Preparation method of solid waste-based high-performance marine concrete

Abstract

The application discloses a preparation method of solid waste-based high-performance marine concrete, and comprises the following steps: (1) dissolving tetraethyl orthosilicate and sodium stearate into hot anhydrous ethanol, and then adding recycled concrete fine aggregate for sufficient impregnation; after the completion, the obtained fine aggregate is placed in saturated limewater for heating reaction to obtain pretreated recycled fine aggregate; (2) performing carbonization treatment on coal gangue fine aggregate, then impregnating the obtained carbonized coal gangue fine aggregate in a zinc source saturated solution, after the completion, impregnating the carbonized coal gangue fine aggregate in an alkali solution, and then performing heat treatment and washing to obtain modified coal gangue fine aggregate; and (3) taking cement, the pretreated recycled fine aggregate, the modified coal gangue fine aggregate, fly ash, silica fume and fiber as raw materials; after being uniformly mixed, adding water reducing agent and mixing water to obtain solid waste-based concrete material. The above method can effectively alleviate the deterioration problem of recycled concrete aggregate and coal gangue on the mechanical properties of the concrete material.

Description

Technical Field

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

[0002] Marine concrete refers to special concrete used in marine engineering, primarily for the construction of offshore bridges, submarine tunnels, drilling platforms, coastal revetments, and offshore wind farms. Due to the harshness of the marine environment, marine concrete structures must withstand the erosion and impact of sea winds, waves, and seawater. Therefore, marine concrete should possess better strength and resistance to seawater erosion than ordinary concrete. Ultra-high performance concrete (UHPC) is an ultra-high strength cementitious material with high strength, high durability, and low porosity. It is mainly composed of millimeter-sized particles (fine aggregates), micron-sized particles (such as cement, fly ash, and mineral powder), submicron-sized particles (such as silica fume), and fibers, and has a low water-cement ratio. UHPC is more suitable for marine engineering than ordinary concrete.

[0003] Recycled concrete aggregate is formed from the crushing of waste construction concrete. When using this aggregate to prepare concrete, its high water absorption rate, combined with the low water-cement ratio of UHPC (Ultra-High-Hydraulic Polymer), easily leads to insufficient hydration in the later stages of concrete development. This results in insufficient strength development and decreased mechanical properties, limiting the utilization of recycled concrete aggregate, which is often ended up in landfills as construction waste. Coal gangue is a rock composed of organic and inorganic compounds deposited along with coal during coal formation. my country has a huge output of coal gangue, but its utilization rate is low, with over 1 billion tons currently stockpiled. Because marine concrete is exposed to a consistently humid environment, concrete materials made from coal gangue containing organic matter are prone to expansion and pulverization during service, leading to cracking of the concrete structure. Therefore, reducing the degradation of the mechanical properties of materials caused by recycled concrete aggregate and coal gangue aggregate in the preparation of marine concrete is crucial for promoting the utilization of these solid wastes. Summary of the Invention

[0004] This invention provides a method for preparing high-performance marine concrete based on solid waste. The concrete material prepared after processing recycled concrete aggregates and coal gangue exhibits excellent mechanical properties and erosion resistance, effectively mitigating the deterioration of the mechanical properties of concrete materials caused by recycled concrete aggregates and coal gangue. Specifically, the technical solution of this invention is as follows.

[0005] A method for preparing solid waste-based high-performance marine concrete includes the following steps: (1) Dissolve tetraethyl orthosilicate and sodium stearate in hot anhydrous ethanol to form a mixture, and then add recycled concrete fine aggregate to fully impregnate it. After completion, place the obtained fine aggregate in saturated lime water for heating reaction. After completion, separate the fine aggregate and dry it to obtain pretreated recycled fine aggregate.

[0006] (2) Carbonize the fine aggregate of coal gangue, and then immerse the resulting carbonized fine aggregate of coal gangue in a zinc source saturated solution. After completion, immerse the carbonized fine aggregate of coal gangue in an alkaline solution. Then, heat treat the fine aggregate in a protective atmosphere, cool it to room temperature after completion, wash the resulting fine aggregate and dry it to obtain modified fine aggregate of coal gangue.

