High-performance corundum-based repairing material and preparation method thereof

Abstract

The invention discloses a high-performance corundum-based repairing material and a preparation method thereof, and belongs to the technical field of furnace lining repairing materials, the high-performance corundum-based repairing material comprises the following preparation raw materials by mass: 60-80 parts of aggregate, 10-30 parts of powder, 8-20 parts of a binder and 0.5-2 parts of an additive; the aggregate comprises fused white corundum and fused magnesium aluminate spinel; the powder comprises white corundum powder, rare earth modified alumina powder and boride. The preparation method of the high-performance corundum-based repairing material comprises the following steps: adding the powder into the aggregate, carrying out uniform dry mixing, adding the organic binding agent, then adding the silica sol, and finally adding the additive. The high-performance corundum-based repairing material disclosed by the invention is high in early strength and still has relatively long service life in a high-temperature environment.

Description

Technical Field

[0001] This invention belongs to the field of furnace lining repair material technology, specifically high-performance corundum-based repair material and its preparation method. Background Technology

[0002] In high-temperature industrial fields such as metallurgy and non-ferrous metals, kiln linings are subjected to the combined damage of high temperature, thermal shock and strong erosion for a long time, which puts forward a series of contradictory performance requirements for repair materials: "rapid hardening and early strength - medium and high temperature strength - long service life". However, existing corundum-based repair materials have three irreconcilable defects, which make it difficult to meet the above requirements: (1) Structural defects: Corundum has a high coefficient of thermal expansion, and stress concentration occurs during the heating-cooling cycle, which easily leads to cracks and spalling. (2) Protective defects: The system lacks a stable and dispersed anti-erosion phase. Once it comes into contact with slag or alloy melt, the repair layer is quickly penetrated and eroded, resulting in short service life and frequent maintenance. (3) Defects in strength evolution: If the focus is on early strength, organic binders or highly reactive fine powders are often used. Although demolding can be done within a few hours, the high temperature carbonization shrinkage of organic matter causes cracking in the later stage. If the focus is on medium and high temperature strength, a dense corundum-mullite structure is preferred. However, due to sintering shrinkage and abnormal grain growth, the early strength is low and it cannot be "repaired and used immediately". Moreover, the strength drops sharply after the crystal phase deteriorates, making it difficult to serve for a long time.

[0003] Traditional improvement approaches involve introducing rigid fibers or high-strength inorganic particles into the matrix, hoping to simultaneously enhance toughness and corrosion resistance. However, these reinforcing phases have significantly different coefficients of thermal expansion from the corundum matrix, leading to interfacial thermal mismatch and additional stress, which in turn becomes a crack initiation point. At high temperatures, their poor chemical compatibility results in interfacial reactions that generate brittle phases, failing to achieve grain refinement or strengthening effects. While organic complex systems can improve low-temperature workability, they exacerbate high-temperature carbonization shrinkage, which, combined with the volume changes of the reinforcing phases, further increases the risk of cracking. Summary of the Invention

[0004] To overcome the aforementioned technical problems, this invention provides a high-performance corundum-based repair material and its preparation method. The high-performance corundum-based repair material of this invention exhibits high early-stage strength and a long service life even under high-temperature conditions.

[0005] The present invention solves the above-mentioned technical problems through the following technical solutions.

[0006] This invention discloses a high-performance corundum-based repair material, comprising the following raw materials in parts by weight: 60-80 parts aggregate, 10-30 parts powder, 8-20 parts binder and 0.5-2 parts additive; Preferably, the high-performance corundum-based repair material comprises the following raw materials in parts by weight: 60-75 parts aggregate, 15-25 parts powder, 8-15 parts binder and 0.5-1.5 parts additives; The aggregates include fused white corundum and fused magnesium aluminum spinel; The powder includes white corundum powder, rare earth modified alumina powder, and borides. The binder is silica sol and an organic binder; the organic binder is phenolic resin and polyethylene glycol; The additives are 0.2 to 0.8 parts of water-reducing agent, 0.2 to 0.7 parts of dispersant and 0 to 0.5 parts of plasticizer.

