A crystal nucleus enhancer, a cementitious material and a preparation method thereof

Abstract

The present application relates to the technical field of admixtures for construction materials, and in particular to a crystal nucleus reinforcing agent, a cementitious material and a preparation method thereof. The crystal nucleus reinforcing agent is prepared by a chemical coprecipitation method, and the raw materials used include a sodium metaaluminate solution, a nanometer alumina suspension, a water glass solution, calcium hydroxide, a sodium hydroxide solution, an alcohol amine small molecule polar promoter solution, a strong anchoring type polymer dispersant solution and water. When the crystal nucleus reinforcing agent is used in a cement-fly ash cementitious material with a fly ash content of 1-50%, and the mixing amount is 0.5-5% of the total weight of the cementitious material, the initial and final setting times are shortened by 11.9-41.5% and 13.7-41.5% respectively, the 8h strength is increased by 45.3-172.1%, and the 28d strength is increased by 3.4-10.9%. The crystal nucleus reinforcing agent has excellent dispersion stability and early strength performance, and has the potential for large-scale application in the field of non-autoclaved production of cement-fly ash based concrete prefabricated components.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of admixtures for building materials, and particularly relates to a crystal nucleus enhancer for cement-fly ash cementitious material and a preparation method thereof. BACKGROUND

[0002] Fabricated construction technology is a new construction method, which has the basic characteristics of intensive, low-carbon and environmental protection, and meets the needs of low-carbon sustainable development in China. Precast components are the main part of fabricated structures, and are mainly produced in a centralized manner. The mold turnover rate is the key to determining the production efficiency. Precast concrete components reach the demolding strength, which is the prerequisite for the demolding process. In order to accelerate the early strength development of concrete to reach the demolding strength as soon as possible, precast component factories often use long-time high-temperature steam curing for early strength. Although the early strength effect is remarkable, this method brings high carbon emissions and energy consumption. When the precast concrete components are mixed with a large amount of fly ash and other low-activity admixtures, longer and higher temperature steam curing is required to reach the demolding strength, which leads to a sharp increase in carbon emissions of precast component production.

[0003] Crystal nucleus seeding technology is a new early strength technology. By adding crystal nucleus early strength agent into cement-based materials, the setting and hardening time of cement-based materials can be significantly shortened, and the early strength development can be promoted. Therefore, crystal nucleus seeding technology is also considered as a revolutionary early strength technology for realizing the steam-free curing preparation of precast concrete components. Among many crystal nucleus seeding materials, the early strength performance of C-S-H gel-based crystal nucleus seeding material (C-S-H gel crystal nucleus early strength agent) is the best. The reason may be that the main component and structure of this type of crystal nucleus early strength agent are the same as the C-S-H gel generated by cement hydration, so the energy barrier for the nucleation and growth of C-S-H gel hydrate on its surface is lower than that of other types of crystal nucleus early strength agents.

[0004] In the production of cement-based concrete prefabricated components, a part of fly ash is usually used to replace cement, one of the effects is to reduce the cost of materials, the second effect is to reduce the early chemical shrinkage and drying shrinkage of concrete under the condition of steam curing, and to improve the volume stability of concrete structure. Another neglected effect of fly ash is to provide additional aluminum source (Al2O3 content in fly ash is generally 25-50%) for composite cementitious materials, to generate C-A-S-H gel with greater strength contribution, smaller elastic modulus and better shrinkage performance, which significantly enhances the late mechanical strength and durability of concrete prefabricated components. Since the main gel type in fly ash-cement cementitious material is C-A-S-H gel, its composition and structure are quite different from C-S-H gel-based crystal nucleus early strength agent, therefore, the early strength performance of C-S-H gel-based crystal nucleus early strength agent in fly ash-cement cementitious material is not good. In addition, the dispersing stabilizer used in the crystal nucleus early strength agent is a general polycarboxylic acid superplasticizer, which is designed to reduce the water consumption of cement-based materials, and its dispersing effect on different types of nano crystal nucleus early strength agent is unstable. Therefore, the molecular structure of the dispersing stabilizer needs to be redesigned according to the composition and structure of the crystal nucleus early strength agent to meet the long-term and efficient dispersing and stabilizing requirements of the crystal nucleus early strength agent. SUMMARY

[0005] In view of the deficiencies of the prior art described above, the purpose of the present application is to provide a crystal nucleus enhancer for cement-fly ash cementitious material and a preparation method thereof, aiming to solve the problems of poor dispersing stability of existing crystal nucleus early strength agent and poor early strength effect on cement-fly ash cementitious material.