[0007] (3) Using 120-150 parts by weight of cement, 70-100 parts by weight of the pretreated recycled fine aggregate, 70-85 parts by weight of the modified coal gangue fine aggregate, 20-30 parts by weight of fly ash, 25-40 parts by weight of silica fume, and 32-47 parts by weight of steel fiber as raw materials. After mixing the above raw materials evenly, add water-reducing agent and mixing water, and stir evenly to obtain solid waste-based concrete material.

[0008] Further, in step (1), the volume ratio of tetraethyl orthosilicate to anhydrous ethanol is 2~3:1, and the sodium stearate is saturated in anhydrous ethanol. Optionally, the temperature of the anhydrous ethanol is 50~60℃.

[0009] Further, in step (1), the ratio of the recycled concrete fine aggregate to the mixture is 1g:10~25ml. Optionally, the impregnation time is 45~60min to facilitate the recycled concrete fine aggregate to fully absorb the tetraethyl orthosilicate and sodium stearate.

[0010] Further, in step (1), the ratio of fine aggregate to saturated lime water is 1g:20~40ml.

[0011] Furthermore, in step (1), the temperature of the heating reaction is 40~55℃ and the reaction time is 8~10 hours.

[0012] Further, in step (2), the carbonization treatment is carried out at a temperature of 500~600℃ for a time of 30~50min. Optionally, the carbonization treatment is carried out in a nitrogen or inert atmosphere.

[0013] Further, in step (2), the ratio of the fine aggregate of carbonized coal gangue to the saturated zinc source solution is 1g:10~20ml. Optionally, the zinc source includes at least one of zinc gluconate, zinc sulfate, zinc nitrate, etc.

[0014] Further, in step (2), the material-to-liquid ratio of the carbonized coal gangue fine aggregate to the alkaline solution is 1g:30~40ml. Optionally, the mass fraction of the alkaline solution is 15~25%. The alkaline solution includes at least one of sodium hydroxide solution, potassium hydroxide solution, ammonia water, etc. Furthermore, in step (2), the soaking time is 20-30 minutes to facilitate a full reaction.

[0015] Further, in step (2), the heat treatment temperature is 850~970℃, and the time is 60~70min. Optionally, the protective atmosphere includes any one of nitrogen, inert gas, etc.

[0016] Further, in step (3), the mixing water is added at a water-cement ratio of 0.22 to 0.26. The "ash" includes the cement, fly ash, and silica fume from the above-mentioned raw materials.

[0017] Furthermore, in step (3), the length of the steel fiber is 10~15mm.

[0018] Further, in step (3), the water-reducing agent dosage is 2-3% of the cement mass. Optionally, the water-reducing agent includes any one of polycarboxylate water-reducing agents, naphthalene-based water-reducing agents, etc.

[0019] Furthermore, in step (3), other additives, such as early strength agents and defoamers, may be added to the raw materials as needed.

[0020] Compared with the prior art, the technical solution of the present invention has at least the following beneficial effects: To alleviate the degradation of the mechanical properties of marine concrete caused by recycled concrete aggregates and coal gangue, this invention pre-treats the recycled concrete aggregates and coal gangue aggregates, resulting in a concrete material with both high strength and resistance to chloride ion erosion. For the recycled concrete aggregates, this invention first utilizes their excellent adsorption properties to absorb tetraethyl orthosilicate and sodium stearate, then reacts them with saturated lime water upon heating. The sodium stearate reacts with the saturated lime water to form calcium stearate solid particles and sodium hydroxide. The sodium hydroxide promotes the hydrolysis of tetraethyl orthosilicate to form nano-silica particles that fill the pores of the recycled concrete aggregates. These nano-silica particles further react with calcium hydroxide provided by the saturated lime water to form calcium silicate hydrate (CSH), which densifies the pores of the recycled concrete aggregates, reducing water absorption while increasing strength. Simultaneously, the calcium stearate solid particles and calcium silicate hydrate bind together, giving this calcium silicate hydrate excellent hydrophobicity, further reducing the water absorption of the recycled concrete aggregates. In addition, the calcium stearate also helps to increase the fluidity of the retarded concrete material.

