Construction waste recycled aggregate concrete and preparation method thereof

Abstract

The application relates to the technical field of concrete, and particularly discloses a construction waste recycled aggregate concrete and a preparation method thereof. The construction waste recycled aggregate concrete comprises the following raw materials in parts by weight: modified recycled aggregate 15-20 parts, polyacrylonitrile fiber 3-5 parts, polycarboxylate high-efficiency water reducing agent 0.2-0.4 parts, calcium silicate 2-4 parts, cement 26-30 parts, water 16-22 parts and gravel 8-10 parts. The modified recycled aggregate is a recycled aggregate modified by alkyl ketene dimer; and the preparation method comprises the following steps: weighing each raw material component, adding cement, gravel, calcium silicate and half of the water into a mixer to obtain a primary mixture, and adding the modified recycled aggregate, the polycarboxylate high-efficiency water reducing agent, polyacrylonitrile fiber and the remaining water into the primary mixture to stir, so as to obtain the construction waste recycled aggregate concrete. The composition disclosed by the application can be used in basic engineering construction and has the advantages of high compressive strength and good crack resistance.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of concrete, in particular to a construction waste recycled aggregate tailing concrete and a preparation method thereof. BACKGROUND

[0002] With the acceleration of global urbanization, the construction industry is facing unprecedented development opportunities, but also facing the dual challenges of resource consumption and environmental pressure. As an indispensable basic material in the construction field, the demand for concrete is growing, but the natural aggregate resources used in its preparation process are becoming increasingly exhausted, and the amount of construction waste is also increasing rapidly. Among the construction waste, abandoned concrete accounts for a considerable proportion. These abandoned concrete is often regarded as useless and is randomly placed or buried, which not only occupies valuable land resources, but also may cause pollution to the surrounding environment, such as soil pollution, water pollution and air pollution. However, from another perspective, abandoned concrete is actually a potential and recyclable resource. Through advanced crushing, screening and reprocessing technologies, abandoned concrete can be converted into recycled aggregate, and then used to prepare recycled concrete, realizing the effective recycling and reuse of resources.

[0003] As an environmentally friendly and sustainable building material, the preparation and application of recycled aggregate concrete have significant environmental and social benefits. However, compared with natural aggregate, recycled aggregate has some deficiencies in performance. Due to the presence of more cracks and defects on the surface of recycled aggregate, the bonding performance between recycled aggregate and cement mortar is poor, which affects the mechanical properties of recycled concrete. SUMMARY

[0004] In order to improve the mechanical properties of recycled concrete, the application provides a construction waste recycled aggregate concrete and a preparation method thereof.

[0005] In the first aspect, the application provides a construction waste recycled aggregate concrete, which adopts the following technical scheme:

[0006] A construction waste recycled aggregate concrete comprises the following raw materials by weight:

[0007] 15-20 parts of modified recycled aggregate, 3-5 parts of polyacrylonitrile fiber, 0.2-0.4 parts of polycarboxylate superplasticizer, 2-4 parts of calcium silicate, 26-30 parts of cement, 16-22 parts of water and 8-10 parts of crushed stone. The modified recycled aggregate is a recycled aggregate modified by alkyl ketene dimer.

[0008] By adopting the technical scheme, the cement hydration degree, microstructure compactness and element content uniformity of the new interface are improved after a proper amount of polyacrylonitrile fiber is mixed. The proper amount of fiber plays a positive role in the uniform distribution and full reaction of water molecules between the cement particles in the curing stage, and the fiber can form a relatively dense network structure with the cement hydration product to enhance the tightness between the phases. Further, the alkyl alkenone dimer is used to modify the recycled aggregate to improve the compatibility and reactivity between the recycled aggregate and the hydration product, and to improve the strength of the interface transition zone. At the same time, the modified recycled aggregate applied to the concrete can play a good compressive strength, and further improve the mechanical properties of the concrete.

