Preparation method and application of low-carbon salt-tolerant ultra-high performance concrete material

Abstract

This invention discloses a method for preparing low-carbon, salt-alkali resistant, ultra-high performance concrete material and its application, comprising the following steps: (1) Dispersing silica fume in a water-ethanol composite liquid containing a silane coupling agent, and then gradually adding anhydrous ethanol containing dissolved aluminum isopropoxide under stirring conditions, and continuing stirring after the addition is complete. After completion, solid-liquid separation is performed to obtain pretreated silica fume. (2) Adding titanium citrate solution to the pretreated silica fume, stirring evenly, drying, and then calcining to obtain modified silica fume. (3) Taking the following raw materials: silicate cement, the stabilized steel slag powder, the modified silica fume, fly ash, fine aggregate, copper-plated steel fiber, and water-reducing agent. Mixing the above raw materials with mixing water to obtain the ultra-high performance concrete material. This invention eliminates the problem of poor stability of steel slag while effectively improving the fluidity of concrete materials, making the ultra-high performance concrete material of this invention have better workability.

Description

Technical Field

[0001] This invention relates to the field of concrete materials technology, specifically to a method for preparing low-carbon, salt-alkali resistant, ultra-high performance concrete materials and their applications. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] my country has vast areas of saline-alkali land, including the western salt lake regions, the inland saline soils of North China, and a long coastal zone. Concrete structures face severe durability challenges when constructing projects in these areas. Surveys show that many structures built in saline-alkali environments experience varying degrees of damage within their service life. The main ions causing concrete damage include chloride ions (Cl⁻) and sulfate ions (SO₄²⁻), which transport through the concrete pore solution and undergo complex physicochemical reactions with cement hydration products. In the western saline-alkali regions, due to the arid climate and large temperature differences, concrete structures are also subjected to the coupled effects of wet-dry cycles and freeze-thaw cycles. This multi-factor environment causes the rate of concrete deterioration to be much higher than in typical atmospheric environments. Therefore, ensuring the long-term durability of concrete in saline-alkali environments has become an important issue in materials science and civil engineering.

[0004] Improving the density of concrete materials to reduce salt and alkali penetration is one of the effective measures to enhance resistance to salt and alkali erosion. Ultra-high performance concrete (UHPC) effectively reduces porosity by using low water-cement ratios and removing coarse aggregates, achieving ultra-high strength and high durability. Steel slag is an industrial solid waste generated during steel smelting, but due to its poor volume stability, it cannot be directly used in UHPC, especially in concrete structures serving in saline-alkali environments. This is because the free calcium oxide in steel slag expands in volume after converting to calcium hydroxide, easily inducing cracks and providing a rapid channel for salt and alkali intrusion, thus limiting the resource utilization of steel slag. In addition, due to the low water-cement ratio of UHPC, the prepared concrete slurry has insufficient fluidity, which is not conducive to transportation and increases the difficulty of construction. Summary of the Invention

[0005] This invention provides a method for preparing a low-carbon, salt-alkali-resistant, ultra-high-performance concrete material and its application, which eliminates the poor stability problem of steel slag while achieving carbon dioxide solidification. Furthermore, the method of this invention effectively improves the fluidity of the concrete material, giving the ultra-high-performance concrete material better workability. Specifically, the technical aspects of this invention are as follows.

[0006] First, this invention provides a method for preparing a low-carbon, salt-alkali-resistant, ultra-high-performance concrete material, comprising the following steps: (1) After mixing steel slag powder, glucose, ethylenediamine and water, a hydrothermal reaction is carried out. After the reaction is completed, the solid and liquid are separated. The resulting wet material is placed in a carbon dioxide atmosphere and sealed for carbonization treatment. After the reaction is completed, it is dried and ground to obtain stabilized steel slag powder for later use.

[0007] (2) Disperse silica fume in a water-ethanol composite solution containing a silane coupling agent, and then gradually add anhydrous ethanol containing dissolved aluminum isopropoxide dropwise under stirring. After the addition is complete, continue stirring. After completion, separate the solid and liquid to obtain pretreated silica fume for later use.

[0008] (3) Add titanium citrate solution to the pretreated silica fume, stir evenly and dry, and then calcine to obtain modified silica fume for later use.