[0021] For coal gangue aggregate, this invention first performs carbonization treatment to convert the unstable organic matter in the coal gangue into stable carbonaceous matter, eliminating the volume instability problem caused by coal gangue. Then, this invention utilizes the good adsorption properties of the carbonaceous matter to load a zinc source onto the coal gangue, and uses an alkaline solution to convert the zinc source into zinc hydroxide. During heat treatment in a protective atmosphere, the zinc hydroxide is pyrolyzed into zinc oxide, and then reduced to elemental zinc under the action of the carbonaceous matter, which is then loaded onto the coal gangue. Simultaneously, this elemental zinc is still in a molten state, and after cooling, it can firmly bond with the coal gangue. Furthermore, the alkaline components in the alkaline solution can also activate the coal gangue during heat treatment, improving its cementitious activity. When using the above-treated coal gangue fine aggregate to prepare concrete materials, not only can the calcium hydroxide produced during cement hydration undergo a hydration reaction to form hydrated calcium silicate, hydrated calcium aluminate, and other cementitious products, improving the mechanical strength of the concrete material. Meanwhile, the carbonaceous material in the coal gangue also adsorbs chloride ions, reducing their diffusion rate, thus better protecting the reinforcing steel in marine concrete structures. Furthermore, when the passivation film on the surface of the reinforcing steel and steel fibers is damaged by chloride ion corrosion, the iron in the reinforcing steel and steel fibers, the zinc loaded on the coal gangue, and the sodium chloride electrolyte provided by seawater form a galvanic cell. The more reactive zinc acts as the negative electrode, and the ruptured passivation film acts as the positive electrode, resulting in an electrochemical reaction (Zn→Zn). 2+ +2e - O2 + H2O + 4e - →4OH - Thus, the OH generated at the positive electrode can be utilized. - This invention repairs damaged passivation films, halting further corrosion of reinforcing bars and steel fibers. This self-healing capability makes concrete materials containing steel fibers and reinforcing bars more suitable for marine engineering applications. Simultaneously, this invention also enables the resource utilization of industrial solid wastes such as recycled concrete aggregates, coal gangue, fly ash, and silica fume. Attached Figure Description

[0022] 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.

[0023] Figure 1 The following is a diagram showing the compressive strength test results for Example 1.

[0024] Figure 2 The following is a graph showing the chloride ion diffusion coefficient test results for Example 1. Detailed Implementation

[0025] 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.

[0026] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as those skilled in the art. The reagents or raw materials used in this invention are readily available through conventional means, and unless otherwise specified, they are used in accordance with conventional methods or product instructions. Furthermore, any methods and materials similar to or equivalent to those described herein can be applied to the methods of this invention. The technical solution of this invention will now be further described in conjunction with the accompanying drawings and specific embodiments.

[0027] Example 1 A method for preparing solid waste-based high-performance marine concrete includes the following steps: (1) Mix tetraethyl orthosilicate with anhydrous ethanol at 50°C at a volume ratio of 2:1, then add excess sodium stearate at the above temperature and stir until it can no longer be dissolved. After filtration, a mixture in which sodium stearate is saturated is obtained.

[0028] (2) The recycled concrete fine aggregate with a particle size distribution between 0.3 and 0.5 mm is mixed with the mixture at a ratio of 1 g: 20 ml and stirred evenly. Then, it is kept at 50°C and left to stand for 60 min. After completion, the obtained fine aggregate is mixed evenly with saturated lime water at a ratio of 1 g: 30 ml and heated to 50°C for 9 hours. After completion, the fine aggregate is filtered out and dried to obtain the pretreated recycled fine aggregate.