[0006] The technical scheme of the present application is as follows:

[0007] In the first aspect of the present application, a crystal nucleus enhancer for cement-fly ash cementitious material is provided, wherein the crystal nucleus enhancer is mainly prepared from the following raw materials in parts by weight: sodium metaaluminate solution 37-43 parts, nano-alumina suspension 48-52 parts, water glass solution 270-320 parts, calcium hydroxide 33-41 parts, sodium hydroxide solution 22-28 parts, alcohol amine small molecule polar promoter solution 45-60 parts, strong anchoring type high molecular dispersant solution 40-60 parts, and water 415-503 parts.

[0008] Optionally, the mass fraction of the sodium metaaluminate solution is 10%, and the mass fraction of the sodium hydroxide solution is 10%.

[0009] Optionally, the average particle size of nano-alumina in the nano-alumina suspension is 20-50 nm, and the mass fraction of the nano-alumina suspension is 10%.

[0010] Optionally, the Na2O / SiO2 modulus of the water glass in the water glass solution is 1.0-1.5, and the mass fraction of the water glass solution is 20%.

[0011] Optionally, the alcohol amine polar small molecule accelerator is a mixture of triisopropanolamine and diethanol monoisopropanolamine in a molar ratio of 1:1, and the mass fraction of the alcohol amine polar small molecule accelerator solution is 10%.

[0012] Optionally, the strong anchoring type high molecular dispersant is a random copolymer of methacrylic acid (MAA), 2-hydroxyethyl methacrylic acid phosphate (HEMAP), gamma-methacryloyloxypropyl trimethoxysilane (MPTS), and methyl alkenyl polyoxyethylene ether (HPEG) obtained under aqueous radical polymerization conditions in a molar ratio of 3-4:0.8-1.2:1-2:1, the molecular weight of the random copolymer is 20,000-100,000, and the mass fraction of the strong anchoring type high molecular dispersant solution is 40-50%.

[0013] Optionally, the median particle size of the crystal nucleus enhancer is 30-100 nm, the theoretical solid content is 12.2-15.3%, and the 28d precipitate volume is ≤1%.

[0014] In a second aspect of the present application, a preparation method of the crystal nucleus enhancer for cement-fly ash cementitious materials is provided, wherein the preparation method comprises the following steps:

[0015] S1, the raw materials are weighed according to the above-mentioned raw material proportions for standby;

[0016] S2, the calcium hydroxide is mixed with water to prepare A material, and is preheated to 35-50 °C;

[0017] S3, the sodium metaaluminate solution is mixed with the nano-aluminum oxide suspension to prepare B material;

[0018] S4, the alcohol amine polar small molecule accelerator solution is mixed with the strong anchoring type high molecular dispersant solution to prepare C material;

[0019] S5, under the conditions of a solution temperature of 35-50 °C and stirring, the water glass solution, B material, C material, and sodium hydroxide solution are added to A material to obtain a mixed solution;

[0020] S6, the mixed solution is incubated at 300-400 rpm and 30-40 °C for 180-420 min to obtain the crystal nucleus enhancer for cement-fly ash cementitious materials.

[0021] Optionally, step S5 specifically comprises: under the conditions that the solution temperature is 35-50 °C and the stirring speed is 600-800 rpm, the water glass solution, the B material, the C material and the sodium hydroxide solution are uniformly dropped into the A material, the dropping time of the water glass solution, the B material and the sodium hydroxide solution is controlled to be 120-150 min, and the dropping time of the C material is controlled to be 150-180 min, so as to obtain the mixed solution.

