Solid-waste-based nano composite grouting material and preparation method thereof

Abstract

The invention belongs to the technical field of building materials, and discloses a solid-waste-based nano-composite grouting material and a preparation method thereof.The solid-waste-based nano-composite grouting material is prepared from cement, blast furnace slag micro-powder, fly ash, quartz sand, nano-silica, nano-cellulose, a composite early strength agent prepared by mixing sulphoaluminate and sodium gluconate, and the like. According to the preparation method, the silane coupling agent is used for promoting the nanometer material, the blast furnace slag micro powder and other components with poor dispersity to be well dispersed, separation and bleeding are prevented, the matrix interface bonding force is improved, all the components in the raw materials of the solid-waste-based nanometer composite grouting material cooperate with one another, a crystal framework and a network structure are rapidly generated, and the solid-waste-based nanometer composite grouting material is prepared. Good bonding is realized, and meanwhile, relatively good early strength is achieved. The method is used for producing the building grouting material, and can be suitable for scenes such as fabricated building nodes, equipment foundation anchoring and the like.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, and relates to a cement-based grouting material, specifically a solid waste-based nanocomposite grouting material and its preparation method. Background Technology

[0002] With the rapid development of the construction industry, grouting materials, as key materials for foundation engineering, structural repair, and equipment installation, directly affect the quality and durability of projects. However, traditional grouting materials, formulated with cement as the matrix and supplemented with aggregates such as sand and gravel, as well as a small amount of admixtures, are prone to shrinkage and cracking due to their high cement content. This can even pose safety hazards for projects requiring long-term stability. During the hardening process, traditional grouting materials are prone to irreversible volume shrinkage due to water evaporation, chemical shrinkage, and autogenous shrinkage. Under constrained conditions, this shrinkage can induce micro-cracks, weakening the bond between the grout layer and the substrate. Especially in dry environments, when the surface water loss rate is too rapid, through-cracks may form within 24 hours, seriously affecting the long-term stability and durability of the structure.

[0003] With the increasing output of solid wastes such as blast furnace slag powder and fly ash, using them as raw materials for grouting materials to achieve resource utilization aligns with the concept of sustainable development. However, existing grouting materials containing slag or fly ash still have performance deficiencies and need improvement. For example, Chinese invention patent application CN112250355A discloses an alkali-activated fly ash / slag recycled concrete that utilizes industrial solid wastes such as slag and fly ash, as well as construction waste, to improve the strength of recycled concrete through alkali activation. Fibers are also incorporated into the raw materials to improve flexural strength. However, this recycled concrete requires alkali activation, which is time-consuming, and the alkali activation process poses safety hazards. It also suffers from high porosity between materials and insufficient bonding between materials, resulting in insufficient water resistance and durability.

[0004] Furthermore, grouting materials contain a wide variety of raw materials, and the synergistic effects between different components are complex, making formula optimization extremely difficult. How to select suitable components, determine appropriate proportions, and ensure good dispersion of poorly dispersible components such as blast furnace slag powder and fly ash added to the grouting material to prevent segregation and bleeding, improve the interfacial bonding strength of the matrix, and achieve good adhesion while also maintaining good early strength are also key technical problems that need to be solved. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention aims to provide a solid waste-based nanocomposite grouting material. This material uses blast furnace slag powder and cement as the main cementing materials, combined with a specific ratio of nano-silica and nano-cellulose to form a low water-cement ratio, high-density grouting system. This achieves the goal of being both environmentally friendly and possessing high early compressive and flexural strength, thus solving problems such as the need for activation treatment, insufficient water resistance, and inadequate durability in existing technologies.

[0006] This invention also provides a method for preparing the above-mentioned solid waste-based nanocomposite grout, thereby achieving the goal of efficiently preparing solid waste-based nanocomposite grout.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A solid waste-based nanocomposite grout, the raw materials for making its effective components include 70-210 parts by weight of cement, 350-490 parts by weight of blast furnace slag powder, 70-140 parts by weight of fly ash, 140-210 parts by weight of quartz sand, 7-21 parts by weight of nano silica, 4-7 parts by weight of nano cellulose, 3-10 parts by weight of composite early strength agent, 0.7-2.1 parts by weight of superabsorbent polymer, and 0.5-1.5 parts by weight of defoamer; The composite early strength agent is prepared by mixing thioaluminate and sodium gluconate in a mass ratio of 3-6:1.