[0009] Optionally, the preparation of the modified recycled aggregate comprises the following steps:

[0010] (1) soaking and treating the recycled aggregate with a strong acid to obtain acid-treated recycled aggregate, and then washing, drying and treating the acid-treated recycled aggregate, and then immersing and reacting the treated recycled aggregate in a nanocellulose suspension for 2-3 hours to obtain activated recycled aggregate;

[0011] (2) mixing the resin material and the alkyl alkenone dimer uniformly and then dispersing them in water, immersing and reacting the activated recycled aggregate in the mixture for 2-3 hours, and then naturally air-drying and solidifying the mixture, and then grinding and sieving the mixture to obtain the modified recycled aggregate.

[0012] By adopting the technical scheme, the recycled aggregate is activated by strong acid treatment, and then nanocellulose suspension is introduced for stirring reaction, the high specific surface area of nanocellulose and the C-S-H gel nucleation site are utilized to stimulate the pozzolanic effect of the recycled aggregate, additional C-S-H gel is generated, the 3D skeleton network is formed by the accumulation of the gel, the internal microstructure of the recycled aggregate is strengthened, and the cohesion between the recycled aggregate and the cement hydration product is enhanced by the nanobridge effect. At the same time, the alkyl alkenone dimer added reacts with the active hydroxyl groups on the nanocellulose to form a stable covalent bond film covering the surface of the recycled aggregate, the film can form strong chemical bonds with other components in the concrete raw materials, and the interface compatibility between the recycled aggregate and the mortar is significantly improved, thereby comprehensively improving the performance of the recycled aggregate in the cement-based material.

[0013] Optionally, the weight ratio of the recycled aggregate to the resin material, the powder and the alkyl alkenone dimer in the modification process is 2:1-1.2:0.2:0.1-0.5.

[0014] The mass concentration of the nanocellulose suspension is 2-3 g / L.

[0015] Optionally, 0.2-0.4 parts of rare earth ferrosilicon powder is further added in the step (2).

[0016] By adopting the technical scheme, the rare earth elements and ferrosilicon in the rare earth ferrosilicon powder can refine the crystal grains in the recycled aggregate, and improve the microstructure thereof. The refining effect helps to reduce defects and stress concentration points in the aggregate, thereby improving the compressive strength and toughness and other mechanical properties of the aggregate, and further improving the resistance of the recycled aggregate to deformation and damage, so that the recycled aggregate has higher mechanical properties.

[0017] Optionally, the particle size of the modified recycled aggregate is 5-10mm.

[0018] Optionally, the resin material is polyurethane resin.

[0019] By adopting the technical scheme, the isocyanate and hydroxyl groups contained in the polyurethane can form a polyurethane chemical bond by reacting with the hydroxyl groups on the surface of the modified recycled aggregate, thereby further enhancing the connection between the modified recycled aggregate and the remaining raw materials of the concrete, improving the interfacial compatibility, and better resisting deformation and damage when subjected to external force, thereby improving the mechanical properties of the concrete.

[0020] Optionally, 1-3 parts of an admixture are added to the raw materials, and the admixture is any one of slag, volcanic ash or fly ash.

[0021] By adopting the technical scheme, these industrial materials with certain activity can continuously fill the interface transition zone between the recycled aggregate and the mortar, react with calcium hydroxide to generate new products to fill the pores, and further improve the pore structure of the microstructure at the interface and improve the density.

[0022] In a first aspect, the application provides a preparation method of construction waste recycled aggregate concrete, which adopts the following technical scheme:

[0023] A preparation method of construction waste recycled aggregate concrete, comprising the following steps:

[0024] (1) weighing each raw material component, adding cement, gravel, calcium silicate and half of the water into a mixer for mixing and stirring to obtain a first mixture;

[0025] (2) adding modified recycled aggregate, polycarboxylate superplasticizer, polyacrylonitrile fiber and the remaining water into the first mixture for stirring to obtain the construction waste recycled aggregate concrete.

[0026] In summary, the application has the following beneficial effects:

[0027] 1、Due to the application by incorporating polyacrylonitrile fibers and modified recycled aggregates, the mechanical properties of the concrete are significantly improved. Polyacrylonitrile fibers can form a dense network structure, enhancing the crack resistance and toughness of the concrete; and the modified recycled aggregate can significantly improve the compressive strength and crack resistance of the concrete by optimizing the internal microstructure and improving the interface compatibility.

