Method for producing recycled aggregate concrete using construction waste

Abstract

The application discloses a method for preparing recycled aggregate concrete by using construction waste, and the concrete comprises the following raw materials in parts by weight: cement 500-600 parts, modified recycled aggregate 1100-1200 parts, sand 600-650 parts, water 150-200 parts, water reducing agent 5-8 parts, benzophenone 3-8 parts and modified additive 50-80 parts; when the raw materials are mixed and used, the thiol groups on the modified recycled aggregate can be grafted with the double bonds on the modified additive under the sunlight, and a continuous polymer film network is formed in the cement stone; when the concrete is about to produce micro-cracks under stress, the polymer film network can bridge the cracks, absorb energy through deformation and sliding of the polymer film network, and prevent the expansion of the cracks, so that the concrete is changed from a brittle material to a more ductile material; the internal gaps of the recycled aggregate are filled with the polymer, and the surface of the recycled aggregate is coated with organic silicon, so that the impermeability of the concrete material is improved.

Description

Technical Field

[0001] This invention relates to the field of concrete preparation technology, and more specifically to a method for preparing recycled aggregate concrete using construction waste. Background Technology

[0002] With the acceleration of global urbanization, the large-scale generation and resource utilization of construction waste has become a core issue in the field of sustainable development. Utilizing construction waste to prepare recycled aggregate concrete can not only alleviate the pressure of depleted natural aggregate resources but also reduce land occupation and environmental pollution caused by waste landfill. Recycled aggregate is coated with a significant amount of cement mortar, resulting in a rough surface with many sharp edges. Due to the high porosity and water absorption of the cement mortar, coupled with the accumulation of damage during the disintegration and crushing of concrete blocks, numerous microcracks exist within the recycled aggregate. This leads to a lower density and apparent density of recycled aggregate compared to ordinary aggregate, resulting in concrete with significantly lower strength and impermeability than conventional concrete. Summary of the Invention

[0003] The purpose of this invention is to provide a method for preparing recycled aggregate concrete using construction waste, which solves the problems of poor mechanical properties and poor impermeability of recycled aggregate concrete, resulting in a short service life.

[0004] The objective of this invention can be achieved through the following technical solutions: A method for preparing recycled aggregate concrete using construction waste specifically includes the following steps: Step A1: Mix hydroxyethyl methacrylate, styrene, ethyl acrylate and potassium persulfate evenly to prepare a treatment solution. Wash and dry the recycled aggregate, place it in a sealable container, and pressurize it for 20-30 minutes at a pressure of -0.1 MPa. Then add the treatment solution and release the vacuum. Soak for 20-30 minutes, filter to remove the filtrate, and heat-treat the substrate at a temperature of 70-80℃ for 6-8 hours to obtain pretreated recycled aggregate. Step A2: Mix 3-mercaptopropyltriethoxysilane, ethanol and deionized water, stir for 15-20 min at a speed of 200-300 r / min and a temperature of 25-30℃, add pretreated recycled aggregate, and sonicate at a frequency of 20-30 kHz for 1-1.5 h. Take out the pretreated recycled aggregate and keep it at a temperature of 70-80℃ for 2-4 h to obtain modified recycled aggregate. Step A3: Weigh the following raw materials by weight: 500-600 parts cement, 1100-1200 parts modified recycled aggregate, 600-650 parts sand, 150-200 parts water, 5-8 parts water-reducing agent, 3-8 parts benzophenone, and 50-80 parts modified additive. Mix the raw materials evenly to obtain recycled aggregate concrete.

[0005] Furthermore, the mass ratio of hydroxyethyl methacrylate, styrene, ethyl acrylate and potassium persulfate in step A1 is 10:2:3:0.2, and the ratio of recycled aggregate to pretreatment is 1g:5mL.

[0006] Furthermore, the mass ratio of 3-mercaptopropyltriethoxysilane, ethanol, deionized water and pretreated recycled aggregate in step A2 is 1g:5mL:1mL:50g.