[0007] According to some embodiments of the present invention, the aggregate is 10-30 wt% fused magnesium aluminum spinel and the balance is fused white corundum; preferably, the aggregate is 15-28 wt% fused magnesium aluminum spinel and the balance is fused white corundum.

[0008] According to some embodiments of the present invention, the powder is 15-30 wt% rare earth modified alumina powder, 3-18 wt% borides and the balance white fused alumina powder; preferably, the powder is 15-23 wt% rare earth modified alumina powder, 6-15 wt% borides and the balance white fused alumina powder.

[0009] According to some embodiments of the present invention, the chemical composition of the fused white fused alumina, by mass fraction, is: Al2O3≥98.5%, Fe2O3≤0.08%, Na2O≤0.40%, SiO2≤0.08%.

[0010] According to some embodiments of the present invention, the bulk density of the fused white fused alumina is 3.6~3.88 g / cm³. 3 .

[0011] The chemical composition of the fused magnesium aluminum spinel, by mass fraction, is: 70~77% Al2O3, 22~28% MgO, SiO2≤0.6%, Fe2O3≤0.4%.

[0012] According to some embodiments of the present invention, the bulk density of the fused magnesium aluminum spinel is ≥3.2 g / cm³. 3 .

[0013] According to some embodiments of the present invention, the D50 of the white fused alumina powder is 20~50μm, preferably 28~45μm.

[0014] According to some embodiments of the present invention, the rare earth modified alumina powder is lanthanum oxide modified alumina powder, wherein the rare earth modified alumina powder contains 3-5 wt% La2O3 and the balance alumina.

[0015] According to some embodiments of the present invention, the D50 of the rare earth modified alumina powder is 3~6 μm.

[0016] According to some embodiments of the present invention, the boride is titanium boride or tungsten boride.

[0017] According to some embodiments of the present invention, the particle size of the boride is 0.8~10 μm.

[0018] According to some embodiments of the present invention, the binder is 5-12 parts of silica sol and 3-7 parts of organic binder.

[0019] According to some embodiments of the present invention, the silica sol is a colloid formed by the uniform diffusion of silica nanoparticles in water.

[0020] According to some embodiments of the present invention, the pH of the silica sol is 9-11, preferably 9-10.

[0021] According to some embodiments of the present invention, the silica sol contains SiO2: 20~40wt% and Na2O≤0.5wt%; preferably, the silica sol contains SiO2: 25~35wt% and Na2O≤0.3wt%.

[0022] According to some embodiments of the present invention, the D50 of the silica nanoparticles in the silica sol is 10~20nm.

[0023] According to some embodiments of the present invention, the water-reducing agent is a polycarboxylate water-reducing agent.

[0024] According to some embodiments of the present invention, the plasticizer is dibutyl phthalate, dioctyl sebacate, or epoxidized soybean oil.

[0025] According to some embodiments of the present invention, the dispersant is sodium hexametaphosphate, sodium tripolyphosphate, or sodium pyrophosphate.

[0026] According to some embodiments of the present invention, the maximum operating temperature of the high-performance corundum-based repair material is 1700~1750℃.

[0027] According to some embodiments of the present invention, the high-performance corundum-based repair material has a compressive strength of 60~100MPa, preferably 80~100MPa.

[0028] According to some embodiments of the present invention, the bulk density of the high-performance corundum-based repair material is 2.70~2.85 g / cm³. 3 Preferably, the high-performance corundum-based repair material has a bulk density of 2.75~2.85 g / cm³. 3 .

[0029] According to some embodiments of the present invention, the high-performance corundum-based repair material has a compressive strength of 35-50 MPa after being cycled 20-40 times at a maximum temperature of 1600-1750°C.

[0030] According to some embodiments of the present invention, the high-performance corundum-based repair material has a bulk density of 2.4~2.6 g / cm³ after cycling at a maximum temperature of 1700~1750℃ for 20~40 cycles. 3 .