[0008] Among them, thioaluminate and sodium gluconate are dry powders, which should be mixed and stirred evenly before use.

[0009] The two nanomaterials, nano-silica and nano-cellulose, are treated with a silane coupling agent and then added to the raw material mixture. The organic functional groups of the silane coupling agent react chemically with the hydroxyl groups on the surface of the two nanomaterials to form covalent bonds, thereby reducing the surface energy, inhibiting the agglomeration of the nanomaterials, and improving the uniform dispersion of the nanomaterials in the slurry.

[0010] The sulfoaluminate component in the composite early strength agent rapidly generates an ettringite crystal framework, which can improve the early strength of the grout. At the same time, sodium gluconate delays the heat release of hydration by adsorbing on the surface of cement particles, avoiding premature hardening of the grout and solving the problem that traditional early strength agents easily lead to excessively short setting time and short construction window.

[0011] Preferably, the blast furnace slag powder is grade S95 with a specific surface area ≥450 m². 2 / kg, CaO content ≥35wt%. Blast furnace slag powder replaces cement as the main cementitious material. Through the pozzolanic effect, it reacts with the cement hydration product Ca(OH)2 to generate CSH gel, which improves the later strength and density of the grout.

[0012] Preferably, the fly ash is Grade I fly ash with a density of 2490 kg / m³. 3 With a moisture content of 0.5%, fly ash undergoes a hydration reaction during the raw material mixing process, generating stable hydration products that further improve the microstructure of the grout. Its micro-aggregate effect can fill the pores in the cement paste, refine the pore structure, and improve the impermeability and compressive strength of the grout.

[0013] Preferably, the water-reducing agent is at least one of naphthalene-based water-reducing agents or polycarboxylate water-reducing agents.

[0014] Preferably, the defoamer is an organosilicon defoamer or a polyether defoamer.

[0015] As a limitation of the present invention, the raw materials also include 70-100 parts by weight of water, 2-5 parts by weight of water-reducing agent and 14-28 parts by weight of expansion agent.

[0016] As another limitation of the present invention, the particle size of nano-silica is 10-30 nm. Nano-silica can fill the micropores between cementitious materials at the nanoscale, reducing the proportion of harmful pores. On the other hand, it can accelerate the formation of hydration product CSH gel, thereby improving the compressive strength of the grout.

[0017] As a further limitation of the present invention, the nanocellulose has a diameter of 5-20 nm and a length of 0.5-2 μm.

[0018] Nanocellulose forms a three-dimensional network structure in the slurry, which inhibits the propagation of microcracks through fiber bridging and crack deflection mechanisms, thereby improving the flexural strength of the grout. At the same time, its surface hydroxyl groups adsorb free water, delaying water evaporation and reducing plastic shrinkage.

[0019] As a further limitation of the present invention, the specific surface area of ​​the blast furnace slag powder is ≥450m². 2 / kg, CaO content ≥35wt%.

[0020] As a further limitation of the present invention, the cement is silicate cement; Preferably, the cement is ordinary Portland cement of grade 52.5; The expanding agent is a calcium-magnesium expanding agent; In the expanding agent, the mass ratio of calcium oxide to magnesium oxide is 2-4:1.

[0021] In the expanding agent, calcium oxide rapidly generates Ca(OH)2 upon contact with water, producing micro-expansion during the plastic period to compensate for early shrinkage. Magnesium oxide hydrates in the middle and late stages to generate Mg(OH)2, delaying expansion and further offsetting drying shrinkage, thus avoiding the stress concentration problem caused by premature or delayed expansion in traditional single-component expanding agents.

[0022] As a further limitation of the present invention, the particle size of the quartz sand is 40-70 mesh, and the silica content in the quartz sand is ≥95wt%; as a skeleton material, quartz sand can improve the strength and wear resistance of the grout, and its high-purity silica content helps to form a uniform slurry structure.

[0023] As a further limitation of the present invention, the superabsorbent polymer is a cross-linked sodium polyacrylate-based polymer material. Furthermore, the amount of superabsorbent polymer can be reduced by partially replacing it with bentonite.

