Alkali-activated solid waste cementing repair material and preparation method thereof

Abstract

The invention relates to an alkali-activated solid waste cementing repair material and a preparation method thereof, and belongs to the technical field of solid waste resource utilization and building materials. The repairing material is prepared from the following raw materials in parts by weight: 30 parts of fly ash, 70 parts of blast furnace slag, 40 parts of machine-made sand, 45-50 parts of water, 7-13 parts of an exciting agent, 1-2 parts of sodium tetraborate, 1-2 parts of calcium oxide, 1-2 parts of magnesium oxide, 1-2 parts of calcium sulphoaluminate, 0.5 part of aluminum oxide, 0.2 part of aluminum potassium sulfate, 0.2 part of aluminum powder, 0.2 part of alunite and 1 part of polyethylene glycol. By optimizing the modulus of the exciting agent, the alkali content, the water-binder ratio and the admixture ratio, the material has the shrinkage-compensating and micro-expansion characteristics, the compressive strength of the material in one day reaches 25-30 MPa, the compressive strength in three days reaches 30-35 MPa, the compressive strength in seven days reaches 35-40 MPa, the compressive strength in 28 days reaches 45-50 MPa, the initial fluidity and the 30min fluidity meet the standard requirements, and the expansion rate is 0.1%. The concrete is completely prepared from industrial solid wastes, does not contain cement clinker, has excellent volume stability and durability, is suitable for repairing roads, bridges and building structures, and is particularly suitable for severe environments such as high humidity, salt mist, freeze thawing and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of solid waste resource utilization and building materials, and specifically to an alkali-activated solid waste cementitious repair material and a preparation method thereof. Background Art

[0002] In recent years, the demand for infrastructure maintenance in China has increased sharply, and road repair materials face three major technical bottlenecks: First, the early strength development of traditional Portland cement-based materials is slow (1-day compressive strength < 15 MPa), making it difficult to meet the demand for rapid opening to traffic; second, the dry shrinkage rate of the materials is high (28-day shrinkage rate > 0.06%), which is prone to cause cracking at the repair interface; third, the durability of conventional formulations decreases significantly in environments with freeze-thaw cycles (> 50 times) or salt erosion (Cl- concentration > 3%).

[0003] The alkali-activated geopolymer technology provides a new idea for solving the above problems. Existing research shows that alkali-activated materials based on fly ash-slag systems can achieve a 1-day compressive strength of 20-25 MPa, but there are problems such as uncontrollable setting time (initial setting < 20 min) and large volume shrinkage (28-day shrinkage rate of 0.08-0.15%).

[0004] The current technology has the following key defects: First, a single expansion component cannot achieve multi-stage volume compensation, and the early expansion of calcium oxide does not match the phase of material shrinkage; second, the synergistic regulation of the activator modulus and alkali content is insufficient, resulting in difficulty in balancing strength development and workability; third, the interface bonding of solid waste-based materials is weak, and interlayer peeling is prone to occur under dynamic loading. Therefore, developing an alkali-activated road repair material with fast hardening, early strength, shrinkage compensation, and durability improvement has become an urgent need in the industry. Summary of the Invention

[0005] In order to solve the problems of the existing technology, the present invention provides an alkali-activated solid waste cementitious repair material and a preparation method thereof.

[0006] In order to solve the above technical problems, the present invention is realized through the following technical solutions: An alkali-activated solid waste cementitious repair material is composed of the following raw materials in parts by weight:

[0007] 28-32 parts of fly ash, 68-72 parts of blast furnace slag, 40 parts of manufactured sand, 40-55 parts of water, 9-13 parts of activator, 1-2 parts of sodium tetraborate, 1-2 parts of calcium oxide, 1-2 parts of magnesium oxide, 1-2 parts of calcium sulfoaluminate, 0.5 part of aluminum oxide, 0.2 part of potassium alum, 0.2 part of aluminum powder, 0.2 part of alunite, and 1 part of polyethylene glycol;

[0008] The activator is compounded from anhydrous sodium silicate and sodium hydroxide, and the SiO2 / Na2O modulus of the anhydrous sodium silicate is 1.4 or 2.

[0009] A specific method, the preparation raw materials of which include the following components in mass percentages:

[0010] 30 parts of fly ash, 70 parts of blast furnace slag, 40 parts of manufactured sand, 45 - 50 parts of water, 9 - 12 parts of activator, 1 part of sodium tetraborate, 1 - 2 parts of calcium oxide, 1 - 2 parts of magnesium oxide, 1 - 2 parts of calcium sulfoaluminate, 0.5 part of alumina, 0.2 part of potassium alum, 0.2 part of aluminum powder, 0.2 part of alunite, 1 part of polyethylene glycol.

