Solid waste-based ultra-high performance concrete material and preparation method thereof

Abstract

This invention relates to the field of concrete preparation technology, specifically to a solid waste-based ultra-high performance concrete material and its preparation method. The material comprises the following components by weight: 620-660 parts slag, 200-250 parts fly ash, 650-750 parts aggregate, 40-50 parts sodium hydroxide, 120-150 parts water glass, 80-120 parts composite reinforcing material, and 180-260 parts water. The composite reinforcing material is composed of modified steel fibers and modified silica fume. The ultra-high performance concrete material prepared by this invention incorporates the composite reinforcing material, the main material of which includes steel fibers. The surface of the steel fibers is improved, and by incorporating silica fume, not only is the surface roughness of the steel fibers further enhanced, improving their bonding ability with other concrete components, but the composite silica fume is also uniformly dispersed in the concrete, further improving the concrete's performance.

Description

Technical Field

[0001] This invention relates to the field of concrete preparation technology, specifically to a solid waste-based ultra-high performance concrete material and its preparation method. Background Technology

[0002] Concrete is a high-strength composite building material formed by mixing cement, aggregates, water, and necessary admixtures in a certain proportion, followed by stirring, molding, and hardening. Concrete is widely used in civil engineering, such as in housing, bridges, roads, tunnels, geothermal engineering, and marine development. Depending on its application and the type of aggregate used, concrete can be classified into heavy concrete, ordinary concrete, lightweight concrete, as well as structural concrete, waterproof concrete, and heat-resistant concrete, among other types.

[0003] To improve environmental performance during concrete preparation, solid waste-based materials such as slag and fly ash are often added. Using these materials enhances the utilization of solid waste, contributing to a greener environment. Furthermore, fibers are frequently used to strengthen concrete. Steel fiber reinforced concrete is a novel multiphase composite material formed by incorporating randomly distributed short steel fibers into ordinary concrete. These randomly distributed steel fibers effectively inhibit the propagation of micro-cracks and the formation of macro-cracks within the concrete, significantly improving its tensile, flexural, impact, and fatigue resistance, and exhibiting good ductility.

[0004] In existing technologies, steel fibers are typically added directly to concrete. However, the smooth surface of the steel fibers results in poor bonding with other components in the concrete. To address this, we have designed a composite reinforcing material that overcomes these shortcomings. This material uses steel fibers as the main component and improves the surface of the steel fibers, not only increasing their roughness but also allowing them to combine with silica fume to jointly enhance the reinforcing effect on the concrete. Summary of the Invention

[0005] The purpose of this invention is to provide a solid waste-based ultra-high performance concrete material and its preparation method to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A solid waste-based ultra-high performance concrete material, comprising the following components by weight: Slag 620-660 parts, fly ash 200-250 parts, aggregate 650-750 parts, sodium hydroxide 40-50 parts, water glass 120-150 parts, composite reinforcing material 80-120 parts, water 180-260 parts; The composite reinforcing material is made by combining modified steel fibers and modified silicon powder; The method for preparing the modified steel fiber includes the following steps: S101. Steel fibers are impregnated in a Tris buffer solution containing dopamine hydrochloride and reacted continuously for 12-18 hours to obtain a mixture. S102. Add hydrogen peroxide and sodium hydroxide solution to the mixture obtained in step S101 and continue heating the reaction for 15-25 minutes. Then take out the product, wash it with water, and dry it at 40-60℃ to constant weight to obtain modified steel fiber. The method for preparing the modified silicon powder includes the following steps: S201. Grind the silicon powder; S202. The silicon powder treated in step S201 is ultrasonically dispersed in anhydrous ethanol, and acetic acid is added dropwise to adjust the pH to 3.5-4.5. Then, γ-glycidoxypropyltrimethoxysilane is added dropwise, and the reaction is carried out for 2-4 hours to obtain the reaction solution. S203. Add chitosan solution to the reaction solution in step S202 and continue the reaction for 15-20 hours. Then separate the product, wash the product with ethanol aqueous solution and dry it at 30-40℃ to constant weight to obtain modified silicon powder. The composite of modified steel fiber and modified silicon powder includes the following steps: Modified steel fibers and modified silicon powder were dispersed in deionized water and stirred for 1-2 hours. Then, all the solvent was evaporated by rotary evaporation to obtain the composite reinforced material.