[0007] Furthermore, the modified additive is prepared by the following steps: Step B1: Mix octamethylcyclotetrasiloxane, methacryloxypropylmethyldiethoxysilane, 1,3-bis(aminopropane)tetramethyldisiloxane, tetramethylammonium hydroxide and deionized water, and purge with nitrogen. React at 200-300 r / min and 90-95℃ for 3-5 h to obtain aminopolysiloxane. Mix aminopolysiloxane, 4-formylphenylboronic acid, xylene and 4A molecular sieve evenly. Stir and add glacial acetic acid at 300-500 r / min and 30-35℃ for 3-5 h to obtain modified polysiloxane. Step B2: Mix polyvinyl alcohol and dimethyl sulfoxide, purge with nitrogen, stir at 200-300 r / min and 0-5℃, add triethylamine and acryloyl chloride, heat to 20-25℃ and react for 4-6 h to obtain pretreated polyvinyl alcohol. Mix lithium trimethylsilanolate and tetrahydrofuran, stir at 150-200 r / min and 0℃, add trifluoropropylmethylcyclotrisiloxane, heat to 25-30℃ and react for 20-25 h, then add trichlorosilane and continue the reaction for 1-1.5 h to obtain fluorinated polysiloxane. Step B3: Mix fluorinated polysiloxane, pretreated polyvinyl alcohol, caster catalyst and DMF, purge with nitrogen, and react for 6-8 hours at a rotation speed of 200-300 r / min and a temperature of 80-85℃ to obtain the pretreated additive. Mix the pretreated additive, modified polysiloxane, 4A molecular sieve and DMF, purge with nitrogen, and react for 6-8 hours at a rotation speed of 300-500 r / min and a temperature of 110-120℃ to obtain the modified additive.

[0008] Furthermore, in step B1, the molar ratio of octamethylcyclotetrasiloxane, methacryloxypropylmethyldiethoxysilane, 1,3-bis(aminopropane)tetramethyldisiloxane and tetramethylammonium hydroxide is 1.2:0.2:1:1.5; the molar ratio of aminopolysiloxane, 4-formylphenylboronic acid, xylene and 4A molecular sieve is 10 mmol:10 mmol:30 mL:1 g; and the amount of glacial acetic acid is 0.1% of the mass of 4-formylphenylboronic acid.

[0009] Furthermore, in step B2, the ratio of polyvinyl alcohol, triethylamine, and acryloyl chloride is 10g:0.2mol:0.21mol, the polyvinyl alcohol is type 1788, and the molar ratio of Si-Cl bonds on lithium trimethylsilanolate, trifluoropropylmethylcyclotrisiloxane, and trichlorosilane is 1:4:1.

[0010] Furthermore, in step B3, the molar ratio of the double bonds on the fluorinated polysiloxane and the pretreated polyvinyl alcohol is 1:1, the amount of the cassette catalyst is 0.01% of the mass of the fluorinated polysiloxane, the mass ratio of the pretreated additive to the modified polysiloxane is 10:3, and the amount of 4A molecular sieve is 1% of the mass of the modified polysiloxane.

[0011] The beneficial effects of this invention are as follows: This invention discloses a method for preparing recycled aggregate concrete using construction waste. The concrete includes the following raw materials: cement, modified recycled aggregate, sand, water, water-reducing agent, benzophenone, and modifying additives. The modified recycled aggregate is prepared by mixing hydroxyethyl methacrylate, styrene, ethyl acrylate, and potassium persulfate to obtain a treatment liquid. The recycled aggregate is immersed in the treatment liquid under negative pressure and the vacuum is released. Under pressure, the treatment liquid enters the gaps in the recycled aggregate. Then, it is kept at high temperature. Hydroxyethyl methacrylate, styrene, and ethyl acrylate are polymerized to obtain pretreated recycled aggregate. 3-mercaptopropyltriethoxysilane is hydrolyzed and added to the pretreated recycled aggregate, so that the silanol produced by the hydrolysis of 3-mercaptopropyltriethoxysilane grafts onto the hydroxyl groups on the pretreated recycled aggregate to obtain modified recycled aggregate.

