Recycled concrete based on waste asphalt and preparation method thereof

Abstract

The invention belongs to the technical field of building materials, and particularly relates to recycled concrete based on waste asphalt and a preparation method of the recycled concrete. Natural coarse aggregate is selected as first coarse aggregate, a waste asphalt composite material is selected as second coarse aggregate, aminated river sand is selected as fine aggregate, carboxylated graphene and modified basalt fiber are used together, the recycled concrete based on waste asphalt is prepared, the compressive strength of the concrete is improved, the anti-freezing capacity is improved, and the service life of the concrete is prolonged. And a good anti-permeability grade is obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of building materials, and particularly relates to recycled concrete based on waste asphalt and a preparation method thereof. Background Art

[0002] Recycled aggregate concrete, or recycled concrete for short, is a concrete made by partially or completely replacing natural aggregate with recycled aggregate obtained by crushing, cleaning, grading, and processing discarded concrete blocks from construction waste. With the development of industry and construction, the demand for natural sand and gravel has increased, and natural resources are becoming increasingly scarce. The application of recycled concrete can not only solve the environmental problems caused by landfilling of construction waste, but also realize the recycling of construction waste. It is an important measure to promote the sustainable development of resources, and has thus attracted widespread attention from all walks of life.

[0003] A Chinese patent (publication number CN116606102A) discloses a waste asphalt pavement coarse aggregate recycled concrete and its preparation method. By adjusting the particle size range and particle set of the waste asphalt pavement recycled aggregate, the concrete prepared by the waste asphalt pavement recycled coarse aggregate completely replaces the natural coarse aggregate, which has higher compressive strength and avoids the adverse effect of reduced mechanical properties of concrete after the recycled aggregate is added. The invention not only provides a better particle size range and particle grading for waste asphalt pavement coarse aggregate used in concrete, but also solves the storage problem after the waste asphalt pavement is demolished, and has good environmental and economic benefits. However, the patent does not solve the problems of low compressive strength, poor frost resistance, and impermeability level in the prior art recycled concrete, which seriously affects its actual use.

[0004] Therefore, how to select suitable materials as coarse aggregate and fine aggregate, and use them together with other functional components to improve the compressive strength of recycled concrete, increase frost resistance, and obtain a good impermeability grade has become a direction that needs to be focused on. Summary of the invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a recycled concrete based on waste asphalt and a preparation method thereof, aiming to solve the problems of low compressive strength, poor frost resistance, and impermeability level of recycled concrete in the prior art to be improved.

[0006] The present invention selects natural coarse aggregate as the first coarse aggregate, waste asphalt composite material as the second coarse aggregate, and amination river sand as fine aggregate, and uses them together with carboxylated graphene and modified basalt fiber to prepare recycled concrete based on waste asphalt, thereby improving the compressive strength of concrete, increasing the frost resistance, and obtaining a good anti-seepage grade.

[0007] The technical solution adopted by the present invention to solve the above technical problems is as follows:

[0008] The first aspect of the present invention provides a method for preparing recycled concrete based on waste asphalt, comprising the following steps:

[0009] Step S1: heating and melting 500-600 parts of waste asphalt by weight, and then adding 30-36 parts of calcium carbonate and 30-36 parts of SBS rubber for high-speed stirring to obtain a waste asphalt composite material;

[0010] Step S2: In parts by weight, 400 to 450 parts of natural coarse aggregate, 100 to 140 parts of the waste asphalt composite material, 300 to 400 parts of fine aggregate, 260 to 280 parts of cement and 220 to 240 parts of limestone powder are mixed, and then 16 to 20 parts of graphene, 4 to 8 parts of basalt fiber and 300 to 340 parts of water are added, and the mixture is stirred evenly to obtain a slurry;

[0011] Step S3: The slurry is injection molded, and then demolded and cured to obtain recycled concrete based on waste asphalt.