[0031] This invention discloses a method for preparing high-performance corundum-based repair material, comprising the following steps: adding powder to aggregate and mixing it evenly, adding an organic binder, adding silica sol, and finally adding additives.

[0032] Both the aggregate and the powder require pretreatment of their raw materials. A qualified pretreatment process can ensure the consistency and quality of high-performance corundum-based repair materials. The pretreatment involves removing impurities from the raw materials of aggregate and powder, sieving them 2-3 times using a 300-400 mesh sieve, drying them at 80-100℃, and controlling the moisture content to ≤0.5%. The raw materials for aggregate preparation are then dry-mixed in a mixer for 3-5 minutes to obtain aggregate, and the raw materials for powder preparation are then dry-mixed in a mixer for 5-8 minutes to obtain powder.

[0033] The silica sol is added by dripping at a rate of 5-10 mL / min.

[0034] The present invention also discloses the construction process of high-performance corundum-based repair material, including smearing, pouring and spraying.

[0035] The application of the high-performance corundum-based repair material in the lining repair of medium-frequency furnaces, metallurgical furnaces, vacuum furnaces or casting transfer ladles, especially in the lining repair of medium-frequency induction furnaces.

[0036] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0037] Compared with the prior art, the beneficial effects of the present invention are: 1. The aggregates of this invention are fused magnesium aluminum spinel and fused white corundum. The spinel and corundum form a magnesium aluminum spinel solid solution at high temperatures, relieving thermal stress. Simultaneously, the microporous structure of the spinel blocks slag penetration. The fused white corundum provides a high-strength framework, ensuring the repair material retains high strength even after operation under high-temperature conditions. Rare earth-modified alumina powder in the powder can refine the corundum and inhibit grain boundary migration. Borides form a glassy phase capping layer at high temperatures, strengthening interfacial bonding.

[0038] 2. The binder system of the present invention is a combination of alkaline silica sol and organic binder. At room temperature, the organic binder has good adhesion and the repair material has good processing performance. At high temperature, the binder forms a Si-OC cross-linked network, thus avoiding the situation of "debonding at room temperature and cracking at high temperature".

[0039] 3. The high-performance corundum-based repair material of the present invention exhibits high compressive strength at high temperatures, maintaining high compressive strength even after 20-40 high-temperature cycles. For example, after 30 cycles at 1750°C, the compressive strength of the repair material sample is 35-50 MPa, and according to some embodiments of the present invention, it is 36-47 MPa; in some preferred embodiments, it can reach 40-47 MPa. After 30 cycles at 1750°C, the bulk density of the repair material sample is 2.40-2.60 g / cm³. 3 According to some embodiments of the present invention, the content is 2.43~2.59 g / cm³. 3 In some preferred embodiments, the concentration is 2.50~2.59 g / cm³. 3 . Detailed Implementation

[0040] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0041] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0042] The "range" disclosed in this invention is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be combined arbitrarily; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for specific parameters, it is understood that ranges of 60-110 and 80-120 are also expected. Furthermore, if minimum range values ​​1 and 2 are listed, and if maximum range values ​​3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this invention, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" have been listed herein; "0-5" is merely a shortened representation of these numerical combinations. Furthermore, when a parameter is described as an integer greater than or equal to 2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0043] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.

[0044] Unless otherwise specified, all technical features and optional technical features of this invention can be combined to form new technical solutions.