[0012] The modified additive is prepared by ring-opening octamethylcyclotetrasiloxane with methacryloyloxypropylmethyldiethoxysilane, followed by end-capping with 1,3-bis(aminopropyl)tetramethyldisiloxane to obtain aminopolysiloxane. The aminopolysiloxane is then reacted with 4-formylphenylboronic acid, causing the amino group on the aminopolysiloxane to react with the aldehyde group on the 4-formylphenylboronic acid, thus obtaining modified polysiloxane. Polyvinyl alcohol is then reacted with acryloyl chloride, causing some of the hydroxyl groups on the polyvinyl alcohol to react with the acyl chloride on the acryloyl chloride, thus obtaining pretreated polyvinyl alcohol. Trimethylsilyl alcohol is used as an initiator... Fluoropropylmethylcyclotrisiloxane is used as a polymer monomer to prepare a polysiloxane with a fluoroalkane side chain and a lithium silanolate at one end. Trichlorosilane is then added, causing the Si-Cl bond on the trichlorosilane to react with the lithium silanolate to prepare a fluorinated polysiloxane. The fluorinated polysiloxane is then reacted with modified polyacrylamide, causing the Si-H bond on the fluorinated polysiloxane to react with the double bond on the modified polyacrylamide to prepare a pretreatment additive. The pretreatment additive is then reacted with modified polysiloxane, causing the hydroxyl group on the pretreatment additive to react with the borate group on the modified polysiloxane to form a borate ester to prepare a modified additive.

[0013] When raw materials are mixed and used, under sunlight, the thiol groups on the modified recycled aggregate can graft onto the double bonds on the modified additives under the action of benzophenone, forming a continuous polymer film network inside the cement paste. When the concrete is about to develop microcracks under stress, the polymer film network can bridge the cracks and absorb energy through its own deformation and slippage, preventing the cracks from expanding. This transforms the concrete from a brittle material to a more resilient one. The internal gaps of the recycled aggregate are filled with polymer, and the surface is coated with organosilicon, which can increase the impermeability of the concrete material. Detailed Implementation

[0014] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0015] Example 1: A method for preparing recycled aggregate concrete using construction waste, specifically including the following steps: Step A1: Mix hydroxyethyl methacrylate, styrene, ethyl acrylate and potassium persulfate evenly to prepare a treatment solution. Wash and dry the recycled aggregate, place it in a sealable container, and pressurize it for 20 minutes at a pressure of -0.1 MPa. Then add the treatment solution and release the vacuum. Soak for 20 minutes, filter to remove the filtrate, and heat the substrate at a temperature of 70°C for 6 hours to obtain pretreated recycled aggregate. Step A2: Mix 3-mercaptopropyltriethoxysilane, ethanol and deionized water, stir for 15 min at 200 r / min and 25℃, add pretreated recycled aggregate, sonicate for 1 h at 20 kHz, remove the pretreated recycled aggregate, and heat-treat at 70℃ for 2 h to obtain modified recycled aggregate; Step A3: Weigh the following raw materials by weight: 500 parts cement, 1100 parts modified recycled aggregate, 600 parts sand, 150 parts water, 5 parts water-reducing agent, 3 parts benzophenone and 50 parts modified additive. Mix the raw materials evenly to obtain recycled aggregate concrete.

[0016] The mass ratio of hydroxyethyl methacrylate, styrene, ethyl acrylate and potassium persulfate in step A1 is 10:2:3:0.2, and the ratio of recycled aggregate to pretreatment is 1g:5mL.

[0017] The mass ratio of 3-mercaptopropyltriethoxysilane, ethanol, deionized water and pretreated recycled aggregate in step A2 is 1g:5mL:1mL:50g.

[0018] The cement used in step A3 is PO 42.5, the modified recycled aggregate has a particle size of 5mm, the sand is washed sand with a fineness modulus of 2.4, and the water-reducing agent is sodium lignosulfonate.

[0019] The modified additive is prepared by the following steps: Step B1: Octamethylcyclotetrasiloxane, methacryloxypropylmethyldiethoxysilane, 1,3-bis(aminopropane)tetramethyldisiloxane, tetramethylammonium hydroxide and deionized water are mixed and purged with nitrogen. The mixture is reacted for 3 hours at 200 r / min and 90 °C to obtain aminopolysiloxane. Aminopolysiloxane, 4-formylphenylboronic acid, xylene and 4A molecular sieve are mixed evenly and stirred at 300 r / min and 30 °C. Glacial acetic acid is added and the mixture is reacted for 3 hours to obtain modified polysiloxane. Step B2: Polyvinyl alcohol and dimethyl sulfoxide are mixed and protected with nitrogen. Under the conditions of 200 r / min and 0°C, triethylamine and acryloyl chloride are added while stirring. The temperature is raised to 20°C and the reaction is carried out for 4 h to obtain pretreated polyvinyl alcohol. Trimethylsilyl alcohol and tetrahydrofuran are mixed and under the conditions of 150 r / min and 0°C, trifluoropropylmethylcyclotrisiloxane is added while stirring. The temperature is raised to 25°C and the reaction is carried out for 20 h. Trichlorosilane is added and the reaction is continued for 1 h to obtain fluorinated polysiloxane. Step B3: Fluorinated polysiloxane, pretreated polyvinyl alcohol, caster catalyst and DMF are mixed, and under nitrogen protection, the mixture is reacted for 6 hours at a speed of 200 r / min and a temperature of 80℃ to obtain the pretreated additive. The pretreated additive, modified polysiloxane, 4A molecular sieve and DMF are mixed, and under nitrogen protection, the mixture is reacted for 6 hours at a speed of 300 r / min and a temperature of 110℃ to obtain the modified additive.