[0009] (4) Take the following raw materials: silicate cement, stabilized steel slag powder, modified silica fume, fly ash, fine aggregate, copper-plated steel fiber, and water-reducing agent. Mix the above raw materials with mixing water to obtain the ultra-high performance concrete material.

[0010] Further, in step (1), the mass ratio of the steel slag powder, glucose, ethylenediamine, and water is 100:7~8.6:2.8~3.4:500~700.

[0011] Furthermore, in step (1), the temperature of the hydrothermal reaction is 180~200℃ and the time is 4.5~6 hours.

[0012] Furthermore, in step (1), the carbonization treatment is carried out at a temperature of 70~90℃ for 2~3 hours.

[0013] Furthermore, in step (1), the fineness of the stabilized steel slag powder is 220~350 mesh.

[0014] Further, in step (2), the ratio of silica fume to composite liquid is 1g:40~50mL. Optionally, the concentration of ethanol in the composite liquid is 10~15wt.%.

[0015] Further, in step (2), the concentration of the silane coupling agent in the composite solution is 0.1~0.25 wt.%. Optionally, the silane coupling agent includes at least one of KH550, KH560, KH570, etc.

[0016] Further, in step (2), the mass ratio of aluminum isopropoxide to silica fume is 0.16~0.23:1.

[0017] Furthermore, in step (2), the duration of the continued stirring process is 1 to 1.5 hours.

[0018] Further, in step (3), the ratio of the pretreated silica fume to the titanium citrate solution is 1g:3~4mL. Optionally, the concentration of the titanium citrate solution is 6.5~8wt.%.

[0019] Furthermore, in step (3), the calcination treatment is carried out at a temperature of 500~600℃ for 25~35 minutes.

[0020] Further, in step (4), the proportions of each raw material are as follows: 665~680 parts by weight of silicate cement, 60~75 parts by weight of stabilized steel slag powder, 195~210 parts by weight of modified silica fume, 90~105 parts by weight of fly ash, 1050~1260 parts by weight of fine aggregate, 150~165 parts by weight of copper-plated steel fiber, and 40~50 parts by weight of water-reducing agent.

[0021] Further, in step (4), the mass ratio of the mixing water to the total mass of silicate cement, stabilized steel slag powder, modified silica fume, and fly ash is 0.2~0.25.

[0022] Further, in step (4), the fine aggregate includes at least one of river sand, quartz sand, and manufactured sand. Optionally, the particle size of the fine aggregate is 30-50 mesh.

[0023] Further, in step (4), the copper-plated steel fiber has a length of 10~20mm and a diameter of 0.18~0.21mm.

[0024] Secondly, this invention discloses the application of the low-carbon, salt-alkali resistant, ultra-high performance concrete material in marine, bridge, road, and water conservancy engineering fields.

[0025] Compared with the prior art, the technical solution of the present invention has at least the following beneficial effects: (1) In this invention, steel slag is first mixed with glucose and ethylenediamine and then subjected to a hydrothermal reaction. This not only converts free calcium oxide and other substances with poor volume stability in the steel slag into calcium hydroxide, but also forms carbon quantum dots in the steel slag. When the steel slag is further carbonized, the calcium hydroxide is converted into more stable calcium carbonate. Moreover, due to the induced nucleation of the carbon quantum dots, the formation of calcium carbonate occurs around the carbon quantum dots. At the same time, the ethylenediamine remaining in the steel slag is protonated in the acidic environment provided by carbonation and attracts carbonate ions formed by carbon dioxide. This causes the formation of calcium carbonate to occur around carbon particles, thus keeping the calcium carbonate in a more porous state. This facilitates the entry of carbon dioxide gas into the interior of the steel slag, increases the degree of carbonation, and prevents the formation of a dense calcium carbonate layer on the surface of the steel slag from preventing the internal calcium hydroxide from being converted into calcium carbonate. This calcium hydroxide is converted into calcium sulfate after encountering sulfate corrosion, which is further converted into the expansive product ettringite, thus easily initiating the formation of cracks.