[0007] Furthermore, in step S101, the mass ratio between the steel fiber and the Tris buffer solution containing dopamine hydrochloride is 1:(200-400), and the mass ratio between the steel fiber and dopamine hydrochloride is 1:(1-2).

[0008] Furthermore, the pH of the Tris buffer solution in step S101 is 8.5.

[0009] Furthermore, the concentrations of the hydrogen peroxide and sodium hydroxide solution are 15-20 wt% and 2.2-2.6 mol / L, respectively, and the mass ratio of hydrogen peroxide, sodium hydroxide solution and Tris buffer solution containing dopamine hydrochloride is (1-2):1:(8-10).

[0010] Furthermore, after silicon powder grinding in step S201, the particle size of the silicon powder is 20-100nm.

[0011] Furthermore, in step S202, the mass ratio of the silicon powder, anhydrous ethanol, and γ-glycidyl etheroxypropyltrimethoxysilane treated in step S201 is 1:(300-350):(2-6).

[0012] Furthermore, in step S203, the concentration of chitosan in the chitosan solution is 0.5-1.5 wt%, and the chitosan solution also contains acetic acid, with a concentration of 3-4 wt%. The mass ratio between the chitosan solution in step S203 and the anhydrous ethanol in step S202 is 1:(1-1.2).

[0013] Furthermore, the mass ratio of the modified steel fiber, modified silicon powder and deionized water is (2-4):1:(40-50).

[0014] A method for preparing a solid waste-based ultra-high performance concrete material, the method comprising the following steps: S1. Add slag, fly ash and aggregate to a mixer according to the mass ratio and mix evenly to obtain a mixture; S2. Add sodium hydroxide and water glass to water according to the mass ratio, and stir to mix evenly to obtain an activation solution; S3. Add half of the activation solution obtained in step S2 to the mixture in step S1. After stirring and mixing evenly, continue to gradually add the remaining half of the activation solution. During the process of adding the remaining activation solution, gradually add the composite reinforcing material according to the mass fraction. After stirring evenly, the concrete slurry is obtained. S4. Pour the concrete slurry obtained in step S3 into the mold, cure it, demold it, and continue curing to obtain ultra-high performance concrete material.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. In this invention, polydopamine is introduced onto the surface of steel fibers. The introduction of the polydopamine layer increases the surface roughness of the steel fibers and improves their bonding ability with other materials in concrete. At the same time, the polydopamine layer is treated with hydrogen peroxide and sodium hydroxide to introduce a large number of negative charges. The modified silica powder is coated with positively charged chitosan. By utilizing the adhesive properties of polydopamine itself and the effect of charge, the modified silica powder can adhere to the outside of the modified steel fibers, thus forming a composite reinforcing material. 2. This composite reinforcing material not only retains the promoting effect of steel fiber on concrete, but also the modified silica fume it carries further enhances the bonding ability between steel fiber and concrete materials. The modified silica fume also enters the concrete along with the steel fiber and disperses. It has pozzolanic properties and together promotes the improvement of concrete strength. 3. This invention utilizes a large amount of solid waste materials such as slag and fly ash, which is beneficial to the construction and development of a green ecological environment. Attached Figure Description

