Viscosity-reducing temperature-inhibiting composite admixture and preparation method thereof

Abstract

The application discloses a viscosity-reducing and temperature-restraining type composite admixture and a preparation method thereof, and belongs to the technical field of ferrite aluminate cement. The composite admixture comprises the following components in parts by weight: fly ash microbeads 20-40 parts, superfine mineral powder 30-50 parts, limestone powder 10-20 parts, temperature-restraining agent 0.5-2 parts and anti-adsorption water reducing agent 1-5 parts. The carboxylic acid-sulfonic acid groups of the temperature-restraining agent preferentially occupy high active sites on the surface of iron-aluminum phases through chemical coordination, thereby reducing invalid adsorption of the water reducing agent. The anti-adsorption water reducing agent reduces adsorption loss of the water reducing agent by iron-aluminum phases through the steric hindrance effect of a polyether long chain and the electrostatic repulsive force of a carboxylic acid group, continuously provides dispersion capacity, and indirectly assists the temperature-restraining agent to realize more uniform hydration heat release.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ferrite aluminate cement, in particular to a viscosity-reducing and temperature-repressing composite admixture and a preparation method thereof. BACKGROUND

[0002] Ferrite aluminate cement has important application value in harsh material performance requirement fields such as marine engineering, underground structure and repair engineering due to its high early strength, excellent corrosion resistance and anti-permeability.

[0003] However, the inherent characteristics in the hydration process have become a key bottleneck restricting engineering application: on the one hand, the hydration heat release curve of the cement presents a significant feature of "fast and concentrated", the highest heat release peak usually appears within 8-10 hours after hydration, and the whole hydration heat release process is basically completed within 1 day. This rapid and concentrated heat release is easy to cause a large temperature gradient in the concrete, and then cause temperature stress cracking risk. Although fly ash, slag and other mineral admixtures are often used in the prior art to reduce hydration heat, such admixtures can only play a limited delaying role through dilution of cement clinker or weak activity effect, and do not optimize the unique kinetic characteristics of the rapid formation of ettringite and the early vigorous hydration of iron and aluminum phases in ferrite aluminate cement, so that the early temperature rise control effect cannot meet the actual engineering needs, and the temperature stress cracking problem still occurs frequently.

[0004] On the other hand, the high content of iron and aluminum phases in ferrite aluminate cement has a strong adsorption capacity to traditional water reducing agents. This strong adsorption effect can greatly weaken the dispersion efficiency of the water reducing agent, resulting in a significant increase in the viscosity of the concrete slurry and an increase in the pumping resistance, which seriously affects the workability and construction efficiency during the construction process. The above-mentioned problems of insufficient hydration heat regulation and viscosity control failure have become technical difficulties that need to be broken through in the engineering application of ferrite aluminate cement, and therefore it is urgent to develop a composite admixture and a preparation method thereof which can simultaneously realize viscosity reduction and temperature repression to solve the performance defects caused by the lack of pertinence in the prior art. SUMMARY

[0005] In view of the above-mentioned shortcomings in the prior art, the present application provides a viscosity-reducing and temperature-repressing composite admixture, which comprises the following components:

[0006] Fly ash microbeads 20-40 parts;

[0007] Superfine mineral powder 30-50 parts;

[0008] Limestone powder 10-20 parts;

[0009] Temperature-repressing agent 0.5-2 parts;

[0010] Anti-adsorption water reducing agent 1-5 parts.

[0011] A preparation method of the viscosity-reducing and temperature-inhibiting composite admixture comprises the following steps:

[0012] S1: surface modification of fly ash cenospheres: adding silane coupling agent to fly ash cenospheres and stirring;

[0013] activation treatment of superfine mineral powder: mixing superfine mineral powder with sodium carbonate and calcining;

[0014] S2: preparation of temperature inhibitor;

[0015] dissolving maleic anhydride, acrylic acid and sodium gluconate in deionized water, heating, adding initiator dropwise, after reaction, adding 2-acrylamide-2-methylpropane sulfonic acid to continue reaction, vacuum distillation and spray drying to obtain temperature inhibitor;