[0026] (2) In this invention, a silane coupling agent is first loaded onto the surface of silica fume to improve its dispersibility, while facilitating the coating of aluminum hydroxide formed by the hydrolysis of aluminum isopropoxide onto the surface of the silica fume particles. Then, titanium citrate is added to the pretreated silica fume obtained by the above treatment and calcined, thereby converting the aluminum hydroxide on the surface of the silica fume particles into aluminum oxide, and also achieving Ti 4+ The doping of ions also contributes to the thermal activation of silica fume, enhancing its cementitious reaction activity. On one hand, when using this silica fume to prepare the ultra-high performance concrete material of this invention, the isolating effect of the surface alumina coating can effectively reduce the water absorption of the silica fume, thereby improving the fluidity of the concrete material and facilitating pouring and construction. On the other hand, as the silicate cement in the concrete material hydrates, the alkalinity of the system continuously increases, and the Ti on the surface of the silica fume... 4+ The Lewis acid sites formed by the ions can rapidly adsorb hydroxide ions, promoting the dissolution of alumina (OH-). - +Al₂O₃→AlO₂ - +H2O), thereby exposing the silica fume. At this time, the hydration products of the silicate cement, the silica fume, and the water and mixing water formed by the above reaction undergo a pozzolanic reaction to form hydrated calcium silicate (CSH). This cementitious component not only helps to improve the mechanical properties of concrete materials, but also consumes calcium hydroxide, a component that is unstable in saline-alkali environments, which helps the concrete material of the present invention to better serve in saline-alkali environments. Attached Figure Description

[0027] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0028] Figure 1 The image shows a sample of stabilized steel slag powder prepared in Example 1 below.

[0029] Figure 2 The image shows a modified silica fume sample prepared in Example 1 below.

[0030] Figure 3 The following is a diagram showing the compressive strength test results for Example 1.

[0031] Figure 4 The image shows a sample of stabilized steel slag powder prepared in Example 2 below.

[0032] Figure 5 The image shows a modified silica fume sample prepared in Example 2 below.

[0033] Figure 6 The image shows a sample of stabilized steel slag powder prepared in Example 3 below.

[0034] Figure 7 The image shows a modified silica fume sample prepared in Example 3 below.

[0035] Figure 8 The image shows a sample of stabilized steel slag powder prepared in Example 4 below.

[0036] Figure 9 The image shows a sample of stabilized steel slag powder prepared in Example 5 below.

[0037] Figure 10 The image shows the silica fume sample used in Example 6 below.

[0038] Figure 11 The image shows a modified silica fume sample prepared in Example 7 below.

[0039] Figure 12 The image shows a sample of stabilized steel slag powder prepared in Example 8 below. Detailed Implementation

[0040] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer.

[0041] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as those skilled in the art. All reagents and raw materials used in this invention are readily available through conventional means, and unless otherwise specified, they shall be used in accordance with conventional methods in the art or as per the product instructions.

[0042] Furthermore, any methods and materials similar to or equivalent to those described herein can be applied to the method of this invention. The technical solution of this invention will now be further described in conjunction with the accompanying drawings and specific embodiments.

[0043] Example 1: A method for preparing a low-carbon, salt-alkali resistant, ultra-high performance concrete material, comprising the following steps: (1) Steel slag powder, glucose, ethylenediamine, and water were mixed in a mass ratio of 100:8:3:600 and stirred until homogeneous. The mixture was then transferred to a reaction vessel and heated to 200°C for 4.5 hours. After the reaction was completed, the mixture was cooled to room temperature and filtered to separate the solid and liquid phases. The resulting wet material was then placed in a sealed environment under a carbon dioxide atmosphere and heated to 85°C for carbonization treatment for 2.5 hours. The solid product was then dried at 90°C to remove moisture, ground, and passed through a 300-mesh sieve to obtain stabilized steel slag powder (e.g., slag powder, glucose, ethylenediamine, and water). Figure 1 (As shown), for later use.

[0044] (2) Silica fume and a water-ethanol composite solution containing silane coupling agent KH550 were mixed at a ratio of 1 g: 45 mL and stirred until homogeneous to obtain a mixture. The concentration of ethanol in the composite solution was 10 wt.%, and the concentration of the silane coupling agent was 0.15 wt.%. Then, anhydrous ethanol containing dissolved aluminum isopropoxide was gradually added dropwise to the mixture at a mass ratio of aluminum isopropoxide to silica fume of 0.2:1 under stirring. After the addition was complete, stirring was continued for 1 hour. After completion, solid-liquid separation was performed by filtration to obtain pretreated silica fume for later use.