[0012] As a preferred technical solution of the present invention, the calcium carbonate is amino-modified calcium carbonate; the preparation method of the amino-modified calcium carbonate comprises: in parts by weight, 80 to 100 parts of calcium carbonate and 360 to 400 parts of anhydrous ethanol are uniformly dispersed by ultrasonication, then 16 to 20 parts of DL-alanine are added, stirred at 80 to 84° C. for 30 to 40 minutes, filtered, washed with water, and dried to obtain the amino-modified calcium carbonate.

[0013] As a preferred technical solution of the present invention, the conditions of the high-speed stirring treatment include: a rotation speed of 2800-3000 r / min, a temperature of 150-160° C., and a time of 60-100 min.

[0014] The nano-calcium carbonate in the waste asphalt composite material can fill the tiny pores and cracks between cement stone and aggregate, reducing the number and size of internal defects. The SBS rubber in the waste asphalt composite material can form a three-dimensional network structure with asphalt molecules. This network structure has a strong binding force and can bind the light components in the asphalt. The rigidity of the concrete can be enhanced by nano-calcium carbonate, and the SBS rubber and waste asphalt can give the necessary flexibility. The combined effect improves the mechanical properties of the recycled concrete.

[0015] As a preferred technical solution of the present invention, the natural coarse aggregate is basalt crushed stone and granite crushed stone; the mass ratio of basalt crushed stone to granite crushed stone in the natural coarse aggregate is (1-2):1.

[0016] As a preferred technical solution of the present invention, the fine aggregate is amination river sand; the preparation method of the amination river sand comprises: adding 10 to 20 parts of river sand to 200 to 220 parts of deionized water by weight and dispersing them evenly, then adding 4 to 8 parts of 3-aminopropyltriethoxysilane to carry out amination reaction, centrifuging after the amination reaction is completed, washing with water, and drying to obtain amination river sand.

[0017] As a preferred technical solution of the present invention, the conditions of the amination reaction include: pH 7.2-7.6, temperature 80-90° C., and time 8-10 h.

[0018] The particles of amination river sand have better dispersibility and can play a better micro-filling role inside the concrete, reducing the porosity and micro-cracks, thereby improving the density and compressive strength of the recycled concrete.

[0019] As a preferred technical solution of the present invention, the graphene is carboxylated graphene; the preparation method of the carboxylated graphene includes: dispersing 10 to 16 parts of graphene oxide in 160 to 180 parts of deionized water, and then adding 1 to 3 parts of acrylic acid, 4 to 6 parts of isopentanol polyoxyethylene ether, 0.1 to 0.3 parts of ammonium cerium nitrate and 120 to 140 parts of deionized water, placing in a nitrogen atmosphere, stirring the reaction at 50 to 60° C. for 6 to 8 hours, and freeze-drying to obtain carboxylated graphene.

[0020] As a preferred technical solution of the present invention, the diameter of the graphene oxide is 2 to 8 μm.

[0021] Carboxylated graphene can form stronger chemical bonds with cement hydration products through its surface functional groups, enhance the adhesion between materials, improve the quality of the interface transition zone, make the overall structure stronger, and enhance the ability to resist freeze-thaw cycles.

[0022] As a preferred technical solution of the present invention, the basalt fiber is a modified basalt fiber; the preparation method of the modified basalt fiber comprises: in parts by weight, 2 to 4 parts of perfluorooctyl triethoxysilane, 3 to 6 parts of tetraethyl orthosilicate, 5 to 7 parts of ammonia water and 190 to 200 parts of anhydrous ethanol are mixed uniformly to obtain a first mixture; 35 to 45 parts of 3-aminopropyl triethoxysilane, 20 to 30 parts of tetraethyl orthosilicate, 20 to 30 parts of anhydrous ethanol and 50 to 60 parts of epoxy resin are mixed and stirred for 4 to 6 hours to obtain a second mixture; 30 to 40 parts of the first mixture and 10 to 14 parts of the second mixture are mixed and ultrasonically dispersed to obtain an impregnation liquid, the basalt fiber is immersed in the impregnation liquid for 48 to 72 hours, and dried to obtain the modified basalt fiber.