[0016] S3: preparation of anti-adsorption water reducing agent;

[0017] dissolving acrylic acid, ethylene glycol monomethyl ether acrylate, isobutyl cyanothiobenzoate and initiator azobisisobutyronitrile in deionized water, stirring, heating under nitrogen atmosphere, and obtaining prepolymer solution after natural cooling;

[0018] adding polyethylene glycol acrylate aqueous solution dropwise into the prepolymer solution, adding initiator potassium persulfate in batches, stirring and reacting to obtain anti-adsorption water reducing agent;

[0019] S4: adding pretreated fly ash cenospheres, activated superfine mineral powder and limestone powder into a ball mill in proportion for grinding;

[0020] adding temperature inhibitor and anti-adsorption water reducing agent and continuing to grind to obtain viscosity-reducing and temperature-inhibiting composite admixture.

[0021] Further, S1 specifically is: placing fly ash cenospheres into a high-speed stirrer, adding 1-3% silane coupling agent A151 or A171 by mass of fly ash cenospheres, and stirring at 80-100°C for 30-60 min;

[0022] mixing superfine mineral powder with 0.5-1% sodium carbonate by mass of superfine mineral powder, and calcining at 300-400°C for 30-60 min.

[0023] Further, S2 specifically is: dissolving maleic anhydride, acrylic acid and sodium gluconate in deionized water, solid content being 30-40%, molar ratio of maleic anhydride to acrylic acid being 1:2-3, sodium gluconate accounting for 15-25% of mass of maleic anhydride, heating to 60-70°C, adding 0.5-1.0% initiator ammonium persulfate by mass of maleic anhydride dropwise, reacting for 3-4 h, adding 5-10% 2-acrylamide-2-methylpropane sulfonic acid by mass of maleic anhydride to continue reaction for 1-2 h, removing water by vacuum distillation, and spray drying to obtain white powder, which is temperature inhibitor.

[0024] Further, S3 is specifically: dissolve acrylic acid, ethylene glycol monomethyl ether acrylate, isobutyl cyano ester of dithiobenzoic acid, initiator azobisisobutyronitrile into deionized water, solid content 30-40%, stir at 200-300 rpm for 15-20 min, heat to 65-75 DEG C under nitrogen atmosphere, react for 3-4 h, naturally cool to 50-60 DEG C, to obtain a light yellow transparent prepolymer solution;

[0025] Drop 40-50 wt% of the preheated polyethylene glycol acrylate aqueous solution at 45-62 DEG C into the prepolymer solution at a speed of 6-10 drops / min, add initiator potassium persulfate in 2-3 times, with an interval of 25-30 min, stir at 60-65 DEG C and 200-300 rpm for 2-3 h, to obtain a milky white viscous liquid, namely an anti-adsorption water reducing agent.

[0026] Further, the mass ratio of acrylic acid, ethylene glycol monomethyl ether acrylate, isobutyl cyano ester of dithiobenzoic acid, initiator azobisisobutyronitrile is 40-60:32-48:0.5-1:0.3-0.6.

[0027] Further, the mass ratio of polyethylene glycol acrylate, acrylic acid and initiator potassium persulfate is 150-250:40-60:0.3-0.5.

[0028] Further, S4 is specifically: add the pretreated fly ash microbeads, activated superfine mineral powder and limestone powder into the ball mill in proportion, and grind for 10-20 min.

[0029] Add the temperature depressant and the anti-adsorption water reducing agent, and continue to grind for 5-10 min, to obtain a viscosity-reducing temperature-depressing composite admixture.

[0030] Compared with the prior art, the present application has the following beneficial effects:

[0031] 1、The temperature depressant of the present application adopts maleic anhydride-acrylic acid-sodium gluconate terpolymer as the main chain, and introduces sulfonic acid side chains to form a unique structure of "carboxylic acid-sulfonic acid double coordination group + polyether flexible chain". The carboxylic acid group is adsorbed on the surface of the cement particles through coordination, delaying the rapid formation of calcium aluminate; the sulfonic acid group disperses the cement particles through electrostatic repulsion, inhibiting the early violent hydration of iron and aluminum phases, and dispersing the hydration heat release process.