[0011] A specific method, the preparation raw materials of which include the following components in mass percentages:

[0012] 30 parts of fly ash, 70 parts of blast furnace slag, 40 parts of manufactured sand, 50 parts of water, 11.7 parts of activator, 1 part of sodium tetraborate, 1 part of calcium oxide, 1 part of magnesium oxide, 1 part of calcium sulfoaluminate, 0.5 part of alumina, 0.2 part of potassium alum, 0.2 part of aluminum powder, 0.2 part of alunite, 1 part of polyethylene glycol.

[0013] In a specific embodiment of the first aspect, calcium oxide, magnesium oxide and calcium sulfoaluminate achieve the micro - expansion effect of the material through synergistic action. Calcium oxide hydrates to form calcium hydroxide to provide early expansion, magnesium oxide slowly hydrates to form magnesium hydroxide to achieve long - term expansion, and calcium sulfoaluminate reacts with sulfate radicals in an alkaline environment to form ettringite.

[0014] In a specific embodiment of the first aspect, the mass ratio of fly ash to blast furnace slag is 3:7, and the total mass ratio of the activator to the cementitious material is 0.09 - 0.12:1, where the cementitious material is the sum of fly ash and blast furnace slag;

[0015] The mass ratio of calcium oxide, magnesium oxide, calcium sulfoaluminate, alumina, potassium alum, aluminum powder, alunite, polyethylene glycol to the cementitious material (fly ash, slag) is 0.03 - 0.07:1.

[0016] In a specific embodiment of the first aspect, the particle fineness of the raw materials is ≤80μm, and the uniform distribution of fly ash and blast furnace slag is achieved through dry - method activation pretreatment, and the pretreatment includes premixing, drying and ball - milling processes.

[0017] In a specific embodiment of the first aspect, the particle size of aluminum powder and alunite is not greater than 100 mesh, and the particle size of potassium alum is not greater than 150 mesh.

[0018] In a specific embodiment of the first aspect, the SiO₂ content in fly ash is 40 - 50wt%, the Al₂O₃ content is 28 - 35wt%; the CaO content in the blast furnace slag is 45 - 55wt%.

[0019] In a specific embodiment of the first aspect, the performance indexes of the material under standard curing conditions are as follows: the compressive strength at 1 day is 25 - 30 MPa, the compressive strength at 28 days is 45 - 50 MPa, the initial fluidity is ≥ 300 mm, the fluidity at 30 min is ≥ 200 mm, and the expansion rate is 0.1%.

[0020] In a second aspect, a preparation method of an alkali-activated solid waste cementitious repair material includes the following steps:

[0021] S1: Pretreatment: Grind fly ash and blast furnace slag to a fineness of ≤ 80 μm and then dry them.

[0022] S2: Slurry preparation: Mix fly ash, slag, and manufactured sand evenly, successively add an activator and sodium tetraborate and stir, then add calcium oxide, magnesium oxide, calcium sulfoaluminate, and other additives, and finally add water to adjust the fluidity.

[0023] S3: Construction and curing: After pouring the slurry into the repair part, cure it under the conditions of a temperature of 20 ± 2 °C and a relative humidity of ≥ 95%.

[0024] Specifically: First, grind fly ash and blast furnace slag separately to a fineness of ≤ 80 μm to promote the uniform distribution of particles and increase the specific surface area, and improve the alkali-activation reaction rate; add the pretreated fly ash and slag to the manufactured sand and mix evenly, and add the activator (a compound of anhydrous sodium silicate and sodium hydroxide) during low-speed stirring, and stir for 3 minutes (100 - 150 r / min) to make the activator evenly dispersed; Second, successively add sodium tetraborate, calcium oxide, magnesium oxide, calcium sulfoaluminate, and other additives, and stir for 5 minutes (100 - 150 r / min) to ensure thorough mixing; Third, finally add water and stir for 5 minutes (200 - 300 r / min) to adjust the fluidity of the slurry and obtain a cementitious slurry with uniform performance.

[0025] In a specific embodiment of the second aspect, in step S2, the stirring process is divided into three stages: the first stage is to stir at 100 - 150 r / min for 3 min to disperse each component, the second stage is to stir at 100 - 150 r / min for 5 min to uniformly mix the additives, and the third stage is to stir at 200 - 300 r / min for 5 min to adjust the fluidity.