[0022] In a third aspect of the present application, a method for preparing a cement-fly ash cementitious material based on the crystal nucleus enhancer is provided, and the method comprises the following steps:

[0023] Under the condition that the water-cement ratio is 0.3, the cementitious material paste is prepared by using 1-50% fly ash and 50-99% cement;

[0024] The crystal nucleus enhancer is added into the cementitious material paste to obtain the cement-fly ash cementitious material.

[0025] Optionally, the content of the crystal nucleus enhancer is 0.5-5% of the total weight of the cementitious material paste.

[0026] In a fourth aspect of the present application, a cement-fly ash cementitious material is provided, which is prepared by the method of the present application.

[0027] Beneficial effects: The crystal nucleus enhancer is prepared by using sodium metaaluminate solution, nano-alumina suspension, water glass solution, calcium hydroxide, sodium hydroxide solution, alcohol amine small molecule polar promoter solution, strong anchoring type high molecular dispersant solution and water. The median particle size of the crystal nucleus enhancer is 30-100 nm, the theoretical solid content is 12.2-15.3%, and the 28 d precipitate volume is ≤1%, which indicates that the dispersion stability of the crystal nucleus enhancer is good. When the crystal nucleus enhancer is used in the cement-fly ash cementitious material with a fly ash weight content of 1-50% and the content is 0.5-5% of the total weight of the cement-fly ash cementitious material, the initial and final setting times are shortened by 11.9-41.5% and 13.7-41.5%, respectively, the 8 h strength is increased by 45.3-172.1%, and the 28 d strength is increased by 3.4-10.9%. The crystal nucleus enhancer of the present application has excellent dispersion stability and early strength performance, and has great potential for large-scale application in the field of non-autoclaved preparation of cement-fly ash based concrete prefabricated components. DETAILED DESCRIPTION

[0028] The present application provides a crystal nucleus enhancer for cement-fly ash cementitious material and a preparation method thereof. In order to make the purpose, technical scheme and effects of the present application more clear and explicit, the present application is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present application and not to limit the present application.

[0029] This invention provides a nucleation enhancer (also referred to herein as a nucleation early strength agent) for cement-fly ash cementitious materials. The nucleation enhancer, by weight, is mainly prepared from the following raw materials: 37-43 parts sodium aluminate solution, 48-52 parts nano-alumina suspension, 270-320 parts water glass solution, 33-41 parts calcium hydroxide, 22-28 parts sodium hydroxide solution, 45-60 parts alkanolamine polar small molecule accelerator solution, 40-60 parts strong anchoring polymeric dispersant solution, and 415-503 parts water (such as deionized water).

[0030] The sodium aluminate solution, nano alumina suspension, water glass solution, sodium hydroxide solution, alkanolamine polar small molecule promoter solution, and strong anchoring polymer dispersant solution can all use water (such as deionized water) as solvent.

[0031] In this embodiment, the nucleation enhancer for cement-fly ash cementitious materials is mainly prepared from the above raw materials. The reactions between the raw materials during the preparation process are mainly as follows:

[0032] xNa₂O·nSiO₂·10H₂O (water glass) + yCa(OH)₂ → zCaO·SiO₂·H₂O (abbreviated as CSH) + pNaOH

[0033] x'CaO·nSiO2·H2O+y'NaAlO2+z'Al(OH)3→m'CaO·Al2O3·SiO2·H2O (abbreviated as CASH)+n'NaOH

[0034] x''CaO·SiO2·H2O+y''NaOH→z''CaO·Na2O·SiO2·H2O (abbreviated as CNSH)

