A method for preparing a modified reinforced recycled aggregate high-strength hydrophobic cement-based material

Abstract

The present invention discloses a method for preparing a modified and reinforced recycled aggregate high-strength hydrophobic cement-based material, comprising the following steps: (1) placing recycled concrete coarse aggregate in an acrylic acid solution and allowing it to stand, separating the coarse aggregate after completion, and coating it in a modified slurry formed by calcined waste concrete fine powder, a silane coupling agent, and water, then separating the coarse aggregate and drying it to obtain a modified and reinforced recycled aggregate. (2) mixing cement powder, the modified and reinforced recycled aggregate, river sand fine aggregate, filler powder, and a water reducer, adding water and stirring evenly to obtain a marine cement-based material. The present invention uses concrete waste generated by a commercial concrete mixing station to modify and reinforce recycled concrete aggregate, and constructs a hydrophobic and anti-seepage system in the concrete material, effectively improving the strength and anti-seepage performance of the concrete material, making it more suitable for use in marine environments.

Description

Technical Field

[0001] The present invention relates to the technical field of preparation of marine engineering cement-based materials, and in particular to a method for preparing a modified reinforced recycled aggregate high-strength hydrophobic cement-based material. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance understanding of the overall background of the invention and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to those skilled in the art.

[0003] With the continuous advancement of urbanization in my country, a large number of activities such as the demolition and relocation of existing buildings and the construction of new buildings have generated a large amount of construction waste. According to statistics, concrete waste accounts for nearly 50% of this construction waste, and waste bricks and stones account for nearly 40%. Most of this is treated as solid waste landfill or transported to on-site storage, which not only occupies a large amount of arable land but also causes environmental pollution. How to utilize these construction wastes as resources has become a long-term problem facing my country. At present, the concrete waste in construction waste is crushed into particles, and then recycled concrete aggregate is obtained after cleaning, grading and other processes. Using this aggregate to partially or completely replace natural sand and gravel aggregate to prepare concrete materials is a widely studied utilization method.

[0004] However, due to the harsh environment of long-term seawater erosion and scouring, marine cement-based materials made from recycled concrete aggregates suffer from insufficient mechanical properties and water seepage resistance. This is primarily due to the higher porosity of recycled concrete aggregates compared to natural sand and gravel aggregates and the presence of numerous microcracks caused by crushing. Consequently, the strength of recycled concrete aggregates is generally lower than that of natural sand and gravel aggregates. Furthermore, the high water absorption of recycled concrete aggregates can lead to insufficient hydration of the concrete material later in the process, resulting in insufficient strength development. Furthermore, the high porosity of recycled concrete aggregates provides more channels for water to penetrate, resulting in insufficient water seepage resistance in concrete structures. Furthermore, according to statistics, my country pours 1.5 to 2 billion cubic meters of concrete annually, the majority of which is produced by commercial concrete mixing plants. This results in a large amount of waste slurry from cleaning concrete mixing equipment at commercial concrete mixing plants. This waste, after sedimentation, generates a large amount of concrete waste, and its disposal poses a major challenge for commercial concrete mixing plants. Summary of the Invention

[0005] To address these issues, the present invention modifies and strengthens recycled concrete aggregate using concrete waste from commercial concrete mixing plants. Furthermore, a hydrophobic and anti-seepage system is constructed within the concrete, effectively improving the concrete's strength and water resistance, making it more suitable for use in marine environments. Specifically, the technical solution of the present invention is as follows.

[0006] A method for preparing a modified and reinforced recycled aggregate high-strength hydrophobic cement-based material comprises the following steps:

[0007] (1) After the waste concrete material slurry is precipitated, the supernatant is removed, and the sediment at the bottom is filtered to remove the aggregate. The resulting slurry is then dried, ground, and calcined to obtain waste concrete fine powder for later use.

[0008] (2) The recycled concrete coarse aggregate is placed in an acrylic acid solution and allowed to stand. After completion, the coarse aggregate is separated and placed in a modified slurry formed by the waste concrete fine powder, a silane coupling agent, and water for coating. The coarse aggregate is then separated and dried to obtain modified reinforced recycled aggregate for later use.

[0009] (3) Cement powder, the modified reinforced recycled aggregate, river sand fine aggregate, filler powder, and water reducer are mixed and then water is added and stirred evenly to obtain a marine cement-based material.

[0010] Furthermore, in step (1), the calcination temperature is 600-680°C and the calcination time is 40-50 minutes to dehydrate the cement hydration products in the powder. Optionally, the fineness of the waste concrete powder is not less than 180 mesh, such as 180 mesh, 200 mesh, 300 mesh, etc.

[0011] Furthermore, in step (2), the mass fraction of the acrylic acid solution is 14-20%. Optionally, the particle size of the recycled concrete coarse aggregate is 8-15 mm. The recycled concrete coarse aggregate can be completely immersed in the acrylic acid solution.