[0023] On the one hand, the surface of modified basalt fiber contains nano-silica, which changes the surface roughness and morphology through the nano-microstructure. The air trapped between the raised nanoparticles prevents water droplets from entering the surface, thereby improving the surface hydrophobicity. On the other hand, the surface is modified with fluorine-containing compounds, and the fluorine atoms with low surface energy easily migrate to the surface, thereby reducing the surface energy and enhancing the surface hydrophobicity of the material, which helps to reduce the water absorption rate inside the concrete, thereby effectively improving the anti-seepage grade.

[0024] The second aspect of the present invention provides a recycled concrete based on waste asphalt prepared by the method described in the first aspect.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] (1) The present invention uses waste asphalt composite materials as recycled coarse aggregate, which is modified by calcium carbonate and SBS rubber. The amino-modified calcium carbonate introduced can react with the carboxyl group of carboxylated graphene and the epoxy group in modified basalt fiber through the active group amino group to construct an interconnected network of coarse aggregate. At the same time, amination river sand is used as fine aggregate, and the fine aggregate interconnected network is established through its combination with carboxylated graphene and basalt fiber. With the help of the connection between the interconnected network of coarse aggregate and the interconnected network of fine aggregate, a dense network structure is constructed, which effectively improves the compressive strength of recycled concrete and obtains good frost resistance and impermeability.

[0027] (2) The nano-calcium carbonate in the waste asphalt composite material of the present invention can fill the tiny pores and cracks between cement stone and aggregate, reducing the number and size of internal defects. The SBS rubber in the waste asphalt composite material can form a three-dimensional network structure with asphalt molecules. This network structure has a strong binding force and can bind the light components in the asphalt. The rigidity of the concrete can be enhanced by the nano-calcium carbonate, and the SBS rubber and waste asphalt can give the necessary flexibility. The combined effect improves the mechanical properties of the recycled concrete.

[0028] (3) The particles of the aminated river sand of the present invention have better dispersibility and can play a better micro-filling role inside the concrete, reduce the porosity and the presence of micro-cracks, and thus improve the density and compressive strength of the recycled concrete.

[0029] (4) The carboxylated graphene of the present invention can form stronger chemical bonds with cement hydration products through the functional groups on its surface, thereby enhancing the bonding force between materials, improving the quality of the interface transition zone, making the overall structure stronger, and improving the ability to resist freeze-thaw cycles.

[0030] (5) On the one hand, the modified basalt fiber of the present invention contains nano-silicon dioxide on its surface, which changes the surface roughness and morphology through the nano-microstructure. The air trapped between the protruding nanoparticles prevents water droplets from entering the surface, thereby improving the surface hydrophobicity. On the other hand, the surface is modified with fluorine-containing compounds, and the fluorine atoms with low surface energy easily migrate to the surface, thereby reducing the surface energy and enhancing the surface hydrophobicity of the material, which helps to reduce the water absorption rate inside the concrete, thereby effectively improving the anti-seepage grade. DETAILED DESCRIPTION

[0031] For the convenience of understanding the present invention, the present invention lists the following embodiments. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0032] The sources of some components in the embodiments and comparative examples are as follows:

[0033] Basalt crushed stone, particle size 5 mm, purchased from Jiangsu Yabang Mining Co., Ltd.;

[0034] Granite crushed stone, particle size 7 mm, purchased from Yidu Jinlian Trading Co., Ltd.;

[0035] Waste asphalt, purchased from Handan Jiajie Chemical Raw Materials Recycling Co., Ltd.;

[0036] River sand, item number 5768, was purchased from Lingshou County Zehong Mineral Products Processing Plant;

[0037] Cement, product number CA-75, was purchased from Zhengzhou Kerui (Group) Refractory Materials Co., Ltd.;

[0038] Limestone powder, product number YW0001, was purchased from Jiangyin Yongwang Chemical Co., Ltd.;

[0039] Graphene oxide I, item number DN-20DY, diameter 5 μm, purchased from Zhejiang Zhiti Nano Micro New Materials Co., Ltd.