[0026] In a specific embodiment of the second aspect, the process of construction and curing in S3 includes: covering with a moisture-keeping film within 12 hours after pouring, and continuously maintaining moisture with wet gunny bags for 7 days after 24 hours.

[0027] The beneficial effects of the present invention are as follows:

[0028] 1. The present invention realizes the rapid hardening, high strength, micro-expansion, high fluidity and excellent durability of the material by optimizing the proportion of solid waste-based cementitious materials, introducing a synergistic expansion mechanism, optimizing the construction process and curing method. Through the synergistic effect of calcium oxide, magnesium oxide and calcium sulfoaluminate, the material can maintain appropriate expansion both in the early stage and in the long term, reduce the risk of dry shrinkage cracking and improve the volume stability. The 1-day compressive strength of the material can reach 25-30 MPa, and the 28-day compressive strength can reach 45-50 MPa, far superior to traditional cement-based repair materials, meeting the requirements of rapid road repair. The reasonable particle gradation and activator proportion ensure that the initial fluidity is ≥200 mm and the 30-min fluidity is ≥180 mm, facilitating construction, allowing self-leveling filling and improving the repair effect. By using the dry pretreatment technology (premixing, drying and ball milling), the fineness of fly ash and slag particles is controlled to ≤80 μm, significantly improving the reaction activity and enhancing the alkali activation effect. The three-stage mixing process (pre-dispersing at 100-150 r / min for 3 min, uniformly mixing at 100-150 r / min for 5 min, and adding water and mixing at 200-300 r / min for 5 min) ensures the uniformity and stability of the slurry, avoiding problems such as local over-hydration or uneven fluidity and improving the construction quality. At the same time, staged curing (covering with a moisture-keeping film within 12 h and curing with a wet gunny bag for 7 days after 24 h) effectively controls the water evaporation rate, reduces the early dry shrinkage risk and ensures the strength and durability of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a schematic process flow diagram of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] 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 a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0031] Please refer to Figure 1 As shown, fly ash and blast furnace slag are mixed in a ratio of 30:70 and activated with an alkaline activator to form a highly active cementitious system. The fly ash and blast furnace slag used in the present invention both have high potential activity. After pretreatment, their activity can be improved and the microstructure can be optimized, thereby enhancing the strength and durability of the cementitious material. In addition, a micro-expansion component is added to achieve the volume stability of the material, avoid dry shrinkage cracking and improve the service performance of the repair material.

[0032] The fineness of the fly ash used in the present invention is ≤80μm, and its main components include 45.86% of SiO2, 2.26% of Al2O3, 8.69% of Fe2O3, and 5.55% of CaO; the fineness of the blast furnace slag is ≤80μm, and its main components include 25.45% of SiO2, 12.76% of Al2O3, 0.37% of Fe2O3, and 50.36% of CaO. The present invention also includes admixtures such as manufactured sand, anhydrous sodium silicate, sodium hydroxide, sodium tetraborate, calcium oxide, magnesium oxide, calcium sulfoaluminate, aluminum oxide, potassium alum, aluminum powder, alunite, and polyethylene glycol, so that the material system has excellent mechanical properties and durability.

[0033] A typical formulation (parts by mass) of the present invention is as follows: fly ash: 30 parts; blast furnace slag: 70 parts; manufactured sand: 40 parts; water: 45 - 50 parts; activator (anhydrous sodium silicate, sodium hydroxide): 9 - 13 parts; sodium tetraborate: 1 - 2 parts; calcium oxide: 1 - 2 parts; magnesium oxide: 1 - 2 parts; calcium sulfoaluminate: 1 - 2 parts; aluminum oxide: 0.5 part; potassium alum: 0.2 part; aluminum powder: 0.2 part; alunite: 0.2 part; polyethylene glycol: 1 part;

[0034] The preparation method of the present invention is as follows:

[0035] S1: Pretreatment:

[0036] The fly ash and blast furnace slag are respectively ball-milled to a fineness of ≤80μm to promote the uniform distribution of particles and increase the specific surface area, thereby improving the alkali activation reaction rate. Subsequently, they are dried to remove excess moisture to prevent material agglomeration.