[0032] 2. The anti-adsorption water reducing agent adopts a three-level gradient structure of main chain (polyacrylic acid)-short branch chain (ethylene glycol monomethyl ether acrylate)-long branch chain (polyethylene glycol acrylate), and resists the strong adsorption of iron phase and aluminum phase in ferrite and aluminate cement through steric hindrance effect. The short branch chain provides initial dispersion force, and the long branch chain continuously maintains dispersion stability through flexible polyether chain segment, so that the water reducing agent can still maintain most of the effective dispersion efficiency in a high adsorption environment, the viscosity of the concrete slurry is reduced, and the pumping resistance is significantly reduced.

[0033] 3. The carboxylic acid-sulfonic acid group of the temperature depressant preferentially occupies the high active sites on the surface of the iron and aluminum phase through chemical coordination, reducing the invalid adsorption of the water reducing agent. The sulfonic acid group forms a stable complex with calcium and aluminum ions, inhibiting the rapid generation of calcium aluminate, while the carboxylic acid group associates with the acrylic acid unit of the main chain of the water reducing agent through hydrogen bonding, enhancing the stability of the adsorption layer. The polyether long chain shields the adsorption sites of the iron and aluminum phase through steric hindrance, and the carboxylic acid group forms a charge synergistic repulsion with the carboxylic acid group of the temperature depressant, further reducing the adsorption loss significantly. The anti-adsorption water reducing agent reduces the adsorption loss of the water reducing agent by the iron and aluminum phase through the steric hindrance effect of the polyether long chain and the electrostatic repulsive force of the carboxylic acid group, and continuously provides dispersion capacity. This long-term dispersion can avoid the local accelerated hydration caused by cement particle agglomeration (high cement concentration in the agglomeration area, more concentrated heat release), which indirectly assists the temperature depressant to achieve more uniform hydration heat release. DETAILED DESCRIPTION

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described below in connection with the embodiments of the present application. Obviously, the described embodiments are some embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0035] Embodiment 1: The present embodiment provides a preparation method of a viscosity-reducing temperature-depressing composite admixture, comprising the following steps:

[0036] S1: Surface modification of fly ash cenospheres: put the fly ash cenospheres into a high-speed stirrer, add 1-3% of silane coupling agent A151 based on the mass of the fly ash cenospheres, and stir at 100°C and 800 rpm for 60 min, so that the silane coupling agent uniformly coats the surface of the fly ash cenospheres, improving the compatibility and dispersibility of the fly ash cenospheres in the cement slurry (the coating layer formed by the silane coupling agent on the surface of the fly ash cenospheres reduces the surface energy between the cenospheres, reduces the agglomeration of the cenospheres, and thus improves the compatibility and dispersibility of the cenospheres in the cement slurry);

[0037] Superfine mineral powder activation treatment: mix the superfine mineral powder with 1% sodium carbonate by mass, calcine at 400℃ for 60min to excite the activity of the mineral powder (high-temperature calcination as a thermal excitation means can change the crystal structure of the mineral powder, increase the active sites, and thus improve the reaction activity);

[0038] S2: preparing a temperature depressant;

[0039] Maleic anhydride, acrylic acid, and sodium gluconate were dissolved in deionized water (solid content 40%), the molar ratio of maleic anhydride to acrylic acid was 1:3, and the mass fraction of sodium gluconate in maleic anhydride was 25%. The temperature was raised to 70℃, and the initiator ammonium persulfate (1.0% of the mass of maleic anhydride) was added dropwise. After 4h of reaction, 2-acrylamide-2-methylpropane sulfonic acid (10% of the mass of maleic anhydride) was added and the reaction continued for 2h. The water was removed by vacuum distillation, and the white powder was obtained by spray drying, which was the temperature depressant;

[0040] S3: preparing an anti-adsorption water reducing agent;

[0041] Acrylic acid, ethylene glycol monomethyl ether acrylate, bis-thiobenzoic acid isobutyl nitrile ester, and initiator azobisisobutyronitrile were dissolved in deionized water at a mass ratio of 60:48:1:0.6, with a solid content of 40%. The solution was stirred at 300rpm for 20min, and then the temperature was raised to 75℃ under a nitrogen atmosphere. The reaction was carried out for 4h, and then the temperature was naturally lowered to 60℃. A light yellow transparent prepolymer solution was obtained.