[0040] Graphene oxide II, product number NO-C-068-1, diameter 18 μm; purchased from Shanghai Naio Nano Technology Co., Ltd.;

[0041] Basalt fiber, product number FD2706, was purchased from Shandong Oude Chemical Fiber Products Co., Ltd.;

[0042] Calcium carbonate, product number GF-100, was purchased from Jiangxi Bairui Calcium Carbonate Co., Ltd.;

[0043] SBS rubber, grade SBSYH-796E, purchased from Sinopec Baling Petrochemical Company;

[0044] Anhydrous ethanol, CAS No. 64-17-5, was purchased from Sinopharm Chemical Reagent Co., Ltd.;

[0045] DL-alanine, CAS No. 302-72-7, was purchased from Shanghai MacLean Biochemical Technology Co., Ltd.;

[0046] 3-Aminopropyltriethoxysilane, CAS No. 919-30-2, purchased from Sinopharm Chemical Reagent Co., Ltd.;

[0047] Acrylic acid, CAS No. 79-10-7, was purchased from Sinopharm Chemical Reagent Co., Ltd.;

[0048] Isoprenoic acid polyoxyethylene ether, brand OXAB-501, Liaoning Aoke Chemical Co., Ltd.;

[0049] Cerium ammonium nitrate, CAS No. 16774-21-3, was purchased from Sinopharm Chemical Reagent Co., Ltd.;

[0050] Perfluorooctyltriethoxysilane, CAS No. 51851-37-7, purchased from Zhongshan Dixin Chemical Co., Ltd.;

[0051] Tetraethyl orthosilicate, CAS No. 78-10-4, was purchased from Sinopharm Chemical Reagent Co., Ltd.;

[0052] 3-Aminopropyltriethoxysilane, CAS No. 919-30-2, purchased from Shanghai MacLean Biochemical Technology Co., Ltd.;

[0053] Epoxy resin, brand 0164, was purchased from Nantong Xingchen Synthetic Materials Co., Ltd.

[0054] Example 1

[0055] This embodiment provides a method for preparing recycled concrete based on waste asphalt, comprising the following steps:

[0056] Step S1: 600 parts by weight of waste asphalt are heated and melted, and then 36 parts of amino-modified calcium carbonate and 36 parts of SBS rubber are added and stirred at a high speed (speed of 3000 r / min, temperature of 160° C., time of 60 min) to obtain a waste asphalt composite material;

[0057] Step S2: In parts by weight, 450 parts of natural coarse aggregate (300 parts of basalt crushed stone and 150 parts of granite crushed stone), 140 parts of the waste asphalt composite material, 400 parts of fine aggregate amination river sand, 280 parts of cement and 240 parts of limestone powder are stirred and mixed, and then 20 parts of carboxylated graphene, 8 parts of modified basalt fiber and 340 parts of water are added, and the mixture is stirred evenly to obtain a slurry;

[0058] Step S3: The slurry is injection molded, and then demolded and cured to obtain recycled concrete based on waste asphalt.

[0059] The preparation of the amino-modified calcium carbonate is as follows: by weight, 100 parts of calcium carbonate and 400 parts of anhydrous ethanol are uniformly dispersed by ultrasonication, and then 20 parts of DL-alanine are added, stirred at 84° C. for 30 minutes, filtered, washed with water, and dried to obtain the amino-modified calcium carbonate.

[0060] Preparation of the amination river sand: by weight, 20 parts of river sand are added to 220 parts of deionized water and dispersed evenly, and then 8 parts of 3-aminopropyltriethoxysilane are added to carry out an amination reaction (pH is 7.6, temperature is 90° C., and time is 8 hours). After the amination reaction is completed, centrifugation, water washing, and drying are performed to obtain the amination river sand.

[0061] Preparation of the carboxylated graphene: In parts by weight, 16 parts of graphene oxide I (article number DN-20DY, diameter 5 μm) are dispersed in 180 parts of deionized water, and then 3 parts of acrylic acid, 6 parts of isopentanol polyoxyethylene ether, 0.3 parts of ammonium cerium nitrate and 140 parts of deionized water are added, placed in a nitrogen atmosphere, stirred for reaction at 60° C. for 6 hours, and freeze-dried to obtain carboxylated graphene.

