heating to react to obtain liquid E; Step S6, according to the mass ratio, 100-225 parts of liquid C, 30-68 parts of liquid D, 40-60 parts of liquid E, and 260-320 parts of water are stirred and mixed, 156-175 parts of liquid A are mixed to form a solution as material 1, and 8.7-14.2 parts of initiator are configured into a solution as material 2; after heating, material 1 and material 2 are added dropwise at the same time, and the temperature is lowered after the addition is completed to obtain a concrete reduction agent; In the concrete insurance reduction agent, the outer shell of the β-cyclodextrin structure has dense hydroxyl groups, the inner core is a hydrophobic cavity, the hydrophilic hydroxyl groups of the outer shell have a steric hindrance effect, and the dispersibility of cement is improved. The hydrophobic cavity carries hydrophobic long chains, which are slowly released during the contact process with cement and adsorbed on the surface of cement particles to prevent the hydration of cement.

2. The method for preparing the concrete insurance reduction agent according to claim 1, characterized in that: The maltose syrup described in step S1 contains maltobiose, glucose and maltotriose, wherein the content of maltobiose is 57.4-61.2%, the content of glucose is 10.3-12.1%, and the content of maltotriose is 7.45-9.2%.

3. The method for preparing the concrete insurance reduction agent according to claim 1, characterized in that: The activator described in step S1 includes one or more of copper sulfate, tin oxide, zinc oxide, aluminum oxide, zinc acetate, manganese acetate, p-toluenesulfonic acid, phosphoric acid, boric acid, and concentrated sulfuric acid; The polymerization inhibitor includes one or more of p-hydroxyanisole, 2-tert-butylhydroquinone, 1,4-hydroquinone, phenothiazine, and dibutyl copper dithiocarbamate.

4. The method for preparing the concrete insurance reduction agent according to claim 1, characterized in that: The hydrophobic long chain described in step S3 includes one or more of dodecanedioic acid, undecanoic acid, tridecanedioic acid, methyl dodecanoate, heptadecanoic acid, methyl tetradecanoate, and tridecanol.

5. The method for preparing the concrete insurance reduction agent according to claim 1, characterized in that: The alcoholamine compound described in step S4 includes one or more of diethanolamine, triethanolamine, triisopropanolamine, diethanol monoisopropanolamine, N,N-di(2-hydroxypropyl)aniline, and methyldiethanolamine.

6. The method for preparing the concrete insurance reduction agent according to claim 1, characterized in that: The polyethylene glycol monomethyl ether described in step S5 includes one or more of polyethylene glycol monomethyl ether MPEG-350 with a molecular weight of 350, polyethylene glycol monomethyl ether MPEG-450 with a molecular weight of 450, polyethylene glycol monomethyl ether MPEG-500 with a molecular weight of 500, and polyethylene glycol monomethyl ether MPEG-1000 with a molecular weight of 1000.

7. The method for preparing the concrete insurance reduction agent according to claim 1, characterized in that: The initiator described in step S6 includes one or more of sodium persulfate, ammonium persulfate, potassium persulfate, tert-butyl hydroperoxide, hydrogen peroxide, and sodium sulfite.

8. A concrete insurance reduction agent, characterized in that: The concrete reducing agent is prepared by the preparation method of any one of claims 1 to 7.

9. The concrete insurance reduction agent according to claim 8, characterized in that: Its structural formula is: Among them, M1=H, CH3; M2=H, C6H5, CH3, CH2CH2OH, M3=H, CH3, n=16.4~33; M=H.

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