Preparation method of modified reinforced recycled aggregate high-strength hydrophobic cement-based material

Abstract

The invention discloses a preparation method of a modified reinforced recycled aggregate high-strength hydrophobic cement-based material, which comprises the following steps: (1) placing recycled concrete coarse aggregate in an acrylic acid solution for standing, separating out the coarse aggregate after standing, placing the coarse aggregate in modified slurry formed by calcined waste concrete micro powder, a silane coupling agent and water for coating, and drying to obtain the modified reinforced recycled aggregate high-strength hydrophobic cement-based material; and then separating out the coarse aggregate and drying to obtain the modified reinforced recycled aggregate. And (2) mixing cement powder, the modified reinforced recycled aggregate, river sand fine aggregate, filler powder and a water reducing agent, adding water, and uniformly stirring to obtain the maritime work cement-based material. According to the invention, the recycled concrete aggregate is modified and reinforced by using the concrete waste generated by the commercial mixing station, and a hydrophobic anti-seepage system is constructed in the concrete material, so that the strength and the water seepage resistance of the concrete material are effectively improved, and the concrete material can better adapt to the application in the marine environment.

Description

Technical Field

[0001] The 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 the 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 a person skilled in the art.

[0003] With the continuous advancement of urbanization in my country, a large number of construction wastes have been generated by the demolition and relocation of existing buildings and the construction of new buildings. According to statistics, concrete waste accounts for nearly 50% of these construction wastes, and waste bricks and stones account for nearly 40%. Most of them are treated as solid waste landfills or transported to sites for storage, which not only occupies a large amount of arable land, but also brings 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 the construction waste is crushed into particles, and then recycled concrete aggregates are obtained after cleaning, grading and other processes. Using this aggregate to partially or completely replace natural sand and gravel aggregates to prepare concrete materials is a widely studied utilization method.

[0004] However, for marine cement-based materials, due to the harsh environment of long-term seawater erosion and scouring, the marine cement-based materials prepared with recycled concrete aggregates have insufficient mechanical properties and water seepage resistance. The main reason is that the porosity of recycled concrete aggregates is higher than that of natural sand and gravel aggregates, and there are also a large number of microcracks caused by crushing. Therefore, the strength of recycled concrete aggregates is usually lower than that of natural sand and gravel aggregates, and the high water absorption rate of recycled concrete aggregates easily causes insufficient late hydration of concrete materials, resulting in insufficient strength development. At the same time, the high porosity of recycled concrete aggregates provides more channels for water to penetrate, resulting in insufficient water seepage resistance of concrete structures. In addition, according to statistics, my country pours as much as 1.5 to 2 billion cubic meters of concrete each year, most of which are produced by commercial mixing stations, which also leads to a large amount of waste slurry generated by cleaning concrete mixing equipment in commercial mixing stations. After precipitation, a large amount of concrete waste will be generated, and its treatment has become a major problem faced by commercial mixing stations. Summary of the invention

[0005] In view of the above problems, the present invention uses the concrete waste generated by the commercial concrete mixing station to modify and strengthen the recycled concrete aggregate, and constructs a hydrophobic and anti-seepage system in the concrete material, which effectively improves the strength and anti-seepage performance of the concrete material, so that it can better adapt to the application in the marine environment. 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: (1) After the waste concrete material slurry is precipitated, the supernatant is removed, and then 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.

[0007] (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 powder, a silane coupling agent, and water for coating. The coarse aggregate is then separated and dried to obtain a modified reinforced recycled aggregate for later use.

[0008] (3) Cement powder, the modified reinforced recycled aggregate, river sand fine aggregate, filler powder and water reducing agent are mixed and then water is added and stirred evenly to obtain a marine cement-based material.

[0009] Furthermore, in step (1), the calcination temperature is 600-680°C and the time is 40-50 minutes, so as 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.

[0010] 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.

[0011] 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.

[0012] Furthermore, in step (2), the ratio of the coarse aggregate to the modified slurry is 1 g: 10-25 ml.

[0013] Furthermore, 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. Optionally, the silane coupling agent includes at least one of KH550, KH560, KH570, etc.

[0014] Furthermore, in step (2), the drying method is: first keep at 30-35°C for 5-10 minutes, then increase the temperature to 60-75°C and keep warm for 15-20 minutes.