[0012] Furthermore, in step (2), the standing time is 20 to 40 minutes, so that the acrylic acid solution can fully penetrate into the coarse aggregate.

[0013] Furthermore, in step (2), the ratio of the coarse aggregate to the modified slurry is 1 g: 10-25 ml.

[0014] Furthermore, in step (2), the ratio of the waste concrete powder, silane coupling agent, and water is 19-26 g: 0.3-0.7 g: 100-105 g. Optionally, the silane coupling agent includes at least one of KH550, KH560, KH570, etc.

[0015] Furthermore, in step (2), the drying method is: first keep the temperature at 30-35°C for 5-10 minutes, then raise the temperature to 60-75°C and keep it warm for 15-20 minutes.

[0016] Furthermore, in step (3), the weight ratios of the cement powder, modified reinforced recycled aggregate, river sand fine aggregate, filler powder, water reducer, and water are: 80-96 weight parts: 170-220 weight parts: 115-140 weight parts: 12-17 weight parts: 1.4-2.0 weight parts: 28-36 weight parts.

[0017] Furthermore, in step (3), the filler powder includes at least one of slag powder, calcium carbonate powder, shell powder, mica powder, fly ash, etc. Optionally, the fineness of the filler is 300-400 mesh.

[0018] Furthermore, in step (3), the marine cement-based material further comprises 3 to 6.5% by weight of a slow-release hydrophobic agent, which is prepared by the following method:

[0019] (I) Mixing γ-type dicalcium silicate (γ-C2S) powder, aluminum hydroxide (Al(OH)3) powder and water to form a coating slurry for later use.

[0020] (II) Particles obtained by crushing discarded red bricks are placed in anhydrous ethanol saturated with a hydrophobic agent and allowed to stand. After completion, the particles are separated and coated in the coating slurry. The separated particles are then carbonized in a carbon dioxide atmosphere and dried to obtain the sustained-release hydrophobic agent.

[0021] Furthermore, in step (I), the coating slurry has a solid content of 20-28%. The mass ratio of the γ-C2S powder to the Al(OH)3 powder is 4-7:1-2. Optionally, the γ-C2S powder has a fineness of 420-550 mesh, and the Al(OH)3 powder has a fineness of 200-300 mesh.

[0022] Furthermore, in step (II), the particle size of the microparticles is 0.3-0.5 mm.

[0023] Furthermore, in step (II), the ratio of the microparticles to anhydrous ethanol containing a saturated hydrophobic agent is 1 g: 5-15 ml. Optionally, the hydrophobic agent includes at least one of tridecafluorooctyltriethoxysilane, heptadecafluorodecyltriethoxysilane, n-octyltriethoxysilane, and hexamethyldisilazane.

[0024] Furthermore, in step (II), the ratio of the microparticles to the coating slurry is 1 g: 5-12 ml.

[0025] Furthermore, in step (II), the carbonization treatment time is 2 to 3 hours.

[0026] Furthermore, in step (II), the drying temperature is 40-60° C., and the drying time is 30-45 minutes.

[0027] Compared with the prior art, the present invention has at least the following beneficial technical effects:

[0028] (1) The modified and reinforced recycled aggregate of the present invention effectively improves the mechanical properties of the prepared marine cement-based material. This is because: on the one hand, the modified slurry can fill the pores on the surface of the coarse aggregate, and on the other hand, the acrylic acid in the coarse aggregate can also play a role in blocking the pores after being polymerized into a three-dimensional structure during the subsequent heating and drying process. At the same time, the silane coupling agent helps the coating layer and the acrylic acid molecules in the coarse aggregate to combine. These acrylic acid molecules can effectively increase the bonding force between the coating layer and the coarse aggregate after being subsequently polymerized into a three-dimensional structure. In addition, the polymerized three-dimensional structure formed by the acrylic acid entering the coating layer can play a role in reinforcing and densifying the coating layer, thereby effectively reducing the porosity of the coarse aggregate, improving the strength, and also helping to improve the water permeability. On the other hand, after the waste concrete powder in the coating layer is calcined, the cement hydration products therein are dehydrated, so that after the modified and reinforced recycled aggregate prepared by the present invention enters the concrete material, the dehydrated hydration products can be hydrated again to form a cementitious component, thereby improving the bonding force between the coarse aggregate and the concrete matrix, thereby further improving the mechanical properties of the marine cement-based material prepared by the present invention.