[0016] Figure 1 This is a process flow diagram of the present invention; Figure 2This is a process flow diagram for preparing modified steel fibers in this invention; Figure 3 This is a process flow diagram for preparing modified silicon powder in this invention. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] Please see Figures 1 to 3 The present invention provides: Example 1 A solid waste-based ultra-high performance concrete material is prepared by the following steps: S1. Put 640g of slag, 220g of fly ash and 720g of aggregate into a mixer and mix evenly to obtain a mixture; S2. Add 45g sodium hydroxide and 130g water glass to 250g water, stir and mix evenly to obtain an activation solution; S3. Add half of the activation solution obtained in step S2 to the mixture in step S1. After stirring and mixing evenly, continue to gradually add the remaining half of the activation solution. During the process of adding the remaining activation solution, gradually add 100g of composite reinforcing material. After stirring evenly, concrete slurry is obtained. S4. Pour the concrete slurry obtained in step S3 into a mold with the inner wall pre-coated with release oil. Vibrate for 30 seconds to remove air bubbles. Then, use a scraper to smooth the surface of the specimen and cover it with plastic film to prevent moisture evaporation. After the specimen is cured at room temperature for 24 hours, it is demolded. The demolded specimen is wrapped with plastic film and transferred to a standard curing chamber (20±2℃, 95±5%RH) for continued curing until the specified age to obtain ultra-high performance concrete material. The aforementioned composite reinforcing material is made by combining modified steel fibers and modified silicon powder; The preparation method of the above-mentioned modified steel fiber includes the following steps: S101. 100g of steel fiber is impregnated in 32.5kg of Tris buffer solution containing dopamine hydrochloride at pH 8.5. The Tris buffer solution containing dopamine hydrochloride contains 140g of dopamine hydrochloride. The reaction is carried out continuously for 16h to obtain a mixed solution. S102. Add 18wt% hydrogen peroxide and 24mol / L sodium hydroxide solution to the mixture obtained in step S101 and continue heating the reaction for 20min. The amounts of hydrogen peroxide and sodium hydroxide solution used are 5.2kg and 3.6kg, respectively. After that, take out the product, wash it with water, and dry it at 50℃ to constant weight to obtain modified steel fiber. The preparation method of the above-mentioned modified silicon powder includes the following steps: S201. Grind 40g of silicon powder, and control the particle size of the silicon powder to about 50nm. S202. 35g of silicon powder treated in step S201 is ultrasonically dispersed in 11.2kg of anhydrous ethanol, acetic acid is added dropwise to adjust the pH to 4, and then 140g of γ-glycidoxypropyltrimethoxysilane is added dropwise. The reaction is carried out for 3h to obtain the reaction solution. S203. Add 10.18 kg of chitosan solution to the reaction solution in step S202. The concentration of chitosan in the chitosan solution is 1.2 wt%. The chitosan solution also contains acetic acid, and the concentration of acetic acid in the chitosan solution is 3.5 wt%. Continue the reaction for 18 h. Then separate the product. After washing the product with an ethanol aqueous solution, dry it at 35 °C to constant weight to obtain modified silicon powder. The composite of the above-mentioned modified steel fiber and modified silica powder includes the following steps: 80g of modified steel fiber and 28g of modified silicon powder were dispersed in 1.26kg of deionized water and stirred for 1.5h. Then, all the solvent was evaporated by rotary evaporation to obtain the composite reinforced material.

