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

Abstract

The invention discloses a viscosity-reducing and temperature-inhibiting composite admixture and a preparation method thereof, and belongs to the technical field of aluminoferrite cement, the viscosity-reducing and temperature-inhibiting composite admixture comprises 20-40 parts of fly ash microbeads, 30-50 parts of superfine mineral powder, 10-20 parts of limestone powder, 0.5-2 parts of a temperature-inhibiting agent, and 1-5 parts of an anti-adsorption water reducing agent. The carboxylic acid-sulfonic acid group of the temperature inhibiting agent preferentially occupies high-activity sites on the surface of the iron-aluminum phase through chemical coordination, so that invalid adsorption of the water reducing agent is reduced. According to the anti-adsorption water reducing agent, the adsorption loss of iron and aluminum relative to the water reducing agent is reduced through the steric hindrance effect of a polyether long chain and the electrostatic repulsive force of a carboxylic acid group, the dispersing capacity is continuously provided, and the temperature suppression agent is indirectly assisted to achieve more uniform hydration heat release.

Description

Technical Field

[0001] The invention relates to the technical field of ferroaluminate cement, and in particular to a viscosity-reducing and temperature-suppressing composite admixture and a preparation method thereof. Background Art

[0002] Ferroaluminate cement, due to its high early strength, excellent corrosion resistance and impermeability, has shown important application value in fields such as marine engineering, underground structures, and emergency repair projects that have stringent requirements on material performance.

[0003] However, the inherent characteristics of its hydration process have become a key bottleneck restricting its engineering application: on the one hand, the cement hydration exothermic curve shows the significant characteristics of being "fast and concentrated", with the highest exothermic peak usually appearing within 8-10 hours after hydration, and the entire hydration exothermic process basically completed within 1 day. This rapid and concentrated heat release can easily lead to a large temperature gradient within the concrete, thereby causing the risk of temperature stress cracking. Although mineral admixtures such as fly ash and slag are often used in existing technologies to try to reduce the hydration heat, such admixtures can only play a limited delaying role by diluting cement clinker or having a weak activity effect. They have not been specifically optimized for the unique kinetic characteristics of ferroaluminate cement, such as the rapid formation of calcium aluminate and the early and intense hydration of iron and aluminum phases. As a result, the early temperature rise control effect is difficult to meet the actual needs of the project, and the problem of temperature stress cracking still occurs frequently.

[0004] On the other hand, the high iron and aluminum content in ferroaluminate cement has a strong adsorption capacity for traditional water reducers. This strong adsorption can significantly weaken the dispersant's dispersant efficiency, leading to a significant increase in concrete paste viscosity and increased pumping resistance, seriously affecting performance and efficiency during construction. The dual problems of insufficient hydration heat regulation and ineffective viscosity control have become technical difficulties that urgently need to be overcome in the engineering application of ferroaluminate cement. Therefore, it is urgent to develop a composite admixture and preparation method that can simultaneously achieve viscosity reduction and temperature suppression to address the performance shortcomings of existing technologies due to insufficient targeting. Summary of the Invention

[0005] In view of the above-mentioned shortcomings of the prior art, the present invention provides a viscosity-reducing and temperature-suppressing composite admixture, comprising the following components:

[0006] 20-40 parts of fly ash microbeads;

[0007] 30-50 parts of ultrafine mineral powder;

[0008] 10-20 parts of limestone powder;

[0009] 0.5-2 parts of temperature inhibitor;

[0010] 1-5 parts of anti-adsorption water reducer.

[0011] A method for preparing the viscosity-reducing and temperature-suppressing composite admixture comprises the following steps:

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

[0013] Ultrafine mineral powder activation treatment: Mix the ultrafine mineral powder with sodium carbonate and calcine;

[0014] S2: Preparation of temperature inhibitor;

[0015] Dissolve maleic anhydride, acrylic acid, and sodium gluconate in deionized water, raise the temperature, add an initiator dropwise, and after the reaction, add 2-acrylamide-2-methylpropanesulfonic acid to continue the reaction, and distill under reduced pressure and spray dry to obtain a temperature inhibitor;