[0045] (3) Add a 6.5 wt.% titanium citrate solution to the pretreated silica fume at a ratio of 1 g: 4 mL, stir evenly, dry at 90 °C to remove moisture, and then calcine at 500 °C for 35 min at a heating rate of 10 °C / min to obtain modified silica fume (e.g. Figure 2 (As shown), for later use.

[0046] (4) Take the following raw materials in the following proportions: 670 parts by weight of 42.5 ordinary Portland cement, 72 parts by weight of the stabilized steel slag powder of this embodiment, 200 parts by weight of the modified silica fume of this embodiment, 100 parts by weight of fly ash, 1150 parts by weight of fine aggregate, 155 parts by weight of copper-plated steel fiber, and 45 parts by weight of polycarboxylate superplasticizer. Wherein: the fine aggregate is quartz sand with a particle size of 30 mesh, and the copper-plated steel fiber has a length of 15 mm and a diameter of 0.2 mm. Add the above raw materials to the mixer and premix for 2 minutes, then add 230 parts by weight of mixing water and continue mixing for 2 minutes to obtain the concrete material.

[0047] Performance Testing: The concrete material prepared in this embodiment was subjected to sulfate attack resistance and chloride ion penetration resistance tests according to the "Standard for Test Methods of Long-Term Performance and Durability of Concrete" (GBT 50082-2024). The compressive strength corrosion resistance coefficient after 150 wet-dry cycles was 98.17%. Its compressive strength test results are as follows: Figure 3 As shown, the chloride ion migration coefficient is 1.96 × 10⁻⁶. -12 m 2 / s. Additionally, a flowability test was performed on the concrete material described in this embodiment, yielding a flowability of 178 mm.

[0048] Example 2: A method for preparing a low-carbon, salt-alkali resistant, ultra-high performance concrete material, comprising the following steps: (1) Steel slag powder, glucose, ethylenediamine, and water were mixed in a mass ratio of 100:7:2.8:500 and stirred until homogeneous. The mixture was then transferred to a reaction vessel and heated to 180°C for 6 hours. After the reaction was completed, the mixture was cooled to room temperature and filtered to separate the solid and liquid phases. The resulting wet material was then placed in a sealed environment under a carbon dioxide atmosphere and heated to 90°C for carbonization treatment for 2 hours. The solid product was then dried at 90°C to remove moisture, ground, and passed through a 350-mesh sieve to obtain stabilized steel slag powder (e.g., slag powder, glucose, ethylenediamine, and water). Figure 4 (As shown), for later use.

[0049] (2) Silica fume and a water-ethanol composite solution containing silane coupling agent KH570 were mixed at a ratio of 1 g: 40 mL and stirred until homogeneous to obtain a mixture. The concentration of ethanol in the composite solution was 15 wt.%, and the concentration of the silane coupling agent was 0.2 wt.%. Then, anhydrous ethanol containing dissolved aluminum isopropoxide was gradually added dropwise to the mixture at a mass ratio of aluminum isopropoxide to silica fume of 0.16:1 under stirring. After the addition was complete, stirring was continued for 1 hour. After completion, solid-liquid separation was performed by filtration to obtain pretreated silica fume for later use.

[0050] (3) Add an 8 wt.% titanium citrate solution to the pretreated silica fume at a ratio of 1 g: 3 mL, stir evenly, dry at 90 °C to remove moisture, and then calcine at a heating rate of 10 °C / min to 540 °C for 30 min to obtain modified silica fume (e.g. Figure 5 (As shown), for later use.

[0051] (4) Take the following raw materials in the following proportions: 665 parts by weight of 42.5 ordinary Portland cement, 60 parts by weight of the stabilized steel slag powder of this embodiment, 195 parts by weight of the modified silica fume of this embodiment, 90 parts by weight of fly ash, 1050 parts by weight of fine aggregate, 150 parts by weight of copper-plated steel fiber, and 40 parts by weight of polycarboxylate superplasticizer. Wherein: the fine aggregate is quartz sand with a particle size of 40 mesh, and the copper-plated steel fiber has a length of 10 mm and a diameter of 0.18 mm. Add the above raw materials to the mixer and premix for 2 minutes, then add 202 parts by weight of mixing water and continue mixing for 2 minutes to obtain the concrete material.

