Multi-scale toughened full-solid-waste ultrahigh-ductility concrete

Abstract

The invention discloses multi-scale toughened full-solid-waste ultrahigh-ductility concrete, which is prepared from the following raw materials in parts by weight: 500 to 650 parts of full-solid-waste cementing materials, 110 to 150 parts of calcined coal gasification slag, 190 to 250 parts of calcined fly ash, 20 to 40 parts of silica fume, 10 to 30 parts of metakaolin, 780 to 930 parts of washed sand, 10 to 25 parts of fly ash fibers, 0.6 to 0.9 part of hydroxypropyl methyl cellulose, 20 to 30 parts of polycarboxylic acid water reducing agents and 300 to 400 parts of water. The calcined coal gasification slag is subjected to gradient heating to 800-960 DEG C, heat preservation is conducted for 30-60 min, then the calcined coal gasification slag is cooled to the room temperature at the cooling rate of 10-15 DEG C / min, and the calcined coal gasification slag is obtained after powder grinding. According to the multi-scale toughened full-solid-waste ultrahigh-ductility concrete provided by the invention, the toughness and the mechanical property of the concrete can be enhanced, the performance of the concrete in an extreme environment is improved, meanwhile, the solid waste utilization rate is increased, and the production cost of the concrete is reduced.

Description

Technical Field

[0002] This application belongs to the field of concrete technology, and more specifically, relates to a multi-scale toughened all-solid-waste ultra-high ductility concrete. Background Technology

[0004] Concrete is a building material made of cement, aggregates, water, mineral admixtures and additives, and is widely used in the construction of infrastructure such as buildings, bridges, roads and tunnels.

[0005] The most widely used type of concrete currently is silicate cement concrete, which uses blast furnace minerals as raw materials and possesses extremely high hardness and strength. However, its brittleness and susceptibility to cracking limit its application range. It cannot meet the complex stress conditions and harsh environments encountered in modern building and municipal engineering projects, nor can it meet the special requirements of some reinforcement and repair areas for concrete's flexural tensile strength and matrix bonding performance. To overcome the shortcomings of silicate cement concrete, existing technology has developed ultra-high ductility concrete. By adding high-ductility fibers to the concrete material, it achieves high flexural tensile strength, high ductility, and high durability. However, the relatively high price of the raw materials required for its preparation increases the cost of concrete, limiting its large-scale application.

[0006] In recent years, researchers have begun to explore incorporating industrial solid waste as a substitute material into concrete to achieve resource utilization of solid waste and reduce concrete preparation costs and environmental impact. For example, fly ash and coal gasification slag produced during coal chemical production are used as mineral admixtures. However, these solid waste materials have a high carbon content. When incorporated into concrete, they not only adsorb admixtures, reducing the workability of the concrete, but also leave residual carbon suspended matter on the concrete surface. This carbon readily adsorbs free water, reducing the overall homogeneity of the concrete, thereby lowering its mechanical properties and increasing brittleness and the risk of cracking. Furthermore, current research mostly focuses on using single or small amounts of solid waste for partial substitution, failing to fundamentally solve the cost problem of concrete. Summary of the Invention

[0008] The technical problem to be solved by this application is to provide a multi-scale toughened all-solid-waste ultra-high ductility concrete to enhance the toughness and mechanical properties of concrete, improve the performance of concrete in extreme environments, and at the same time increase the utilization rate of solid waste and reduce the production cost of concrete.

[0009] To achieve the above-mentioned technical effects, this application provides a multi-scale toughened all-solid-waste ultra-high ductility concrete, which is composed of the following raw materials in parts by weight: 500-650 parts of all-solid-waste cementitious material, 110-150 parts of calcined coal gasification slag, 190-250 parts of calcined fly ash, 20-40 parts of silica fume, 10-30 parts of metakaolin, 780-930 parts of washed sand, 10-25 parts of fly ash fiber, 0.6-0.9 parts of hydroxypropyl methylcellulose, 20-30 parts of polycarboxylate superplasticizer, and 300-400 parts of water;

[0010] The calcined coal gasification slag is obtained through the following steps: heating the first coal gasification slag to 300-400°C at a heating rate of 8-10°C / min and holding it at that temperature for 10-20 min to obtain the second coal gasification slag; heating the second coal gasification slag to 400-700°C at a heating rate of 4-6°C / min and holding it at that temperature for 20-30 min to obtain the third coal gasification slag; heating the third coal gasification slag to 800-960°C at a heating rate of 2-4°C / min and holding it at that temperature for 30-60 min to obtain the fourth coal gasification slag; cooling the fourth coal gasification slag to room temperature at a cooling rate of 10-15°C / min and grinding it to obtain the calcined coal gasification slag.