[0029] (3) Coal gangue fine aggregate with a particle size distribution between 0.1 and 0.2 mm was heated to 580°C in a nitrogen atmosphere at a heating rate of 10°C / min, and then held at that temperature for 40 min for carbonization treatment. Then, it was cooled to room temperature in the nitrogen atmosphere, and the obtained carbonized coal gangue fine aggregate was mixed evenly with zinc gluconate saturated solution at a ratio of 1 g: 10 ml and allowed to stand for 30 min. After completion, the carbonized coal gangue fine aggregate was filtered out, and it was mixed evenly with 20% sodium hydroxide solution at a ratio of 1 g: 35 ml and allowed to stand for 30 min. Then, the obtained coal gangue fine aggregate was heated to 920°C in a nitrogen atmosphere at a heating rate of 10°C / min, and then held at that temperature for 65 min for heat treatment. After completion, it was cooled to room temperature in the nitrogen atmosphere, and the obtained fine aggregate was washed three times with deionized water and then dried to obtain modified coal gangue fine aggregate.

[0030] (4) Weigh 130 parts by weight of 42.5 ordinary Portland cement, 80 parts by weight of the pretreated recycled fine aggregate of this embodiment, 75 parts by weight of the modified coal gangue fine aggregate of this embodiment, 20 parts by weight of fly ash, 30 parts by weight of silica fume, 40 parts by weight of steel fiber, and polycarboxylate superplasticizer. Wherein: the fly ash has a specific surface area greater than 600 m². 2 / k. The specific surface area of ​​the silica fume is greater than 15000 m². 2 / kg. The steel fiber length is 10mm. The water-reducing agent is 2.6% of the cement mass, and the water reduction rate of the polycarboxylate water-reducing agent is 22%.

[0031] (5) Mix the above raw materials and stir for 5 minutes, then add the water-reducing agent, and add mixing water at a water-cement ratio of 0.25 and stir for 3 minutes to obtain solid waste-based concrete material.

[0032] The solid waste-based concrete material was poured into a mold, and after hardening and shaping, it was demolded and then naturally cured for 28 days. The specimens were then tested for compressive strength (according to standard: GB / T 50081-2019) and Cl-resistance. - Performance (based on standard: GB / T50082-2009) was tested, as follows: Figure 1 , Figure 2 As shown. The test results are as follows: compressive strength = 137.46 MPa, chloride ion diffusion coefficient = 0.91 × 10⁻⁶ MPa. −12 m 2 s −1 .

[0033] Example 2 A method for preparing solid waste-based high-performance marine concrete includes the following steps: (1) Mix tetraethyl orthosilicate with anhydrous ethanol at 60°C at a volume ratio of 2.5:1, then add excess sodium stearate at the above temperature and stir until it can no longer be dissolved. After filtration, a mixture in which sodium stearate is saturated is obtained.

[0034] (2) The recycled concrete fine aggregate with a particle size distribution between 0.3 and 0.5 mm is mixed with the mixture at a ratio of 1 g: 10 ml and stirred evenly. Then, it is kept at 60°C and allowed to stand for 45 minutes. After completion, the obtained fine aggregate is mixed evenly with saturated lime water at a ratio of 1 g: 20 ml and heated to 40°C for 10 hours. After completion, the fine aggregate is filtered out and dried to obtain the pretreated recycled fine aggregate.

[0035] (3) Coal gangue fine aggregate with a particle size distribution between 0.1 and 0.2 mm was heated to 500°C in a nitrogen atmosphere at a heating rate of 10°C / min, and then held at that temperature for 50 min for carbonization treatment. Then, it was cooled to room temperature in the nitrogen atmosphere, and the obtained carbonized coal gangue fine aggregate was mixed evenly with zinc nitrate saturated solution at a ratio of 1 g: 20 ml and allowed to stand for 25 min. After completion, the carbonized coal gangue fine aggregate was filtered out, and it was mixed evenly with 25% potassium hydroxide solution at a ratio of 1 g: 30 ml and allowed to stand for 20 min. Then, the obtained coal gangue fine aggregate was heated to 850°C in a nitrogen atmosphere at a heating rate of 10°C / min, and then held at that temperature for 70 min for heat treatment. After completion, it was cooled to room temperature in the nitrogen atmosphere, and the obtained fine aggregate was washed three times with deionized water and then dried to obtain modified coal gangue fine aggregate.