[0062] Preparation of the modified basalt fiber: in parts by weight, 4 parts of perfluorooctyl triethoxysilane, 6 parts of tetraethyl orthosilicate, 7 parts of ammonia water and 200 parts of anhydrous ethanol are evenly mixed to obtain a first mixture; 45 parts of 3-aminopropyl triethoxysilane, 30 parts of tetraethyl orthosilicate, 30 parts of anhydrous ethanol and 60 parts of epoxy resin are mixed and stirred for 6 hours to obtain a second mixture; 40 parts of the first mixture and 14 parts of the second mixture are mixed and ultrasonically dispersed to obtain an impregnation liquid, and the basalt fiber is immersed in the impregnation liquid for 72 hours, and dried to obtain the modified basalt fiber.

[0063] Example 2

[0064] This embodiment provides a method for preparing recycled concrete based on waste asphalt, comprising the following steps:

[0065] Step S1: 500 parts by weight of waste asphalt are heated and melted, and then 30 parts of amino-modified calcium carbonate and 30 parts of SBS rubber are added and stirred at a high speed (speed of 2800 r / min, temperature of 150° C., time of 100 min) to obtain a waste asphalt composite material;

[0066] Step S2: In parts by weight, 400 parts of natural coarse aggregate (200 parts of basalt crushed stone and 200 parts of granite crushed stone), 100 parts of the waste asphalt composite material, 300 parts of fine aggregate amination river sand, 260 parts of cement and 220 parts of limestone powder are stirred and mixed, and then 16 parts of carboxylated graphene, 4 parts of modified basalt fiber and 300 parts of water are added, and the mixture is stirred evenly to obtain a slurry;

[0067] Step S3: The slurry is injection molded, and then demolded and cured to obtain recycled concrete based on waste asphalt.

[0068] The preparation of the amino-modified calcium carbonate is as follows: by weight, 80 parts of calcium carbonate and 360 parts of anhydrous ethanol are uniformly dispersed by ultrasonication, and then 16 parts of DL-alanine are added, stirred at 80° C. for 40 minutes, filtered, washed with water, and dried to obtain the amino-modified calcium carbonate.

[0069] Preparation of the amination river sand: by weight, 10 parts of river sand are added to 200 parts of deionized water and dispersed evenly, then 4 parts of 3-aminopropyltriethoxysilane are added to carry out an amination reaction (pH is 7.2, temperature is 80° C., and time is 10 hours). After the amination reaction is completed, centrifugation, water washing, and drying are performed to obtain the amination river sand.

[0070] Preparation of the carboxylated graphene: In parts by weight, 10 parts of graphene oxide I (article number DN-20DY, diameter 5 μm) are dispersed in 160 parts of deionized water, and then 1 part of acrylic acid, 4 parts of isopentanol polyoxyethylene ether, 0.1 part of ammonium cerium nitrate and 120 parts of deionized water are added, placed in a nitrogen atmosphere, stirred for reaction at 50° C. for 8 hours, and freeze-dried to obtain carboxylated graphene.

[0071] Preparation of the modified basalt fiber: in parts by weight, 2 parts of perfluorooctyl triethoxysilane, 3 parts of tetraethyl orthosilicate, 5 parts of ammonia water and 190 parts of anhydrous ethanol are evenly mixed to obtain a first mixture; 35 parts of 3-aminopropyl triethoxysilane, 20 parts of tetraethyl orthosilicate, 20 parts of anhydrous ethanol and 50 parts of epoxy resin are mixed and stirred for 4 hours to obtain a second mixture; 30 parts of the first mixture and 10 parts of the second mixture are mixed and ultrasonically dispersed to obtain an impregnation liquid, and the basalt fiber is immersed in the impregnation liquid for 48 hours, and dried to obtain the modified basalt fiber.