[0028] 2、In the application, nanocellulose and alkyl enone dimer are preferably used to modify the recycled aggregate. Nanocellulose can react with substances in the recycled aggregate and adhere to the surface of the recycled aggregate, while alkyl enone dimer can interact with nanocellulose to form a film attached to the surface of the recycled aggregate and react with the remaining raw materials in the concrete raw materials. The addition of rare earth silicon iron powder can penetrate into the cracks of the recycled aggregate, repair pores and improve the microstructure, further improving the compressive and crack resistance of the concrete.

[0029] 3、The method of the application uses a large amount of modified recycled aggregate, which is derived from construction waste. Through scientific modification treatment, the waste is reused, and the exploitation of new natural resources is reduced. DETAILED DESCRIPTION

[0030] The application will be further described in detail below in conjunction with the examples.

[0031] Unless otherwise specified in the examples, the routine conditions or the conditions recommended by the manufacturer are used. Unless otherwise specified, the reagents or instruments used are conventional products that can be purchased on the market.

[0032] The portland cement was purchased from Sanhe Yanhong Trade Co., Ltd., with the product code ZP-001; the nanocellulose was purchased from Wuhan Lvjingfenghua Biological Technology Co., Ltd., with the model number CB2311; the polyurethane was purchased from Laizhangshengbang Organic Silicon Technology Co., Ltd., with the model number SI-2045; the alkyl enone dimer was purchased from Shandong Haoyao New Material Co., Ltd., with the model number HY1541; the gravel was obtained by mixing 5mm-10mm and 10mm-20mm gravel at a mass ratio of 3:17; the epoxy resin was purchased from Langfang Nanze Anticorrosion Material Co., Ltd., with the model number E-44; the polyacrylonitrile fiber had a length of 1-2mm; the volcanic ash was purchased from Shijiazhuang Tomaline Mineral Products Co., Ltd., with the bulk density of 4450kg / m 3 ; the slag was purchased from Lingshou Changwang Mineral Processing Factory, with the product code A201902; the fly ash was purchased from Lingshou Shuangshi Mineral Processing Factory, with the density of 2.65g / cm 3 .

[0033] Preparation example of raw materials and / or intermediates

[0034] Preparation example 1

[0035] A modified recycled aggregate, the preparation comprising the following steps:

[0036] (1) Take the nanocellulose into water and control the temperature to 10℃ for ultrasonic treatment for 30min to obtain a nanocellulose suspension with a mass concentration of 2g / L. Add 20kg of recycled aggregate into a mixed strong acid mixed by sulfuric acid and nitric acid at a ratio of 3:1, and ultrasonic immersion treatment for 2h. After washing with water and drying treatment, add the nanocellulose suspension for immersion reaction for 2h to obtain activated recycled aggregate;

[0037] (2) Mix 10kg of polyurethane and 3kg of alkyl enone dimer uniformly, and then disperse them in 20kg of water. Put the activated recycled aggregate into the stirring reaction for 3h, and then naturally air dry and solidify. After grinding and sieving, the modified recycled aggregate with a particle size of 5-10mm is obtained.

[0038] Preparation Example 2

[0039] A modified recycled aggregate, the preparation comprising the following steps:

[0040] (1) Take the nanocellulose into water and control the temperature to 10℃ for ultrasonic treatment for 30min to obtain a nanocellulose suspension with a mass concentration of 2g / L. Add 20kg of recycled aggregate into a mixed strong acid mixed by sulfuric acid and nitric acid at a ratio of 3:1, and ultrasonic immersion treatment for 3h. After washing with water and drying treatment, add the nanocellulose suspension for stirring reaction for 2h to obtain activated recycled aggregate;

[0041] (2) Mix 11kg of polyurethane and 1kg of alkyl enone dimer uniformly, and then disperse them in 20kg of water. Put the activated recycled aggregate into the immersion reaction for 8h, and then take it out for natural air drying and solidification to obtain the modified recycled aggregate.