[0015] Furthermore, in step (3), the weight ratios of the cement powder, modified reinforced recycled aggregate, river sand fine aggregate, filler powder, water reducing agent 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.

[0016] 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.

[0017] 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: (I) γ-type dicalcium silicate (γ-C 2 S) powder, aluminum hydroxide (Al(OH) 3 ) The powder is mixed with water to form a coating slurry for later use.

[0018] (II) The microparticles obtained by crushing the waste red bricks are placed in anhydrous ethanol dissolved with a saturated hydrophobic agent and allowed to stand. After completion, the microparticles are separated and placed in the coating slurry for coating. The separated microparticles are then placed in a carbon dioxide atmosphere for carbonization treatment and dried to obtain the slow-release hydrophobic agent.

[0019] Furthermore, in step (I), the solid content of the coating slurry is 20-28%. 2 S powder and Al(OH) 3 The mass ratio of the powder is 4-7:1-2. Optionally, the γ-C 2 The fineness of the S powder is 420-550 mesh. 3 The fineness of the powder is 200~300 mesh.

[0020] Furthermore, in step (II), the particle size of the microparticles is 0.3-0.5 mm.

[0021] 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, hexamethyldisilazane, and the like.

[0022] Furthermore, in step (II), the ratio of the microparticles to the coating slurry is 1 g: 5-12 ml.

[0023] Furthermore, in step (II), the carbonization treatment time is 2 to 3 hours.

[0024] Furthermore, in step (II), the drying temperature is 40-60° C. and the drying time is 30-45 min.

[0025] Compared with the prior art, the present invention has at least the following beneficial technical effects: (1) The modified and reinforced recycled aggregate of the present invention effectively improves the mechanical properties of the prepared marine cement-based materials. 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, and 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 compacting the coating layer, thereby effectively reducing the porosity of the coarse aggregate, improving the strength while 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 to improve 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.

[0026] (2) For cement-based materials that need to be used 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 waste red bricks as the hydrophobic agent carrier, and coats the surface of the microparticles with γ-C 2 S and Al(OH) 3 The formed coating layer is then carbonized with carbon dioxide. The carbon dioxide enters the coating layer and acts together with the water it provides to promote the γ-C 2 S undergoes carbonization reaction, and the nano-silica gel formed densifies the coating layer and fixes it more firmly 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 cement particles and affecting their hydration reaction. As the hydration reaction proceeds, the Al(OH) 3Under the action of the hydroxide ions generated by hydration, the coating layer is gradually dissolved, thereby converting the coating layer into a porous structure, and the hydrophobic agent therein is gradually released outward to construct a hydrophobic system, so that the cement-based material prepared by the present invention has good water permeability resistance. In addition, the nano-silicon dioxide particles in the coating layer can also use the calcium hydroxide, a hydration product of cement, to undergo a rehydration reaction to form a hydrated calcium silicate gelling component, which helps to improve the mechanical strength of the cement-based material. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. The embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein: Figure 1 The following is a compressive strength test diagram of Example 1.

[0028] Figure 2 The following is a test diagram of the water-proof performance of Example 1.

[0029] Figure 3 This is a compressive strength test diagram of the following Example 2.

[0030] Figure 4 This is a compressive strength test diagram of the following Example 3. DETAILED DESCRIPTION

[0031] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. The experimental methods in the following examples without specifying specific conditions are usually carried out under conventional conditions or according to the conditions recommended by the manufacturer.

[0032] Unless otherwise defined, all professional and scientific terms used herein have the same meanings 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 instructions. 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 of the specification.

[0033] Example 1 A method for preparing a modified and reinforced recycled aggregate high-strength hydrophobic cement-based material comprises the following steps: 1. Preparation of modified and reinforced recycled aggregate: (1) After the waste slurry generated by the cleaning of the concrete mixing equipment in the commercial concrete mixing station is precipitated, the supernatant is poured out, and then 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°C and kept warm for 45 minutes. After completion, it is cooled to room temperature to obtain the waste concrete fine powder for standby use.

[0034] (2) Place the recycled concrete coarse aggregate with a particle size distribution of 8-10 mm in a 15wt.% acrylic acid solution, stir evenly and let it stand for 30 minutes. After completion, filter out the coarse aggregate and place it in a modified slurry formed by the waste concrete 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 is 1g:20ml. After stirring evenly, filter out the coarse aggregate and place it in an oven at 35°C for 7 minutes, then heat it to 70°C and keep it for 15 minutes to obtain modified reinforced recycled aggregate for use.