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

[0017] Dissolve acrylic acid, ethylene glycol monomethyl ether acrylate, isobutyronitrile bisthiobenzoate, and initiator azobisisobutyronitrile in deionized water, stir, heat and react under a nitrogen atmosphere, and cool naturally to obtain a prepolymer solution;

[0018] The polyethylene glycol acrylate aqueous solution is dropped into the prepolymer solution, and the initiator potassium persulfate is added in batches, and the mixture is stirred to react to obtain an anti-adsorption water reducing agent;

[0019] S4: adding the pretreated fly ash microbeads, activated ultrafine mineral powder and limestone powder into a ball mill according to proportion and grinding;

[0020] Add temperature inhibitor and anti-adsorption water reducer, and continue grinding to obtain viscosity-reducing and temperature-inhibiting composite admixture.

[0021] Furthermore, S1 is specifically as follows: placing fly ash microbeads into a high-speed mixer, adding 1-3% by weight of silane coupling agent A151 or A171, and stirring at 80-100° C. for 30-60 min;

[0022] The ultrafine mineral powder is mixed with 0.5-1% sodium carbonate by weight and calcined at 300-400°C for 30-60 minutes.

[0023] Furthermore, S2 is specifically as follows: maleic anhydride, acrylic acid, and sodium gluconate are dissolved in deionized water with a solid content of 30-40%, a molar ratio of maleic anhydride to acrylic acid of 1:2-3, and sodium gluconate accounting for 15-25% of the mass of maleic anhydride; the temperature is raised to 60-70°C, and ammonium persulfate as an initiator accounting for 0.5-1.0% of the mass of maleic anhydride is added dropwise. After reacting for 3-4 hours, 2-acrylamide-2-methylpropanesulfonic acid accounting for 5-10% of the mass of maleic anhydride is added and the reaction is continued for 1-2 hours. Water is removed by distillation under reduced pressure, and the powder is spray-dried to obtain a white powder, which is the temperature inhibitor.

[0024] Furthermore, S3 is specifically as follows: acrylic acid, ethylene glycol monomethyl ether acrylate, isobutyronitrile bisthiobenzoate, and initiator azobisisobutyronitrile are dissolved in deionized water with a solid content of 30-40%, stirred at 200-300 rpm for 15-20 minutes, heated to 65-75°C under a nitrogen atmosphere, reacted for 3-4 hours, and naturally cooled to 50-60°C to obtain a light yellow transparent prepolymer solution;

[0025] A 40-50wt% polyethylene glycol acrylate aqueous solution preheated to 45-62°C is added dropwise to the prepolymer solution at a rate of 6-10 drops / min. The initiator potassium persulfate is added in 2-3 times, each time with an interval of 25-30 minutes. The mixture is stirred at 60-65°C and 200-300 rpm for 2-3 hours to obtain a milky white viscous liquid, which is an anti-adsorption water reducer.

[0026] Furthermore, the mass ratio of acrylic acid, ethylene glycol monomethyl ether acrylate, isobutyronitrile bisthiobenzoate, and initiator azobisisobutyronitrile is 40-60:32-48:0.5-1:0.3-0.6.

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

[0028] Furthermore, S4 specifically comprises: adding the pretreated fly ash microbeads, activated ultrafine mineral powder and limestone powder into a ball mill in proportion, and grinding for 10-20 minutes;

[0029] Add temperature inhibitor and anti-adsorption water reducer, continue grinding for 5-10 minutes, and obtain viscosity-reducing and temperature-inhibiting composite admixture.

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

[0031] 1. The temperature inhibitor of this invention utilizes a maleic anhydride-acrylic acid-sodium gluconate terpolymer as its backbone, with sulfonic acid side chains incorporated, creating a unique structure of "carboxylic acid-sulfonic acid bidentate groups + polyether flexible chains." The carboxylic acid groups adsorb onto the surface of cement particles through coordination, slowing the rapid formation of ettringite. The sulfonic acid groups disperse the cement particles through electrostatic repulsion, inhibiting the early, intense hydration of the iron and aluminum phases and dispersing the exothermic hydration process.

[0032] 2. The anti-adsorption water reducer adopts a three-level gradient structure: main chain (polyacrylic acid) - short chain branches (ethylene glycol monomethyl ether acrylate) - long chain branches (polyethylene glycol acrylate). This structure resists the strong adsorption of iron and aluminum phases in ferroaluminate cement through steric hindrance. The short chain branches provide initial dispersing force, while the long chain branches maintain dispersion stability through flexible polyether segments. This allows the water reducer to maintain most of its effective dispersing performance even in highly adsorbed environments, reducing concrete paste viscosity and significantly reducing pumping resistance.