[0036] (4) Weigh 120 parts by weight of 42.5 ordinary Portland cement, 70 parts by weight of the pretreated recycled fine aggregate of this embodiment, 70 parts by weight of the modified coal gangue fine aggregate of this embodiment, 22 parts by weight of fly ash, 25 parts by weight of silica fume, 32 parts by weight of steel fiber, and polycarboxylate superplasticizer. Wherein: the fly ash has a specific surface area greater than 500 m². 2 / k. The specific surface area of ​​the silica fume is greater than 18000 m². 2 / kg. The steel fiber length is 15mm. The water-reducing agent is 2% of the cement mass. The water reduction rate of the polycarboxylate water-reducing agent is 24%.

[0037] (5) Mix the above raw materials and stir for 5 minutes, then add the water-reducing agent, and add mixing water at a water-cement ratio of 0.22 and stir for 3 minutes to obtain solid waste-based concrete material.

[0038] The solid waste-based concrete material described in this embodiment was prepared into specimens using the same method as in Example 1, and then the 28-day compressive strength and Cl-resistance were tested. - Performance. Test results are as follows: compressive strength = 134.17 MPa, chloride ion diffusion coefficient = 0.83 × 10⁻⁶ −12 m 2 s −1 .

[0039] Example 3 A method for preparing solid waste-based high-performance marine concrete includes the following steps: (1) Mix tetraethyl orthosilicate with anhydrous ethanol at 55°C at a volume ratio of 3:1, then add excess sodium stearate at the above temperature and stir until it can no longer be dissolved. After filtration, a mixture in which sodium stearate is saturated is obtained.

[0040] (2) The recycled concrete fine aggregate with a particle size distribution between 0.3 and 0.5 mm is mixed with the mixture at a ratio of 1 g: 25 ml and stirred evenly. Then, it is kept at 60°C and left to stand for 50 min. After that, the obtained fine aggregate is mixed evenly with saturated lime water at a ratio of 1 g: 40 ml and heated to 55°C for 8 hours. After that, the fine aggregate is filtered out and dried to obtain the pretreated recycled fine aggregate.

[0041] (3) Coal gangue fine aggregate with a particle size distribution between 0.1 and 0.2 mm was heated to 600°C in a nitrogen atmosphere at a heating rate of 10°C / min, and then held at that temperature for 30 min for carbonization treatment. Then, it was cooled to room temperature in the nitrogen atmosphere, and the obtained carbonized coal gangue fine aggregate was mixed evenly with zinc sulfate saturated solution at a ratio of 1 g: 18 ml and allowed to stand for 30 min. After completion, the carbonized coal gangue fine aggregate was filtered out, and it was mixed evenly with 15% ammonia water at a ratio of 1 g: 40 ml and allowed to stand for 30 min. Then, the obtained coal gangue fine aggregate was heated to 970°C in a nitrogen atmosphere at a heating rate of 10°C / min, and then held at that temperature for 60 min for heat treatment. After completion, it was cooled to room temperature in the nitrogen atmosphere, and the obtained fine aggregate was washed three times with deionized water and then dried to obtain modified coal gangue fine aggregate.

[0042] (4) Weigh 150 parts by weight of 42.5 ordinary Portland cement, 100 parts by weight of pretreated recycled fine aggregate of this embodiment, 85 parts by weight of modified coal gangue fine aggregate of this embodiment, 30 parts by weight of fly ash, 40 parts by weight of silica fume, 47 parts by weight of steel fiber, and naphthalene-based water-reducing agent. Wherein: the fly ash has a specific surface area greater than 600 m². 2 / k. The specific surface area of ​​the silica fume is greater than 20000 m². 2 / kg. The steel fiber length is 12mm. The water-reducing agent is 3% of the cement mass. The water reduction rate of the polycarboxylate water-reducing agent is 22%.

[0043] (5) Mix the above raw materials and stir for 6 minutes, then add the water-reducing agent, and add mixing water at a water-cement ratio of 0.26 and stir for 3 minutes to obtain solid waste-based concrete material.

[0044] The solid waste-based concrete material described in this embodiment was prepared into specimens using the same method as in Example 1, and then the 28-day compressive strength and Cl-resistance were tested. - Performance. Test results are as follows: compressive strength = 129.73 MPa, chloride ion diffusion coefficient = 1.14 × 10⁻⁶ −12 m 2 s −1 .