[0035] As can be seen from the above, the nucleation reinforcing agent for cement-fly ash cementitious materials mainly consists of nano-sized amorphous CSH gel, CASH gel, and CNSH gel. Its composition and structure are similar to the gel generated during the hydration of cement-fly ash cementitious materials, strongly inducing the dissolution of mineral phases in cement and fly ash, as well as the nucleation and growth of hydration products, thus accelerating the hydration reaction kinetics of cement and fly ash materials. Furthermore, the presence of nano-CASH gel and CNSH gel can induce the aluminum source in the cement pore solution (the collective term for the liquid phase components other than the solid phase in cement mixtures) to exist in the form of Al(OH)4, replacing the CASH gel in CSH gel, which has a greater contribution to SiO4 formation strength, lower elastic modulus, and better shrinkage performance. It also induces the Na in the pore solution... +It enters the interlayer of CASH gel to balance charges and stabilize products. In the presence of the nucleation enhancer in this embodiment, the hydration reaction of cement is accelerated, the amount of calcium hydroxide product generated increases, the alkalinity of the pore solution increases, and the pozzolanic reaction of fly ash intensifies. It can start to participate in the hydration reaction in about 7 days, continuously providing calcium and aluminum sources, resulting in rapid development of the mechanical properties of the cementitious material in the later stage.

[0036] Furthermore, in this embodiment, the nucleation enhancer uses a comb-type polymer grafted with strongly anchoring groups as a dispersing stabilizer. The siloxane groups in MPTS, after hydrolysis, can condense with the silanol groups on the surface of nano-CSH gel, CASH gel, and CNSH gel to form strong Si-O-Si chemical bonds. The carboxyl and phosphate groups in MAA and HEMAP can interact with the CaO groups on the surface of nano-CSH gel, CASH gel, and CNSH gel through electrostatic adsorption. 2+ And Al 3+ By forming ionic bonds, the adsorption performance of the dispersion stabilizer on the surface of nanomaterials is enhanced through chemical / ionic bond composite anchoring, which inhibits the aggregation and growth of nanomaterials and significantly improves the dispersion stability of the nucleation enhancer.

[0037] Therefore, the nucleation enhancer for cement-fly ash cementitious materials of this embodiment has excellent dispersion stability and early strength effect, and has the potential to be applied on a large scale to the preparation of cement-fly ash based precast concrete components without steam curing.

[0038] In one embodiment, the sodium aluminate solution has a mass fraction of 10%, and the sodium hydroxide solution has a mass fraction of 10%.

[0039] In one embodiment, the average particle size of the nano-alumina in the nano-alumina suspension is 20-50 nm, and the mass fraction of the nano-alumina suspension is 10%.

[0040] In one embodiment, the Na2O / SiO2 modulus of the water glass in the water glass solution is 1.0~1.5, and the mass fraction of the water glass solution is 20%.

[0041] In one embodiment, the alkanolamine polar small molecule promoter is a mixture of triethylpropanolamine and diethanol monoisopropanolamine in a molar ratio of 1:1, and the mass fraction of the alkanolamine polar small molecule promoter solution is 10%. The alkanolamine polar small molecule promoter is adsorbed onto the surface of the crystal nucleation enhancer through a chelation reaction, which can reduce the particle size of the crystal nucleation enhancer.

[0042] In one embodiment, the strongly anchoring polymeric dispersant is a random copolymer obtained by free radical polymerization of methacrylic acid (MAA), 2-hydroxyethyl methacrylate phosphate (HEMAP), γ-methacryloyloxypropyltrimethoxysilane (MPTS), and methyl allyl polyoxyethylene ether (HPEG) in an aqueous solution at a molar ratio of 3~4:0.8~1.2:1~2:1. The random copolymer has a molecular weight of 20,000~100,000, and the mass fraction of the strongly anchoring polymeric dispersant solution is 40~50%, such as 50%.

[0043] This invention provides a method for preparing the nucleation enhancer for cement-fly ash cementitious materials, comprising the following steps:

[0044] S1. Weigh out each raw material according to the above proportions and set aside.