[0011] This scheme utilizes all-solid-waste cementitious materials to replace traditional cement in the preparation of multi-scale toughened all-solid-waste ultra-high ductility concrete. Leveraging the low heat, micro-expansion, and high toughness characteristics of all-solid-waste cementitious materials, it addresses the shortcomings of traditional Type II silicate cement concrete, such as high exothermicity, easy cracking, and low toughness. Through the synergistic effect of various industrial solid wastes, including calcined coal gasification slag, calcined fly ash, microsilica, metakaolin, and fly ash fiber, the toughness and mechanical properties of the all-solid-waste ultra-high ductility concrete are further improved. This achieves both low cost and high ductility in concrete, while simultaneously realizing the efficient utilization of industrial solid waste. Furthermore, this scheme optimizes the calcination process of the coal gasification slag by employing a gradient heating-cooling calcination regime. During the gradient heating process, residual carbon in the coal gasification slag is effectively removed. During high-temperature calcination and rapid cooling, the breakage of silicon-oxygen and aluminum-oxygen bonds within the coal gasification slag is effectively promoted, stimulating its potential activity and further enhancing the performance of the multi-scale toughened all-solid-waste ultra-high ductility concrete.

[0012] As a preferred option, the specific surface area of ​​the calcined coal gasification slag is 500–700 m². 2 / kg.

[0013] As a preferred option, the fly ash fiber includes modified fly ash fiber; the modified fly ash fiber is obtained through the following steps:

[0014] The first fly ash fiber was fully oxidized in H2O2 solution. The oxidized solid was washed and dried to constant weight, then immersed in 0.75 mol / L glacial acetic acid solution and ultrasonically treated to fully disperse it. After washing and drying, the second fly ash fiber was obtained.

[0015] The second fly ash fiber was added to the hydrolysis solution of bis(trimethoxysilylpropyl)ammonium and refluxed at 78°C. After washing and drying to constant weight, the third fly ash fiber was obtained.

[0016] The third fly ash fiber was placed in a mixed solvent of anhydrous ethanol and deionized water and the pH of the solution was adjusted to 9±1. After thorough stirring, tetraethyl silicate was added to the solution and stirred continuously. After washing, filtering and drying, modified fly ash fiber was obtained.

[0017] In this scheme, the strong oxidizing properties of H2O2 are used to oxidize the surface of the first fly ash fiber, generating more hydroxyl active groups on its surface, thereby improving the hydrophilicity of the first fly ash fiber surface and enhancing the interfacial bonding force of the first fly ash fiber. Glacial acetic acid is used to further etch the first fly ash fiber with acidic substances, forming more active sites and grooves on the surface of the first fly ash fiber, increasing the mechanical anchoring effect between the first fly ash fiber and the matrix material, and further improving the interfacial bonding strength. Bis(trimethoxysilylpropyl)amine and tetraethyl silicate are mainly used to form a dense protective film on the surface of the second and third fly ash fibers, while also giving the surface certain hydrophilicity, corrosion resistance, and mechanical properties, which helps to improve the overall performance of multi-scale toughened all-solid waste ultra-high ductility concrete.

[0018] Furthermore, the hydrolysis solution of bis(trimethoxysilylpropyl)amine is obtained by dispersing 1.5 parts of bis(trimethoxysilylpropyl)amine in 200-400 parts of 95% ethanol and hydrolyzing for 1 hour.

[0019] As a preferred option, the microsilica powder includes modified microsilica powder; the specific steps for preparing the modified microsilica powder are as follows: 70-80% microsilica powder, 10-20% nano-silica, 5-10% sulfoaluminate cement clinker, and 0.03-0.08% triethanolamine are mixed evenly, and the mixture is ground until the specific surface area reaches 14000-20000 m². 2 / kg, to obtain modified microsilica powder.

[0020] In this scheme, by introducing nano-silica into the microsilica, the high surface energy and activity of nano-silica can act as seed nucleation, thereby accelerating the early hydration of the microsilica and improving the overall performance and strength of the concrete.