[0042] A 50wt% polyethylene glycol acrylate aqueous solution preheated to 62℃ was added dropwise into the prepolymer solution at a rate of 10 drops / min. The initiator potassium persulfate was added in three portions, and the mass ratio of polyethylene glycol acrylate, acrylic acid, and initiator potassium persulfate was 250:60:0.5. Each addition was separated by 30min. The reaction was carried out at 65℃ and 300rpm for 3h. A milky white viscous liquid was obtained, which was the anti-adsorption water reducing agent.

[0043] S4: weighing the raw materials;

[0044] Fly ash microbeads 40 parts; have good ball effect, can reduce the viscosity of concrete slurry and improve the construction fluidity;

[0045] Superfine mineral powder 50 parts; can fill the pores of concrete, improve the density, and at the same time, the active ingredients can participate in the secondary hydration reaction, consume part of the hydration products, delay the hydration process, and reduce the early hydration heat;

[0046] Limestone powder 20 parts; can react with aluminum in ferrite cement to form calcium aluminate, adjust the composition of hydration products, and inhibit the rapid formation of ettringite, thereby controlling the heat release rate of hydration;

[0047] Temperature depressant 2 parts;

[0048] Anti-adsorption water reducing agent 5 parts;

[0049] S5: The pretreated fly ash beads, activated superfine mineral powder and limestone powder are added into the ball mill in proportion, and ground for 20 min;

[0050] The temperature depressant and the anti-adsorption water reducing agent are added, and the grinding is continued for 10 min to obtain the viscosity-reducing temperature-depressing composite admixture.

[0051] Embodiment 2: The present embodiment provides a preparation method of a viscosity-reducing temperature-depressing composite admixture, comprising the following steps:

[0052] S1: Surface modification of fly ash beads: the fly ash beads are put into a high-speed mixer, 1-3% silane coupling agent A171 by mass of the fly ash beads is added, and stirring is carried out at 80°C for 30 min, so that the silane coupling agent uniformly coats the surface of the fly ash beads, improving the compatibility and dispersibility of the fly ash beads in the cement paste;

[0053] Superfine mineral powder activation treatment: the superfine mineral powder is mixed with 0.5% sodium carbonate by mass of the superfine mineral powder, and calcination is carried out at 300°C for 30 min to excite the activity of the mineral powder;

[0054] S2: Preparation of temperature depressant;

[0055] Maleic anhydride, acrylic acid and sodium gluconate are dissolved in deionized water (solid content 30%), the molar ratio of maleic anhydride to acrylic acid is 1:2, and sodium gluconate accounts for 15% of the mass of maleic anhydride, the temperature is raised to 60°C, the initiator ammonium persulfate (0.5% of the mass of maleic anhydride) is added dropwise, after 3h of reaction, 2-acrylamide-2-methylpropanesulfonic acid (5% of the mass of maleic anhydride) is added and the reaction is continued for 1h, water is removed by vacuum distillation, and white powder is obtained by spray drying, which is the temperature depressant;

[0056] S3: Preparation of anti-adsorption water reducing agent;

[0057] Acrylic acid, ethylene glycol monomethyl ether acrylate, bis-thiobenzoic acid isobutyl nitrile ester and initiator azobisisobutyronitrile in a mass ratio of 40:32:0.5:0.3 are dissolved in deionized water, the solid content is 30%, stirring is carried out at 200 rpm for 15 min, the temperature is raised to 65°C under nitrogen atmosphere, the reaction is carried out for 3h, and the temperature is naturally lowered to 50°C to obtain a light yellow transparent prepolymer solution;