[0035] 2. Preparation of sustained-release hydrophobic agent: (I) Place 450 mesh γ-C 2 S powder, 250 mesh Al(OH) 3 After the powder is mixed with water, it is quickly stirred to obtain a coating slurry with a solid content of 28%. 2 S and Al(OH) 3 The mass ratio is 6:2.

[0036] (II) The waste red bricks are crushed and sieved, and the particles with a particle size of 0.3-0.5 mm are placed in anhydrous ethanol dissolved with saturated tridecafluorooctyl triethoxysilane, with the ratio of the two being 1 g:10 ml. After standing for 25 minutes, the particles are filtered out, and the particles are mixed with the coating slurry in a ratio of 1 g:8 ml and stirred to make the surface of the particles evenly coated with slurry, and then the particles are taken out and placed in a carbon dioxide atmosphere for 2 hours for carbonization treatment. After completion, they are dried in an oven at 40°C for 45 minutes to obtain a slow-release hydrophobic agent for standby use.

[0037] 3. 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, 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. Mix the above raw materials evenly, then add 32 parts by weight of clean water and stir evenly to obtain the marine cement-based material.

[0038] Performance test: (1) The compressive strength (such as 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.

[0039] Example 2 A method for preparing a modified and reinforced recycled aggregate high-strength hydrophobic cement-based material comprises the following steps: 1. Preparation of modified and reinforced recycled aggregate: (1) After the waste slurry generated by the cleaning of the concrete mixing equipment in the commercial concrete mixing station is precipitated, the supernatant is poured out, and then 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, which is then set aside.

[0040] (2) Place the recycled concrete coarse aggregate with a particle size distribution of 12-15 mm in a 20wt.% acrylic acid solution, stir evenly and let it stand for 20 minutes. After completion, filter out the coarse aggregate and place it in a modified slurry formed by the waste concrete 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 is 1g:25ml. Stir evenly and filter out the coarse aggregate, place it in an oven at 30°C for 10 minutes, then heat it to 60°C and keep it for 20 minutes to obtain modified reinforced recycled aggregate for use.

[0041] 2. Preparation of sustained-release hydrophobic agent: (I) Place 420-mesh γ-C 2 S powder, 300 mesh Al(OH) 3 After the powder is mixed with water, it is quickly stirred to obtain a coating slurry with a solid content of 20%. 2 S and Al(OH) 3 The mass ratio is 4:1.

[0042] (II) The abandoned red bricks are crushed and sieved, and the particles with a particle size of 0.3-0.5 mm are placed in anhydrous ethanol dissolved with saturated n-octyl triethoxysilane, and the ratio of the two is 1g:15ml. After standing for 10 minutes, the particles are filtered out, and the particles are mixed with the coating slurry in a ratio of 1g:5ml and stirred to make the surface of the particles evenly coated with slurry, and then the particles are taken out and placed in a carbon dioxide atmosphere for 3 hours for carbonization treatment. After completion, they are dried in an oven at 60°C for 30 minutes to obtain a slow-release hydrophobic agent for standby use.

[0043] 3. Take the following raw materials: 80 parts by weight of cement powder (PO 42.5), 170 parts by weight of the modified 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 polycarboxylate water reducer, and 5.2 parts by weight of the slow-release hydrophobic agent. Mix the above raw materials evenly, then add 28 parts by weight of clean water and stir evenly to obtain the marine cement-based material.

[0044] Performance test: (1) The compressive strength (such as Figure 3 (2) According to the Standard for Test Methods for Long-term Performance and Durability of Concrete (GB / T 50082-2024), the test piece made of the marine cement-based material of this embodiment was subjected to a water penetration test. The test results were: compressive strength = 47.33 MPa, water penetration height = 5.4 mm.

[0045] Example 3 A method for preparing a modified and reinforced recycled aggregate high-strength hydrophobic cement-based material comprises the following steps: 1. Preparation of modified and reinforced recycled aggregate: (1) After the waste slurry generated by the cleaning of the concrete mixing equipment in the commercial concrete mixing station is precipitated, the supernatant is poured out, and then 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 the waste concrete fine powder for use.