[0045] Unless otherwise specified, all steps of the present invention may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order; for example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0046] Unless otherwise specified, the terms "comprising" and "including" as used in this invention can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0047] Unless otherwise specified, the term "or" is inclusive in this invention. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0048] The raw material information used in the following examples is as follows: The fused white fused alumina (fine powder) was purchased from Zhengzhou Haixu Abrasives Co., Ltd. Its chemical composition is: Al₂O₃ ≥ 98.5%, Fe₂O₃ ≤ 0.08%, Na₂O ≤ 0.40%, SiO₂ ≤ 0.08%; its bulk density is 3.6 g / cm³. 3 ; The fused magnesium aluminum spinel was purchased from Sanmenxia Shuntai Fused Corundum Co., Ltd. Its chemical composition is: 70~77% Al₂O₃, 22~28% MgO, SiO₂≤0.6%, Fe₂O₃≤0.4%; its bulk density is 3.2 g / cm³. 3 ; White corundum powder was purchased from Henan Sicheng Abrasive Technology Co., Ltd. (F240), with a D50 of 44.5 ± 2.0 μm. Rare earth modified alumina powder was purchased from Suzhou Zhengde Rare Earth Materials Co., Ltd., and its chemical composition is 4% La2O3 and 95% Al2O3, with a D50 of 3~6μm. Tungsten diboride was purchased from Jinzhou Haixin Metal Materials Co., Ltd., with a D50 of 8.3 μm; Titanium diboride was purchased from Jiamai New Materials Co., Ltd., with a D50 of 8.4 μm; The silica sol was purchased from Qingdao Jiyida Silica Gel Reagent Co., Ltd. as JN25 alkaline silica sol, containing 25-26% SiO2, ≤0.3% Na2O, with a pH of 9-10 and a density of 1.15-1.17 g / cm³. 3 The average particle size of its nano-silica is 10~20nm; The phenolic resin was purchased from Hebei Zetian Chemical Co., Ltd. as PF900B. Its viscosity (25℃) is 1500~3000cp, its free phenol content is 9~12%, its solid content is 76~81%, and its residual carbon content is ≥35%. This includes, but is not limited to, the models from the above manufacturers.

[0049] Example 1 1. The high-performance corundum-based repair material of this embodiment has the following composition: 70 parts aggregate, 20.5 parts powder, 12.5 parts binder, and 1.1 parts additive; In this embodiment, the aggregate consists of 18 wt% fused magnesium aluminum spinel and the balance fused white corundum; In this embodiment, the powder consists of 20.8 wt% rare earth modified alumina powder, 11.3 wt% boride (titanium diboride) and the balance white corundum powder. In this embodiment, the binder consists of 8.2 parts silica sol and 4.3 parts organic binder; the organic binder is phenolic resin and polyethylene glycol (PEG400), with a mass ratio of phenolic resin to polyethylene glycol of 4:1; In this embodiment, the additives are 0.4 parts of polycarboxylate superplasticizer (PCA-I from Jiangsu Subote New Material Co., Ltd.), 0.4 parts of plasticizer (dibutyl phthalate), and 0.3 parts of dispersant (sodium hexametaphosphate). 2. The preparation method of the high-performance corundum-based repair material in this embodiment is as follows: Pretreatment: Remove impurities from the raw materials of aggregate and powder, then sieve twice with a 400-mesh sieve, dry at 100℃, and control the moisture content to 0.2%; dry mix the raw materials for aggregate preparation in a mixer for 3 minutes to obtain aggregate, and dry mix the raw materials for powder preparation in a mixer for 5 minutes to obtain powder. Add powder to aggregate and stir at 300 rpm for 5 minutes to dry mix evenly; add organic binder and continue stirring for 3 minutes; then add silica sol at a dropping rate of 5 mL / min, keeping stirring throughout the process. After the dropping is completed, stir for another 10 minutes. Finally, add additives and stir for 8 minutes to obtain high-performance corundum-based repair material.

[0050] Example 2 The difference between this embodiment and Embodiment 1 is as follows: The aggregate consists of 26.4 wt% fused magnesium aluminum spinel and the balance fused white corundum; The other raw materials, steps and parameters are the same as in Example 1.

[0051] Example 3 The difference between this embodiment and Embodiment 1 is as follows: The powder consists of 15.7% rare earth modified alumina powder, 8.6% borides, and the balance white corundum powder. The other raw materials, steps and parameters are the same as in Example 1.

[0052] Example 4 The difference between this embodiment and Embodiment 1 is as follows: The powder consists of 10.7 wt% rare earth modified alumina powder, 18.1 wt% borides and the balance white corundum powder; The other raw materials, steps and parameters are the same as in Example 1.