[0024] The present invention also provides a method for preparing a solid waste-based nanocomposite grout, wherein nano-silica, nano-cellulose and silane coupling agent are taken according to the specified weight parts, and ultrasonically dispersed at 50-60℃ for 30 min to obtain a suspension; The following ingredients are added to the suspension: cement, blast furnace slag powder, fly ash, quartz sand, expansion agent, composite early strength agent, water-reducing agent, super absorbent polymer and defoamer. Water is added and the mixture is stirred evenly to obtain solid waste-based nanocomposite grouting material. The amount of the silane coupling agent used is 0.8-1.3% of the total weight of nano-silica and nano-cellulose.

[0025] As a further limitation of the present invention, during the water addition process, the raw material particles are first moistened by stirring at a low speed of less than 100 r / min. Then stir at a high speed of 450-550 r / min for 5-8 minutes to form a uniform slurry.

[0026] By adopting the above-described technical solution, the beneficial effects achieved by this invention compared to the prior art are as follows: This invention solves the problems of shrinkage cracking and insufficient density of traditional grouting materials. This invention uses blast furnace slag powder and fly ash to replace part of the cement as cementing materials, which significantly reduces the amount of cement used, reduces carbon emissions, makes full use of industrial solid waste, achieves efficient resource utilization, and is environmentally friendly. Both materials can fill pores and refine pore structure through pozzolanic reaction and micro-aggregate effect, reduce bleeding and segregation, and improve the density and durability of the material.

[0027] During the research and development of this invention, it was unexpectedly discovered that nano-silica, compared to other nanomaterials such as starch nanocrystals and polyvinyl alcohol nanofibers, possesses an extremely high specific surface area, enabling it to undergo a strong chemical reaction with cement hydration products. This generates a denser calcium silica hydrate gel, which can fill the micropores in the grout, improving the material's density and durability while enhancing the strength of the hydration products, significantly increasing the compressive and flexural strength of the grout. Nano-silica can also synergistically enhance the effects of nano-cellulose. Through bridging and crack-blocking effects, the two enhance the material's toughness and crack resistance, filling 10-100 nm pores, accelerating the hydration reaction, bridging cracks through a three-dimensional network, and improving the uniformity of nanomaterial dispersion through silane coupling agent surface modification, avoiding performance degradation caused by agglomeration. Simultaneously, the surface activity of nano-cellulose can improve the fluidity and stability of the grout, reducing bleeding and segregation, thereby improving the workability and construction performance of the grout.

[0028] In this invention, blast furnace slag powder and fly ash can significantly reduce cement usage and achieve high-value utilization of industrial solid waste. Through a cementitious system based on blast furnace slag powder and fly ash, 60%-80% of the cement in traditional grouting materials can be replaced. Since cement production is a major source of carbon emissions in the building materials industry, reducing cement usage can directly reduce carbon emissions. At the same time, by calculating the proportion of total solid waste mass (total solid waste / total grouting material), the total utilization rate of solid waste is approximately 50%, which solves the environmental pressure caused by the stockpiling of these solid wastes.

[0029] This invention is applicable to the utilization of steel slag waste and the production and processing of cement-based grouting materials. Detailed Implementation

[0030] The present invention will be further described in detail below through specific embodiments. It should be understood that the described embodiments are only used to explain the present invention and do not limit the present invention.

[0031] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods in the art.

[0032] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0033] Unless otherwise specified in the embodiments or comparative examples, the cement used is P052.5 cement; the blast furnace slag powder grade is S95, with a specific surface area ≥450m². 2 / kg, CaO content ≥35%; the fly ash used is Grade I fly ash with a density of 2490kg / m³. 3The water content is 0.5%; the quartz sand particle size is 40-70 mesh, and the SiO2 content is ≥95wt%; the nano silica particle size is 10-30nm; the nano cellulose has a diameter of 5-20nm and a length of 0.5-2μm; the water-reducing agent is a naphthalene-based water-reducing agent; the superabsorbent polymer is a cross-linked sodium polyacrylate-based polymer material; and the defoamer is an organosilicon defoamer.