[0033] 3. The carboxylic acid-sulfonic acid groups of the temperature inhibitor preferentially occupy highly active sites on the surface of the iron and aluminum phases through chemical coordination, reducing ineffective adsorption of the water reducer. The sulfonic acid groups form stable complexes with calcium and aluminum ions, inhibiting the rapid formation of ettringite. The carboxylic acid groups hydrogen-bond with the acrylic acid units in the water reducer backbone, enhancing the stability of the adsorption layer. The long polyether chains sterically shield the adsorption sites on the iron and aluminum phases. Simultaneously, the carboxylic acid groups form a charge-synergistic repulsion with the carboxylic acid groups of the temperature inhibitor, further significantly reducing adsorption losses. The anti-adsorption water reducer utilizes the steric hindrance of the long polyether chains and the electrostatic repulsion of the carboxylic acid groups to reduce adsorption losses of the water reducer on the iron and aluminum phases, providing continuous dispersibility. This long-lasting dispersibility prevents localized hydration acceleration caused by cement particle agglomeration (high cement concentration and concentrated heat release in agglomerated areas), indirectly assisting the temperature inhibitor in achieving more uniform hydration heat release. DETAILED DESCRIPTION

[0034] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with 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 making creative efforts are within the scope of protection of the present invention.

[0035] Example 1: This example provides a method for preparing a viscosity-reducing and temperature-suppressing composite admixture, comprising the following steps:

[0036] S1: Surface modification of fly ash microbeads: Place the fly ash microbeads in a high-speed mixer and add 1-3% of their mass of silane coupling agent A151. Stir at 100°C and 800 rpm for 60 minutes to evenly coat the surface of the fly ash microbeads with the silane coupling agent, thereby improving their compatibility and dispersibility with the cement paste. (The coating formed by the silane coupling agent on the surface of the fly ash microbeads reduces the surface energy between the microbeads and reduces the agglomeration of the microbeads, thereby improving their compatibility and dispersibility in the cement paste.)

[0037] Ultrafine mineral powder activation treatment: The ultrafine mineral powder is mixed with 1% sodium carbonate by weight and calcined at 400°C for 60 minutes to activate the activity of the mineral powder (high-temperature calcination as a thermal activation method can change the crystal structure of the mineral powder, increase its active sites, and thus improve its reaction activity);

[0038] S2: Preparation of temperature inhibitor;

[0039] Dissolve maleic anhydride, acrylic acid, and sodium gluconate in deionized water (solid content 40%), with a molar ratio of maleic anhydride to acrylic acid of 1:3 and sodium gluconate accounting for 25% of the mass of maleic anhydride. Heat to 70°C, add dropwise initiator ammonium persulfate (accounting for 1.0% of the mass of maleic anhydride), and react for 4 hours. Then, add 2-acrylamide-2-methylpropanesulfonic acid (accounting for 10% of the mass of maleic anhydride) and continue to react for 2 hours. Remove water by distillation under reduced pressure, and spray dry to obtain a white powder, which is a temperature inhibitor.

[0040] S3: Preparation of anti-adsorption water reducing agent;

[0041] Acrylic acid, ethylene glycol monomethyl ether acrylate, isobutyronitrile bisthiobenzoate, and initiator azobisisobutyronitrile in a mass ratio of 60:48:1:0.6 were dissolved in deionized water with a solid content of 40%. The mixture was stirred at 300 rpm for 20 minutes. The temperature was raised to 75°C under a nitrogen atmosphere, reacted for 4 hours, and then naturally cooled to 60°C to obtain a light yellow transparent prepolymer solution.

[0042] A 50 wt% polyethylene glycol acrylate aqueous solution preheated to 62°C was added dropwise to the prepolymer solution at a rate of 10 drops / min, and the initiator potassium persulfate was added in three portions with a mass ratio of polyethylene glycol acrylate, acrylic acid, and initiator potassium persulfate of 250:60:0.5. Each addition was separated by 30 minutes, and the mixture was stirred at 65°C and 300 rpm for 3 hours to obtain a milky white viscous liquid, i.e., an anti-adsorption water reducer.