[0053] Example 5 The difference between this embodiment and Embodiment 1 is as follows: The diboride in this embodiment is tungsten diboride; The other raw materials, steps and parameters are the same as in Example 1.

[0054] Example 6 The difference between this embodiment and Embodiment 1 is as follows: In this embodiment, the binder consists of 3.8 parts silica sol and 8.7 parts organic binder; The other raw materials, steps and parameters are the same as in Example 1.

[0055] Example 7 The difference between this comparative example and Example 1 is as follows: The binder in this comparative example is an organic binder only and does not contain silica sol; The other raw materials, steps and parameters are the same as in Example 1.

[0056] Comparative Example 1 The difference between this comparative example and Example 1 is as follows: The aggregate in this comparative example contains 25 wt% rare earth modified alumina powder and the remainder is white corundum powder. The other raw materials, steps and parameters are the same as in Example 1.

[0057] Comparative Example 2 The difference between this comparative example and Example 1 is as follows: The powder consists of 10.4 wt% boride (titanium diboride) and the balance white corundum powder, meaning that the powder does not contain rare earth modified alumina powder. The other raw materials, steps and parameters are the same as in Example 1.

[0058] Test Example – High Temperature Cycling Test (1) Sample preparation: The high-performance corundum-based repair material prepared by the above examples and comparative examples was used in an electric furnace to make cylindrical samples with a pressure of 80 MPa on a pressure testing machine. After demolding, the samples were dried at 100°C for 24 h. (2) Heat treatment test: Heat the sample to 1750℃ for 3 hours, then cool it to room temperature in the furnace. After repeating this heat treatment step 30 times, perform the following performance tests on the sample and record the performance changes before and after the highest temperature (1750℃) cycle. That is, record the performance of the sample after the first heat treatment and the tenth heat treatment. The test results are shown in Table 1. (3) Performance test items Bulk density: The test method is in accordance with GB / T2997-2015; Compressive strength: The test method is in accordance with GB / T5072-2008.

[0059]

[0060] Based on the aforementioned results, it can be concluded that: Compared with Example 1, Example 2 increased the amount of fused magnesium aluminum spinel in the aggregate, utilizing its high-temperature reaction with corundum to form a solid solution, releasing thermal stress and blocking slag, thus improving overall performance.

[0061] Examples 3 and 4 adjusted the ratio of rare earth modified alumina and titanium diboride in the powder; in Example 3, the grain refinement and interface strengthening effects were weakened, and the strength before and after cycling was lower than that in Example 1; in Example 4, the rare earth modified alumina was insufficient, and the grain coarsening led to a decrease in density and strength.

[0062] In Example 5, titanium diboride was replaced with tungsten diboride. Titanium diboride showed a slight decrease in interfacial bonding at room temperature, but better high-temperature stability and a smaller decrease in strength after cycling.

[0063] The binder in Example 6 contained a large amount of organic binder, resulting in poor strength and density after high-temperature cycling. Example 7 contained no silica sol, only an organic binder; its adhesion was acceptable at room temperature, but carbonization shrinkage was significant at high temperatures, leading to a substantial decrease in compressive strength.

[0064] Comparative Example 1 lacks borides and has no high-temperature glass phase protection, resulting in weakened grain boundaries and a significant decrease in bulk density and strength retention after high-temperature cycling.

[0065] Comparative Example 2, which does not contain rare earth modified alumina, cannot refine its grains, has poor initial density, and the grains grow further under high-temperature cycling, leading to crack propagation and a continuous decrease in strength and density.