[0029] (2) For cement-based materials that need to serve in marine environments, they also need to have good water resistance to prevent chloride ions in seawater from corroding steel bars in concrete structures. To this end, a slow-release hydrophobic agent is added to the marine cement-based material of the present invention, which can not only effectively improve the water resistance of the cement-based material, but also help prevent the strength reduction caused by the influence of the hydrophobic agent on cement hydration. To this end, the present invention first uses the microparticles obtained by crushing discarded red bricks as a hydrophobic agent carrier, and then uses carbon dioxide to carbonize the surface of the microparticles after coating the surface with a coating layer formed by γ-C2S and Al(OH)3. The carbon dioxide enters the coating layer and acts together with the moisture it provides to promote the carbonization reaction of the γ-C2S. The nano-silica gel formed by the carbonization reaction densifies the coating layer and is more firmly fixed on the hydrophobic agent carrier. After the slow-release hydrophobic agent of the present invention enters the cement-based material, the hydrophobic agent will not enter the cement-based material under the isolation of the coating layer in the early stage of cement hydration, thereby preventing the hydrophobic agent molecules from coating the surface of the cement particles and affecting their hydration reaction. As the hydration reaction proceeds, the Al(OH)3 gradually dissolves under the action of the hydroxide ions produced by hydration, thereby converting the coating layer into a porous structure. The hydrophobic agent therein is gradually released outward to form a hydrophobic system, which gives the cement-based material prepared by the present invention excellent water permeability. In addition, the nano-silica particles in the coating layer can also undergo a rehydration reaction with the calcium hydroxide produced by the cement hydration reaction to form a calcium silicate hydrate cementitious component, which helps to improve the mechanical strength of the cement-based material. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings, which constitute part of the present invention, are provided to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are provided to explain the present invention and do not constitute undue limitations thereon. The embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein:

[0031] Figure 1 This is a compressive strength test diagram of the following Example 1.

[0032] Figure 2 This is a test diagram of the anti-water seepage performance of the following Example 1.

[0033] Figure 3 This is a compressive strength test diagram of the following Example 2.

[0034] Figure 4 This is a compressive strength test diagram of the following Example 3. DETAILED DESCRIPTION

[0035] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are intended to illustrate the present invention only and are not intended to limit the scope of the invention. The experimental methods in the following examples, for which specific conditions are not specified, are generally performed under conventional conditions or as recommended by the manufacturer.

[0036] Unless otherwise defined, all professional and scientific terms used herein have the same meaning as those familiar to those skilled in the art. The reagents or raw materials used in the present invention can be purchased through conventional channels. Unless otherwise specified, the reagents or raw materials used in the present invention are used in a conventional manner in the art or in accordance with the product specifications. The preparation method of the modified reinforced recycled aggregate high-strength hydrophobic cement-based material of the present invention is now further described in conjunction with the accompanying drawings and specific embodiments.

[0037] Example 1

[0038] A method for preparing a modified and reinforced recycled aggregate high-strength hydrophobic cement-based material comprises the following steps:

[0039] 1. Preparation of modified and reinforced recycled aggregate:

[0040] (1) After the waste slurry generated by the concrete mixing equipment of the commercial concrete mixing station is settled, the supernatant is poured out, and the sediment at the bottom is filtered to remove the coarse and fine aggregates. The obtained slurry is then dried and ground. After passing through a 200-mesh sieve, the obtained powder is heated to 650℃ and kept warm for 45 minutes. After completion, it is cooled to room temperature to obtain waste concrete fine powder for standby use.

[0041] (2) Recycled concrete coarse aggregate with a particle size distribution of 8 to 10 mm was placed in a 15 wt.% acrylic acid solution, stirred evenly, and allowed to stand for 30 minutes. After completion, the coarse aggregate was filtered out and placed in a modified slurry formed by the waste concrete fine powder, silane coupling agent (KH550), and water in a mass ratio of 23:0.5:100. The ratio of the coarse aggregate to the modified slurry was 1 g:20 ml. After stirring evenly, the coarse aggregate was filtered out and placed in an oven at 35°C for 7 minutes, then heated to 70°C for 15 minutes to obtain modified reinforced recycled aggregate for later use.

[0042] 2. Preparation of sustained-release hydrophobic agent:

[0043] (I) 450-mesh γ-C2S powder and 250-mesh Al(OH)3 powder were mixed with water and stirred rapidly to obtain a coating slurry with a solid content of 28%, wherein the mass ratio of γ-C2S to Al(OH)3 was 6:2.

[0044] (II) Crushing and sieving discarded red bricks, placing particles with a particle size of 0.3-0.5 mm in anhydrous ethanol dissolved in saturated tridecafluorooctyltriethoxysilane at a ratio of 1 g:10 ml. After standing for 25 minutes, the particles were filtered out and mixed with the coating slurry at a ratio of 1 g:8 ml. The mixture was stirred to uniformly coat the particles. The particles were then removed and placed in a carbon dioxide atmosphere for 2 hours for carbonization. After completion, they were dried in an oven at 40°C for 45 minutes to obtain a sustained-release hydrophobic agent for future use.

[0045] 3. Prepare the following raw materials: 90 parts by weight of cement powder (PO 42.5), 200 parts by weight of the modified and reinforced recycled aggregate, 130 parts by weight of river sand fine aggregate with a particle size of 0.5-0.7 mm, 14 parts by weight of 400-mesh shell powder, 1.6 parts by weight of a polycarboxylate superplasticizer, and 4.5 parts by weight of the slow-release hydrophobic agent. Mix and stir these ingredients until uniformly distributed. Then, add 32 parts by weight of clean water and stir until uniformly distributed. This will yield the marine cement-based material.