[0046] (2) Place the recycled concrete coarse aggregate with a particle size distribution of 9 to 13 mm in a 14wt.% acrylic acid solution, stir evenly and let it stand for 40 minutes. After completion, filter out the coarse aggregate and place it in a modified slurry formed by the waste concrete 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 is 1g:10ml. Stir evenly and filter out the coarse aggregate, place it in an oven at 35°C for 5 minutes, then heat it to 75°C for 15 minutes to obtain modified reinforced recycled aggregate for use.

[0047] 2. Preparation of sustained-release hydrophobic agent: (I) Place 550 mesh γ-C 2 S powder, 200 mesh Al(OH) 3 After the powder is mixed with water, it is quickly stirred to obtain a coating slurry with a solid content of 24%. 2 S and Al(OH) 3 The mass ratio is 7:1.

[0048] (II) The waste red bricks are crushed and sieved, and the particles with a particle size of 0.3-0.5 mm are placed in anhydrous ethanol dissolved with saturated hexamethyldisilazane, and the ratio of the two is 1g:5ml. After standing for 20 minutes, the particles are filtered out, and the particles are mixed with the coating slurry in a ratio of 1g:12ml and stirred to make the surface of the particles evenly coated with slurry, and then the particles are taken out and placed in a carbon dioxide atmosphere for 3 hours for carbonization treatment. After completion, they are dried in an oven at 45°C for 40 minutes to obtain a slow-release hydrophobic agent for standby use.

[0049] 3. Take the following raw materials: 96 parts by weight of cement powder (PO 42.5), 220 parts by weight of the modified 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 polycarboxylate water reducer, and 2.9 parts by weight of the slow-release hydrophobic agent. Mix the above raw materials evenly, then add 36 parts by weight of clean water and stir evenly to obtain the marine cement-based material.

[0050] Performance test: (1) The compressive strength (such as Figure 4 (2) According to the Standard for Test Methods for Long-term Performance and Durability of Concrete (GB / T 50082-2024), the test piece made of the marine cement-based material of this embodiment was subjected to a water penetration test. The test results were: compressive strength = 51.75 MPa, water seepage height = 11.2 mm.

[0051] Example 4 A method for preparing a modified and reinforced recycled aggregate high-strength hydrophobic cement-based material comprises the following steps: (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 polycarboxylic acid water reducer.

[0052] (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.

[0053] Performance test: (1) The compressive strength of the test piece (age 28d) 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). (2) The water penetration resistance test of the test piece made of the marine cement-based material of this embodiment was carried out according to the "Standard for Test Methods of Long-term Performance and Durability of Concrete" (GB / T 50082-2024). The test results are: compressive strength = 51.09 MPa, water seepage height = 34.7 mm.

[0054] Example 5 A method for preparing a modified and reinforced recycled aggregate high-strength hydrophobic cement-based material comprises the following steps: (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.

[0055] (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.

[0056] Performance test: (1) The compressive strength of the test piece (age 28d) 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). (2) The water penetration resistance test of the test piece made of the marine cement-based material of this embodiment was carried out according to the "Standard for Test Methods of Long-term Performance and Durability of Concrete" (GB / T 50082-2024). The test results are: compressive strength = 38.62MPa, water seepage height = 14.3mm.

[0057] Example 6 A method for preparing a modified and reinforced recycled aggregate high-strength hydrophobic cement-based material. Compared with the above-mentioned embodiment 2, the modified and reinforced recycled aggregate of this embodiment is prepared by the following steps: (1) After the waste slurry generated by the cleaning of the concrete mixing equipment in the commercial concrete mixing station is precipitated, the supernatant is poured out, and then 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.

[0058] (2) The recycled concrete coarse aggregate with a particle size distribution of 12-15 mm is placed in a modified slurry formed by the waste concrete powder, silane coupling agent (KH570), and water in a mass ratio of 19:0.3:102, and the ratio of the coarse aggregate to the modified slurry is 1g:25ml. After stirring evenly, the coarse aggregate is filtered out and placed in an oven at 30°C for 10 minutes, and then heated to 60°C for 20 minutes to obtain a modified reinforced recycled aggregate.

[0059] Performance test: (1) The compressive strength of the test piece (age 28d) 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). (2) The water penetration resistance test of the test piece made of the marine cement-based material of this embodiment was carried out according to the "Standard for Test Methods of Long-term Performance and Durability of Concrete" (GB / T 50082-2024). The test results are: compressive strength = 44.98MPa, water seepage height = 6.9mm.