[0021] As a preferred option, the specific steps for preparing the calcined fly ash are as follows: calcining fly ash at a reaction temperature of 600–800℃ for 0.5–1 h, followed by grinding to obtain calcined fly ash; the specific surface area of ​​the calcined fly ash is 450–600 m². 2 / kg.

[0022] Furthermore, the composition of the all-solid waste cementitious material includes: 10-20% industrial by-product gypsum, 50-80% slag, 0-10% fly ash or coal gangue, and 0-20% other raw materials; the other raw materials include carbide slag, steel slag, and cement.

[0023] Furthermore, the specific surface area of ​​the metakaolin is 23,000 to 30,000 m² / kg.

[0024] Furthermore, the fineness modulus of the washed sand is 2.4 to 2.7.

[0025] Furthermore, the water reduction rate of the polycarboxylate superplasticizer is 35-50%.

[0026] The beneficial effects of this application are as follows:

[0027] 1. This application proposes a method to replace traditional cement with all-solid-waste cementitious materials to prepare multi-scale toughened all-solid-waste ultra-high ductility concrete. Utilizing the low heat, micro-expansion, and high toughness characteristics of all-solid-waste cementitious materials, it addresses the shortcomings of traditional Type II silicate cement concrete, such as high exothermicity, easy cracking, and low toughness. Through the synergistic effect of various industrial solid wastes, including calcined coal gasification slag, calcined fly ash, microsilica, metakaolin, and fly ash fiber, the toughness and mechanical properties of the all-solid-waste ultra-high ductility concrete are further improved. This achieves both low cost and high ductility in the concrete, while also realizing the efficient utilization of industrial solid waste. Furthermore, this method optimizes the calcination process of the coal gasification slag by employing a gradient heating-cooling calcination regime. During the gradient heating process, residual carbon in the coal gasification slag is effectively removed. During high-temperature calcination and rapid cooling, the breakage of silicon-oxygen and aluminum-oxygen bonds within the coal gasification slag is effectively promoted, stimulating its potential activity and further enhancing the performance of the multi-scale toughened all-solid-waste ultra-high ductility concrete.

[0028] 2. This application utilizes the strong oxidizing properties of H2O2 to oxidize the surface of the first fly ash fiber, generating more hydroxyl active groups on its surface, thereby improving the hydrophilicity of the first fly ash fiber surface and enhancing the interfacial bonding force of the first fly ash fiber; glacial acetic acid is mainly used to further etch the first fly ash fiber with acidic substances, forming more active sites and grooves on the surface of the first fly ash fiber, increasing the mechanical anchoring effect between the first fly ash fiber and the matrix material, and further improving the interfacial bonding strength; bis(trimethoxysilylpropyl)amine and tetraethyl silicate are mainly used to form a dense protective film on the surface of the second and third fly ash fibers, while also giving the surface certain hydrophilicity, corrosion resistance, and mechanical properties, which helps to improve the overall performance of multi-scale toughened all-solid waste ultra-high ductility concrete.

[0029] 3. The present application proposes to introduce nano-silica into microsilica powder. The high surface energy and activity of nano-silica can act as seed nucleation, thereby accelerating the early hydration of microsilica powder and improving the overall performance and strength of concrete. Detailed Implementation

[0031] The embodiments of the technical solution of this application will be described in detail below. The following embodiments are only used to illustrate the technical solution of this application more clearly, and are therefore only examples, and should not be used to limit the scope of protection of this application.

[0032] The multi-scale toughened all-solid-waste ultra-high ductility concrete provided in this application is composed of the following raw materials in parts by weight: 500-650 parts of all-solid-waste cementitious material, 110-150 parts of calcined coal gasification slag, 190-250 parts of calcined fly ash, 20-40 parts of silica fume, 10-30 parts of metakaolin, 780-930 parts of washed sand, 10-25 parts of fly ash fiber, 0.6-0.9 parts of hydroxypropyl methylcellulose, 20-30 parts of polycarboxylate superplasticizer, and 300-400 parts of water;

[0033] The calcined coal gasification slag is obtained through the following steps:

[0034] The first coal gasification slag is heated to 300-400℃ at a heating rate of 8-10℃ / min and then held for 10-20min to obtain the second coal gasification slag.

[0035] The second coal gasification slag is heated to 400-700°C at a heating rate of 4-6°C / min and held at that temperature for 20-30min to obtain the third coal gasification slag.