[0058] 40wt% polyethylene glycol acrylate aqueous solution preheated to 45°C is added dropwise into the prepolymer solution at a speed of 6 drops / min, the initiator potassium persulfate is added in two portions, the mass ratio of polyethylene glycol acrylate, acrylic acid and initiator potassium persulfate is 150:40:0.3, each interval is 25 min, and the reaction is carried out at 60°C and 200 rpm for 2h to obtain a milky white viscous liquid, which is the anti-adsorption water reducing agent;

[0059] S4: Weigh the raw materials;

[0060] 20 parts of fly ash microspheres; have a good ball effect, which can reduce the viscosity of concrete paste and improve the fluidity of construction.

[0061] 30 parts of ultrafine mineral powder; can fill concrete pores and improve density. At the same time, its active ingredients can participate in secondary hydration reaction, consume some hydration products, slow down the hydration process, and reduce early hydration heat.

[0062] 10 parts of limestone powder; can react with the aluminum phase in aluminoferrite cement to produce calcium aluminate, which can adjust the composition of hydration products, inhibit the excessively rapid formation of ettringite, and thus control the hydration heat release rate.

[0063] 0.5 parts of temperature suppressant;

[0064] 1 part of anti-adsorption water-reducing agent;

[0065] S5: Add the pretreated fly ash microspheres, activated ultrafine mineral powder and limestone powder to the ball mill in proportion and grind for 10 minutes;

[0066] Add a temperature suppressant and an anti-adsorption water-reducing agent, and continue grinding for 5 minutes to obtain a viscosity-reducing and temperature-suppressing composite admixture.

[0067] Example 3: This example provides a method for preparing a viscosity-reducing and temperature-suppressing composite admixture, including the following steps:

[0068] S1: Surface modification of fly ash microspheres: Place fly ash microspheres in a high-speed mixer, add 1-3% of silane coupling agent A171 by mass, and stir at 92℃ for 45 minutes to make the silane coupling agent uniformly coat the surface of fly ash microspheres, thereby improving its compatibility and dispersibility with cement paste.

[0069] Activation treatment of ultrafine mineral powder: Mix ultrafine mineral powder with sodium carbonate at a mass of 0.7% and calcine at 360℃ for 55 min to activate the mineral powder.

[0070] S2: Preparation of a temperature suppressant;

[0071] Maleic anhydride, acrylic acid, and sodium gluconate were dissolved in deionized water (solid content 38%). The molar ratio of maleic anhydride to acrylic acid was 1:2.4, and sodium gluconate accounted for 22% of the mass of maleic anhydride. The mixture was heated to 66°C, and ammonium persulfate (0.8% of the mass of maleic anhydride) was added dropwise. After reacting for 3.5 hours, 2-acrylamido-2-methylpropanesulfonic acid (8% of the mass of maleic anhydride) was added, and the reaction was continued for another hour. The water was removed by vacuum distillation, and the mixture was spray-dried to obtain a white powder, which is the temperature suppressant.

[0072] S3: Preparation of anti-adsorption water-reducing agent;

[0073] Acrylic acid, ethylene glycol monomethyl ether acrylate, isobutyl terephthalate dithiobenzoate, and initiator azobisisobutyronitrile were dissolved in deionized water in a mass ratio of 48:42:0.7:0.5, with a solid content of 37%. The mixture was stirred at 280 rpm for 18 min, heated to 69 °C under a nitrogen atmosphere, reacted for 3 h, and then cooled naturally to 56 °C to obtain a pale yellow and transparent prepolymer solution.

[0074] A 47wt% aqueous solution of polyethylene glycol acrylate preheated to 54℃ was added dropwise to the prepolymer solution at a rate of 8 drops / min. Potassium persulfate initiator was added in 3 portions. The mass ratio of polyethylene glycol acrylate, acrylic acid and potassium persulfate initiator was 210:48:0.4, with each addition 28 min apart. The mixture was stirred at 62℃ and 260 rpm for 2 h to obtain a milky white viscous liquid, which is the anti-adsorption water-reducing agent.