[0037] S2: Slurry preparation:

[0038] The pretreated fly ash and slag are added to the manufactured sand and mixed evenly. The activator (a compound of anhydrous sodium silicate and sodium hydroxide) is added during low-speed stirring, and stirred for 3 minutes (100 - 150r / min) to evenly disperse the activator;

[0039] S3: Sodium tetraborate, calcium oxide, magnesium oxide, calcium sulfoaluminate and other admixtures are added in sequence and stirred for 5 minutes (100 - 150r / min) to ensure thorough mixing;

[0040] Finally, water is added and stirred for 5 minutes (200 - 300r / min) to adjust the fluidity of the slurry and obtain a gelling slurry with uniform properties.

[0041] In some embodiments, the material system of the present invention can adapt to various environmental conditions, including high temperature, humid or freeze-thaw environments. By reasonably designing the modulus of the alkali activator, the alkali content, and the water-binder ratio, the setting time and early strength of the paste can be optimized to ensure the applicability of the material in different application scenarios. In addition, the alkali-activated solid waste cementitious repair material of the present invention can be prepared by the method of industrial solid waste resource utilization, which has significant environmental protection value and economic benefits.

[0042] Example 1

[0043] This example provides a solid waste cementitious material, and its preparation raw materials include the following components in parts by mass:

[0044] 30 parts of fly ash; 70 parts of blast furnace slag; 40 parts of manufactured sand; 50 parts of water; 11.77 parts of sodium silicate; 1 part of sodium tetraborate.

[0045] The preparation method of the solid waste cementitious material in this example includes:

[0046] S1: Pretreatment:

[0047] The fly ash and blast furnace slag are respectively ball milled to a fineness of ≤80 μm to promote the uniform distribution of particles and increase the specific surface area, thereby improving the alkali activation reaction rate. Subsequently, they are dried to remove excess moisture to prevent material agglomeration.

[0048] S2: Paste preparation:

[0049] The pretreated fly ash and slag are added to the manufactured sand and mixed evenly. The activator (compound of anhydrous sodium silicate and sodium hydroxide) is added during low-speed stirring, and stirred for 3 minutes (100 - 150 r / min) to make the activator evenly dispersed;

[0050] S3: Sodium tetraborate, calcium oxide, magnesium oxide, calcium sulfoaluminate and other additives are added in sequence and stirred for 5 minutes (100 - 150 r / min) to ensure full mixing; finally, water is added and stirred for 5 minutes (200 - 300 r / min) to adjust the fluidity of the paste, and a cementitious paste with uniform performance is obtained.

[0051] Example 2

[0052] This example provides a solid waste cementitious material, and its preparation raw materials include the following components in parts by mass:

[0053] 30 parts of fly ash; 70 parts of blast furnace slag; 40 parts of manufactured sand; 50 parts of water; 9.2 parts of sodium silicate; 1 part of sodium tetraborate; 0.9 part of sodium hydroxide.

[0054] The preparation method of the solid waste cementitious material in this example is the same as that of Example 1.

[0055] Example 3

[0056] This embodiment provides a solid waste cementitious material, and its preparation raw materials include the following components in parts by mass:

[0057] 30 parts of fly ash; 70 parts of blast furnace slag; 40 parts of manufactured sand; 45 parts of water; 11.77 parts of sodium silicate; 1 part of sodium tetraborate; 0.9 part of sodium hydroxide.

[0058] The preparation method of the solid waste cementitious material in this embodiment is the same as that in Example 1.

[0059] Example 4

[0060] This embodiment provides a solid waste cementitious material, and its preparation raw materials include the following components in parts by mass:

[0061] 30 parts of fly ash; 70 parts of blast furnace slag; 40 parts of manufactured sand; 50 parts of water; 11.77 parts of sodium silicate; 1 part of sodium tetraborate; 2 parts of calcium oxide; 1 part of magnesium oxide; 1 part of calcium sulfoaluminate; 0.5 part of alumina; 0.2 part of potassium alum; 0.2 part of aluminum powder; 0.2 part of alunite; 1 part of polyethylene glycol.

[0062] The preparation method of the solid waste cementitious material in this embodiment is the same as that in Example 1.

[0063] Comparative Example 1

[0064] This comparative example provides a solid waste cementitious material, and its preparation raw materials include the following components in parts by mass:

[0065] 30 parts of fly ash; 70 parts of blast furnace slag; 40 parts of manufactured sand; 50 parts of water; 7 parts of sodium silicate; 1 part of sodium tetraborate; 1.8 parts of sodium hydroxide.

[0066] The preparation method in this comparative example is the same as that in Example 1.