[0034] Example 1 Example 1 is a solid waste-based nanocomposite grout J1. The raw materials for its effective components are: 140 kg of cement, 420 kg of blast furnace slag powder, 90 kg of fly ash, 170 kg of quartz sand, 90 kg of water, 15 kg of nano silica, 5 kg of nano cellulose, 20 kg of calcium magnesium expansion agent, 8 kg of composite early strength agent, 4 kg of water-reducing agent, 1 kg of superabsorbent polymer, and 1 kg of defoamer.

[0035] The composite early strength agent is prepared by mixing thioaluminate and sodium gluconate in a mass ratio of 4:1.

[0036] In calcium-magnesium expanding agents, the mass ratio of calcium oxide to magnesium oxide is 3:1.

[0037] Example 2 Example 2 is a solid waste-based nanocomposite grout J2. The raw materials for making its effective components are: 140 kg of cement, 420 kg of blast furnace slag powder, 120 kg of fly ash, 200 kg of quartz sand, 100 kg of water, 15 kg of nano silica, 5 kg of nano cellulose, 20 kg of calcium magnesium expansion agent, 8 kg of composite early strength agent, 4 kg of water-reducing agent, 1 kg of super absorbent polymer and 1 kg of defoamer. The composite early strength agent is prepared by mixing thioaluminate and sodium gluconate in a mass ratio of 4:1.

[0038] In calcium-magnesium expanding agents, the mass ratio of calcium oxide to magnesium oxide is 2:1.

[0039] Example 3 Example 3 is a solid waste-based nanocomposite grout J3. The raw materials for making its effective components are: 70 kg of cement, 420 kg of blast furnace slag powder, 120 kg of fly ash, 140 kg of quartz sand, 70 kg of water, 21 kg of nano silica, 7 kg of nano cellulose, 20 kg of calcium magnesium expansion agent, 3 kg of composite early strength agent, 2 kg of water-reducing agent, 2.1 kg of super absorbent polymer and 1.5 kg of defoamer; The composite early strength agent is prepared by mixing thioaluminate and sodium gluconate in a mass ratio of 3:1.

[0040] In calcium-magnesium expanding agents, the mass ratio of calcium oxide to magnesium oxide is 2:1.

[0041] Example 4 Example 4 is a solid waste-based nanocomposite grout J4. The raw materials for its effective components are: 140 kg of cement, 420 kg of blast furnace slag powder, 120 kg of fly ash, 210 kg of quartz sand, 100 kg of water, 7 kg of nano silica, 4 kg of nano cellulose, 20 kg of calcium magnesium expansion agent, 10 kg of composite early strength agent, 5 kg of water-reducing agent, 0.7 kg of super absorbent polymer, and 0.5 kg of defoamer. The composite early strength agent is prepared by mixing thioaluminate and sodium gluconate in a mass ratio of 6:1.

[0042] In calcium-magnesium expanding agents, the mass ratio of calcium oxide to magnesium oxide is 4:1.

[0043] Example 5 Example 5 describes a method for preparing solid waste-based nanocomposite grout J2, which specifically includes the following steps: Nano-silica and nano-cellulose were weighed according to Example 2, mixed evenly, and then 1% of the total mass of the two nanomaterials was added as silane coupling agent. The mixture was ultrasonically dispersed at 50°C for 30 minutes to form a uniform suspension. Cement, blast furnace slag powder, and fly ash are mixed evenly, and then quartz sand is added and mixed evenly to obtain mixture I. Add the suspension to mixture 1 and stir until homogeneous to obtain mixture II; Weigh out calcium magnesium expansion agent, composite early strength agent, water reducing agent, super absorbent polymer, and defoamer, stir evenly to obtain mixed additives; Add the mixed additives and water to mixture II. During the water addition process, first stir at a low speed of less than 100 r / min to wet the raw material particles; then stir at a high speed of 450 r / min for 5 minutes to form a uniform slurry, which yields solid waste-based nanocomposite grouting material J2.

[0044] In other embodiments, the preparation method of solid waste-based nanocomposite grout J1 differs from that in Example 5, except for the amount of each raw material: the amount of silane coupling agent is 0.8% of the total mass of nano-silica and nano-cellulose; during the water addition process, the raw material particles are first wetted by stirring at a low speed of less than 100 r / min; then, the raw material particles are stirred at a high speed of 480 r / min for 8 min to form a uniform slurry.