[0036] The third coal gasification slag is heated to 800-960°C at a heating rate of 2-4°C / min and then held at that temperature for 30-60min to obtain the fourth coal gasification slag.

[0037] The fourth coal gasification slag is cooled to room temperature at a cooling rate of 10-15℃ / min, and then ground to obtain calcined coal gasification slag.

[0038] Specifically, the chemical composition and mass percentage of the first coal gasification slag include: SiO2: 41%–50%, Al2O3: 15%–21%, CaO: 7%–18%, Fe2O3: 6%–12%, and residual carbon 2%–12%. Since the composition of each particle of the first coal gasification slag is not uniform, and the above-defined component range is already a relatively small range, the components of the first coal gasification slag used are all within a reasonable range of fluctuations, which does not affect the product performance obtained by those skilled in the art when implementing the embodiments of this application.

[0039] This embodiment utilizes all-solid-waste cementitious materials to replace traditional cement, and combines them with various industrial solid wastes to prepare multi-scale toughened all-solid-waste ultra-high ductility concrete. Leveraging the low heat, micro-expansion, and high toughness characteristics of the all-solid-waste cementitious materials, it addresses the shortcomings of traditional Type II silicate cement concrete, such as high exothermic reaction, easy cracking, and low toughness. For coal gasification slag in industrial solid waste, this embodiment employs a gradient heating-cooling calcination process to address the high residual carbon content within the coal gasification slag, promoting the breakage of silicon-oxygen and aluminum-oxygen bonds within the slag, stimulating its potential activity, and further improving the toughness and mechanical properties of the all-solid-waste ultra-high ductility concrete. Preferably, the specific surface area of ​​the calcined coal gasification slag is 500–700 m² / g. 2 / kg.

[0040] Preferably, the solid waste cementitious material used in the following specific embodiments is the Type III solid waste cementitious material in the DB 64 / T 2004-2024 standard, whose components include: 10-20% industrial by-product gypsum, 50-80% slag, 0-10% fly ash or coal gangue, and 0-20% other raw materials; the other raw materials include carbide slag, steel slag, and cement.

[0041] Preferably, the specific surface area of ​​the metakaolin used in the following specific embodiments is 23,000 to 30,000 m² / kg.

[0042] Preferably, the fineness modulus of the washed sand used in the following specific embodiments is 2.4 to 2.7.

[0043] Preferably, the water reduction rate of the polycarboxylate superplasticizer used in the following specific embodiments is 35-50%.

[0044] Optionally, the hydroxypropyl methylcellulose used in the following specific embodiments has a 100-mesh pass rate of greater than 98.5%.

[0045] To further improve the toughness of ultra-high ductility concrete made entirely from solid waste, in one implementation, the fly ash fiber includes modified fly ash fiber; the modified fly ash fiber is obtained through the following steps:

[0046] The first fly ash fiber was fully oxidized in H2O2 solution. The oxidized solid was washed and dried to constant weight, then immersed in 0.75 mol / L glacial acetic acid solution and ultrasonically treated to fully disperse it. After washing and drying, the second fly ash fiber was obtained.

[0047] The second fly ash fiber was added to the hydrolysis solution of bis(trimethoxysilylpropyl)ammonium and refluxed at 78°C. After washing and drying to constant weight, the third fly ash fiber was obtained.

[0048] The third fly ash fiber was placed in a mixed solvent of anhydrous ethanol and deionized water and the pH of the solution was adjusted to 9±1. After thorough stirring, tetraethyl silicate was added to the solution and stirred continuously. After washing, filtering and drying, fly ash fiber was obtained.

[0049] In this embodiment, the strong oxidizing properties of H2O2 are used to oxidize the surface of the first fly ash fiber, generating more hydroxyl active groups on its surface, thereby improving the hydrophilicity of the first fly ash fiber surface and enhancing the interfacial bonding force of the first fly ash fiber. Glacial acetic acid is used to further etch the first fly ash fiber with acidic substances, forming more active sites and grooves on the surface of the first fly ash fiber, increasing the mechanical anchoring effect between the first fly ash fiber and the matrix material, and further improving the interfacial bonding strength. Bis(trimethoxysilylpropyl)amine and tetraethyl silicate are mainly used to form a dense protective film on the surface of the second and third fly ash fibers, while also giving the surface certain hydrophilicity, corrosion resistance, and mechanical properties, which helps to improve the overall performance of multi-scale toughened all-solid waste ultra-high ductility concrete.