[0067] Comparative Example 2

[0068] This comparative example provides a solid waste cementitious material, and its preparation raw materials include the following components in parts by mass:

[0069] 30 parts of fly ash; 70 parts of blast furnace slag; 40 parts of manufactured sand; 50 parts of water; 11.74 parts of dimodal powdered sodium silicate; 12.9 parts of sodium hydroxide, 1 part of sodium tetraborate.

[0070] The preparation method in this comparative example is the same as that in Example 1.

[0071] Comparative Example 3

[0072] This comparative example provides a solid waste cementitious material, and its preparation raw materials include the following components in parts by mass:

[0073] 30 parts of fly ash; 70 parts of blast furnace slag; 40 parts of manufactured sand; 35 parts of water; 11.74 parts of sodium silicate; 1 part of sodium tetraborate;

[0074] The preparation method of this comparative example is the same as that of Example 1.

[0075] Comparative Example 4

[0076] This comparative example provides a solid waste cementitious material, and its preparation raw materials include the following components in parts by mass:

[0077] 30 parts of fly ash; 70 parts of blast furnace slag; 40 parts of manufactured sand; 50 parts of water; 7 parts of sodium silicate; 1 part of sodium tetraborate;

[0078] The preparation method of this comparative example is the same as that of Example 1.

[0079] Test Example

[0080] In this test example, the mortar strength of the solid waste cementitious materials obtained in the above examples and comparative examples was tested according to the standard of GB / T17671-2021 "Test Method for Cement Mortar Strength (ISO Method)". The mechanical property test results at 1d, 3d, 7d and 28d are shown in Table 1, the workability test is shown in Table 2, and the dry shrinkage test is shown in Table 3.

[0081] Table 1

[0082]

[0083] Table 2

[0084]

[0085] Table 3

[0086]

[0087] It can be seen from Table 1, Table 2 and Table 3 that:

[0088] Mechanical properties (Table 1): The solid waste cementitious materials provided in Examples 2-3 of the present invention have a compressive strength equivalent to that of 42.5-grade ordinary Portland cement (3d compressive strength ≥ 17.0 MPa, 28d compressive strength ≥ 42.5 MPa). Among them, the compressive strength of Example 1 is better, reaching the strength grade of 42.5R-grade ordinary Portland cement (3d compressive strength ≥ 22.0 MPa, 28d compressive strength ≥ 42.5 MPa). The 1d compressive strength of Example 3 is as high as 34.5 MPa, and the 28d compressive strength reaches 57.4 MPa, showing excellent early and long-term strength. In contrast, the compressive strengths of Comparative Examples 1-4 are all relatively low. Among them, the 7d compressive strength of Comparative Example 2 is only 1.57 MPa, and the 28d compressive strength is also only 21.2 MPa, verifying the superiority of the materials of the present invention.

[0089] Working performance (Table 2): The initial fluidity of Examples 1-4 is between 305-315 mm, which can meet the construction requirements, and the fluidity loss within 30 min is small. Among them, the 30-min fluidity of Example 2 still reaches 239.5 mm, showing good water retention and construction adaptability. In addition, the initial setting times of Examples 1-4 are between 14-26 min, and the final setting times are between 40-75 min, far superior to those of Comparative Examples 1-4. For example, the initial setting time of Comparative Example 1 is as long as 190 min, and the final setting time reaches 360 min, which is not conducive to rapid construction, while the materials of the present invention can better meet the rapid construction requirements such as road repair and emergency repair.

[0090] Drying shrinkage performance (Table 3): The 28-day shrinkage rates of Examples 1-3 are 0.13%, 0.14% and 0.12% respectively, which have lower shrinkage compared with ordinary alkali-activated materials, indicating that the materials of the present invention can effectively reduce shrinkage cracks during long-term use. Among them, the shrinkage rates of Example 4 from 1 day to 28 days are all negative values (the lowest can reach -0.13%), showing a micro-expansion characteristic, effectively inhibiting drying shrinkage cracking and improving the long-term durability of the materials. While the shrinkage rates of Comparative Examples 1-4 are relatively high, and the 28-day shrinkage rate of Comparative Example 4 reaches 0.13%, indicating its poor long-term volume stability.

[0091] By optimizing the ratios of sodium silicate, sodium hydroxide, sodium tetraborate and auxiliary components, the solid waste cementitious material of the present invention reaches a relatively high level in terms of mechanical properties, construction adaptability and durability, overcoming the problems of poor fluidity, high shrinkage rate and insufficient strength of traditional alkali-activated materials. The solid waste cementitious material of the present invention adopts a non-clinker system and is mainly prepared from industrial solid wastes such as fly ash and blast furnace slag. It can not only replace ordinary Portland cement in concrete production, but also provide a green and high-performance building material solution, realizing the efficient utilization of solid waste resources.