[0045] The preparation method of solid waste-based nanocomposite grouting material J3-J5 differs from that of Example 5, except for the amount of each raw material: the amount of silane coupling agent is 1.3% of the total mass of nano-silica and nano-cellulose; during the water addition process, the raw material particles are first wetted by stirring at a low speed of less than 100 r / min; then the mixture is stirred at a high speed of 500 r / min for 7 min to form a uniform slurry.

[0046] Comparative Example 1 This comparative example is a solid waste-based grouting material based on Example 2, which reduces the content of blast furnace slag powder and increases the content of cement and quartz sand. Its raw material composition is as follows: 200 kg of cement, 330 kg of blast furnace slag powder, 120 kg of fly ash, 200 kg of quartz sand, 100 kg of water, 15 kg of nano silica, 5 kg of nano cellulose, 20 kg of calcium magnesium expansion agent, 8 kg of composite early strength agent, 4 kg of water-reducing agent, 1 kg of superabsorbent polymer, and 1 kg of defoamer.

[0047] Comparative Example 2 This comparative example is a solid waste-based grouting material without blast furnace slag powder, based on Example 2. The raw material composition is: 140 kg of cement, 120 kg of fly ash, 200 kg of quartz sand, 50 kg of water, 15 kg of nano silica, 5 kg of nano cellulose, 20 kg of calcium magnesium expansion agent, 8 kg of composite early strength agent, 4 kg of water-reducing agent, 1 kg of super absorbent polymer, and 1 kg of defoamer.

[0048] Comparative Example 3 This comparative example is a solid waste-based grouting material without nano-silica, based on Example 2. The raw material composition is: 140 kg of cement, 420 kg of blast furnace slag powder, 120 kg of fly ash, 200 kg of quartz sand, 100 kg of water, 5 kg of nano-cellulose, 20 kg of calcium magnesium expansion agent, 8 kg of composite early strength agent, 4 kg of water-reducing agent, 1 kg of superabsorbent polymer, and 1 kg of defoamer.

[0049] Comparative Example 4 This comparative example is a solid waste-based grouting material without nanocellulose, compared to Example 2. The raw material composition is: 140kg cement, 420kg blast furnace slag powder, 120kg fly ash, 200kg quartz sand, 100kg water, 15kg nano silica, 20kg calcium magnesium expansion agent, 8kg composite early strength agent, 4kg water-reducing agent, 1kg super absorbent polymer, and 1kg defoamer.

[0050] Comparative Example 5 This comparative example is a solid waste-based grouting material, with the following raw material composition: 140 kg of cement, 420 kg of blast furnace slag powder, 120 kg of fly ash, 200 kg of quartz sand, 100 kg of water, 20 kg of calcium magnesium expansion agent, 8 kg of composite early strength agent, 4 kg of water-reducing agent, 1 kg of super absorbent polymer, and 1 kg of defoamer.

[0051] Comparative Example 6 This comparative example is a solid waste-based grouting material, with the following raw material composition: 140 kg of cement, 420 kg of blast furnace slag powder, 120 kg of fly ash, 200 kg of quartz sand, 100 kg of water, 15 kg of nano silica, 5 kg of nano cellulose, 8 kg of calcium magnesium expansion agent, 1 kg of composite early strength agent, 4 kg of water-reducing agent, 1 kg of super absorbent polymer, and 1 kg of defoamer.

[0052] Comparative Example 7 This comparative example is a solid waste-based grouting material, with the following raw material composition: 140 kg of cement, 420 kg of blast furnace slag powder, 120 kg of fly ash, 200 kg of quartz sand, 100 kg of water, 15 kg of starch nanocrystals, 5 kg of nanocellulose, 20 kg of calcium magnesium expansion agent, 8 kg of composite early strength agent, 4 kg of water-reducing agent, 1 kg of superabsorbent polymer, and 1 kg of defoamer.