[0050] The following is a preferred modification method for fly ash fibers: First, 5-10g of the first fly ash fiber is oxidized in 200-400 mL of 5% H2O2 solution for 1-2 hours. Then, it is repeatedly washed with distilled water and dried to constant weight. Next, the first fly ash fiber is immersed in 50-100 mL of 0.75 mol / L glacial acetic acid solution and ultrasonically treated at 30 kHz for 2 hours. Then, it is washed with deionized water until neutral and dried to obtain the second fly ash fiber. Next, 1.5g of bis(trimethoxysilylpropyl)amine is dispersed in 200-400 mL of 95% ethanol and hydrolyzed for 1 hour. Then, 15g of the second fly ash fiber is added, and the mixture is refluxed at 78℃ for 12-18 hours. Finally, the resulting solid is washed with ethanol 3-5 times and dried to constant weight to obtain the third fly ash fiber. Finally, 6–10 g of the third type of fly ash fiber was placed in 200–240 mL of anhydrous ethanol and 60–100 mL of deionized water and mixed thoroughly. Then, ammonia solution was added to adjust the pH to 9–10. The mixture was stirred at low speed with a non-magnetic stirrer for 20–40 min. Then, 3 mL of tetraethyl silicate was added over 1–2 h, and the mixture was stirred for 4–6 h. Finally, the mixture was washed with deionized water, filtered, and dried for 20–24 h to obtain the modified fly ash fiber.

[0051] To further improve the performance of ultra-high ductility concrete made entirely from solid waste, in one implementation, the microsilica powder includes modified microsilica powder; the preparation steps of the modified microsilica powder are as follows:

[0052] Mix 70-80% of first-grade silica powder, 10-20% of nano-silica, 5-10% of sulfoaluminate cement clinker, and 0.03-0.08% of triethanolamine evenly, and then grind the mixture until the specific surface area reaches 14,000-20,000 m². 2 / kg, to obtain modified microsilica powder.

[0053] Specifically, nano-silica, with its high surface energy and activity, can act as a seed nucleator. Introducing nano-silica into microsilica can accelerate its early hydration, improving the overall performance and strength of concrete. Furthermore, sulfoaluminate cement clinker can rapidly hydrate to form alkaline substances, promoting the formation of early hydration products and increasing the early strength of microsilica. Simultaneously, it can enhance the microsilica's resistance to sulfate and chloride erosion, further improving the toughness of concrete.

[0054] In one implementation, the preparation steps of the calcined fly ash specifically include: calcining fly ash at a reaction temperature of 600–800℃ for 0.5–1 h, followed by grinding to obtain calcined fly ash; the specific surface area of ​​the calcined fly ash is 450–600 m². 2 / kg.

[0055] Specifically, the chemical composition and mass percentage of fly ash include: SiO2 25-45%, Al2O3 28-40%, Fe2O3 1-4%, CaO 1-5%, MgO 0-1%, K2O 0-1%, Na2O 0-1%, SO3 0-1%, TiO2 0-1%, and residual carbon 2-8%. Fly ash also contains a small amount of residual carbon, which can be reduced by calcining the fly ash.

[0056] To verify the performance and toughness of the multi-scale toughened all-solid-waste ultra-high ductility concrete described in the above embodiments, some specific experiments have been conducted based on the embodiments provided in this application. Specifically, by controlling variables such as the type of raw materials and preparation method of the multi-scale toughened all-solid-waste ultra-high ductility concrete, different examples of multi-scale toughened all-solid-waste ultra-high ductility concrete were prepared. The test results of these examples show that the solution provided in this application achieves good results.

[0057] It should be noted that the following embodiments and comparative examples are only used to illustrate the present invention in detail and do not limit the scope of protection of the invention in any way.

[0058] Preparation of calcined coal gasification slag - Example 1:

[0059] Example 1-1

[0060] S11: The first coal gasification slag is heated to 350°C at a heating rate of 9°C / min and held at that temperature for 15min to obtain the second coal gasification slag.

[0061] S12: The second coal gasification slag is heated to 600°C at a heating rate of 5°C / min and then held at that temperature for 25 min to obtain the third coal gasification slag.