[0046] Performance test: (1) The compressive strength of the specimens (aged 28 days) made of the marine cement-based material of this embodiment was tested according to the "Standard for Test Methods of Physical and Mechanical Properties of Concrete" (GBT 50081-2019). Figure 1 (2) According to the "Standard for Test Methods of Long-term Performance and Durability of Concrete" (GB / T 50082-2024), the test piece made of the marine cement-based material of this embodiment is subjected to a water penetration resistance test (as shown in FIG. Figure 2 The test results are as follows: compressive strength = 50.14 MPa, water seepage height = 7.6 mm.

[0047] Example 2

[0048] A method for preparing a modified and reinforced recycled aggregate high-strength hydrophobic cement-based material comprises the following steps:

[0049] 1. Preparation of modified and reinforced recycled aggregate:

[0050] (1) After the waste slurry generated by the concrete mixing equipment of the commercial concrete mixing station is settled, the supernatant is poured out, and the sediment at the bottom is filtered to remove the coarse and fine aggregates. The obtained slurry is then dried and ground. After passing through a 300-mesh sieve, the obtained powder is heated to 600°C and kept warm for 50 minutes. After completion, it is cooled to room temperature to obtain waste concrete fine powder for standby use.

[0051] (2) Recycled concrete coarse aggregate with a particle size distribution of 12-15 mm was placed in a 20 wt.% acrylic acid solution, stirred evenly, and allowed to stand for 20 minutes. After completion, the coarse aggregate was filtered out and placed in a modified slurry formed by the waste concrete fine powder, silane coupling agent (KH570), and water in a mass ratio of 19:0.3:102, with the ratio of the coarse aggregate to the modified slurry being 1 g:25 ml. After stirring evenly, the coarse aggregate was filtered out and placed in an oven at 30°C for 10 minutes, then heated to 60°C for 20 minutes to obtain modified reinforced recycled aggregate for later use.

[0052] 2. Preparation of sustained-release hydrophobic agent:

[0053] (I) 420-mesh γ-C2S powder and 300-mesh Al(OH)3 powder were mixed with water and stirred rapidly to obtain a coating slurry with a solid content of 20%, wherein the mass ratio of γ-C2S to Al(OH)3 was 4:1.

[0054] (II) Crushing and sieving discarded red bricks, placing particles with a particle size of 0.3-0.5 mm in anhydrous ethanol dissolved in saturated n-octyltriethoxysilane at a ratio of 1 g:15 ml. After standing for 10 minutes, the particles were filtered out and mixed with the coating slurry at a ratio of 1 g:5 ml. The mixture was stirred to uniformly coat the particles. The particles were then removed and placed in a carbon dioxide atmosphere for 3 hours for carbonization. After completion, they were dried in an oven at 60°C for 30 minutes to obtain a sustained-release hydrophobic agent for future use.

[0055] 3. Prepare the following raw materials: 80 parts by weight of cement powder (PO 42.5), 170 parts by weight of the modified and reinforced recycled aggregate, 115 parts by weight of river sand fine aggregate with a particle size of 0.4-0.6 mm, 12 parts by weight of 300-mesh slag powder, 1.4 parts by weight of a polycarboxylate superplasticizer, and 5.2 parts by weight of the slow-release hydrophobic agent. Mix and stir these ingredients until uniformly distributed. Then, add 28 parts by weight of clean water and stir until uniformly distributed. This will produce the marine cement-based material.

[0056] Performance test: (1) The compressive strength of the specimens (aged 28 days) made of the marine cement-based material of this embodiment was tested according to the "Standard for Test Methods of Physical and Mechanical Properties of Concrete" (GBT 50081-2019). Figure 3 (2) According to the "Standard for Test Methods for Long-term Performance and Durability of Concrete" (GB / T 50082-2024), the test specimens made of the marine cement-based material of this embodiment were subjected to a water penetration test. The test results were: compressive strength = 47.33 MPa, water penetration height = 5.4 mm.

[0057] Example 3

[0058] A method for preparing a modified and reinforced recycled aggregate high-strength hydrophobic cement-based material comprises the following steps:

[0059] 1. Preparation of modified and reinforced recycled aggregate:

[0060] (1) After the waste slurry generated by the concrete mixing equipment of the commercial concrete mixing station is settled, the supernatant is poured out, and the sediment at the bottom is filtered to remove the coarse and fine aggregates. The obtained slurry is then dried and ground. After passing through a 180-mesh sieve, the obtained powder is heated to 680°C and kept warm for 40 minutes. After completion, it is cooled to room temperature to obtain waste concrete fine powder for standby use.