[0075] S4: Weigh the raw materials;

[0076] 32 parts of fly ash microspheres; have a good ball effect, which can reduce the viscosity of concrete paste and improve the fluidity of construction.

[0077] 41 parts of ultrafine mineral powder; it can fill the pores of concrete, improve the density, and its active ingredients can participate in the secondary hydration reaction, consume some of the hydration products, slow down the hydration process, and reduce the early hydration heat.

[0078] 18 parts of limestone powder; can react with the aluminum phase in aluminoferrite cement to generate calcium aluminate, which can adjust the composition of hydration products, inhibit the excessively rapid formation of ettringite, and thus control the hydration heat release rate.

[0079] 1.3 parts of temperature suppressant;

[0080] 2 parts of anti-adsorption water-reducing agent;

[0081] S5: Add the pretreated fly ash microspheres, activated ultrafine mineral powder and limestone powder to the ball mill in proportion and grind for 15 minutes;

[0082] Add a temperature suppressant and an anti-adsorption water-reducing agent, and continue grinding for 8 minutes to obtain a viscosity-reducing and temperature-suppressing composite admixture.

[0083] Comparative Example 1: The difference between this comparative example and Example 3 is that no temperature suppressant was added.

[0084] Comparative Example 2: The difference between this comparative example and Example 3 is that no anti-adsorption water-reducing agent was added.

[0085] Comparative Example 3: The difference between this comparative example and Example 3 is that neither a temperature suppressant nor an anti-adsorption water-reducing agent was added.

[0086] Experimental Example 1: Preparation of mixture: Ferroaluminate cement + composite admixture + water (water-binder ratio 0.35).

[0087] 2. In accordance with GB / T 12959-2024 "Determination of Heat of Hydration of Cement", the isothermal conduction calorimetry method (standard method) was adopted. The cumulative heat release J / g of the cement paste hydration process was monitored using an isothermal calorimeter (TAM Air 8-channel type). The test period was 24h and 72h.

[0088] 3. According to the plastic viscosity ratio method of neat paste in Appendix A of T / CECS 10157-2021, the plastic viscosity Pa·s at 60 min was tested.

[0089]

[0090] The results are shown in the table below:

[0091] As shown in the table above, the present invention introduces sulfonic acid side chains into the maleic anhydride-acrylic acid-sodium gluconate terpolymer to form a temperature suppressant with a molecular structure of "carboxylic acid-sulfonic acid dual coordination groups + polyether flexible chain", thereby reducing the heat of hydration of aluminoferrite cement.

[0092] A three-level gradient structure of main chain (polyacrylic acid) - short branch chain (ethylene glycol monomethyl ether acrylate) - long branch chain (polyethylene glycol acrylate) anti-adsorption water-reducing agent, which achieves anti-adsorption and thus reduces viscosity;

[0093] When combined, the two have a synergistic effect on viscosity reduction and temperature suppression.

[0094] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a viscosity-reducing and temperature-suppressing composite admixture, characterized in that, Includes the following components: 20-40 parts of fly ash microspheres; 30-50 parts of ultrafine mineral powder; 10-20 parts limestone powder; Temperature suppressant 0.5-2 parts; 1-5 parts of anti-adsorption water-reducing agent; The preparation method of the aforementioned viscosity-reducing and temperature-suppressing composite admixture includes the following steps: S1: Surface modification of fly ash microspheres: Add silane coupling agent to fly ash microspheres and stir; Activation treatment of ultrafine mineral powder: Mix ultrafine mineral powder with sodium carbonate and calcine; S2: Preparation of a temperature suppressant; Maleic anhydride, acrylic acid, and sodium gluconate were dissolved in deionized water, heated, and an initiator was added dropwise. After the reaction, 2-acrylamide-2-methylpropanesulfonic acid was added to continue the reaction. The temperature inhibitor was obtained by vacuum distillation and spray drying. S3: Preparation of anti-adsorption water-reducing agent; Acrylic acid, ethylene glycol monomethyl ether acrylate, dithiobenzoic acid isobutyl nitrile ester, and initiator azobisisobutyronitrile are dissolved in deionized water, stirred, heated and reacted under a nitrogen atmosphere, and then cooled naturally to obtain a prepolymer solution. An aqueous solution of polyethylene glycol acrylate was added dropwise to the prepolymer solution, and potassium persulfate initiator was added in batches. The mixture was stirred and reacted to obtain an anti-adsorption water-reducing agent. S4: Add the pretreated fly ash microspheres, activated ultrafine mineral powder and limestone powder into a ball mill for grinding in proportion; Add a temperature suppressant and an anti-adsorption water-reducing agent, and continue grinding to obtain a viscosity-reducing and temperature-suppressing composite admixture.