[0045] Example 4 A method for preparing solid waste-based high-performance marine concrete includes the following steps: (1) Weigh 130 parts by weight of 42.5 ordinary Portland cement, 80 parts by weight of recycled concrete fine aggregate, 75 parts by weight of modified coal gangue fine aggregate prepared in Example 1 above, 20 parts by weight of fly ash, 30 parts by weight of silica fume, 40 parts by weight of steel fiber, and polycarboxylate superplasticizer. The particle size distribution of the recycled concrete fine aggregate is between 0.3 and 0.5 mm. The fly ash has a specific surface area greater than 600 m². 2 / k. The specific surface area of ​​the silica fume is greater than 15000 m². 2 / kg. The steel fiber length is 10mm. The water-reducing agent accounts for 2.6% of the cement mass. The water reduction rate of the polycarboxylate water-reducing agent is 22%.

[0046] (2) Mix the above raw materials and stir for 5 minutes, then add the water-reducing agent, and add mixing water at a water-cement ratio of 0.25 and stir for 3 minutes to obtain solid waste-based concrete material.

[0047] The solid waste-based concrete material described in this embodiment was prepared into specimens using the same method as in Example 1, and then the 28-day compressive strength and Cl-resistance were tested. - Performance. Test results are as follows: compressive strength = 116.24 MPa, chloride ion diffusion coefficient = 4.08 × 10⁻⁶ −12 m 2 s −1 .

[0048] Example 5 A method for preparing high-performance marine concrete based on solid waste, compared with Example 3 above, involves the following steps for preparing modified coal gangue fine aggregate: Coal gangue fine aggregate with a particle size distribution between 0.1 and 0.2 mm is heated to 600°C in a nitrogen atmosphere at a heating rate of 10°C / min, and then held at that temperature for 30 min for carbonization treatment. Then, it is cooled to room temperature in the same nitrogen atmosphere, and the resulting carbonized coal gangue fine aggregate is mixed evenly with saturated zinc sulfate solution at a ratio of 1 g: 18 ml, and allowed to stand for 30 min. After completion, the carbonized coal gangue fine aggregate is filtered out and the moisture is drained. It is then heated to 970°C in a nitrogen atmosphere at a heating rate of 10°C / min, and then held at that temperature for 60 min for heat treatment. After completion, it is cooled to room temperature in the same nitrogen atmosphere, and the resulting fine aggregate is washed three times with deionized water and then dried to obtain the modified coal gangue fine aggregate.

[0049] The solid waste-based concrete material described in this embodiment was prepared into specimens using the same method as in Example 1, and then the 28-day compressive strength and Cl-resistance were tested. - Performance. Test results are as follows: compressive strength = 122.06 MPa, chloride ion diffusion coefficient = 4.82 × 10⁻⁶ MPa.−12 m 2 s −1 .

[0050] Example 6 A method for preparing high-performance marine concrete based on solid waste, compared with Example 2 above, involves the following steps for preparing recycled fine aggregate: Tetraethyl orthosilicate and anhydrous ethanol at 60°C are mixed at a volume ratio of 2.5:1. Then, recycled concrete fine aggregate with a particle size distribution between 0.3 and 0.5 mm is mixed with the mixture at a ratio of 1 g:10 ml and stirred until homogeneous. The mixture is then allowed to stand at 60°C for 45 minutes. After this process, the resulting fine aggregate is mixed with saturated lime water at a ratio of 1 g:20 ml and heated to 40°C for 10 hours. Finally, the fine aggregate is filtered out and dried to obtain pretreated recycled fine aggregate.

[0051] The solid waste-based concrete material described in this embodiment was prepared into specimens using the same method as in Example 1, and then the 28-day compressive strength and Cl-resistance were tested. - Performance. Test results are as follows: compressive strength = 125.53 MPa, chloride ion diffusion coefficient = 2.79 × 10⁻⁶ −12 m 2 s −1 .