[0061] (2) Recycled concrete coarse aggregate with a particle size distribution of 9 to 13 mm was placed in a 14 wt.% acrylic acid solution, stirred evenly, and then allowed to stand for 40 minutes. After completion, the coarse aggregate was filtered out and placed in a modified slurry formed by the waste concrete fine powder, silane coupling agent (KH560), and water in a mass ratio of 26:0.7:105, with the ratio of the coarse aggregate to the modified slurry being 1 g:10 ml. After stirring evenly, the coarse aggregate was filtered out and placed in an oven at 35°C for 5 minutes, then heated to 75°C for 15 minutes to obtain modified reinforced recycled aggregate for later use.

[0062] 2. Preparation of sustained-release hydrophobic agent:

[0063] (I) 550-mesh γ-C2S powder and 200-mesh Al(OH)3 powder were mixed with water and stirred rapidly to obtain a coating slurry with a solid content of 24%, wherein the mass ratio of γ-C2S to Al(OH)3 was 7:1.

[0064] (II) Crushing and sieving discarded red bricks, placing particles with a particle size of 0.3-0.5 mm in anhydrous ethanol dissolved in saturated hexamethyldisilazane at a ratio of 1 g:5 ml. After standing for 20 minutes, the particles were filtered out and mixed with the coating slurry at a ratio of 1 g:12 ml. The mixture was stirred to uniformly coat the particles. The particles were then removed and placed in a carbon dioxide atmosphere for 3 hours for carbonization. After completion, they were dried in an oven at 45°C for 40 minutes to obtain a sustained-release hydrophobic agent for future use.

[0065] 3. Prepare the following raw materials: 96 parts by weight of cement powder (PO 42.5), 220 parts by weight of the modified and reinforced recycled aggregate, 140 parts by weight of river sand fine aggregate with a particle size of 0.5-0.8 mm, 17 parts by weight of 300-mesh mica powder, 2 parts by weight of a polycarboxylate superplasticizer, and 2.9 parts by weight of the slow-release hydrophobic agent. Mix and stir these ingredients until uniformly distributed. Then, add 36 parts by weight of clean water and stir until uniformly distributed. This will yield the marine cement-based material.

[0066] Performance test: (1) The compressive strength of the specimens (aged 28 days) made of the marine cement-based material of this embodiment was tested according to the "Standard for Test Methods of Physical and Mechanical Properties of Concrete" (GBT 50081-2019). Figure 4 (2) According to the "Standard for Test Methods for Long-term Performance and Durability of Concrete" (GB / T 50082-2024), the test specimens made of the marine cement-based material of this embodiment were subjected to a water penetration test. The test results were: compressive strength = 51.75 MPa, water penetration height = 11.2 mm.

[0067] Example 4

[0068] A method for preparing a modified and reinforced recycled aggregate high-strength hydrophobic cement-based material comprises the following steps:

[0069] (1) Take the following raw materials: 90 parts by weight of cement powder (PO 42.5), 200 parts by weight of the modified reinforced recycled aggregate prepared in Example 1, 130 parts by weight of river sand fine aggregate with a particle size of 0.5-0.7 mm, 14 parts by weight of 400-mesh shell powder, and 1.6 parts by weight of polycarboxylate water reducer.

[0070] (2) The above raw materials are mixed and stirred evenly, and then 32 parts by weight of clean water are added and stirred evenly to obtain a marine cement-based material.

[0071] Performance tests: (1) The compressive strength of the specimens (aged 28 days) made of the marine cement-based material of this embodiment was tested in accordance with the "Standard for Test Methods for Physical and Mechanical Properties of Concrete" (GBT 50081-2019). (2) The water penetration resistance test of the specimens made of the marine cement-based material of this embodiment was conducted in accordance with the "Standard for Test Methods for Long-term Performance and Durability of Concrete" (GB / T 50082-2024). The test results were: compressive strength = 51.09 MPa, water penetration height = 34.7 mm.

[0072] Example 5

[0073] A method for preparing a modified and reinforced recycled aggregate high-strength hydrophobic cement-based material comprises the following steps:

[0074] (1) Take the following raw materials: 90 parts by weight of cement powder (PO 42.5), 200 parts by weight of recycled concrete coarse aggregate with a particle size distribution of 8-10 mm, 130 parts by weight of river sand fine aggregate with a particle size of 0.5-0.7 mm, 14 parts by weight of 400-mesh shell powder, 1.6 parts by weight of polycarboxylate water reducer, and 4.5 parts by weight of the slow-release hydrophobic agent described in Example 1.

[0075] (2) The above raw materials are mixed and stirred evenly, and then 32 parts by weight of clean water are added and stirred evenly to obtain a marine cement-based material.

[0076] Performance tests: (1) The compressive strength of the specimens (aged 28 days) made of the marine cement-based material of this embodiment was tested in accordance with the "Standard for Test Methods for Physical and Mechanical Properties of Concrete" (GBT 50081-2019). (2) The water penetration resistance test of the specimens made of the marine cement-based material of this embodiment was conducted in accordance with the "Standard for Test Methods for Long-term Performance and Durability of Concrete" (GB / T 50082-2024). The test results were: compressive strength = 38.62 MPa, water penetration height = 14.3 mm.