[0072] Example 3

[0073] This embodiment provides a method for preparing recycled concrete based on waste asphalt, comprising the following steps:

[0074] Step S1: 550 parts by weight of waste asphalt are heated and melted, and then 33 parts of amino-modified calcium carbonate and 33 parts of SBS rubber are added and stirred at a high speed (speed of 2900 r / min, temperature of 155° C., time of 80 min) to obtain a waste asphalt composite material;

[0075] Step S2: In parts by weight, 430 parts of natural coarse aggregate (230 parts of basalt crushed stone and 200 parts of granite crushed stone), 120 parts of the waste asphalt composite material, 350 parts of fine aggregate amination river sand, 270 parts of cement and 230 parts of limestone powder are stirred and mixed, and then 18 parts of carboxylated graphene, 6 parts of modified basalt fiber and 320 parts of water are added, and the mixture is stirred evenly to obtain a slurry;

[0076] Step S3: The slurry is injection molded, and then demolded and cured to obtain recycled concrete based on waste asphalt.

[0077] The preparation of the amino-modified calcium carbonate is as follows: by weight, 90 parts of calcium carbonate and 380 parts of anhydrous ethanol are uniformly dispersed by ultrasonication, and then 18 parts of DL-alanine are added, stirred at 82° C. for 35 minutes, filtered, washed with water, and dried to obtain the amino-modified calcium carbonate.

[0078] Preparation of the amination river sand: by weight, 15 parts of river sand are added to 210 parts of deionized water and dispersed evenly, and then 6 parts of 3-aminopropyltriethoxysilane are added to carry out an amination reaction (pH is 7.4, temperature is 85° C., and time is 9 hours). After the amination reaction is completed, centrifugation, water washing, and drying are performed to obtain the amination river sand.

[0079] Preparation of the carboxylated graphene: In parts by weight, 12 parts of graphene oxide I (article number DN-20DY, diameter 5 μm) are dispersed in 170 parts of deionized water, and then 2 parts of acrylic acid, 5 parts of isopentanol polyoxyethylene ether, 0.2 parts of ammonium cerium nitrate and 130 parts of deionized water are added, placed in a nitrogen atmosphere, stirred for reaction at 55° C. for 7 hours, and freeze-dried to obtain carboxylated graphene.

[0080] Preparation of the modified basalt fiber: in parts by weight, 3 parts of perfluorooctyl triethoxysilane, 4 parts of tetraethyl orthosilicate, 6 parts of ammonia water and 195 parts of anhydrous ethanol are mixed evenly to obtain a first mixture; 40 parts of 3-aminopropyl triethoxysilane, 25 parts of tetraethyl orthosilicate, 25 parts of anhydrous ethanol and 55 parts of epoxy resin are mixed and stirred for 5 hours to obtain a second mixture; 35 parts of the first mixture and 12 parts of the second mixture are mixed and ultrasonically dispersed to obtain an impregnation liquid, and the basalt fiber is immersed in the impregnation liquid for 60 hours, and dried to obtain the modified basalt fiber.

[0081] Comparative Example 1

[0082] This comparative example provides a method for preparing recycled concrete, which differs from Example 1 in that commercially available waste asphalt (purchased from Handan Jiajie Chemical) is used instead of the waste asphalt composite material.

[0083] Comparative Example 2

[0084] This comparative example provides a method for preparing recycled concrete, which is different from Example 1 in that the amount of basalt crushed stone in the natural coarse aggregate is changed to 400 parts, and the amount of granite crushed stone is changed to 50 parts.

[0085] Comparative Example 3

[0086] This comparative example provides a method for preparing recycled concrete, which is different from Example 1 in that the amount of basalt crushed stone in the natural coarse aggregate is changed to 100 parts, and the amount of granite crushed stone is changed to 350 parts.

[0087] Comparative Example 4

[0088] This comparative example provides a method for preparing recycled concrete, which differs from Example 1 in that commercially available river sand (Article No. 5768) is used instead of amination river sand as fine aggregate.

[0089] Comparative Example 5

[0090] This comparative example provides a method for preparing recycled concrete, which differs from Example 1 in that graphene oxide I is used instead of carboxylated graphene.

[0091] Comparative Example 6

[0092] This comparative example provides a method for preparing recycled concrete, which differs from Example 1 in that graphene oxide II is used instead of graphene oxide I to prepare carboxylated graphene.