[0043] S4: weigh the raw materials;

[0044] 40 parts of fly ash microspheres; they have a good ball-bearing effect, which can reduce the viscosity of concrete paste and improve construction fluidity;

[0045] 50 parts of ultrafine mineral powder; it can fill the pores of concrete and improve its density. At the same time, its 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] 20 parts of limestone powder; it can react with the aluminum in ferroaluminate cement to form calcium carbonate aluminate, adjust the composition of hydration products, inhibit the rapid formation of ettringite, and thus control the hydration heat release rate;

[0047] 2 parts of temperature inhibitor;

[0048] 5 parts of anti-adsorption water reducer;

[0049] S5: Add the pretreated fly ash microbeads, activated ultrafine mineral powder and limestone powder into the ball mill in proportion and grind for 20 minutes;

[0050] Add temperature inhibitor and anti-adsorption water reducer, continue grinding for 10 minutes, and obtain viscosity-reducing and temperature-inhibiting composite admixture.

[0051] Example 2: This example provides a method for preparing a viscosity-reducing and temperature-suppressing composite admixture, comprising the following steps:

[0052] S1: Surface modification of fly ash microspheres: Place fly ash microspheres in a high-speed mixer, add 1-3% of their mass of silane coupling agent A171, and stir at 80°C for 30 minutes to evenly coat the surface of the fly ash microspheres with the silane coupling agent, thereby improving their compatibility and dispersibility with cement paste.

[0053] Ultrafine mineral powder activation treatment: Mix the ultrafine mineral powder with 0.5% sodium carbonate by weight and calcine at 300°C for 30 minutes to activate the activity of the mineral powder;

[0054] S2: Preparation of temperature inhibitor;

[0055] Dissolve maleic anhydride, acrylic acid, and sodium gluconate in deionized water (solid content 30%), with a molar ratio of maleic anhydride to acrylic acid of 1:2 and sodium gluconate accounting for 15% of the mass of maleic anhydride. Heat to 60°C, add dropwise initiator ammonium persulfate (accounting for 0.5% of the mass of maleic anhydride), and react for 3 hours. Then, add 2-acrylamide-2-methylpropanesulfonic acid (accounting for 5% of the mass of maleic anhydride) and continue the reaction for 1 hour. Remove moisture by vacuum distillation and spray dry to obtain a white powder, which is the temperature inhibitor.

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

[0057] Acrylic acid, ethylene glycol monomethyl ether acrylate, isobutyronitrile bisthiobenzoate, and initiator azobisisobutyronitrile in a mass ratio of 40:32:0.5:0.3 were dissolved in deionized water with a solid content of 30%. The mixture was stirred at 200 rpm for 15 minutes. The temperature was raised to 65°C under a nitrogen atmosphere, reacted for 3 hours, and then naturally cooled to 50°C to obtain a light yellow transparent prepolymer solution.

[0058] A 40 wt% polyethylene glycol acrylate aqueous solution preheated to 45°C was added dropwise to the prepolymer solution at a rate of 6 drops / min, and the initiator potassium persulfate was added in two portions with a mass ratio of polyethylene glycol acrylate, acrylic acid, and initiator potassium persulfate of 150:40:0.3. Each addition was separated by 25 minutes, and the mixture was stirred at 60°C and 200 rpm for 2 hours to obtain a milky white viscous liquid, i.e., an anti-adsorption water reducer.

[0059] S4: weigh the raw materials;

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

[0061] 30 parts of ultrafine mineral powder; it can fill the pores of concrete and improve its density. At the same time, its 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;

[0062] 10 parts of limestone powder; it can react with the aluminum in ferroaluminate cement to form calcium carbonate aluminate, adjust the composition of hydration products, inhibit the rapid formation of ettringite, and thus control the hydration exothermic rate;

[0063] 0.5 parts of temperature inhibitor;

[0064] 1 part of anti-adsorption water reducer;

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

[0066] Add temperature inhibitor and anti-adsorption water reducer, continue grinding for 5 minutes, and obtain viscosity-reducing and temperature-inhibiting composite admixture.