[0052] Example 7 A method for preparing high-performance marine concrete based on solid waste, compared with Example 2 above, involves the following steps for preparing modified coal gangue fine aggregate: Coal gangue fine aggregate with a particle size distribution between 0.1 and 0.2 mm is mixed evenly with saturated zinc nitrate solution at a ratio of 1 g: 20 ml, and then allowed to stand for 25 min. After completion, the coal gangue fine aggregate is filtered out, and then mixed evenly with a 25% potassium hydroxide solution at a ratio of 1 g: 30 ml, and allowed to stand for 20 min. The obtained coal gangue fine aggregate is then heated to 850°C in a nitrogen atmosphere at a heating rate of 10°C / min, and then held at that temperature for 70 min for heat treatment. After completion, it is cooled to room temperature in the nitrogen atmosphere, and the obtained fine aggregate is washed three times with deionized water and then dried to obtain the modified coal gangue fine aggregate.

[0053] The solid waste-based concrete material described in this embodiment was prepared into specimens using the same method as in Example 1, and then the 28-day compressive strength and Cl-resistance were tested. - Performance. Test results are as follows: compressive strength = 127.32 MPa, chloride ion diffusion coefficient = 2.46 × 10⁻⁶ −12 m 2 s −1 .

[0054] Example 8 A method for preparing high-performance marine concrete based on solid waste, compared with Example 1 above, wherein the recycled fine aggregate in this example is prepared using the following steps: (1) Mix tetraethyl orthosilicate with anhydrous ethanol at 50°C at a volume ratio of 2:1, then add excess sodium stearate at the above temperature and stir until it can no longer be dissolved. After filtration, a mixture in which sodium stearate is saturated is obtained.

[0055] (2) The recycled concrete fine aggregate with a particle size distribution between 0.3 and 0.5 mm is mixed with the mixture at a ratio of 1 g: 20 ml and stirred evenly. Then, it is kept at 50°C and left to stand for 60 min. After completion, the fine aggregate is filtered out and dried to obtain the pretreated recycled fine aggregate.

[0056] The solid waste-based concrete material described in this embodiment was prepared into specimens using the same method as in Example 1, and then the 28-day compressive strength and Cl-resistance were tested. - Performance. Test results are as follows: compressive strength = 121.63 MPa, chloride ion diffusion coefficient = 3.57 × 10⁻⁶ −12 m 2 s −1 .

[0057] Example 9 A method for preparing solid waste-based high-performance marine concrete includes the following steps: (1) Weigh 150 parts by weight of 42.5 ordinary Portland cement, 100 parts by weight of the pretreated recycled fine aggregate prepared in Example 3 above, 85 parts by weight of coal gangue fine aggregate, 30 parts by weight of fly ash, 40 parts by weight of silica fume, 47 parts by weight of fiber, and naphthalene-based water-reducing agent. Wherein: the particle size distribution of the coal gangue fine aggregate is between 0.1 and 0.2 mm. The specific surface area of ​​the fly ash is greater than 600 m². 2 / k. The specific surface area of ​​the silica fume is greater than 20000 m². 2 / kg. The steel fiber length is 12mm. The water-reducing agent is 3% of the cement mass. The water reduction rate of the polycarboxylate water-reducing agent is 22%.

[0058] (2) Mix the above raw materials and stir for 6 minutes, then add the water-reducing agent, and add mixing water at a water-cement ratio of 0.26 and stir for 3 minutes to obtain solid waste-based concrete material.

[0059] The solid waste-based concrete material described in this embodiment was prepared into specimens using the same method as in Example 1, and then the 28-day compressive strength and Cl-resistance were tested. - Performance. Test results are as follows: compressive strength = 108.92 MPa, chloride ion diffusion coefficient = 6.11 × 10⁻⁶. −12 m2 s −1 .