[0077] Example 6

[0078] A method for preparing a modified and reinforced recycled aggregate high-strength hydrophobic cement-based material. Compared with the above-mentioned Example 2, the modified and reinforced recycled aggregate of this embodiment is prepared using the following steps:

[0079] (1) After the waste slurry generated by the cleaning of the concrete mixing equipment in the commercial concrete mixing station is settled, the supernatant is poured out, and the sediment at the bottom is filtered to remove the coarse and fine aggregates. The obtained slurry is then dried and ground. After passing through a 300-mesh sieve, the obtained powder is heated to 600°C and kept warm for 50 minutes. After completion, it is cooled to room temperature to obtain waste concrete fine powder.

[0080] (2) Recycled concrete coarse aggregate with a particle size distribution of 12-15 mm was placed in a modified slurry formed by the waste concrete fine powder, silane coupling agent (KH570), and water in a mass ratio of 19:0.3:102. The ratio of the coarse aggregate to the modified slurry was 1 g:25 ml. After stirring evenly, the coarse aggregate was filtered out and placed in an oven at 30°C for 10 minutes, then heated to 60°C for 20 minutes to obtain modified reinforced recycled aggregate.

[0081] Performance tests: (1) The compressive strength of the specimens (aged 28 days) made of the marine cement-based material of this embodiment was tested in accordance with the "Standard for Test Methods for Physical and Mechanical Properties of Concrete" (GBT 50081-2019). (2) The water penetration resistance test of the specimens made of the marine cement-based material of this embodiment was conducted in accordance with the "Standard for Test Methods for Long-term Performance and Durability of Concrete" (GB / T 50082-2024). The test results were: compressive strength = 44.98 MPa, water penetration height = 6.9 mm.

[0082] Example 7

[0083] A method for preparing a modified and reinforced recycled aggregate high-strength hydrophobic cement-based material. Compared with the above-mentioned Example 3, the modified and reinforced recycled aggregate of this embodiment is prepared using the following steps:

[0084] (1) After the waste slurry generated by the cleaning of the concrete mixing equipment in the commercial concrete mixing station is settled, the supernatant is poured out, and the sediment at the bottom is filtered to remove the coarse and fine aggregates. The obtained slurry is then dried and ground, and the waste concrete powder is obtained after passing through a 180-mesh sieve for standby use.

[0085] (2) Recycled concrete coarse aggregate with a particle size distribution of 9 to 13 mm was placed in a 14 wt.% acrylic acid solution, stirred evenly, and then allowed to stand for 40 minutes. After completion, the coarse aggregate was filtered out and placed in a modified slurry formed by the waste concrete fine powder, silane coupling agent (KH560), and water in a mass ratio of 26:0.7:105. The ratio of the coarse aggregate to the modified slurry was 1 g:10 ml. After stirring evenly, the coarse aggregate was filtered out and placed in an oven at 35°C for 5 minutes, then heated to 75°C for 15 minutes to obtain modified reinforced recycled aggregate.

[0086] Performance tests: (1) The compressive strength of the specimens (aged 28 days) made of the marine cement-based material of this embodiment was tested in accordance with the "Standard for Test Methods for Physical and Mechanical Properties of Concrete" (GBT 50081-2019). (2) The water penetration resistance test of the specimens made of the marine cement-based material of this embodiment was conducted in accordance with the "Standard for Test Methods for Long-term Performance and Durability of Concrete" (GB / T 50082-2024). The test results were: compressive strength = 45.53 MPa, water penetration height = 12.6 mm.

[0087] Example 8

[0088] A method for preparing a modified reinforced recycled aggregate high-strength hydrophobic cement-based material. Compared with the above-mentioned Example 2, the slow-release hydrophobic agent of this embodiment is prepared by the following steps:

[0089] (I) 420-mesh γ-C2S powder and 300-mesh Al(OH)3 powder were mixed with water and stirred rapidly to obtain a coating slurry with a solid content of 20%, wherein the mass ratio of γ-C2S to Al(OH)3 was 4:1.

[0090] (II) Crushing and sieving discarded red bricks, placing particles with a particle size of 0.3-0.5 mm in anhydrous ethanol dissolved in saturated n-octyltriethoxysilane at a ratio of 1 g:15 ml. After standing for 10 minutes, the particles were filtered out and mixed with the coating slurry at a ratio of 1 g:5 ml. The mixture was stirred to uniformly coat the particles. The particles were then removed and dried in an oven at 60°C for 30 minutes to obtain a sustained-release hydrophobic agent.

[0091] Performance tests: (1) The compressive strength of the specimens (aged 28 days) made of the marine cement-based material of this embodiment was tested in accordance with the Standard for Test Methods for Physical and Mechanical Properties of Concrete (GBT 50081-2019). (2) The water penetration resistance test of the specimens made of the marine cement-based material of this embodiment was conducted in accordance with the Standard for Test Methods for Long-term Performance and Durability of Concrete (GB / T 50082-2024). The test results were: compressive strength = 35.27 MPa, water penetration height = 4.8 mm.