[0020] In step B1, the molar ratio of octamethylcyclotetrasiloxane, methacryloxypropylmethyldiethoxysilane, 1,3-bis(aminopropane)tetramethyldisiloxane and tetramethylammonium hydroxide is 1.2:0.2:1:1.5; the molar ratio of aminopolysiloxane, 4-formylphenylboronic acid, xylene and 4A molecular sieve is 10 mmol:10 mmol:30 mL:1 g; and the amount of glacial acetic acid is 0.1% of the mass of 4-formylphenylboronic acid.

[0021] The ratio of polyvinyl alcohol, triethylamine and acryloyl chloride used in step B2 is 10g:0.2mol:0.21mol, the polyvinyl alcohol is type 1788, and the molar ratio of Si-Cl bonds on lithium trimethylsilanolate, trifluoropropylmethylcyclotrisiloxane and trichlorosilane is 1:4:1.

[0022] In step B3, the molar ratio of the double bonds on the fluorinated polysiloxane and the pretreated polyvinyl alcohol is 1:1, the amount of the cassette catalyst is 0.01% of the mass of the fluorinated polysiloxane, the mass ratio of the pretreated additive to the modified polysiloxane is 10:3, and the amount of 4A molecular sieve is 1% of the mass of the modified polysiloxane.

[0023] Example 2, a method for preparing recycled aggregate concrete using construction waste, specifically includes the following steps: Step A1: Mix hydroxyethyl methacrylate, styrene, ethyl acrylate and potassium persulfate evenly to prepare a treatment solution. Wash and dry the recycled aggregate, place it in a sealable container, and pressurize it for 25 minutes at a pressure of -0.1 MPa. Then add the treatment solution and release the vacuum. Soak for 25 minutes, filter to remove the filtrate, and heat the substrate at a temperature of 75°C for 7 hours to obtain pretreated recycled aggregate. Step A2: Mix 3-mercaptopropyltriethoxysilane, ethanol and deionized water, stir for 20 min at 200 r / min and 30℃, add pretreated recycled aggregate, sonicate for 1.5 h at 25 kHz, remove the pretreated recycled aggregate, and heat-treat at 75℃ for 3 h to obtain modified recycled aggregate; Step A3: Weigh the following raw materials by weight: 550 parts cement, 1150 parts modified recycled aggregate, 630 parts sand, 180 parts water, 6.5 parts water-reducing agent, 5 parts benzophenone and 65 parts modified additive. Mix the raw materials evenly to obtain recycled aggregate concrete.

[0024] The mass ratio of hydroxyethyl methacrylate, styrene, ethyl acrylate and potassium persulfate in step A1 is 10:2:3:0.2, and the ratio of recycled aggregate to pretreatment is 1g:5mL.

[0025] The mass ratio of 3-mercaptopropyltriethoxysilane, ethanol, deionized water and pretreated recycled aggregate in step A2 is 1g:5mL:1mL:50g.

[0026] The cement used in step A3 is PO 42.5, the modified recycled aggregate has a particle size of 5mm, the sand is washed sand with a fineness modulus of 2.4, and the water-reducing agent is sodium lignosulfonate.