[0052] Performance testing: The concrete material prepared in this embodiment was tested using the same methods as in Example 1 above, including sulfate resistance test, chloride ion penetration test, and flowability test. The results showed a compressive strength corrosion resistance coefficient of 98.82% and a chloride ion migration coefficient of 1.34 × 10⁻⁶. -12 m 2 / s, flowability = 169mm.

[0053] Example 3: A method for preparing a low-carbon, salt-alkali resistant, ultra-high performance concrete material, comprising the following steps: (1) Steel slag powder, glucose, ethylenediamine, and water were mixed in a mass ratio of 100:8.6:3.4:700 and stirred until homogeneous. The mixture was then transferred to a reaction vessel and heated to 190°C for 5 hours. After the reaction was completed, the mixture was cooled to room temperature and filtered to separate the solid and liquid phases. The resulting wet material was then placed in a sealed environment under a carbon dioxide atmosphere and heated to 70°C for carbonization treatment for 3 hours. The solid product was then dried at 90°C to remove moisture, ground, and passed through a 220-mesh sieve to obtain stabilized steel slag powder (e.g., slag powder, glucose, ethylenediamine, and water). Figure 6 (As shown), for later use.

[0054] (2) Silica fume and a water-ethanol composite solution containing silane coupling agent KH550 were mixed at a ratio of 1 g: 50 mL and stirred until homogeneous to obtain a mixture. The concentration of ethanol in the composite solution was 15 wt.%, and the concentration of the silane coupling agent was 0.25 wt.%. Then, anhydrous ethanol containing dissolved aluminum isopropoxide was gradually added dropwise to the mixture at a mass ratio of aluminum isopropoxide to silica fume of 0.23:1 under stirring. After the addition was complete, stirring was continued for 1.5 hours. After completion, solid-liquid separation was performed by filtration to obtain pretreated silica fume for later use.

[0055] (3) Add a 7.5 wt.% titanium citrate solution to the pretreated silica fume at a ratio of 1 g: 3.5 mL, stir evenly, dry at 90 °C to remove moisture, and then heat to 600 °C at a heating rate of 10 °C / min and hold for 25 min for calcination treatment to obtain modified silica fume (e.g. Figure 7 (As shown), for later use.

[0056] (4) Take the following raw materials in the following proportions: 680 parts by weight of 42.5 ordinary Portland cement, 75 parts by weight of stabilized steel slag powder (in this embodiment), 210 parts by weight of modified silica fume (in this embodiment), 105 parts by weight of fly ash, 1260 parts by weight of fine aggregate, 165 parts by weight of copper-plated steel fiber, and 50 parts by weight of polycarboxylate superplasticizer. Wherein: the fine aggregate is quartz sand with a particle size of 50 mesh, and the copper-plated steel fiber has a length of 20 mm and a diameter of 0.21 mm. Add the above raw materials to the mixer and premix for 2 minutes, then add 267.5 parts by weight of mixing water and continue mixing for 2 minutes to obtain the concrete material.

[0057] Performance testing: The concrete material prepared in this embodiment was tested using the same methods as in Example 1 above, including sulfate resistance test, chloride ion penetration test, and flowability test. The results showed a compressive strength corrosion resistance coefficient of 97.27% and a chloride ion migration coefficient of 2.08 × 10⁻⁶. -12 m 2 / s, flowability = 183mm.

[0058] Example 4: A method for preparing a low-carbon, salt-alkali resistant, ultra-high performance concrete material, comprising the following steps: (1) Steel slag powder and water were mixed at a mass ratio of 100:600 and stirred evenly. The mixture was then transferred to a reactor and heated to 200°C for 4.5 hours. After the reaction was completed, the mixture was cooled to room temperature and filtered to separate the solid and liquid phases. The resulting wet material was placed in a sealed environment under a carbon dioxide atmosphere and heated to 85°C for carbonization treatment for 2.5 hours. The solid product was then dried at 90°C to remove moisture, ground, and passed through a 300-mesh sieve to obtain stabilized steel slag powder (e.g., Figure 8 (As shown), for later use.