[0093] Comparative Example 7

[0094] This comparative example provides a method for preparing recycled concrete, which differs from Example 1 in that commercially available basalt fiber (item number FD2706) is used instead of modified basalt fiber.

[0095] The performance of the recycled concrete provided in the above embodiments and comparative examples was tested, and the testing method was as follows:

[0096] (1) Compressive strength test: The test is carried out in accordance with the requirements of GB / T 50081-2019 Standard for Test Methods for Physical and Mechanical Properties of Concrete.

[0097] (2) Antifreeze performance test: Test in accordance with the requirements of GB / T 50082-2024 Standard for Test Methods for Long-term Performance and Durability of Concrete.

[0098] (3) Water resistance test: Test in accordance with the requirements of GB / T 50082-2024 Standard for Test Methods for Long-term Performance and Durability of Concrete.

[0099] The above performance test data is shown in Table 1.

[0100] Table 1 Performance test results

[0101]

[0102]

[0103] From the above content, it can be seen that the present invention selects natural coarse aggregate as the first coarse aggregate, waste asphalt composite material as the second coarse aggregate, and amination river sand as fine aggregate, and uses them together with carboxylated graphene and modified basalt fiber to prepare recycled concrete based on waste asphalt (Examples 1 to 3), which has a 28d compressive strength of 60.5 to 61.1 MPa, a frost resistance of F350, and a water-resistance grade of P8.

[0104] Compared with Example 1, commercially available waste asphalt (purchased from Handan Jiajie Chemical) is used to replace the waste asphalt composite material, the compressive strength is reduced, the antifreeze ability is deteriorated, and the impermeability grade is reduced (Comparative Example 1); Compared with Example 1, the amount of basalt crushed stone in the natural coarse aggregate is changed to 400 parts, and the amount of granite crushed stone is changed to 50 parts. Due to the excessive amount of basalt crushed stone, the compounding effect is not good, the compressive strength is reduced, the antifreeze ability is deteriorated, and the impermeability grade is reduced (Comparative Example 2); Compared with Example 1, the amount of basalt crushed stone in the natural coarse aggregate is changed to 100 parts, and the amount of granite crushed stone is changed to 350 parts. Due to the small amount of basalt crushed stone, the compounding effect is not good, the compressive strength is reduced, the antifreeze ability is deteriorated, and the impermeability grade is reduced (Comparative Example 3); Compared with Example 1, the use of commercial Compared with Example 1, when graphene oxide I was used to replace carboxylated graphene, the compressive strength was reduced, the antifreeze ability was deteriorated, and the anti-permeability grade was reduced (Comparative Example 4); compared with Example 1, when graphene oxide I was used to replace carboxylated graphene, the compressive strength was reduced, the antifreeze ability was deteriorated, and the anti-permeability grade was reduced (Comparative Example 5); compared with Example 1, when graphene oxide II was used to replace graphene oxide I for the preparation of carboxylated graphene, the diameter of graphene oxide II was too large and the modification effect was not good, the compressive strength was reduced, the antifreeze ability was deteriorated, and the anti-permeability grade was reduced (Comparative Example 6); compared with Example 1, when commercially available basalt fiber (article number FD2706) was used to replace modified basalt fiber, the compressive strength was reduced, the antifreeze ability was deteriorated, and the anti-permeability grade was reduced (Comparative Example 7).

[0105] In summary, the present invention selects natural coarse aggregate as the first coarse aggregate, waste asphalt composite material as the second coarse aggregate, and amination river sand as fine aggregate, and uses them together with carboxylated graphene and modified basalt fiber to prepare recycled concrete based on waste asphalt, thereby improving the compressive strength of concrete, increasing frost resistance, and obtaining a good anti-permeability grade.