[0027] The modified additive is prepared by the following steps: Step B1: Octamethylcyclotetrasiloxane, methacryloyloxypropylmethyldiethoxysilane, 1,3-bis(aminopropane)tetramethyldisiloxane, tetramethylammonium hydroxide and deionized water are mixed and purged with nitrogen. The mixture is reacted for 4 hours at 200 r / min and 95 °C to obtain aminopolysiloxane. Aminopolysiloxane, 4-formylphenylboronic acid, xylene and 4A molecular sieve are mixed evenly and stirred at 500 r / min and 30 °C. Glacial acetic acid is added and the mixture is reacted for 4 hours to obtain modified polysiloxane. Step B2: Polyvinyl alcohol and dimethyl sulfoxide were mixed and protected with nitrogen. Under the conditions of 200 r / min and 5°C, triethylamine and acryloyl chloride were added and stirred. The temperature was raised to 20°C and the reaction was carried out for 5 h to obtain pretreated polyvinyl alcohol. Trimethylsilyl alcohol and tetrahydrofuran were mixed and under the conditions of 150 r / min and 0°C, trifluoropropylmethylcyclotrisiloxane was added and stirred. The temperature was raised to 30°C and the reaction was carried out for 20 h. Trichlorosilane was added and the reaction was continued for 1.3 h to obtain fluorinated polysiloxane. Step B3: Fluorinated polysiloxane, pretreated polyvinyl alcohol, caster catalyst and DMF are mixed, and under nitrogen protection, the mixture is reacted for 7 hours at a speed of 200 r / min and a temperature of 85℃ to obtain the pretreated additive. The pretreated additive, modified polysiloxane, 4A molecular sieve and DMF are mixed, and under nitrogen protection, the mixture is reacted for 7 hours at a speed of 300 r / min and a temperature of 115℃ to obtain the modified additive.

[0028] In step B1, the molar ratio of octamethylcyclotetrasiloxane, methacryloxypropylmethyldiethoxysilane, 1,3-bis(aminopropane)tetramethyldisiloxane and tetramethylammonium hydroxide is 1.2:0.2:1:1.5; the molar ratio of aminopolysiloxane, 4-formylphenylboronic acid, xylene and 4A molecular sieve is 10 mmol:10 mmol:30 mL:1 g; and the amount of glacial acetic acid is 0.1% of the mass of 4-formylphenylboronic acid.

[0029] The ratio of polyvinyl alcohol, triethylamine and acryloyl chloride used in step B2 is 10g:0.2mol:0.21mol, the polyvinyl alcohol is type 1788, and the molar ratio of Si-Cl bonds on lithium trimethylsilanolate, trifluoropropylmethylcyclotrisiloxane and trichlorosilane is 1:4:1.

[0030] In step B3, the molar ratio of the double bonds on the fluorinated polysiloxane and the pretreated polyvinyl alcohol is 1:1, the amount of the cassette catalyst is 0.01% of the mass of the fluorinated polysiloxane, the mass ratio of the pretreated additive to the modified polysiloxane is 10:3, and the amount of 4A molecular sieve is 1% of the mass of the modified polysiloxane.

[0031] Example 3: A method for preparing recycled aggregate concrete using construction waste, specifically including the following steps: Step A1: Mix hydroxyethyl methacrylate, styrene, ethyl acrylate and potassium persulfate evenly to prepare a treatment solution. Wash and dry the recycled aggregate, place it in a sealable container, and pressurize it for 30 minutes at a pressure of -0.1 MPa. Then add the treatment solution and release the vacuum. Soak for 30 minutes, filter to remove the filtrate, and heat the substrate at a temperature of 80℃ for 8 hours to obtain pretreated recycled aggregate. Step A2: Mix 3-mercaptopropyltriethoxysilane, ethanol and deionized water, stir for 20 min at 300 r / min and 30℃, add pretreated recycled aggregate, sonicate for 1.5 h at 30 kHz, remove the pretreated recycled aggregate, and heat-treat at 80℃ for 4 h to obtain modified recycled aggregate; Step A3: Weigh the following raw materials by weight: 600 parts cement, 1200 parts modified recycled aggregate, 650 parts sand, 200 parts water, 8 parts water-reducing agent, 8 parts benzophenone, and 80 parts modified additive. Mix the raw materials evenly to obtain recycled aggregate concrete.

[0032] The mass ratio of hydroxyethyl methacrylate, styrene, ethyl acrylate and potassium persulfate in step A1 is 10:2:3:0.2, and the ratio of recycled aggregate to pretreatment is 1g:5mL.

[0033] The mass ratio of 3-mercaptopropyltriethoxysilane, ethanol, deionized water and pretreated recycled aggregate in step A2 is 1g:5mL:1mL:50g.