[0059] (2) Take the following raw materials in the following proportions: 670 parts by weight of 42.5 ordinary Portland cement, 72 parts by weight of the stabilized steel slag powder of this embodiment, 200 parts by weight of the modified silica fume of the above embodiment 1, 100 parts by weight of fly ash, 1150 parts by weight of fine aggregate, 155 parts by weight of copper-plated steel fiber, and 45 parts by weight of polycarboxylate superplasticizer. Wherein: the fine aggregate is quartz sand with a particle size of 30 mesh, and the copper-plated steel fiber has a length of 15 mm and a diameter of 0.2 mm. Add the above raw materials to the mixer and premix for 2 minutes, then add 230 parts by weight of mixing water and continue mixing for 2 minutes to obtain the concrete material.

[0060] Performance testing: The concrete material prepared in this embodiment was tested using the same methods as in Example 1 above, including sulfate resistance test, chloride ion penetration test, and flowability test. The results showed a compressive strength corrosion resistance coefficient of 82.46% and a chloride ion migration coefficient of 4.51 × 10⁻⁶. -12 m 2 / s, flowability = 176mm.

[0061] Example 5: A method for preparing a low-carbon, salt-alkali resistant, ultra-high performance concrete material, comprising the following steps: (1) Steel slag powder, glucose, and water were mixed in a mass ratio of 100:8.6:700 and stirred evenly. The mixture was then transferred to a reaction vessel and heated to 190°C for 5 hours. After the reaction was completed, the mixture was cooled to room temperature and filtered to separate the solid and liquid phases. The resulting wet material was placed in a sealed environment under a carbon dioxide atmosphere and heated to 70°C for carbonization treatment for 3 hours. The solid product was then dried at 90°C to remove moisture, ground, and passed through a 220-mesh sieve to obtain stabilized steel slag powder (e.g., slag powder, glucose, and water). Figure 9 (As shown), for later use.

[0062] (2) Take the following raw materials in the following proportions: 680 parts by weight of 42.5 ordinary Portland cement, 75 parts by weight of the stabilized steel slag powder of this embodiment, 210 parts by weight of the modified silica fume of the above embodiment 3, 105 parts by weight of fly ash, 1260 parts by weight of fine aggregate, 165 parts by weight of copper-plated steel fiber, and 50 parts by weight of polycarboxylate superplasticizer. Wherein: the fine aggregate is quartz sand with a particle size of 50 mesh, and the copper-plated steel fiber has a length of 20 mm and a diameter of 0.21 mm. Add the above raw materials to the mixer and premix for 2 minutes, then add 267.5 parts by weight of mixing water and continue mixing for 2 minutes to obtain the concrete material.

[0063] Performance testing: The concrete material prepared in this embodiment was tested using the same methods as in Example 1 above, including sulfate resistance test, chloride ion penetration test, and flowability test. The results showed a compressive strength corrosion resistance coefficient of 90.48% and a chloride ion migration coefficient of 3.13 × 10⁻⁶. -12 m 2 / s, flowability = 180mm.

[0064] Example 6: A method for preparing a low-carbon, salt-alkali resistant, ultra-high performance concrete material, comprising the following steps: Take the following raw materials in the following proportions: 670 parts by weight of 42.5 ordinary Portland cement, 72 parts by weight of the stabilized steel slag powder from Example 1 above, and silica fume (such as... Figure 10 The following ingredients are listed: 200 parts by weight of fly ash, 100 parts by weight of fine aggregate, 1150 parts by weight of copper-plated steel fiber, and 45 parts by weight of polycarboxylate superplasticizer. The fine aggregate is 30-mesh quartz sand, and the copper-plated steel fiber has a length of 15 mm and a diameter of 0.2 mm. The above raw materials are added to a mixer and premixed for 2 minutes. Then, 230 parts by weight of mixing water are added, and mixing continues for 2 minutes to obtain the concrete material.

[0065] Performance testing: The concrete material prepared in this embodiment was tested using the same methods as in Example 1 above, including sulfate resistance test, chloride ion penetration test, and flowability test. The results showed a compressive strength corrosion resistance coefficient of 85.37% and a chloride ion migration coefficient of 3.91 × 10⁻⁶. -12 m 2 / s, flowability = 144mm.