[0092] Example 9

[0093] A method for preparing a modified reinforced recycled aggregate high-strength hydrophobic cement-based material. Compared with the above-mentioned Example 1, the slow-release hydrophobic agent of this embodiment is prepared by the following steps:

[0094] (I) Mix 450-mesh γ-C2S powder with water and stir rapidly until uniformly mixed to obtain a coating slurry with a solid content of 28% for later use.

[0095] (II) Crushing and sieving discarded red bricks, placing particles with a particle size of 0.3-0.5 mm in anhydrous ethanol dissolved in saturated tridecafluorooctyltriethoxysilane at a ratio of 1 g:10 ml. After standing for 25 minutes, the particles were filtered out and mixed with the coating slurry at a ratio of 1 g:8 ml. The mixture was stirred to uniformly coat the particles. The particles were then removed and carbonized in a carbon dioxide atmosphere for 2 hours. After completion, they were dried in an oven at 40°C for 45 minutes to obtain a sustained-release hydrophobic agent.

[0096] Performance tests: (1) The compressive strength of the specimens (aged 28 days) made of the marine cement-based material of this embodiment was tested in accordance with the "Standard for Test Methods for Physical and Mechanical Properties of Concrete" (GBT 50081-2019). (2) The water penetration resistance test of the specimens made of the marine cement-based material of this embodiment was conducted in accordance with the "Standard for Test Methods for Long-term Performance and Durability of Concrete" (GB / T 50082-2024). The test results were: compressive strength = 50.83 MPa, water penetration height = 20.5 mm.

[0097] Example 10

[0098] A method for preparing a modified reinforced recycled aggregate high-strength hydrophobic cement-based material. Compared with the above-mentioned Example 3, the slow-release hydrophobic agent of this embodiment is prepared by the following steps:

[0099] (I) Mix 200-mesh Al(OH)3 powder with water and stir rapidly until uniformly mixed to obtain a coating slurry with a solid content of 24% for later use.

[0100] (II) Waste red bricks were crushed and sieved, and particles with a particle size of 0.3-0.5 mm were placed in anhydrous ethanol dissolved in saturated hexamethyldisilazane at a ratio of 1 g:5 ml. After standing for 20 minutes, the particles were filtered out and mixed with the coating slurry at a ratio of 1 g:12 ml. The mixture was stirred to uniformly coat the particles. The particles were then removed and placed in a carbon dioxide atmosphere for 3 hours for carbonization. After completion, the particles were dried in an oven at 45°C for 40 minutes to obtain a sustained-release hydrophobic agent.

[0101] Performance tests: (1) The compressive strength of the specimens (aged 28 days) made of the marine cement-based material of this embodiment was tested in accordance with the Standard for Test Methods for Physical and Mechanical Properties of Concrete (GBT 50081-2019). (2) The water penetration resistance test of the specimens made of the marine cement-based material of this embodiment was conducted in accordance with the Standard for Test Methods for Long-term Performance and Durability of Concrete (GB / T 50082-2024). The test results were: compressive strength = 41.16 MPa, water penetration height = 10.7 mm.

[0102] 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 aforementioned embodiments, those skilled in the art will be able to repair the technical solutions described in the aforementioned embodiments or replace some of the technical features therein with equivalents. Any repairs, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for preparing a modified and reinforced recycled aggregate high-strength hydrophobic cement-based material, characterized in that: The steps include: (1) After the waste concrete material slurry is precipitated, the supernatant is removed, and the sediment at the bottom is filtered to remove the aggregate therein. The obtained slurry is then dried, ground, and calcined to obtain waste concrete fine powder for later use; (2) placing the recycled concrete coarse aggregate in an acrylic acid solution and allowing it to stand, separating the coarse aggregate after completion, and coating it in a modified slurry formed by the waste concrete fine powder, a silane coupling agent, and water, and then separating the coarse aggregate and drying it to obtain modified reinforced recycled aggregate for later use; (3) Cement powder, the modified reinforced recycled aggregate, river sand fine aggregate, filler powder, and water reducer are mixed and then water is added and stirred evenly to obtain a marine cement-based material; and a slow-release hydrophobic agent is also included in an amount of 3 to 6.5% by weight of the marine cement-based material, which is prepared by the following method: (I) mixing γ-C2S powder, Al(OH)3 powder and water to form a coating slurry; (II) placing the microparticles obtained by crushing the waste red bricks in anhydrous ethanol dissolved with a saturated hydrophobic agent and allowing it to stand, separating the microparticles after completion, and placing them in the coating slurry for coating; then separating the microparticles and placing them in a carbonization treatment in a carbon dioxide atmosphere, and drying them after completion to obtain the slow-release hydrophobic agent.