[0034] The cement used in step A3 is PO 42.5, the modified recycled aggregate has a particle size of 5mm, the sand is washed sand with a fineness modulus of 2.4, and the water-reducing agent is sodium lignosulfonate.

[0035] The modified additive is prepared by the following steps: Step B1: Octamethylcyclotetrasiloxane, methacryloxypropylmethyldiethoxysilane, 1,3-bis(aminopropane)tetramethyldisiloxane, tetramethylammonium hydroxide and deionized water are mixed and purged with nitrogen. The mixture is reacted for 5 hours at 300 r / min and 95 °C to obtain aminopolysiloxane. Aminopolysiloxane, 4-formylphenylboronic acid, xylene and 4A molecular sieve are mixed evenly and stirred at 500 r / min and 35 °C. Glacial acetic acid is added and the mixture is reacted for 5 hours to obtain modified polysiloxane. Step B2: Polyvinyl alcohol and dimethyl sulfoxide were mixed and protected with nitrogen. Under the conditions of 300 r / min and 5°C, triethylamine and acryloyl chloride were added and the mixture was heated to 25°C and reacted for 6 h to obtain pretreated polyvinyl alcohol. Lithium trimethylsilanolate and tetrahydrofuran were mixed and stirred at 200 r / min and 0°C. Trifluoropropylmethylcyclotrisiloxane was added and the mixture was heated to 30°C and reacted for 25 h. Trichlorosilane was then added and the reaction was continued for 1.5 h to obtain fluorinated polysiloxane. Step B3: Fluorinated polysiloxane, pretreated polyvinyl alcohol, caster catalyst and DMF are mixed, and under nitrogen protection, the mixture is reacted for 8 hours at a speed of 300 r / min and a temperature of 85℃ to obtain the pretreated additive. The pretreated additive, modified polysiloxane, 4A molecular sieve and DMF are mixed, and under nitrogen protection, the mixture is reacted for 8 hours at a speed of 500 r / min and a temperature of 120℃ to obtain the modified additive.

[0036] In step B1, the molar ratio of octamethylcyclotetrasiloxane, methacryloxypropylmethyldiethoxysilane, 1,3-bis(aminopropane)tetramethyldisiloxane and tetramethylammonium hydroxide is 1.2:0.2:1:1.5; the molar ratio of aminopolysiloxane, 4-formylphenylboronic acid, xylene and 4A molecular sieve is 10 mmol:10 mmol:30 mL:1 g; and the amount of glacial acetic acid is 0.1% of the mass of 4-formylphenylboronic acid.

[0037] The ratio of polyvinyl alcohol, triethylamine and acryloyl chloride used in step B2 is 10g:0.2mol:0.21mol, the polyvinyl alcohol is type 1788, and the molar ratio of Si-Cl bonds on lithium trimethylsilanolate, trifluoropropylmethylcyclotrisiloxane and trichlorosilane is 1:4:1.

[0038] In step B3, the molar ratio of the double bonds on the fluorinated polysiloxane and the pretreated polyvinyl alcohol is 1:1, the amount of the cassette catalyst is 0.01% of the mass of the fluorinated polysiloxane, the mass ratio of the pretreated additive to the modified polysiloxane is 10:3, and the amount of 4A molecular sieve is 1% of the mass of the modified polysiloxane.

[0039] Comparative Example 1: This comparative example did not include benzophenone, but the remaining steps were the same as in Example 1.

[0040] Comparative Example 2: This comparative example uses pretreated recycled aggregate instead of modified recycled aggregate, while the other steps are the same as in Example 1.

[0041] Comparative Example 3: This comparative example did not include fluorinated polysiloxane compared to Example 1, but the remaining steps were the same.

[0042] The concrete prepared in Examples 1-3 and Comparative Examples 1-3 was made into 100mm×100mm×100mm specimens according to the standard of GB / T50081-2019, and irradiated with 365nm ultraviolet light for 24h. The compressive strength was tested after curing for 28 days. Standard frustum cone specimens with a top diameter of 175mm, a bottom diameter of 185mm, and a height of 150mm were prepared according to the standard of GB / T50082-2024. The initial pressure was 0.1MPa, and the pressure was increased by 0.1MPa every 8 hours. The pressure test results during water seepage are recorded as shown in Table 1 below.

[0043] Table 1

[0044] As shown in Table 1, this application has excellent mechanical strength and impermeability.