[0066] Example 7: A method for preparing a low-carbon, salt-alkali resistant, ultra-high performance concrete material, comprising the following steps: (1) Silica fume and a water-ethanol composite solution containing silane coupling agent KH570 were mixed at a ratio of 1 g: 40 mL and stirred until homogeneous to obtain a mixture. The concentration of ethanol in the composite solution was 15 wt.%, and the concentration of the silane coupling agent was 0.2 wt.%. Then, anhydrous ethanol containing dissolved aluminum isopropoxide was gradually added dropwise to the mixture at a mass ratio of aluminum isopropoxide to silica fume of 0.16:1 under stirring. After the addition was complete, stirring was continued for 1 hour. After completion, solid-liquid separation was performed by filtration to obtain pretreated silica fume for later use.

[0067] (2) The pretreated silica fume is heated to 540℃ at a heating rate of 10℃ / min and held at that temperature for 30min for calcination to obtain modified silica fume (e.g. Figure 11 (As shown), for later use.

[0068] (3) Take the following raw materials in the following proportions: 665 parts by weight of 42.5 ordinary Portland cement, 60 parts by weight of the stabilized steel slag powder of Example 2 above, 195 parts by weight of the modified silica fume of this example, 90 parts by weight of fly ash, 1050 parts by weight of fine aggregate, 150 parts by weight of copper-plated steel fiber, and 40 parts by weight of polycarboxylate superplasticizer. Wherein: the fine aggregate is quartz sand with a particle size of 40 mesh, and the copper-plated steel fiber has a length of 10 mm and a diameter of 0.18 mm. Add the above raw materials to the mixer and premix for 2 minutes, then add 202 parts by weight of mixing water and continue mixing for 2 minutes to obtain the concrete material.

[0069] Performance testing: The concrete material prepared in this embodiment was tested using the same methods as in Example 1 above, including sulfate resistance test, chloride ion penetration test, and flowability test. The results showed a compressive strength corrosion resistance coefficient of 89.94% and a chloride ion migration coefficient of 2.87 × 10⁻⁶. -12 m 2 / s, flowability = 165mm.

[0070] Example 8: A method for preparing a low-carbon, salt-alkali resistant, ultra-high performance concrete material, comprising the following steps: (1) Steel slag powder, glucose, ethylenediamine, and water were mixed in a mass ratio of 100:8.6:3.4:700 and stirred until homogeneous. The mixture was then transferred to a reaction vessel and heated to 190°C for 5 hours. After the reaction was completed, the mixture was cooled to room temperature and filtered to separate the solid and liquid phases. The solid product was then dried at 90°C to remove moisture, ground, and passed through a 220-mesh sieve to obtain stabilized steel slag powder (e.g., slag powder, glucose, ethylenediamine, and water). Figure 12 (As shown), for later use.

[0071] (2) Take the following raw materials in the following proportions: 680 parts by weight of 42.5 ordinary Portland cement, 75 parts by weight of the stabilized steel slag powder of this embodiment, 210 parts by weight of the modified silica fume of the above embodiment 3, 105 parts by weight of fly ash, 1260 parts by weight of fine aggregate, 165 parts by weight of copper-plated steel fiber, and 50 parts by weight of polycarboxylate superplasticizer. Wherein: the fine aggregate is quartz sand with a particle size of 50 mesh, and the copper-plated steel fiber has a length of 20 mm and a diameter of 0.21 mm. Add the above raw materials to the mixer and premix for 2 minutes, then add 267.5 parts by weight of mixing water and continue mixing for 2 minutes to obtain the concrete material.

[0072] Performance testing: The concrete material prepared in this embodiment was tested using the same methods as in Example 1 above, including sulfate resistance test, chloride ion penetration test, and flowability test. The results showed a compressive strength corrosion resistance coefficient of 73.96% and a chloride ion migration coefficient of 5.74 × 10⁻⁶. -12 m 2 / s, flowability = 181mm.

[0073] 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 foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing 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 protection scope of the present invention.