[0062] S13: The third coal gasification slag is heated to 900°C at a heating rate of 3°C / min and then held at that temperature for 50 min to obtain the fourth coal gasification slag.

[0063] S14: The fourth coal gasification slag is cooled to room temperature at a cooling rate of 15℃ / min, and then ground to obtain calcined coal gasification slag.

[0064] Examples 1-2 to 1-3

[0065] The difference between Examples 1-2 and 1-3 and Example 1-1 lies in the different control conditions for each step. For details of the control conditions, please refer to Table 1.

[0066] Comparative Examples 1-1 to 1-2

[0067] The difference between Comparative Example 1-1 and Example 1-1 is that Comparative Example 1-1 heats up at a fixed heating rate without gradient heating. The difference between Comparative Example 1-2 and Example 1-1 is that the temperature control conditions of Comparative Example 1-2 are different. The specific control conditions are detailed in Table 1.

[0068] Table 1. Examples and comparative control conditions for preparing calcined coal gasification slag

[0069]

[0070] The calcined coal gasification slag obtained in Example 1 and Comparative Example 1 were compared with the first coal gasification slag for component determination. The specific results are shown in Table 2.

[0071] Table 2. Chemical composition and mass determination results of calcined coal gasification slag and first coal gasification slag

[0072]

[0073] Note: The results of the determination of each chemical component in the calcined coal gasification slag in Table 2 are the average values ​​of three measurements.

[0074] Preparation of modified fly ash fibers - Example 2:

[0075] S21: Place 3g of the first fly ash fiber in 200 mL of 5% H2O2 solution for oxidation for 2 hours, then wash repeatedly with distilled water and dry to constant weight. Soak the first fly ash fiber in 100 mL of 0.75 mol / L glacial acetic acid solution for ultrasonic treatment for 2 hours. Then wash the ultrasonically treated first fly ash fiber with deionized water until neutral and dry to obtain the second fly ash fiber.

[0076] S22: 1.5g of bis(trimethoxysilylpropyl)amine was dispersed in 250ml of 95% ethanol and hydrolyzed for 1h. Then, 15g of the second fly ash fiber was added, and the mixture was refluxed at 78℃ for 13h. The resulting solid was washed with ethanol 5 times and dried to constant weight to obtain the third fly ash fiber.

[0077] S23: 6 g of third-generation fly ash fiber was placed in 220 mL of anhydrous ethanol and 80 mL of deionized water and mixed evenly. Then, ammonia solution was added to adjust the pH to 9. The mixture was stirred at low speed with a non-magnetic stirrer for 25 min. Then, 3 mL of tetraethyl silicate was added over 2 h and stirred for 6 h. Finally, the mixture was washed with deionized water, filtered, and dried for 20 h to obtain modified fly ash fiber.

[0078] Preparation of modified microsilica powder - Example 3:

[0079] S31: Mix 80% of the first micro silica powder, 15% of nano silica, 5% of sulfoaluminate cement clinker and 0.04% of triethanolamine evenly;

[0080] S32: Grind the mixture from the previous step until the specific surface area reaches 14000-20000 m². 2 / kg, to obtain modified microsilica powder.

[0081] Preparation of calcined fly ash - Example 4:

[0082] S41: Calcining fly ash at 800℃ for 0.6h;

[0083] S42: Grind the calcined fly ash from the previous step until the specific surface area reaches 450-600 m². 2 / kg, to obtain calcined fly ash.

[0084] Preparation of Multi-Scale Toughened All-Solid Waste Ultra-High Ductility Concrete - Example 5:

[0085] Example 5-1

[0086] Multi-scale toughened all-solid-waste ultra-high ductility concrete was obtained by thoroughly mixing 560 parts of all-solid-waste cementitious material, 140 parts of calcined coal gasification slag obtained in Example 1-1, 250 parts of calcined fly ash, 20 parts of microsilica powder, 10 parts of metakaolin, 800 parts of washed sand, 12 parts of fly ash fiber, 0.6 parts of hydroxypropyl methylcellulose, 20 parts of polycarboxylate superplasticizer, and 325 parts of water.

[0087] Examples 5-2 to 5-5

[0088] The difference between Examples 5-2 to 5-5 and Example 5-1 lies in the different types and mass fractions of each component. For specific control conditions, please refer to Table 3.