[0045] S2, calcium hydroxide is mixed with water to prepare material A, and preheated to 35~50 °C;

[0046] S3, prepare material B by mixing sodium aluminate solution with nano-alumina suspension;

[0047] S4, mix the alkanolamine polar small molecule accelerator solution with the strongly anchoring polymeric dispersant solution to prepare material C;

[0048] S5, under the conditions of solution temperature of 35~50 °C and stirring, water glass solution, material B, material C and sodium hydroxide solution are added to material A to obtain a mixed solution;

[0049] S6. The mixed solution is kept at 300-400 rpm and 30-40 °C for 180-420 min to obtain the nucleation enhancer for cement-fly ash cementitious materials.

[0050] In one embodiment, step S5 specifically includes: under the conditions of a solution temperature of 35~50 °C and a stirring rate of 600~800 rpm, water glass solution, component B, component C and sodium hydroxide solution are uniformly dripped into component A, and the dripping time of water glass solution, component B and sodium hydroxide solution is controlled to be 120~150 min, and the dripping time of component C is controlled to be 150~180 min, to obtain the mixed solution.

[0051] This invention provides a method for preparing cement-fly ash cementitious materials based on the aforementioned nucleation enhancer, comprising the following steps:

[0052] Under the condition of water-cement ratio of 0.3, a cementitious paste is prepared by using 1~50% fly ash (% is by weight) and 50~99% cement;

[0053] The nucleation enhancer is added to the cementitious slurry to obtain a cement-fly ash cementitious material.

[0054] In one embodiment, the amount of the nucleation enhancer is 0.5 to 5% of the total weight of the cementitious slurry.

[0055] This invention provides a cement-fly ash cementitious material, which is prepared using the method described in this invention.

[0056] In this embodiment, the nucleation enhancer is prepared by chemical co-precipitation. The raw materials used include sodium aluminate solution, nano-alumina suspension, water glass solution, calcium hydroxide, sodium hydroxide solution, alkanolamine polar small molecule promoter solution, strong anchoring polymeric dispersant solution, and water. The median particle size of the nucleation enhancer is 30~100 nm, the theoretical solid content is 12.2~15.3%, and the 28-day precipitate volume is ≤1%, indicating that the nucleation enhancer has good dispersion stability. The 28-day precipitate volume refers to the proportion of the bottom precipitate volume to the total volume of the nucleation enhancer after standing for 28 days. For details, please refer to GB / T 8077-2012.

[0057] When the nucleation enhancer is used in cement-fly ash cementitious materials with a fly ash content of 1-50% by weight, and the dosage is 0.5-5% of the total weight of the cement-fly ash cementitious materials, the initial and final setting times are shortened by 11.9-41.5% and 13.7-41.5%, respectively; the 8-hour strength is increased by 45.3%-172.1%; and the 28-day strength is increased by 3.4-10.9%. The nucleation enhancer of this embodiment has extremely excellent dispersion stability and early strength performance, and has the potential for large-scale application in the field of steam-free preparation of cement-fly ash based concrete precast components.

[0058] The present invention will be further described below through specific embodiments.

[0059] In Examples 1-6 of this invention, the chemical compositions of the 42.5 grade ordinary silicate cement and fly ash used are shown in Table 1. Furthermore, the sodium aluminate, nano-alumina, water glass (Na2O / SiO2 modulus of 1.2), calcium hydroxide, sodium hydroxide, and alkanolamine (a mixture of triethylpropanolamine and diethanolmonoisopropanolamine in a 1:1 molar ratio) used in Examples 1-6 are all commercially available products; the strong anchoring polymeric dispersant solution (50% by mass) was prepared in the laboratory, and its specific model, raw material ratio, and molecular weight are shown in Table 2.

[0060] Table 1. Oxide composition of raw materials used in the examples

[0061]

[0062] Table 2. Types, raw material ratios, and molecular weights of strongly anchoring polymeric dispersants

[0063]

[0064] The nucleation enhancers used in Examples 1-6 were prepared using the following method:

[0065] S1. Weigh each raw material precisely according to the proportions in Table 3 for later use. The solvents for sodium aluminate solution, nano alumina suspension, water glass solution, sodium hydroxide solution, alkanolamine polar small molecule promoter solution and strong anchoring polymer dispersant solution are all deionized water.