[0066] Unless otherwise specified, all raw materials, reagents, instruments, and equipment used in this invention can be purchased commercially or prepared using existing methods. The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this invention. It should be understood that the above descriptions are merely specific embodiments of this invention and are not intended to limit the invention. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A high-performance corundum-based repair material, characterized in that, The preparation raw materials include the following parts by weight: 60-80 parts aggregate, 10-30 parts powder, 8-20 parts binder and 0.5-2 parts additive; The aggregates include fused white corundum and fused magnesium aluminum spinel; The powder includes white corundum powder, rare earth modified alumina powder, and borides. The binder is a silica sol and an organic binder, wherein the organic binder is a phenolic resin and polyethylene glycol; The additives are 0.2 to 0.8 parts of water-reducing agent, 0.2 to 0.7 parts of dispersant and 0 to 0.5 parts of plasticizer.

2. The high-performance corundum-based repair material as described in claim 1, characterized in that, The aggregate consists of 10-30 wt% fused magnesium aluminum spinel and the balance fused white corundum; And / or, the powder is 15-30 wt% rare earth modified alumina powder, 3-18 wt% boride and the balance white corundum powder.

3. The high-performance corundum-based repair material as described in claim 2, characterized in that, The bulk density of the fused white corundum is 3.6~3.88 g / cm³. 3 ; And / or, the bulk density of the fused magnesium aluminum spinel is ≥3.2 g / cm³. 3 .

4. The high-performance corundum-based repair material as described in claim 2, characterized in that, The rare earth modified alumina powder is lanthanum oxide modified alumina powder, and the rare earth modified alumina powder contains 3~5wt% La2O3 and the balance alumina. And / or, the D50 of the rare earth modified alumina powder is 3~6μm.

5. The high-performance corundum-based repair material as described in claim 1, characterized in that, The boride is titanium boride or tungsten boride; And / or, the particle size of the boride is 0.8~10 μm.

6. The high-performance corundum-based repair material as described in claim 5, characterized in that, At least one of the following conditions a to c must be met: a. The pH of the silica sol is 9-11; b. The silica sol contains SiO2: 20~40wt%, Na2O ≤0.5wt%; c. The D50 of the silica nanoparticles in the silica sol is 10~20nm.

7. The high-performance corundum-based repair material as described in claim 5, characterized in that, At least one of the following conditions a to c must be met: a. The water-reducing agent is a polycarboxylate water-reducing agent; b. The plasticizers are dibutyl phthalate, dioctyl sebacate, or epoxidized soybean oil; c. The dispersant is sodium hexametaphosphate, sodium tripolyphosphate, or sodium pyrophosphate.

8. The high-performance corundum-based repair material according to any one of claims 1 to 7, characterized in that, At least one of the following conditions a to e must be satisfied: a. The maximum operating temperature of the high-performance corundum-based repair material is 1700~1750℃; b. The high-performance corundum-based repair material has a compressive strength of 60-100 MPa after sintering at a maximum temperature of 1600-1750℃; d. The bulk density of the high-performance corundum-based repair material is 2.70~2.85 g / cm³. 3 The preferred value is 2.75~2.85 g / cm³. 3 ; c. The high-performance corundum-based repair material has a compressive strength of 35-55 MPa after 20-40 cycles at a maximum temperature of 1600-1750℃, preferably 40-55 MPa; e. The bulk density of the high-performance corundum-based repair material after 20-40 cycles at a maximum temperature of 1700-1750℃ is 2.4-2.6 g / cm³. 3 .

9. The method for preparing the high-performance corundum-based repair material according to any one of claims 1 to 7, characterized in that, Includes the following steps: Add powder to the aggregate and dry mix evenly, then add organic binder, then silica sol, and finally add additives.

10. The method for preparing the high-performance corundum-based repair material as described in claim 9, characterized in that, Both the aggregate and the powder require pretreatment of their raw materials. The pretreatment involves removing impurities from the raw materials of the aggregate and the powder, sieving them 2-3 times with a 300-400 mesh sieve, drying them at 80-100℃, and controlling the moisture content to ≤0.5%. The raw materials for preparing the aggregate are dry-mixed in a mixer for 3-5 minutes to obtain the aggregate, and the raw materials for preparing the powder are dry-mixed in a mixer for 5-8 minutes to obtain the powder. And / or, the silica sol is added by dripping, and the dripping rate is 5~10mL / min.

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