Claims

1. A method for preparing a low-carbon, salt-alkali-resistant, ultra-high-performance concrete material, characterized in that, Includes the following steps: (1) After mixing steel slag powder, glucose, ethylenediamine and water, a hydrothermal reaction is carried out. After the reaction is completed, the solid and liquid are separated. The resulting wet material is placed in a carbon dioxide atmosphere and sealed for carbonization treatment. After the reaction is completed, it is dried and ground to obtain stabilized steel slag powder for later use. (2) Disperse silica fume in a water-ethanol composite solution containing silane coupling agent, and then gradually add anhydrous ethanol containing aluminum isopropoxide under stirring. After the addition is complete, continue stirring. After the process is completed, separate the solid and liquid to obtain pretreated silica fume for later use. (3) Add titanium citrate solution to the pretreated silica fume, stir evenly, dry, and then calcine to obtain modified silica fume for later use; (4) Take the following raw materials: silicate cement, the stabilized steel slag powder, the modified silica fume, fly ash, fine aggregate, copper-plated steel fiber, and water-reducing agent; mix the above raw materials with mixing water to obtain the ultra-high performance concrete material.

2. The method for preparing low-carbon, salt-alkali-resistant, ultra-high-performance concrete material according to claim 1, characterized in that, In step (1), the mass ratio of steel slag powder, glucose, ethylenediamine and water is 100:7~8.6:2.8~3.4:500~700.

3. The method for preparing low-carbon, salt-alkali-resistant, ultra-high-performance concrete material according to claim 1, characterized in that, In step (1), the temperature of the hydrothermal reaction is 180~200℃ and the time is 4.5~6 hours.

4. The method for preparing low-carbon, salt-alkali-resistant, ultra-high-performance concrete material according to claim 1, characterized in that, In step (1), the carbonization treatment temperature is 70~90℃ and the time is 2~3 hours; optionally, in step (1), the fineness of the stabilized steel slag powder is 220~350 mesh.

5. The method for preparing low-carbon, salt-alkali-resistant, ultra-high-performance concrete material according to claim 1, characterized in that, In step (2), the ratio of silica fume to composite liquid is 1g: 40~50mL; Optionally, in step (2), the concentration of ethanol in the composite solution is 10~15 wt.%; Optionally, in step (2), the concentration of the silane coupling agent in the composite solution is 0.1~0.25 wt.%; Optionally, in step (2), the silane coupling agent includes at least one of KH550, KH560, and KH570.

6. The method for preparing low-carbon, salt-alkali-resistant, ultra-high-performance concrete material according to claim 1, characterized in that, In step (2), the mass ratio of aluminum isopropoxide to silica fume is 0.16~0.23:1; optionally, in step (2), the time for continued stirring is 1~1.5 hours.

7. The method for preparing low-carbon, salt-alkali-resistant, ultra-high-performance concrete material according to claim 1, characterized in that, In step (3), the ratio of the pretreated silica fume to the titanium citrate solution is 1g:3~4mL; Optionally, in step (3), the concentration of the titanium citrate solution is 6.5~8 wt.%; Optionally, in step (3), the calcination treatment is carried out at a temperature of 500~600℃ for 25~35 minutes.

8. The method for preparing low-carbon, salt-alkali resistant, ultra-high performance concrete material according to any one of claims 1-7, characterized in that, In step (4), the proportions of each raw material are as follows: 665-680 parts by weight of silicate cement, 60-75 parts by weight of stabilized steel slag powder, 195-210 parts by weight of modified silica fume, 90-105 parts by weight of fly ash, 1050-1260 parts by weight of fine aggregate, 150-165 parts by weight of copper-plated steel fiber, and 40-50 parts by weight of water-reducing agent. Optionally, in step (4), the mass ratio of the mixing water to the total of silicate cement, stabilized steel slag powder, modified silica fume, and fly ash is 0.2 to 0.

25.

9. The method for preparing low-carbon, salt-alkali-resistant, ultra-high-performance concrete material according to any one of claims 1-7, characterized in that, In step (4), the fine aggregate includes at least one of river sand, quartz sand, and manufactured sand; Optionally, in step (4), the particle size of the fine aggregate is 30-50 mesh; Optionally, in step (4), the copper-plated steel fiber has a length of 10~20mm and a diameter of 0.18~0.21mm.

10. The application of the low-carbon, salt-alkali resistant, ultra-high performance concrete material obtained by the preparation method according to any one of claims 1-9 in the fields of marine, bridge, road or water conservancy engineering.

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