[0019] Example 2 A solid waste-based ultra-high performance concrete material is prepared by the following steps: S1. Put 620g of slag, 200g of fly ash and 650g of aggregate into a mixer and mix evenly to obtain a mixture; S2. Add 40g sodium hydroxide and 120g water glass to 180g water, stir and mix evenly to obtain an activation solution; S3. Add half of the activation solution obtained in step S2 to the mixture in step S1. After stirring and mixing evenly, continue to gradually add the remaining half of the activation solution. During the process of adding the remaining activation solution, gradually add 80g of composite reinforcing material. After stirring evenly, the concrete slurry is obtained. S4. Pour the concrete slurry obtained in step S3 into a mold with the inner wall pre-coated with release oil. Vibrate for 30 seconds to remove air bubbles. Then, use a scraper to smooth the surface of the specimen and cover it with plastic film to prevent moisture evaporation. After the specimen is cured at room temperature for 24 hours, it is demolded. The demolded specimen is wrapped with plastic film and transferred to a standard curing chamber (20±2℃, 95±5%RH) for continued curing until the specified age to obtain ultra-high performance concrete material. The aforementioned composite reinforcing material is made by combining modified steel fibers and modified silicon powder; The preparation method of the above-mentioned modified steel fiber includes the following steps: S101. 100g of steel fiber is impregnated in 20kg of Tris buffer solution containing dopamine hydrochloride at pH 8.5. The Tris buffer solution containing dopamine hydrochloride contains 140g of dopamine hydrochloride and 100g of dopamine hydrochloride. The reaction is carried out continuously for 12h to obtain a mixed solution. S102. Add 15wt% hydrogen peroxide and 2.2mol / L sodium hydroxide solution to the mixture obtained in step S101 and continue heating the reaction for 15min. The amounts of hydrogen peroxide and sodium hydroxide solution used are 2.5kg and 2.5kg, respectively. After that, take out the product, wash it with water, and dry it at 40℃ to constant weight to obtain modified steel fiber. The preparation method of the above-mentioned modified silicon powder includes the following steps: S201. Grind 55g of silicon powder, and control the particle size of the silicon powder to about 20nm. S202. 45g of silicon powder treated in step S201 is ultrasonically dispersed in 13.5kg of anhydrous ethanol, acetic acid is added dropwise to adjust the pH to 3.5, and then 90g of γ-glycidoxypropyltrimethoxysilane is added dropwise. The reaction is carried out for 2 hours to obtain the reaction solution. S203. Add 13.5 kg of chitosan solution to the reaction solution in step S202. The concentration of chitosan in the chitosan solution is 0.5 wt%. The chitosan solution also contains acetic acid, and the concentration of acetic acid in the chitosan solution is 3 wt%. Continue the reaction for 15 h. Then separate the product. After washing the product with an ethanol aqueous solution, dry it at 30 °C to constant weight to obtain modified silicon powder. The composite of the above-mentioned modified steel fiber and modified silica powder includes the following steps: 80g of modified steel fiber and 40g of modified silicon powder were dispersed in 1.6kg of deionized water and stirred for 1 hour. Then, all the solvent was evaporated by rotary evaporation to obtain the composite reinforced material.

[0020] Example 3 A solid waste-based ultra-high performance concrete material is prepared by the following steps: S1. Put 660g of slag, 250g of fly ash and 750g of aggregate into a mixer and mix evenly to obtain a mixture; S2. Add 50g sodium hydroxide and 150g water glass to 260g water, stir and mix evenly to obtain an activation solution; S3. Add half of the activation solution obtained in step S2 to the mixture in step S1. After stirring and mixing evenly, continue to gradually add the remaining half of the activation solution. During the process of adding the remaining activation solution, gradually add 120g of composite reinforcing material. After stirring evenly, the concrete slurry is obtained. S4. Pour the concrete slurry obtained in step S3 into a mold with the inner wall pre-coated with release oil. Vibrate for 30 seconds to remove air bubbles. Then, use a scraper to smooth the surface of the specimen and cover it with plastic film to prevent moisture evaporation. After the specimen is cured at room temperature for 24 hours, it is demolded. The demolded specimen is wrapped with plastic film and transferred to a standard curing chamber (20±2℃, 95±5%RH) for continued curing until the specified age to obtain ultra-high performance concrete material. The aforementioned composite reinforcing material is made by combining modified steel fibers and modified silicon powder; The preparation method of the above-mentioned modified steel fiber includes the following steps: S101. 100g of steel fiber is impregnated in 40kg of Tris buffer solution containing dopamine hydrochloride at pH 8.5. The Tris buffer solution containing dopamine hydrochloride contains 200g of dopamine hydrochloride. The reaction is carried out continuously for 18h to obtain a mixed solution. S102. Add 20wt% hydrogen peroxide and 2.6mol / L sodium hydroxide solution to the mixture obtained in step S101 and continue heating the reaction for 25min. The amounts of hydrogen peroxide and sodium hydroxide solution used are 8kg and 4kg, respectively. After that, take out the product, wash it with water, and dry it at 60℃ to constant weight to obtain modified steel fiber. The preparation method of the above-mentioned modified silicon powder includes the following steps: S201. Grind 40g of silicon powder, and control the particle size of the silicon powder to be around 100nm. S202. 35g of silicon powder treated in step S201 is ultrasonically dispersed in 12.25kg of anhydrous ethanol, acetic acid is added dropwise to adjust the pH to 4.5, and then 210g of γ-glycidoxypropyltrimethoxysilane is added dropwise. The reaction is carried out for 4h to obtain the reaction solution. S203. Add 10.2 kg of chitosan solution to the reaction solution in step S202. The concentration of chitosan in the chitosan solution is 1.5 wt%. The chitosan solution also contains acetic acid, and the concentration of acetic acid in the chitosan solution is 4 wt%. Continue the reaction for 20 h. Then separate the product. After washing the product with an ethanol aqueous solution, dry it at 40 °C to constant weight to obtain modified silicon powder. The composite of the above-mentioned modified steel fiber and modified silica powder includes the following steps: 100g of modified steel fiber and 25g of modified silicon powder were dispersed in 1.25kg of deionized water and stirred for 2 hours. Then, all the solvent was evaporated by rotary evaporation to obtain the composite reinforced material.