[0089] Comparative Examples 5-1 to 5-3

[0090] The difference between Comparative Example 5-1 and Example 5-6 is that Type II silicate cement was used instead of all-solid waste cementitious materials. The specific control conditions are detailed in Table 3.

[0091] The difference between Comparative Examples 5-2 and 5-3 and Example 5-6 lies in the different types of calcined coal gasification slag used. For specific control conditions, please refer to Table 3.

[0092] Table 3. Examples and comparative control conditions for preparing multi-scale toughened all-solid-waste ultra-high ductility concrete

[0093]

[0094] Note: The first microsilica powder in Table 3 above is the first microsilica powder in Example 3, which is unmodified microsilica powder; the first fly ash fiber is the first fly ash fiber in Example 2, which is unmodified fly ash fiber.

[0095] The workability and mechanical properties of the ultra-high ductility concretes obtained in Examples 5-1 to 5-5 and Comparative Examples 5-1 to 5-3 were tested. The specific performance test results are shown in Table 4.

[0096] Table 4. Test results of ultra-high ductility concrete obtained in Examples 5-1 to 5-5 and Comparative Examples 5-1 to 5-3

[0097]

[0098] Experimental conclusion:

[0099] Concrete prepared using all-solid-waste cementitious materials in Examples 5-1 to 5-6 exhibits superior mechanical properties compared to Comparative Example 5-1 (using traditional Portland cement) in terms of compressive strength, equivalent flexural toughness, equivalent flexural strength, ultimate tensile strength, and ultimate elongation. This demonstrates that all-solid-waste cementitious materials have significant advantages in improving the mechanical properties and ductility of concrete.

[0100] Examples 5-1 to 5-3, using coal gasification slag with different calcination processes (Examples 1-1 to 1-3), all showed superior performance compared to Comparative Examples 5-2 and 5-3 (coal gasification slag using the unoptimized calcination process). In particular, Example 5-3 exhibited significantly higher compressive strength (73.6 MPa) and equivalent flexural toughness (763.4 KJ / m³) than Comparative Examples 5-2 (58.2 MPa and 734.7 KJ / m³) and 5-3 (52.4 MPa and 708.4 KJ / m³). This indicates that optimizing the calcination process can effectively remove residual carbon from the coal gasification slag, activate its activity, and thus improve concrete performance.

[0101] Examples 5-4 to 5-6, employing modified silica fume and modified fly ash fiber, further enhanced the mechanical properties of the concrete. In particular, Examples 5-6 achieved the highest values ​​for compressive strength (81.7 MPa), equivalent flexural toughness (874.3 KJ / m³), ultimate tensile strength (6.9 MPa), and ultimate elongation (6.8%). This indicates that modified silica fume and modified fly ash fiber can further enhance the toughness and ductility of concrete.

[0102] The consistency and water retention of Examples 5-1 to 5-6 were superior to those of Comparative Examples 5-1 to 5-3. In particular, Example 5-6 achieved the highest values ​​for both consistency (164 mm) and water retention (98.7%), indicating that the all-solid waste cementitious material and optimized process can improve the workability and homogeneity of concrete.

[0103] The tensile bond strength of bricks in Examples 5-1 to 5-6 (2.3~2.4 MPa) was slightly higher than that in Comparative Examples 5-1 to 5-3 (1.8~2.2 MPa), indicating that the all-solid waste cementitious material has certain advantages in improving the bonding performance between concrete and the matrix.

[0104] The multi-scale toughened all-solid-waste ultra-high ductility concrete provided in this application utilizes a gradient heating-cooling calcination process to calcine coal gasification slag, promoting the breakage of silicon-oxygen and aluminum-oxygen bonds within the slag and stimulating its potential activity, thereby further improving the workability and mechanical properties of the all-solid-waste ultra-high ductility concrete. Simultaneously, by modifying fly ash fibers, their surface acquires certain hydrophilicity, corrosion resistance, and mechanical properties, which helps improve the toughening performance of the multi-scale all-solid-waste ultra-high ductility concrete. Finally, by introducing nano-silica into microsilica, utilizing the high surface energy and activity of nano-silica, it can act as a seed nucleation agent, thereby accelerating the early hydration of microsilica and further enhancing the overall performance and strength of the all-solid-waste ultra-high ductility concrete.