2. The preparation method of the viscosity-reducing and temperature-suppressing composite admixture according to claim 1, characterized in that, S1 specifically involves placing fly ash microspheres into a high-speed mixer, adding 1-3% of silane coupling agent A151 or A171 by mass, and stirring at 80-100℃ for 30-60 minutes. Mix ultrafine mineral powder with sodium carbonate at a mass of 0.5-1% and calcine at 300-400℃ for 30-60 minutes.

3. The preparation method of the viscosity-reducing and temperature-suppressing composite admixture according to claim 1, characterized in that, S2 is specifically prepared by dissolving maleic anhydride, acrylic acid, and sodium gluconate in deionized water, with a solid content of 30-40%. The molar ratio of maleic anhydride to acrylic acid is 1:2-3, and sodium gluconate accounts for 15-25% of the mass of maleic anhydride. The temperature is raised to 60-70℃, and 0.5-1.0% of the mass of maleic anhydride initiator ammonium persulfate is added dropwise. After reacting for 3-4 hours, 5-10% of the mass of maleic anhydride 2-acrylamido-2-methylpropanesulfonic acid is added, and the reaction continues for 1-2 hours. The water is removed by vacuum distillation, and the product is spray-dried to obtain a white powder, which is the temperature suppressant.

4. The preparation method of the viscosity-reducing and temperature-suppressing composite admixture according to claim 1, characterized in that, S3 is specifically as follows: dissolve acrylic acid, ethylene glycol monomethyl ether acrylate, dithiobenzoic acid isobutyl nitrile ester, and initiator azobisisobutyronitrile in deionized water, with a solid content of 30-40%, stir at 200-300 rpm for 15-20 min, heat to 65-75℃ under a nitrogen atmosphere, react for 3-4 h, and then naturally cool to 50-60℃ to obtain a pale yellow transparent prepolymer solution; A 40-50 wt% aqueous solution of polyethylene glycol acrylate, preheated to 45-62℃, is added dropwise to the prepolymer solution at a rate of 6-10 drops / min. The initiator potassium persulfate is added in 2-3 portions, with an interval of 25-30 minutes between each addition. The mixture is stirred at 60-65℃ and 200-300 rpm for 2-3 hours to obtain a milky white viscous liquid, which is the anti-adsorption water-reducing agent.

5. The preparation method of the viscosity-reducing and temperature-suppressing composite admixture according to claim 4, characterized in that, The mass ratio of acrylic acid, ethylene glycol monomethyl ether acrylate, isobutyl nitrile dithiobenzoate, and initiator azobisisobutyronitrile is 40-60:32-48:0.5-1:0.3-0.

6.

6. The preparation method of the viscosity-reducing and temperature-suppressing composite admixture according to claim 4, characterized in that, The mass ratio of polyethylene glycol acrylate, acrylic acid, and potassium persulfate initiator is 150-250:40-60:0.3-0.

5.

7. The preparation method of the viscosity-reducing and temperature-suppressing composite admixture according to claim 1, characterized in that, S4 specifically involves adding pretreated fly ash microspheres, activated ultrafine mineral powder, and limestone powder to a ball mill in a certain proportion and grinding for 10-20 minutes. Add a temperature suppressant and an anti-adsorption water-reducing agent, and continue grinding for 5-10 minutes to obtain a viscosity-reducing and temperature-suppressing composite admixture.

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