[0060] 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 solid waste-based high-performance marine concrete, characterized in that, Includes the following steps: (1) Dissolve tetraethyl orthosilicate and sodium stearate in hot anhydrous ethanol to form a mixture, and then add recycled concrete fine aggregate to fully impregnate it; after completion, place the obtained fine aggregate in saturated lime water for heating reaction, and after completion, separate the fine aggregate and dry it to obtain pretreated recycled fine aggregate; (2) Carbonize the fine aggregate of coal gangue at 500~600℃ for 30~50min in nitrogen or inert atmosphere, and then immerse the carbonized fine aggregate of coal gangue in zinc source saturated solution. After completion, the carbonized coal gangue fine aggregate is immersed in an alkaline solution; then the fine aggregate is heat-treated at 850~970℃ for 60~70min in a protective atmosphere, and after completion, it is cooled to room temperature. The obtained fine aggregate is washed and dried to obtain modified coal gangue fine aggregate; the zinc source includes at least one of zinc gluconate, zinc sulfate, and zinc nitrate. (3) Using 120-150 parts by weight of cement, 70-100 parts by weight of the pretreated recycled fine aggregate, 70-85 parts by weight of the modified coal gangue fine aggregate, 20-30 parts by weight of fly ash, 25-40 parts by weight of silica fume, and 32-47 parts by weight of steel fiber as raw materials; after mixing the above raw materials evenly, add water-reducing agent and mixing water, and stir evenly to obtain solid waste-based concrete material.

2. The method for preparing solid waste-based high-performance marine concrete according to claim 1, characterized in that, In step (1), the volume ratio of tetraethyl orthosilicate to anhydrous ethanol is 2~3:1, and the sodium stearate is saturated in anhydrous ethanol.

3. The method for preparing solid waste-based high-performance marine concrete according to claim 1, characterized in that, In step (1), the temperature of the anhydrous ethanol is 50~60℃.

4. The method for preparing solid waste-based high-performance marine concrete according to claim 1, characterized in that, In step (1), the ratio of the recycled concrete fine aggregate to the mixture is 1g:10~25ml.

5. The method for preparing solid waste-based high-performance marine concrete according to claim 1, characterized in that, In step (1), the soaking time is 45~60 min.

6. The method for preparing solid waste-based high-performance marine concrete according to claim 1, characterized in that, In step (1), the ratio of fine aggregate to saturated lime water is 1g:20~40ml.

7. The method for preparing solid waste-based high-performance marine concrete according to claim 1, characterized in that, In step (1), the temperature of the heating reaction is 40~55℃ and the reaction time is 8~10 hours.

8. The method for preparing solid waste-based high-performance marine concrete according to claim 1, characterized in that, In step (2), the ratio of the fine aggregate of carbonized coal gangue to the zinc source saturated liquid is 1g:10~20ml.

9. The method for preparing solid waste-based high-performance marine concrete according to claim 1, characterized in that, In step (2), the ratio of the fine aggregate of carbonized coal gangue to the alkaline solution is 1g:30~40ml.

10. The method for preparing solid waste-based high-performance marine concrete according to claim 1, characterized in that, In step (2), the mass fraction of the alkaline solution is 15-25%.

11. The method for preparing solid waste-based high-performance marine concrete according to claim 1, characterized in that, In step (2), the alkaline solution includes at least one of sodium hydroxide solution, potassium hydroxide solution, and ammonia water.

12. The method for preparing solid waste-based high-performance marine concrete according to claim 1, characterized in that, In step (2), the protective atmosphere includes any one of nitrogen or an inert gas.

13. The method for preparing solid waste-based high-performance marine concrete according to claim 1, characterized in that, In step (2), the soaking time is 20-30 minutes.

14. The method for preparing solid waste-based high-performance marine concrete according to any one of claims 1-13, characterized in that, In step (3), the mixing water is added at a water-cement ratio of 0.22 to 0.

26.

15. The method for preparing solid waste-based high-performance marine concrete according to any one of claims 1-13, characterized in that, In step (3), the length of the steel fiber is 10~15mm.

16. The method for preparing solid waste-based high-performance marine concrete according to any one of claims 1-13, characterized in that, In step (3), the water-reducing agent dosage is 2-3% of the cement mass.

17. The method for preparing solid waste-based high-performance marine concrete according to any one of claims 1-13, characterized in that, The water-reducing agent includes any one of polycarboxylate water-reducing agents and naphthalene-based water-reducing agents.

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