[0045] The above description is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the concept of the invention or exceed the scope defined in the claims, they should all fall within the protection scope of the present invention.

Claims

1. A method for preparing recycled aggregate concrete using construction waste, characterized in that: Specifically, the steps include the following: Step A1: Mix hydroxyethyl methacrylate, styrene, ethyl acrylate and potassium persulfate evenly to prepare a treatment solution. Wash and dry the recycled aggregate, place it in a sealable container, maintain negative pressure, add the treatment solution and release the vacuum, soak it, filter to remove the filtrate, and heat the substrate to obtain pretreated recycled aggregate. Step A2: Mix 3-mercaptopropyltriethoxysilane, ethanol and deionized water, add pretreated recycled aggregate, sonicate, remove the pretreated recycled aggregate, heat-keep, and obtain modified recycled aggregate. Step A3: Weigh the following raw materials by weight: 500-600 parts cement, 1100-1200 parts modified recycled aggregate, 600-650 parts sand, 150-200 parts water, 5-8 parts water-reducing agent, 3-8 parts benzophenone and 50-80 parts modified additive. Mix the raw materials evenly to obtain recycled aggregate concrete. The modified additive is prepared by the following steps: Step B1: Octamethylcyclotetrasiloxane, methacryloxypropylmethyldiethoxysilane, 1,3-bis(aminopropane)tetramethyldisiloxane, tetramethylammonium hydroxide and deionized water are mixed and reacted under nitrogen protection to obtain aminopolysiloxane. Aminopolysiloxane, 4-formylphenylboronic acid, xylene and 4A molecular sieve are mixed and stirred and glacial acetic acid is added to react to obtain modified polysiloxane. Step B2: Mix polyvinyl alcohol and dimethyl sulfoxide, purge with nitrogen, stir and add triethylamine and acryloyl chloride, heat and react to obtain pretreated polyvinyl alcohol. Mix lithium trimethylsilyl alcohol and tetrahydrofuran, stir and add trifluoropropylmethylcyclotrisiloxane, heat and react, add trichlorosilane and continue the reaction to obtain fluorinated polysiloxane. Step B3: Mix fluorinated polysiloxane, pretreated polyvinyl alcohol, caster catalyst and DMF, purge with nitrogen, and react to obtain pretreated additive. Mix pretreated additive, modified polysiloxane, 4A molecular sieve and DMF, purge with nitrogen, and react to obtain modified additive.

2. The method for preparing recycled aggregate concrete using construction waste according to claim 1, characterized in that: The mass ratio of hydroxyethyl methacrylate, styrene, ethyl acrylate and potassium persulfate in step A1 is 10:2:3:0.

2.

3. The method for preparing recycled aggregate concrete using construction waste according to claim 1, characterized in that: The mass ratio of 3-mercaptopropyltriethoxysilane, ethanol, deionized water and pretreated recycled aggregate in step A2 is 1g:5mL:1mL:50g.

4. The method for preparing recycled aggregate concrete using construction waste according to claim 1, characterized in that: In step B1, the molar ratio of octamethylcyclotetrasiloxane, methacryloxypropylmethyldiethoxysilane, 1,3-bis(aminopropane)tetramethyldisiloxane and tetramethylammonium hydroxide is 1.2:0.2:1:1.5; the molar ratio of aminopolysiloxane, 4-formylphenylboronic acid, xylene and 4A molecular sieve is 10 mmol:10 mmol:30 mL:1 g; and the amount of glacial acetic acid is 0.1% of the mass of 4-formylphenylboronic acid.

5. The method for preparing recycled aggregate concrete using construction waste according to claim 1, characterized in that: The ratio of polyvinyl alcohol, triethylamine and acryloyl chloride used in step B2 is 10g:0.2mol:0.21mol, and the molar ratio of Si-Cl bonds on lithium trimethylsilanolate, trifluoropropylmethylcyclotrisiloxane and trichlorosilane is 1:4:

1.

6. The method for preparing recycled aggregate concrete using construction waste according to claim 1, characterized in that: In step B3, the molar ratio of the double bonds on the fluorinated polysiloxane and the pretreated polyvinyl alcohol is 1:1, the mass ratio of the pretreated additive and the modified polysiloxane is 10:3, and the amount of 4A molecular sieve is 1% of the mass of the modified polysiloxane.

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