[0021] The slag used in the above embodiments is blast furnace slag, provided by Shaanxi Delong Powder Engineering Materials Co., Ltd., and its chemical composition is shown in Table 1 below: Table 1: Chemical Composition of Slag The fly ash used in the above embodiments came from Henan Borun Foundry Materials Co., Ltd., and its chemical composition is shown in Table 2 below: Table 2: Chemical Composition of Fly Ash The aggregate used in the above embodiments is natural tailings sand, which is a sandy material obtained after processing the tailings generated during the mineral processing process. It is provided by Shaanxi Daxigou Mining Co., Ltd. in Shangluo City, Shaanxi Province, and the maximum particle size does not exceed 4.75mm.

[0022] The steel fibers used in the above embodiments have a length of 13±2mm and an equivalent diameter of 0.20±0.1mm.

[0023] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that step S102 was completely omitted in the process of preparing the composite reinforced material, while the remaining steps are exactly the same as in Example 1.

[0024] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that step S203 was completely omitted in the process of preparing the composite reinforced material, while the remaining steps are exactly the same as in Example 1.

[0025] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that the addition of composite reinforcing material was completely eliminated, and the 100g of composite reinforcing material in step S3 was replaced with steel fiber and silicon powder. The total mass of steel fiber and silicon powder was equal to 100g, and the mass ratio of steel fiber and silicon powder was the same as the mass ratio of modified steel fiber to modified silicon powder in the composite reinforcing material in Example 1.

[0026] The flexural strength of the ultra-high performance concrete materials prepared in Examples 1-3 and Comparative Examples 1-3 was tested according to the standard of "Test Method for Strength of Cement Mortar (ISO Method)" (GB / T17671-2021). The test results are shown in Table 3 below: Table 3: Flexural strength test results of ultra-high performance concrete materials prepared in Examples 1-3 and Comparative Examples 1-3 As can be seen from the data in Table 3 above, the ultra-high performance concrete prepared in Example 1 of this invention is significantly better than that of Comparative Examples 1-3 in terms of flexural strength. In Comparative Example 1, step S102 was omitted, which reduced the negative charge on the surface of the modified steel fiber and weakened its bonding ability with the positively charged chitosan, resulting in a decrease in the composite effect of the composite reinforcement material and a reduction in the performance of the concrete. In Comparative Example 2, the lack of chitosan introduction on the modified silica powder weakened its bonding ability with the negatively charged polydopamine outer layer, which also reduced the composite effect of the composite reinforcement material. In Comparative Example 3, steel fiber and silica powder were used directly, which greatly reduced their dispersibility and bonding ability with other materials in the concrete, resulting in the worst concrete performance.