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

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

[0069] Ultrafine mineral powder activation treatment: Mix the ultrafine mineral powder with 0.7% sodium carbonate by weight and calcine at 360°C for 55 minutes to activate the activity of the mineral powder;

[0070] S2: Preparation of temperature inhibitor;

[0071] Dissolve maleic anhydride, acrylic acid, and sodium gluconate in deionized water (solid content 38%), with a molar ratio of maleic anhydride to acrylic acid of 1:2.4 and sodium gluconate accounting for 22% of the mass of maleic anhydride. Heat to 66°C, add dropwise initiator ammonium persulfate (accounting for 0.8% of the mass of maleic anhydride), and react for 3.5 hours. Then, add 2-acrylamide-2-methylpropanesulfonic acid (accounting for 8% of the mass of maleic anhydride) and continue the reaction for 1 hour. Remove moisture by distillation under reduced pressure, and spray dry to obtain a white powder, which is the temperature inhibitor.

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

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

[0074] A 47 wt% polyethylene glycol acrylate aqueous solution preheated to 54°C was added dropwise to the prepolymer solution at a rate of 8 drops / min, and the initiator potassium persulfate was added in three portions with a mass ratio of polyethylene glycol acrylate, acrylic acid, and initiator potassium persulfate of 210:48:0.4. Each addition was separated by 28 minutes, and the mixture was stirred at 62°C and 260 rpm for 2 hours to obtain a milky white viscous liquid, i.e., an anti-adsorption water reducer.

[0075] S4: weigh the raw materials;

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

[0077] 41 parts of ultrafine mineral powder; it can fill the pores of concrete and improve its density. At the same time, its 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;

[0078] 18 parts of limestone powder; it can react with the aluminum in ferroaluminate cement to form calcium carbonate aluminate, adjust the composition of hydration products, inhibit the rapid formation of ettringite, and thus control the hydration exothermic rate;

[0079] 1.3 parts of temperature inhibitor;

[0080] 2 parts of anti-adsorption water reducer;

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

[0082] Add temperature inhibitor and anti-adsorption water reducer, continue grinding for 8 minutes, and obtain viscosity-reducing and temperature-inhibiting composite admixture.

[0083] Comparative Example 1: This comparative example differs from Example 3 in that no temperature inhibitor is added.

[0084] Comparative Example 2: This comparative example differs from Example 3 in that no anti-adsorption water-reducing agent is added.

[0085] Comparative Example 3: This comparative example differs from Example 3 in that neither a temperature inhibitor nor an anti-adsorption water reducing agent is added.

[0086] Experimental example: 1. Mixture preparation: ferroaluminate cement + composite admixture + water (water-binder ratio 0.35).

[0087] 2. According to GB / T 12959-2024 "Determination of Heat of Hydration of Cement", the isothermal conduction calorimetry method (reference method) was used. An isothermal calorimeter (TAM Air 8-channel type) was used to monitor the cumulative heat release (J / g) during the hydration process of the cement paste. The test cycles were 24 hours and 72 hours.

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

[0089]

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

[0091] As can be seen from the above table, the present invention introduces sulfonic acid side chains into the maleic anhydride-acrylic acid-sodium gluconate terpolymer to form a temperature inhibitor with a molecular structure of "carboxylic acid-sulfonic acid bidentate group + polyether flexible chain", thereby achieving the effect of reducing the hydration heat of ferroaluminate cement;

[0092] The three-level gradient structure of main chain (polyacrylic acid) - short side chain (ethylene glycol monomethyl ether acrylate) - long side chain (polyethylene glycol acrylate) anti-adsorption water reducer achieves anti-adsorption, thereby reducing viscosity;

[0093] The combination of the two can produce a synergistic effect in reducing viscosity and inhibiting temperature.

[0094] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A viscosity-reducing and temperature-suppressing composite admixture, characterized in that: Includes the following components: 20-40 parts of fly ash microbeads; 30-50 parts of ultrafine mineral powder; 10-20 parts of limestone powder; 0.5-2 parts of temperature inhibitor; 1-5 parts of anti-adsorption water reducer.