[0060] Example 7 A method for preparing a modified and reinforced recycled aggregate high-strength hydrophobic cement-based material. Compared with the above-mentioned embodiment 3, the modified and reinforced recycled aggregate of this embodiment is prepared by the following steps: (1) After the waste slurry generated by the cleaning of the concrete mixing equipment in the commercial concrete mixing station is precipitated, the supernatant is poured out, and then the sediment at the bottom is filtered to remove the coarse and fine aggregates therein. 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.

[0061] (2) Place the recycled concrete coarse aggregate with a particle size distribution of 9 to 13 mm in a 14wt.% acrylic acid solution, stir evenly and let it stand for 40 minutes. After completion, filter out the coarse aggregate and place it in a modified slurry formed by the waste concrete 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 is 1g:10ml. Stir evenly and filter out the coarse aggregate, place it in an oven and keep it at 35°C for 5 minutes, then heat it to 75°C and keep it for 15 minutes to obtain modified reinforced recycled aggregate.

[0062] Performance test: (1) The compressive strength of the test piece (age 28d) 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). (2) The water penetration resistance test of the test piece made of the marine cement-based material of this embodiment was carried out according to the "Standard for Test Methods of Long-term Performance and Durability of Concrete" (GB / T 50082-2024). The test results are: compressive strength = 45.53MPa, water seepage height = 12.6mm.

[0063] Example 8 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 example is prepared by the following steps: (I) Place 420-mesh γ-C 2 S powder, 300 mesh Al(OH) 3 After the powder is mixed with water, it is quickly stirred to obtain a coating slurry with a solid content of 20%. 2 S and Al(OH) 3 The mass ratio is 4:1.

[0064] (II) The waste red bricks are crushed and sieved, and particles with a particle size of 0.3-0.5 mm are placed in anhydrous ethanol dissolved with saturated n-octyltriethoxysilane in a ratio of 1 g:15 ml. After standing for 10 minutes, the particles are filtered out, and the particles are mixed with the coating slurry in a ratio of 1 g:5 ml and stirred to evenly coat the surface of the particles. Then, the particles are taken out and placed in an oven at 60°C for 30 minutes to obtain a slow-release hydrophobic agent.

[0065] Performance test: (1) The compressive strength of the test piece (age 28d) 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). (2) The water penetration resistance test of the test piece made of the marine cement-based material of this embodiment was carried out according to the "Standard for Test Methods of Long-term Performance and Durability of Concrete" (GB / T 50082-2024). The test results are: compressive strength = 35.27MPa, water seepage height = 4.8mm.

[0066] Example 9 A method for preparing a modified reinforced recycled aggregate high-strength hydrophobic cement-based material. Compared with the above-mentioned embodiment 1, the slow-release hydrophobic agent of this embodiment is prepared by the following steps: (I) Place 450 mesh γ-C 2 After the S powder is mixed with water, it is quickly stirred to obtain a coating slurry with a solid content of 28% for use.

[0067] (II) The waste red bricks are crushed and sieved, and the particles with a particle size of 0.3-0.5 mm are placed in anhydrous ethanol dissolved with saturated tridecafluorooctyl triethoxysilane, and the ratio of the two is 1g:10ml. After standing for 25 minutes, the particles are filtered out, and the particles are mixed with the coating slurry in a ratio of 1g:8ml and stirred to make the surface of the particles evenly coated with slurry, and then the particles are taken out and placed in a carbon dioxide atmosphere for 2 hours for carbonization treatment. After completion, they are dried in an oven at 40°C for 45 minutes to obtain a slow-release hydrophobic agent.

[0068] Performance test: (1) The compressive strength of the test piece (age 28d) 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). (2) The water penetration resistance test of the test piece made of the marine cement-based material of this embodiment was carried out according to the "Standard for Test Methods of Long-term Performance and Durability of Concrete" (GB / T 50082-2024). The test results are: compressive strength = 50.83MPa, water seepage height = 20.5mm.

[0069] Example 10 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 example is prepared by the following steps: (I) 200 mesh Al(OH) 3 After the powder is mixed with water, it is quickly stirred to obtain a coating slurry with a solid content of 24% for use.