[0053] Comparative Example 8 This comparative example is a solid waste-based grouting material, with the following raw material composition: 140 kg of cement, 420 kg of blast furnace slag powder, 120 kg of fly ash, 200 kg of quartz sand, 100 kg of water, 15 kg of polyvinyl alcohol nanofiber, 5 kg of nanocellulose, 20 kg of calcium magnesium expansion agent, 8 kg of composite early strength agent, 4 kg of water-reducing agent, 1 kg of superabsorbent polymer, and 1 kg of defoamer.

[0054] Effect verification example For the solid waste-based nanocomposite grouts J1 and J2 prepared in Examples 1-2, and the solid waste-based grouts prepared in Comparative Examples 1-8, shrinkage rate, compressive strength or flexural strength were tested at 24h and 28d respectively, according to the "Technical Specification for Application of Cement-based Grouting Materials" (GB / T 50488-2015).

[0055] The test results show: The solid waste-based nanocomposite grout J1 of Example 1 has a 24h compressive strength of 39.5 MPa, a 24h flexural strength of 4.5 MPa, a 28d compressive strength of 78.6 MPa, a 28d flexural strength of 7.7 MPa, and a shrinkage rate of 0.040%.

[0056] The solid waste-based nanocomposite grout J2 of Example 2 has a 24h compressive strength of 40.1 MPa, a 24h flexural strength of 4.8 MPa, a 28d compressive strength of 80.7 MPa, a 28d flexural strength of 8.2 MPa, and a shrinkage rate of 0.037%.

[0057] The solid waste-based grouting material of Comparative Example 1 exhibited a 24-hour compressive strength of 35.9 MPa, a 24-hour flexural strength of 4.0 MPa, a 28-day compressive strength of 76.2 MPa, a 28-day flexural strength of 8.8 MPa, and a shrinkage rate of 0.050%. The results indicate that blast furnace slag powder can balance environmental friendliness and performance to a certain extent when replacing cement, while excessive cement may lead to resource waste without significant strength gain.

[0058] The solid waste-based grout of Comparative Example 2 exhibited a 24-hour compressive strength of 28.8 MPa, a 24-hour flexural strength of 4.2 MPa, a 28-day compressive strength of 67.0 MPa, a 28-day flexural strength of 7.5 MPa, and a shrinkage rate of 0.058%. These results indicate that the pozzolanic effect of blast furnace slag powder and the filling effect of micro-aggregates play a crucial role in improving the density and strength of the grout.

[0059] The solid waste-based grout of Comparative Example 3 exhibited a 24-hour compressive strength of 25.1 MPa, a 24-hour flexural strength of 4.3 MPa, a 28-day compressive strength of 73.5 MPa, a 28-day flexural strength of 7.8 MPa, and a shrinkage rate of 0.048%. These results indicate that the bridging effect and three-dimensional network structure of nanocellulose can inhibit crack propagation and improve the crack resistance of the grout.

[0060] The solid waste-based grout in Comparative Example 4 exhibited a 24-hour compressive strength of 30.1 MPa, a 24-hour flexural strength of 3.7 MPa, a 28-day compressive strength of 76.2 MPa, a 28-day flexural strength of 6.6 MPa, and a shrinkage rate of 0.052%. These results indicate that nano-silica can fill micropores and accelerate CSH gel formation, thereby improving the early strength of the grout.

[0061] The solid waste-based grout of Comparative Example 5 has a 24-hour compressive strength of 22.1 MPa, a 24-hour flexural strength of 3.4 MPa, a 28-day compressive strength of 69.8 MPa, a 28-day flexural strength of 6.5 MPa, and a shrinkage rate of 0.056%.

[0062] The results show that the combination of nanomaterials used in this invention can achieve a dual improvement in strength and toughness, which is something that a single material cannot achieve, and solves the problems of shrinkage cracking and insufficient density of traditional grouting materials.

[0063] The solid waste-based grout of Comparative Example 6 exhibited a 24-hour compressive strength of 25.4 MPa, a 24-hour flexural strength of 4.0 MPa, a 28-day compressive strength of 70.1 MPa, a 28-day flexural strength of 7.0 MPa, and a shrinkage rate of 0.052%. The results indicate that the composite early-strength agent and calcium-magnesium expanding agent play a crucial role in improving the strength of the grout, compensating for shrinkage, and preventing stress concentration.