[0066] S2, calcium hydroxide is mixed with deionized water to prepare material A, and then preheated to S2-T °C;

[0067] S3, prepare material B by mixing sodium aluminate solution (mass fraction of 10%) with nano alumina suspension (mass fraction of 10%, average particle size of nano alumina of 30 nm);

[0068] S4, mix the alkanolamine polar small molecule accelerator solution with the strongly anchoring polymeric dispersant solution to prepare material C;

[0069] S5, under the conditions of solution temperature of S5-T °C and stirring speed of S5-R rpm, water glass solution (mass fraction of 20%), material B, material C and sodium hydroxide solution (mass fraction of 10%) are uniformly dropped into material A, and the dropping time of water glass solution, material B and sodium hydroxide solution is controlled to be S5-t1 min, and the dropping time of material C is S5-t2 min;

[0070] S6. After all raw materials have been added, the mixed solution is kept at S6-R rpm and S6-T °C for S6-tmin to obtain the nucleation enhancer for cement-fly ash cementitious materials.

[0071] For details of the specific preparation parameters of the nucleation enhancers in Examples 1 to 6, please refer to Table 4.

[0072] Table 3. Mass ratio of raw materials used in the examples

[0073]

[0074] Table 4. Specific preparation parameters of the nucleation enhancer in the examples

[0075]

[0076] To verify the beneficial effects of the nucleation enhancer prepared in the embodiments of the present invention, cement-fly ash cementitious paste was prepared using 30% fly ash and 70% silicate cement at a water-cement ratio of 0.3. The effects of adding the nucleation enhancer on the setting time, 8-hour compressive strength, and 28-day compressive strength of the cement-fly ash cementitious paste were studied. Examples 1-6 are experimental groups with the addition of the nucleation enhancer, and the dosage is shown in Table 5. Example 7 is the control group without the nucleation enhancer. The cement paste was prepared and the setting time and compressive strength were tested according to GB 8076-2008 "Concrete Admixtures".

[0077] Table 5. Technical parameters, dosage, and performance of crystal nucleation enhancers

[0078]

[0079] Table 5 shows the median particle size, solid content, and 28-day precipitate volume of the nucleation reinforcing agents prepared in Examples 1-6. It can be seen that the median particle size of the nucleation reinforcing agents is in the range of 30-100 nm, the actual solid content is 12.7-14.7%, and the 28-day precipitate volume is 0.5-1%, indicating that the nucleation reinforcing agents have good dispersion stability. Furthermore, Table 5 also shows the relevant properties of the cement-fly ash cementitious paste prepared in Examples 1-7. Under the condition of a dosage of 0.5-5%, the nucleation reinforcing agents (Examples 1-6) can shorten the initial and final setting times of the control group paste (Example 7) by 11.9-41.5% and 13.7-41.5%, respectively, and can increase the 8-hour and 28-day compressive strength of the paste by 45.3%-172.1% and 3.4-10.9%, respectively.

[0080] In summary, this invention provides a nucleation enhancer for cement-fly ash cementitious materials and its preparation method, addressing the problems of poor dispersion stability and poor early strength effect of existing nucleation early strength agents on cement-fly ash cementitious materials. The nucleation enhancer is prepared by a chemical co-precipitation method, using raw materials including sodium aluminate solution, nano-alumina suspension, water glass solution, calcium hydroxide, sodium hydroxide solution, alkanolamine polar small molecule accelerator solution, strong anchoring polymeric dispersant solution, and deionized water. When the nucleation enhancer is used in cement-fly ash cementitious materials with a fly ash content of 1-50%, and the dosage is 0.5-5% of the total weight of the cementitious material, the initial and final setting times are shortened by 11.9-41.5% and 13.7-41.5%, respectively; the 8-hour strength is increased by 45.3%-172.1%; and the 28-day strength is increased by 3.4-10.9%. The nucleation enhancer of the present invention has extremely excellent dispersion stability and early strength performance, and has the potential for large-scale application in the field of steam curing-free preparation of cement-fly ash based concrete precast components.