[0070] (II) The waste red bricks are crushed and sieved, and the particles with a particle size of 0.3-0.5 mm are placed in anhydrous ethanol dissolved with saturated hexamethyldisilazane, and the ratio of the two is 1g:5ml. After standing for 20 minutes, the particles are filtered out, and the particles are mixed with the coating slurry in a ratio of 1g:12ml and stirred to make the surface of the particles evenly coated with slurry, and then the particles are taken out and placed in a carbon dioxide atmosphere for 3 hours for carbonization treatment. After completion, they are dried in an oven at 45°C for 40 minutes to obtain a slow-release hydrophobic agent.

[0071] Performance test: (1) The compressive strength of the test piece (age 28d) 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). (2) The water penetration resistance test of the test piece made of the marine cement-based material of this embodiment was carried out according to the "Standard for Test Methods of Long-term Performance and Durability of Concrete" (GB / T 50082-2024). The test results are: compressive strength = 41.16 MPa, water seepage height = 10.7 mm.

[0072] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention is described in detail with reference to the aforementioned embodiments, those skilled in the art can still repair the technical solutions recorded in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any repair, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope 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 then the sediment at the bottom is filtered to remove the aggregate therein, and then the obtained slurry is dried, ground, and calcined to obtain waste concrete fine powder for standby use; (2) placing the recycled concrete coarse aggregate in an acrylic acid solution and allowing it to stand, separating the coarse aggregate after completion, placing it in a modified slurry formed by the waste concrete powder, a silane coupling agent, and water for coating, and then separating the coarse aggregate and drying it to obtain modified reinforced recycled aggregate for standby use; (3) Cement powder, the modified reinforced recycled aggregate, river sand fine aggregate, filler powder and water reducing agent are mixed and then water is added and stirred evenly to obtain a marine cement-based material.

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; Optionally, in step (1), the fineness of the waste concrete powder is not less than 180 mesh.

3. 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%; Optionally, in step (2), the particle size of the recycled concrete coarse aggregate is 8-15 mm; Optionally, in step (2), the standing time is 20 to 40 minutes.

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 ratio of the coarse aggregate to the modified slurry is 1g:10~25ml.

5. 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, silane coupling agent and water is 19-26 g: 0.3-0.7 g: 100-105 g; Optionally, in step (2), the silane coupling agent includes at least one of KH550, KH560, and KH570; Optionally, in step (2), the drying method is: first keep at 30-35°C for 5-10 minutes, then increase the temperature to 60-75°C and keep warm for 15-20 minutes.

6. 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 ratio of the cement powder, modified reinforced recycled aggregate, river sand fine aggregate, filler powder, water reducing agent and water is: 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; Optionally, in step (3), the filler powder includes: at least one of slag powder, calcium carbonate powder, shell powder, mica powder, and fly ash; Optionally, in step (3), the fineness of the filler is 300-400 mesh.

7. The method for preparing the modified reinforced recycled aggregate high-strength hydrophobic cement-based material according to any one of claims 1 to 6, characterized in that: 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: (I) mixing γ-C2S powder, Al(OH)3 powder and water to form a coating slurry for later use; (II) The microparticles obtained by crushing the waste red bricks are placed in anhydrous ethanol dissolved with a saturated hydrophobic agent and allowed to stand. After completion, the microparticles are separated and placed in the coating slurry for coating; then the separated microparticles are placed in a carbon dioxide atmosphere for carbonization treatment, and after completion, they are dried to obtain the slow-release hydrophobic agent.

8. The method for preparing the modified reinforced recycled aggregate high-strength hydrophobic cement-based material according to claim 7, 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; Optionally, in step (II), the fineness of the γ-C2S powder is 420-550 mesh; Optionally, in step (II), the fineness of the Al(OH)3 powder is 200-300 mesh.

9. The method for preparing the modified reinforced recycled aggregate high-strength hydrophobic cement-based material according to claim 7, 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; Optionally, in step (II), the hydrophobic agent includes at least one of tridecafluorooctyltriethoxysilane, heptadecafluorodecyltriethoxysilane, n-octyltriethoxysilane, and hexamethyldisilazane; Optionally, in step (II), the ratio of the microparticles to the coating slurry is 1 g: 5-12 ml; Optionally, in step (II), the particle size of the microparticles is 0.3-0.5 mm.

10. The method for preparing the modified reinforced recycled aggregate high-strength hydrophobic cement-based material according to claim 7, characterized in that: In step (II), the carbonization treatment time is 2 to 3 hours; optionally, in step (II), the drying temperature is 40 to 60° C. and the time is 30 to 45 minutes.

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