[0105] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A multi-scale toughened all-solid-waste ultra-high ductility concrete, characterized in that, It is composed of the following raw materials in parts by weight: 500-650 parts of solid waste cementitious material, 110-150 parts of calcined coal gasification slag, 190-250 parts of calcined fly ash, 20-40 parts of silica fume, 10-30 parts of metakaolin, 780-930 parts of washed sand, 10-25 parts of fly ash fiber, 0.6-0.9 parts of hydroxypropyl methylcellulose, 20-30 parts of polycarboxylate superplasticizer, and 300-400 parts of water; The calcined coal gasification slag is obtained through the following steps: The first coal gasification slag is heated to 300-400℃ at a heating rate of 8-10℃ / min and then held for 10-20min to obtain the second coal gasification slag. The second coal gasification slag is heated to 400-700°C at a heating rate of 4-6°C / min and held at that temperature for 20-30min to obtain the third coal gasification slag. The third coal gasification slag is heated to 800-960°C at a heating rate of 2-4°C / min and then held at that temperature for 30-60min to obtain the fourth coal gasification slag. The fourth coal gasification slag is cooled to room temperature at a cooling rate of 10-15℃ / min, and then ground to obtain calcined coal gasification slag.

2. The multi-scale toughened all-solid-waste ultra-high ductility concrete as described in claim 1, characterized in that, The specific surface area of ​​the calcined coal gasification slag is 500-700 m². 2 / kg.

3. The multi-scale toughened all-solid-waste ultra-high ductility concrete as described in claim 1, characterized in that, The fly ash fiber includes modified fly ash fiber; the modified fly ash fiber is obtained through the following steps: The first fly ash fiber was fully oxidized in H2O2 solution. The oxidized solid was washed and dried to constant weight, then immersed in 0.75 mol / L glacial acetic acid solution for ultrasonic treatment to fully disperse it. After washing and drying, the second fly ash fiber was obtained. The second fly ash fiber was added to the hydrolysis solution of bis(trimethoxysilylpropyl)ammonium and refluxed at 78°C. After washing and drying to constant weight, the third fly ash fiber was obtained. The third fly ash fiber was placed in a mixed solvent of anhydrous ethanol and deionized water and the pH of the solution was adjusted to 9±1. After thorough stirring, tetraethyl silicate was added to the solution and stirred continuously. After washing, filtering and drying, modified fly ash fiber was obtained.

4. The multi-scale toughened all-solid-waste ultra-high ductility concrete as described in claim 3, characterized in that, The hydrolysis solution of bis(trimethoxysilylpropyl)amine is obtained by dispersing 1.5 parts of bis(trimethoxysilylpropyl)amine in 200-400 parts of 95% ethanol and hydrolyzing for 1 hour.

5. The multi-scale toughened all-solid-waste ultra-high ductility concrete as described in claim 1, characterized in that, The microsilica powder includes modified microsilica powder; the specific steps for preparing the modified microsilica powder are as follows: Mix 70-80% of first-grade silica powder, 10-20% of nano-silica, 5-10% of sulfoaluminate cement clinker, and 0.03-0.08% of triethanolamine evenly, and then grind the mixture until the specific surface area reaches 14,000-20,000 m². 2 / kg, to obtain modified microsilica powder.

6. The multi-scale toughened all-solid-waste ultra-high ductility concrete as described in claim 1, characterized in that, The specific steps for preparing the calcined fly ash are as follows: calcining fly ash at a reaction temperature of 600–800℃ for 0.5–1 h, followed by grinding to obtain the calcined fly ash; the specific surface area of ​​the calcined fly ash is 450–600 m². 2 / kg.

7. The multi-scale toughened all-solid-waste ultra-high ductility concrete as described in claim 1, characterized in that, The composition of the all-solid waste cementitious material includes: 10-20% industrial by-product gypsum, 50-80% slag, 0-10% fly ash or coal gangue, and 0-20% other raw materials; the other raw materials include carbide slag, steel slag, and cement.

8. The multi-scale toughened all-solid-waste ultra-high ductility concrete as described in claim 1, characterized in that, The specific surface area of ​​the metakaolin is 23,000 to 30,000 m² / kg.

9. The multi-scale toughened all-solid-waste ultra-high ductility concrete as described in claim 1, characterized in that, The fineness modulus of the washed sand is 2.4 to 2.

7.

10. The multi-scale toughened all-solid-waste ultra-high ductility concrete as described in claim 1, characterized in that, The water reduction rate of the polycarboxylate superplasticizer is 35-50%.

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