Claims

1. A method for preparing recycled concrete based on waste asphalt, characterized in that: The following steps are involved: Step S1: heating and melting 500-600 parts of waste asphalt by weight, and then adding 30-36 parts of calcium carbonate and 30-36 parts of SBS rubber for high-speed stirring to obtain a waste asphalt composite material; Step S2: In parts by weight, 400 to 450 parts of natural coarse aggregate, 100 to 140 parts of the waste asphalt composite material, 300 to 400 parts of fine aggregate, 260 to 280 parts of cement and 220 to 240 parts of limestone powder are mixed, and then 16 to 20 parts of graphene, 4 to 8 parts of basalt fiber and 300 to 340 parts of water are added, and the mixture is stirred evenly to obtain a slurry; Step S3: The slurry is injection molded, and then demolded and cured to obtain recycled concrete based on waste asphalt.

2. The method for preparing recycled concrete based on waste asphalt according to claim 1, characterized in that: The calcium carbonate is amino-modified calcium carbonate; The preparation method of the amino-modified calcium carbonate comprises: uniformly dispersing 80-100 parts of calcium carbonate and 360-400 parts of anhydrous ethanol by ultrasonic method, adding 16-20 parts of DL-alanine, stirring at 80-84° C. for 30-40 minutes, filtering, washing with water, and drying to obtain the amino-modified calcium carbonate.

3. The method for preparing recycled concrete based on waste asphalt according to claim 1, characterized in that: The conditions of the high-speed stirring treatment include: a rotation speed of 2800 to 3000 r / min, a temperature of 150 to 160° C., and a time of 60 to 100 min.

4. The method for preparing recycled concrete based on waste asphalt according to claim 1, characterized in that: The natural coarse aggregate is basalt crushed stone and granite crushed stone; the mass ratio of basalt crushed stone to granite crushed stone in the natural coarse aggregate is (1-2):

1.

5. The method for preparing recycled concrete based on waste asphalt according to claim 1, characterized in that: The fine aggregate is amination river sand; The preparation method of the amination river sand comprises: adding 10 to 20 parts of river sand to 200 to 220 parts of deionized water by weight and dispersing the mixture evenly, then adding 4 to 8 parts of 3-aminopropyltriethoxysilane to carry out an amination reaction, and after the amination reaction is completed, centrifuging, washing with water, and drying to obtain the amination river sand.

6. The method for preparing recycled concrete based on waste asphalt according to claim 5, characterized in that: The conditions of the amination reaction include: pH 7.2-7.6, temperature 80-90° C., and time 8-10 hours.

7. The method for preparing recycled concrete based on waste asphalt according to claim 1, characterized in that: The graphene is carboxylated graphene; The preparation method of the carboxylated graphene comprises: dispersing 10 to 16 parts of graphene oxide in 160 to 180 parts of deionized water, and then adding 1 to 3 parts of acrylic acid, 4 to 6 parts of isopentanol polyoxyethylene ether, 0.1 to 0.3 parts of ammonium cerium nitrate and 120 to 140 parts of deionized water, placing in a nitrogen atmosphere, stirring and reacting at 50 to 60° C. for 6 to 8 hours, and freeze-drying to obtain the carboxylated graphene.

8. The method for preparing recycled concrete based on waste asphalt according to claim 7, characterized in that: The diameter of the graphene oxide is 2-8 μm.

9. The method for preparing recycled concrete based on waste asphalt according to claim 1, characterized in that: The basalt fiber is modified basalt fiber; The preparation method of the modified basalt fiber comprises: in parts by weight, 2 to 4 parts of perfluorooctyl triethoxysilane, 3 to 6 parts of tetraethyl orthosilicate, 5 to 7 parts of ammonia water and 190 to 200 parts of anhydrous ethanol are mixed uniformly to obtain a first mixture; 35 to 45 parts of 3-aminopropyl triethoxysilane, 20 to 30 parts of tetraethyl orthosilicate, 20 to 30 parts of anhydrous ethanol and 50 to 60 parts of epoxy resin are mixed and stirred for 4 to 6 hours to obtain a second mixture; 30 to 40 parts of the first mixture and 10 to 14 parts of the second mixture are mixed and ultrasonically dispersed to obtain an impregnation liquid, basalt fiber is immersed in the impregnation liquid for 48 to 72 hours, and dried to obtain the modified basalt fiber.

10. A recycled concrete based on waste asphalt, characterized in that: Prepared according to the method according to any one of claims 1 to 9.

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