2. The method for preparing the modified reinforced recycled aggregate high-strength hydrophobic cement-based material according to claim 1, characterized in that: In step (1), the calcination temperature is 600-680° C. and the calcination time is 40-50 min.

3. The method for preparing a modified reinforced recycled aggregate high-strength hydrophobic cement-based material according to claim 1, wherein in step (1), the fineness of the waste concrete powder is not less than 180 mesh.

4. The method for preparing the modified reinforced recycled aggregate high-strength hydrophobic cement-based material according to claim 1, characterized in that: In step (2), the mass fraction of the acrylic acid solution is 14-20%.

5. The method for preparing a modified and reinforced recycled aggregate high-strength hydrophobic cement-based material according to claim 1, wherein in step (2), the particle size of the recycled concrete coarse aggregate is 8-15 mm.

6. The method for preparing the modified reinforced recycled aggregate high-strength hydrophobic cement-based material according to claim 1, wherein in step (2), the standing time is 20 to 40 minutes.

7. The method for preparing the modified reinforced recycled aggregate high-strength hydrophobic cement-based material according to claim 1, characterized in that: In step (2), the ratio of the coarse aggregate to the modified slurry is 1g:10~25ml.

8. The method for preparing the modified reinforced recycled aggregate high-strength hydrophobic cement-based material according to claim 1, characterized in that: In step (2), the ratio of the waste concrete powder, the silane coupling agent, and the water is 19-26 g: 0.3-0.7 g: 100-105 g.

9. The method for preparing a modified reinforced recycled aggregate high-strength hydrophobic cement-based material according to claim 1, wherein in step (2), the silane coupling agent comprises at least one of KH550, KH560, and KH570.

10. The method for preparing a modified reinforced recycled aggregate high-strength hydrophobic cement-based material according to claim 1, wherein in step (2), the drying method is: first maintaining the temperature at 30-35°C for 5-10 minutes, then heating to 60-75°C and maintaining the temperature for 15-20 minutes.

11. The method for preparing the modified reinforced recycled aggregate high-strength hydrophobic cement-based material according to claim 1, characterized in that: In step (3), the weight ratios of the cement powder, modified reinforced recycled aggregate, river sand fine aggregate, filler powder, water reducer and water are: 80-96 weight parts: 170-220 weight parts: 115-140 weight parts: 12-17 weight parts: 1.4-2.0 weight parts: 28-36 weight parts.

12. The method for preparing a modified and reinforced recycled aggregate high-strength hydrophobic cement-based material according to claim 1, wherein in step (3), the filler powder comprises: At least one of slag powder, calcium carbonate powder, shell powder, mica powder, and fly ash.

13. The method for preparing a modified reinforced recycled aggregate high-strength hydrophobic cement-based material according to claim 1, wherein in step (3), the fineness of the filler is 300-400 mesh.

14. The method for preparing the modified reinforced recycled aggregate high-strength hydrophobic cement-based material according to any one of claims 1 to 13, characterized in that: In step (I), the solid content of the coating slurry is 20-28%; wherein the mass ratio of the γ-C2S powder to the Al(OH)3 powder is 4-7:1-2.

15. The method for preparing a modified and reinforced recycled aggregate high-strength hydrophobic cement-based material according to any one of claims 1 to 13, wherein in step (II), the fineness of the γ-C2S powder is 420-550 mesh.

16. The method for preparing a modified and reinforced recycled aggregate high-strength hydrophobic cement-based material according to any one of claims 1 to 13, wherein in step (II), the fineness of the Al(OH)3 powder is 200-300 mesh.

17. The method for preparing a modified and reinforced recycled aggregate high-strength hydrophobic cement-based material according to any one of claims 1 to 13, characterized in that: In step (II), the ratio of the microparticles to anhydrous ethanol containing a saturated hydrophobic agent is 1 g: 5-15 ml.

18. The method for preparing a modified reinforced recycled aggregate high-strength hydrophobic cement-based material according to any one of claims 1 to 13, wherein in step (II), the hydrophobizing agent comprises at least one of tridecafluorooctyltriethoxysilane, heptadecafluorodecyltriethoxysilane, n-octyltriethoxysilane, and hexamethyldisilazane.

19. The method for preparing a modified reinforced recycled aggregate high-strength hydrophobic cement-based material according to any one of claims 1 to 13, wherein in step (II), the ratio of the microparticles to the coating slurry is 1 g: 5-12 ml.

20. The method for preparing a modified reinforced recycled aggregate high-strength hydrophobic cement-based material according to any one of claims 1 to 13, wherein in step (II), the particle size of the microparticles is 0.3-0.5 mm.

21. The method for preparing a modified and reinforced recycled aggregate high-strength hydrophobic cement-based material according to any one of claims 1 to 13, characterized in that: In step (II), the carbonization treatment time is 2 to 3 hours.

22. The method for preparing a modified reinforced recycled aggregate high-strength hydrophobic cement-based material according to any one of claims 1 to 13, wherein in step (II), the drying temperature is 40-60°C and the drying time is 30-45 minutes.

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