2. A method for preparing the viscosity-reducing and temperature-suppressing composite admixture according to claim 1, characterized in that: The following steps are involved: S1: Surface modification of fly ash microbeads: adding silane coupling agent to fly ash microbeads and stirring; Ultrafine mineral powder activation treatment: Mix the ultrafine mineral powder with sodium carbonate and calcine; S2: Preparation of temperature inhibitor; Dissolve maleic anhydride, acrylic acid, and sodium gluconate in deionized water, raise the temperature, add an initiator dropwise, and after the reaction, add 2-acrylamide-2-methylpropanesulfonic acid to continue the reaction, and distill under reduced pressure and spray dry to obtain a temperature inhibitor; S3: Preparation of anti-adsorption water reducing agent; Dissolve acrylic acid, ethylene glycol monomethyl ether acrylate, isobutyronitrile bisthiobenzoate, and initiator azobisisobutyronitrile in deionized water, stir, heat and react under a nitrogen atmosphere, and cool naturally to obtain a prepolymer solution; The polyethylene glycol acrylate aqueous solution is dropped into the prepolymer solution, and the initiator potassium persulfate is added in batches, and the mixture is stirred to react to obtain an anti-adsorption water reducing agent; S4: adding the pretreated fly ash microbeads, activated ultrafine mineral powder and limestone powder into a ball mill according to proportion and grinding; Add temperature inhibitor and anti-adsorption water reducer, and continue grinding to obtain viscosity-reducing and temperature-inhibiting composite admixture.

3. The method for preparing the viscosity-reducing and temperature-suppressing composite admixture according to claim 2, wherein: S1 is specifically as follows: put the fly ash microbeads into a high-speed mixer, add 1-3% of the mass of the silane coupling agent A151 or A171, and stir at 80-100°C for 30-60 minutes; The ultrafine mineral powder is mixed with 0.5-1% sodium carbonate by weight and calcined at 300-400°C for 30-60 minutes.

4. The method for preparing the viscosity-reducing and temperature-suppressing composite admixture according to claim 2, wherein: S2 specifically comprises: dissolving maleic anhydride, acrylic acid, and sodium gluconate in deionized water with a solid content of 30-40%, a molar ratio of maleic anhydride to acrylic acid of 1:2-3, and sodium gluconate accounting for 15-25% of the mass of maleic anhydride; heating to 60-70°C; adding dropwise 0.5-1.0% of the mass of maleic anhydride as an initiator, ammonium persulfate; reacting for 3-4 hours; adding 5-10% of the mass of maleic anhydride as 2-acrylamide-2-methylpropanesulfonic acid; continuing the reaction for 1-2 hours; removing water by distillation under reduced pressure; and spray drying to obtain a white powder, which is the temperature inhibitor.

5. The method for preparing the viscosity-reducing and temperature-suppressing composite admixture according to claim 2, characterized in that: S3 specifically comprises: dissolving acrylic acid, ethylene glycol monomethyl ether acrylate, isobutyronitrile bisthiobenzoate, and initiator azobisisobutyronitrile in deionized water to a solid content of 30-40%, stirring at 200-300 rpm for 15-20 minutes, heating to 65-75°C under a nitrogen atmosphere, reacting for 3-4 hours, and naturally cooling to 50-60°C to obtain a light yellow transparent prepolymer solution; A 40-50wt% polyethylene glycol acrylate aqueous solution preheated to 45-62°C is added dropwise to the prepolymer solution at a rate of 6-10 drops / min. The initiator potassium persulfate is added in 2-3 times, each time with an interval of 25-30 minutes. The mixture is stirred at 60-65°C and 200-300 rpm for 2-3 hours to obtain a milky white viscous liquid, which is an anti-adsorption water reducer.

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

6.

7. The method for preparing the viscosity-reducing and temperature-suppressing composite admixture according to claim 5, characterized in that: The mass ratio of polyethylene glycol acrylate, acrylic acid and initiator potassium persulfate is 150-250:40-60:0.3-0.

5.

8. The method for preparing the viscosity-reducing and temperature-suppressing composite admixture according to claim 2, wherein: S4 specifically comprises: adding the pretreated fly ash microbeads, activated ultrafine mineral powder and limestone powder into a ball mill in proportion, and grinding for 10-20 minutes; Add temperature inhibitor and anti-adsorption water reducer, continue grinding for 5-10 minutes, and obtain viscosity-reducing and temperature-inhibiting composite admixture.

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