[0064] The solid waste-based grout of Comparative Example 7 exhibits a 24-hour compressive strength of 28.0 MPa, a 24-hour flexural strength of 3.9 MPa, a 28-day compressive strength of 72.5 MPa, a 28-day flexural strength of 7.1 MPa, and a shrinkage rate of 0.054%. Starch nanocrystals are prone to hydrolysis in alkaline environments, leading to structural damage and performance degradation. Furthermore, they have poor dispersibility, easily agglomerating in the grout and failing to distribute evenly. Additionally, their water resistance and durability are also relatively poor.

[0065] The solid waste-based grout of Comparative Example 8 exhibits a 24-hour compressive strength of 30.1 MPa, a 24-hour flexural strength of 4.5 MPa, a 28-day compressive strength of 73.0 MPa, a 28-day flexural strength of 7.6 MPa, and a shrinkage rate of 0.053%. It exhibits poor water resistance, easily dissolving or expanding in humid environments, leading to structural damage and consequently affecting the grout's strength. The polyvinyl alcohol nanofibers also exhibit poor aging resistance, readily degrading under conditions such as light and oxidation, reducing the grout's durability. Furthermore, their weak interfacial bonding with the grout matrix prevents the formation of a good bond.

[0066] It should be noted that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art can still modify the technical solutions described in the above embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A solid waste-based nanocomposite grouting material, characterized in that, The raw materials used to make its effective components include 70-210 parts by weight of cement, 350-490 parts by weight of blast furnace slag powder, 70-140 parts by weight of fly ash, 140-210 parts by weight of quartz sand, 7-21 parts by weight of nano silica, 4-7 parts by weight of nano cellulose, 3-10 parts by weight of composite early strength agent, 0.7-2.1 parts by weight of superabsorbent polymer, and 0.5-1.5 parts by weight of defoamer; The composite early strength agent is prepared by mixing thioaluminate and sodium gluconate in a mass ratio of 3-6:

1.

2. The solid waste-based nanocomposite grouting material according to claim 1, characterized in that, The raw materials also include 70-100 parts by weight of water, 2-5 parts by weight of water-reducing agent, and 14-28 parts by weight of expansion agent.

3. The solid waste-based nanocomposite grouting material according to claim 1 or 2, characterized in that, The particle size of the nano-silica is 10-30 nm.

4. The solid waste-based nanocomposite grouting material according to claim 3, characterized in that, The nanocellulose has a diameter of 5-20 nm and a length of 0.5-2 μm.

5. The solid waste-based nanocomposite grouting material according to claim 4, characterized in that, The specific surface area of ​​the blast furnace slag powder is ≥450m². 2 / kg, CaO content ≥35wt%.

6. The solid waste-based nanocomposite grouting material according to claim 5, characterized in that, The cement is silicate cement; the expanding agent is a calcium-magnesium expanding agent. In the expanding agent, the mass ratio of calcium oxide to magnesium oxide is 2-4:

1.

7. The solid waste-based nanocomposite grouting material according to claim 6, characterized in that, The quartz sand has a particle size of 40-70 mesh and a SiO2 content of ≥95wt%.

8. The solid waste-based nanocomposite grouting material according to claim 7, characterized in that, The superabsorbent polymer is a cross-linked sodium polyacrylate-based polymer material.

9. A method for preparing the solid waste-based nanocomposite grouting material according to any one of claims 2-8, characterized in that, Take nano-silica, nano-cellulose and silane coupling agent according to the stated weight parts, and ultrasonically disperse them at 50-60℃ for 30 min to obtain a suspension; The following ingredients are added to the suspension: cement, blast furnace slag powder, fly ash, quartz sand, expansion agent, composite early strength agent, water-reducing agent, super absorbent polymer and defoamer. Water is added and the mixture is stirred evenly to obtain solid waste-based nanocomposite grouting material. The amount of the silane coupling agent used is 0.8-1.3% of the total weight of nano-silica and nano-cellulose.

10. The method for preparing solid waste-based nanocomposite grouting material according to claim 9, characterized in that, During the water addition process, first stir at a low speed of less than 100 r / min to wet the raw material particles; Then stir at a high speed of 450-550 r / min for 5-8 minutes to form a uniform slurry.