[0027] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A solid waste-based ultra-high performance concrete material, characterized in that, Materials comprising the following components by weight: The composition includes 620-660 parts slag, 200-250 parts fly ash, 650-750 parts aggregate, 40-50 parts sodium hydroxide, 120-150 parts water glass, 80-120 parts composite reinforcing material, and 180-260 parts water. The composite reinforcing material is made by combining modified steel fibers and modified silicon powder; The method for preparing the modified steel fiber includes the following steps: S101. Steel fibers are impregnated in a Tris buffer solution containing dopamine hydrochloride and reacted continuously for 12-18 hours to obtain a mixture. S102. Add hydrogen peroxide and sodium hydroxide solution to the mixture obtained in step S101 and continue heating the reaction for 15-25 minutes. Then take out the product, wash it with water, and dry it at 40-60℃ to constant weight to obtain modified steel fiber. The method for preparing the modified silicon powder includes the following steps: S201. Grind the silicon powder; S202. The silicon powder treated in step S201 is ultrasonically dispersed in anhydrous ethanol, and acetic acid is added dropwise to adjust the pH to 3.5-4.

5. Then, γ-glycidoxypropyltrimethoxysilane is added dropwise, and the reaction is carried out for 2-4 hours to obtain the reaction solution. S203. Add chitosan solution to the reaction solution in step S202 and continue the reaction for 15-20 hours. Then separate the product, wash the product with ethanol aqueous solution and dry it at 30-40℃ to constant weight to obtain modified silicon powder. The composite of modified steel fiber and modified silicon powder includes the following steps: Modified steel fibers and modified silicon powder were dispersed in deionized water and stirred for 1-2 hours. Then, all the solvent was evaporated by rotary evaporation to obtain the composite reinforced material.

2. The solid waste-based ultra-high performance concrete material according to claim 1, characterized in that, In step S101, the mass ratio between steel fiber and Tris buffer solution containing dopamine hydrochloride is 1:(200-400), and the mass ratio between steel fiber and dopamine hydrochloride is 1:(1-2).

3. The solid waste-based ultra-high performance concrete material of claim 1, wherein, The pH of the Tris buffer solution in step S101 is 8.

5.

4. The solid waste-based ultra-high performance concrete material of claim 1, wherein, The concentrations of the hydrogen peroxide and sodium hydroxide solution are 15-20 wt% and 2.2-2.6 mol / L, respectively, and the mass ratio of hydrogen peroxide, sodium hydroxide solution and Tris buffer solution containing dopamine hydrochloride is (1-2):1:(8-10).

5. The solid waste-based ultra-high performance concrete material of claim 1, wherein, After grinding the silicon powder in step S201, the particle size of the silicon powder is 20-100nm.

6. The solid waste-based ultra-high performance concrete material according to claim 1, characterized in that, In step S202, the mass ratio of the silicon powder, anhydrous ethanol, and γ-glycidoxypropyltrimethoxysilane processed in step S201 is 1:(300-350):(2-6).

7. The solid waste-based ultra-high performance concrete material of claim 1, wherein, In step S203, the concentration of chitosan in the chitosan solution is 0.5-1.5 wt%, and the chitosan solution also contains acetic acid, with a concentration of 3-4 wt%. The mass ratio between the chitosan solution in step S203 and the anhydrous ethanol in step S202 is 1:(1-1.2).

8. The solid waste-based ultra-high performance concrete material of claim 1, wherein, The mass ratio of the modified steel fiber, modified silicon powder and deionized water is (2-4):1:(40-50).

9. A method of preparing a solid waste-based ultra-high performance concrete material as claimed in any one of claims 1-8, characterized in that, The preparation method includes the following steps: S1. Add slag, fly ash and aggregate to a mixer according to the mass ratio and mix evenly to obtain a mixture; S2. Add sodium hydroxide and water glass to water according to the mass ratio, and stir to mix evenly to obtain an activation solution; S3. Add half of the activation solution obtained in step S2 to the mixture in step S1. After stirring and mixing evenly, continue to gradually add the remaining half of the activation solution. During the process of adding the remaining activation solution, gradually add the composite reinforcing material according to the mass fraction. After stirring evenly, the concrete slurry is obtained. S4. Pour the concrete slurry obtained in step S3 into the mold, cure it, demold it, and continue curing to obtain ultra-high performance concrete material.

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