[0092] The above examples are only specific application modes of the present invention, aiming to help those skilled in the art understand and apply the present invention. Without departing from the spirit and scope of the present invention, those skilled in the art can make appropriate adjustments and optimizations to the specific implementation modes, and these adjustments and optimizations should be regarded as the protection scope of the present invention.

Claims

1. An alkali-activated solid waste gelling repair material, characterized in that: It is composed of the following raw materials in parts by weight: 28-32 parts of fly ash, 68-72 parts of blast furnace slag, 40 parts of machine-made sand, 40-55 parts of water, 9-13 parts of activator, 1-2 parts of sodium tetraborate, 1-2 parts of calcium oxide, 1-2 parts of magnesium oxide, 1-2 parts of calcium sulfoaluminate, 0.5 parts of aluminum oxide, 0.2 parts of potassium aluminum sulfate, 0.2 parts of aluminum powder, 0.2 parts of alunite, 1 part of polyethylene glycol; The activator is prepared by compounding anhydrous sodium silicate and sodium hydroxide, wherein the SiO2 / Na2O modulus of the anhydrous sodium silicate is 1.4 or 2.

2. The alkali-activated solid waste gelling repair material according to claim 1, characterized in that: The calcium oxide, magnesium oxide and calcium sulfoaluminate achieve a micro-expansion effect of the material through synergistic action. Calcium oxide is hydrated to generate calcium hydroxide to provide early expansion, magnesium oxide is slowly hydrated to generate magnesium hydroxide to achieve long-term expansion, and calcium sulfoaluminate reacts with sulfate in an alkaline environment to generate ettringite.

3. The alkali-activated solid waste gelling repair material according to claim 1, characterized in that: The mass ratio of the fly ash to the blast furnace slag is 3:7, the total mass ratio of the activator to the cementitious material is 0.09-0.12:1, and the cementitious material is the sum of the fly ash and the blast furnace slag.

4. The alkali-activated solid waste gelling repair material according to claim 1, characterized in that: The particle size of the raw materials is ≤80μm, and the uniform distribution of fly ash and blast furnace slag is achieved through dry activation pretreatment, which includes premixing, drying and ball milling processes.

5. The alkali-activated solid waste gelling repair material according to claim 1, characterized in that: The particle size of the aluminum powder and alum stone is not greater than 100 meshes, and the particle size of potassium aluminum sulfate is not greater than 150 meshes.

6. The alkali-activated solid waste gelling repair material according to claim 1, characterized in that: The SiO2 content in the fly ash is 40-50wt%, and the Al2O3 content is 28-35wt%; the CaO content in the blast furnace slag is 45-55wt%.

7. The alkali-activated solid waste gelling repair material according to claim 1, characterized in that: The performance indicators of the material under standard curing conditions are: 1-day compressive strength 25-30MPa, 28-day compressive strength 45-50MPa, initial fluidity ≥300mm, 30min fluidity ≥200mm, expansion rate 0.1%.

8. A method for preparing an alkali-activated solid waste gelling repair material, characterized in that: The following steps are involved: S1： Pretreatment: ball-mill fly ash and blast furnace slag to a fineness of ≤80μm and then dry; S2: Slurry preparation: fly ash, slag and machine-made sand are mixed evenly, activator and sodium tetraborate are added in sequence for stirring, calcium oxide, magnesium oxide, calcium sulfoaluminate and other additives are added, and finally water is added to adjust fluidity; S3: Construction and maintenance: After pouring the slurry to the repaired area, maintain it at a temperature of 20±2℃ and a relative humidity of ≥95%.

9. The method for preparing an alkali-activated solid waste gelling repair material according to claim 8, characterized in that: The stirring process in step S2 is divided into three stages: the first stage is stirring at 100-150 r / min for 3 minutes to disperse the components, the second stage is stirring at 100-150 r / min for 5 minutes to evenly mix the additives, and the third stage is stirring at 200-300 r / min for 5 minutes to adjust the fluidity.

10. The method for preparing an alkali-activated solid waste gelling repair material according to claim 8, characterized in that: The construction and curing process in S3 includes: covering with a moisture-retaining film within 12 hours after pouring, and using wet sacks for continuous moisture-retaining curing for 7 days after 24 hours.

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