[0081] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A nucleation enhancer for cement-fly ash cementitious materials, characterized in that, The crystal nucleation enhancer is mainly prepared from the following raw materials by weight: 37-43 parts sodium aluminate solution, 48-52 parts nano alumina suspension, 270-320 parts water glass solution, 33-41 parts calcium hydroxide, 22-28 parts sodium hydroxide solution, 45-60 parts alkanolamine polar small molecule promoter solution, 40-60 parts strong anchoring polymer dispersant solution, and 415-503 parts water; The strongly anchoring polymeric dispersant is a random copolymer obtained by free radical polymerization of methacrylic acid, 2-hydroxyethyl methacrylate phosphate, γ-methacryloyloxypropyltrimethoxysilane, and methyl allyl polyoxyethylene ether in an aqueous solution at a molar ratio of 3~4:0.8~1.2:1~2:

1. The molecular weight of the random copolymer is 20,000~100,000, and the mass fraction of the strongly anchoring polymeric dispersant solution is 40~50%.

2. The nucleation enhancer for cement-fly ash cementitious materials according to claim 1, characterized in that, The sodium aluminate solution has a mass fraction of 10%, and the sodium hydroxide solution has a mass fraction of 10%. The average particle size of the nano-alumina in the nano-alumina suspension is 20~50 nm, and the mass fraction of the nano-alumina suspension is 10%. The Na2O / SiO2 modulus of the water glass in the water glass solution is 1.0~1.5, and the mass fraction of the water glass solution is 20%.

3. The nucleation enhancer for cement-fly ash cementitious materials according to claim 1, characterized in that, The alkanolamine polar small molecule promoter is a mixture of triethylpropanolamine and diethanol monoisopropanolamine in a molar ratio of 1:1, and the mass fraction of the alkanolamine polar small molecule promoter solution is 10%.

4. The nucleation enhancer for cement-fly ash cementitious materials according to claim 1, characterized in that, The nucleation enhancer has a median particle size of 30~100 nm, a theoretical solid content of 12.2~15.3%, and a precipitate volume of ≤1% after 28 days.

5. A method for preparing a nucleation enhancer for cement-fly ash cementitious materials according to any one of claims 1 to 4, characterized in that, Including the following steps: S1. Weigh out each raw material according to the above proportions and set aside. S2, calcium hydroxide is mixed with water to prepare material A, and preheated to 35~50 °C; S3, prepare material B by mixing sodium aluminate solution with nano-alumina suspension; S4, mix the alkanolamine polar small molecule accelerator solution with the strongly anchoring polymeric dispersant solution to prepare material C; S5, under the conditions of solution temperature of 35~50 °C and stirring, water glass solution, material B, material C and sodium hydroxide solution are added to material A to obtain a mixed solution; S6. The mixed solution is kept at 300-400 rpm and 30-40 °C for 180-420 min to obtain the nucleation enhancer for cement-fly ash cementitious materials.

6. The method for preparing the nucleation enhancer for cement-fly ash cementitious materials according to claim 5, characterized in that, Step S5 specifically includes: under the conditions of solution temperature of 35~50 °C and stirring speed of 600~800 rpm, water glass solution, material B, material C and sodium hydroxide solution are uniformly dripped into material A, and the dripping time of water glass solution, material B and sodium hydroxide solution is controlled to be 120~150 min, and the dripping time of material C is 150~180 min, to obtain the mixed solution.

7. A method for preparing cement-fly ash cementitious materials based on the nucleation enhancer according to any one of claims 1 to 4, characterized in that, Including the following steps: Under a water-cement ratio of 0.3, a cementitious paste is prepared using 1-50% fly ash and 50-99% cement. The nucleation enhancer is added to the cementitious slurry to obtain a cement-fly ash cementitious material.

8. The method according to claim 7, characterized in that, The amount of the nucleation enhancer is 0.5-5% of the total weight of the cementitious slurry.

9. A cement-fly ash binder, characterized in that, It is prepared by the method described in any one of claims 7 to 8.

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