[0042] Preparation Example 3

[0043] A modified recycled aggregate, the preparation comprising the following steps:

[0044] (1) Take the nanocellulose into water and control the temperature to 10℃ for ultrasonic treatment for 30min to obtain a nanocellulose suspension with a mass concentration of 2g / L. Add 20kg of recycled aggregate into a mixed strong acid mixed by sulfuric acid and nitric acid at a ratio of 3:1, and ultrasonic immersion treatment for 2.5h. After washing with water and drying treatment, add the nanocellulose suspension for stirring reaction for 2h to obtain activated recycled aggregate;

[0045] (2) Mix 12kg of polyurethane and 5kg of alkyl enone dimer uniformly, and then disperse them in 20kg of water. Put the activated recycled aggregate into the immersion reaction for 7.5h, and then take it out for natural air drying and solidification to obtain the modified recycled aggregate.

[0046] Preparation Example 4

[0047] A modified recycled aggregate, different from Preparation Example 1 is that the resin material added in the present preparation example is an epoxy resin.

[0048] Preparation Example 5

[0049] A modified recycled aggregate, different from Preparation Example 1 is that the present preparation example further adds 0.2 kg of rare earth ferrosilicon powder, and the preparation comprises the following steps:

[0050] (1) Take the nanocellulose and put it into water to control the temperature at 10°C and ultrasonic treatment for 30 min to obtain a nanocellulose suspension with a mass concentration of 2 g / L. Add 20 kg of recycled aggregate into a mixed strong acid mixed by sulfuric acid and nitric acid at a ratio of 3:1, ultrasonic immersion treatment for 2 h, and then clean and dry with water. After that, add the nanocellulose suspension into the activated recycled aggregate for impregnation reaction for 2 h to obtain the activated recycled aggregate;

[0051] (2) Mix 10 kg of polyurethane, 0.2 kg of rare earth ferrosilicon powder, and 3 kg of alkyl enone dimer uniformly, and then disperse them in 20 kg of water. Put the activated recycled aggregate into the stirred reaction for 3 h, and then naturally air dry and solidify. After that, grind and sieve to obtain the modified recycled aggregate with a particle size of 5-10 mm.

[0052] Preparation Example 6

[0053] A modified recycled aggregate, different from Preparation Example 1 is that the present preparation example further adds 0.3 kg of rare earth ferrosilicon powder, and the preparation comprises the following steps:

[0054] (1) Take the nanocellulose and put it into water to control the temperature at 10°C and ultrasonic treatment for 30 min to obtain a nanocellulose suspension with a mass concentration of 2 g / L. Add 20 kg of recycled aggregate into a mixed strong acid mixed by sulfuric acid and nitric acid at a ratio of 3:1, ultrasonic immersion treatment for 2 h, and then clean and dry with water. After that, add the nanocellulose suspension into the activated recycled aggregate for impregnation reaction for 2 h to obtain the activated recycled aggregate;

[0055] (2) Mix 10 kg of polyurethane, 0.3 kg of rare earth ferrosilicon powder, and 3 kg of alkyl enone dimer uniformly, and then disperse them in 20 kg of water. Put the activated recycled aggregate into the stirred reaction for 3 h, and then naturally air dry and solidify. After that, grind and sieve to obtain the modified recycled aggregate with a particle size of 5-10 mm.

[0056] Preparation Example 7

[0057] A modified recycled aggregate, different from Preparation Example 1 is that the present preparation example further adds 0.4 kg of rare earth ferrosilicon powder, and the preparation comprises the following steps:

[0058] (1) Take nanocellulose into water to control the temperature to 10℃ and ultrasonic treatment for 30min to obtain nanocellulose suspension with a mass concentration of 2g / L. 20kg of recycled aggregate is added into a mixed strong acid mixed by sulfuric acid and nitric acid at a ratio of 3:1, ultrasonic immersion treatment is carried out for 2h, and then the recycled aggregate is washed with water, dried, and then added into the nanocellulose suspension for immersion reaction for 2h to obtain activated recycled aggregate;

[0059] (2) 10kg of polyurethane, 0.4kg of rare earth ferrosilicon powder and 3kg of alkyl enone dimer are uniformly mixed and then dispersed in 20kg of water. The activated recycled aggregate is put into the stirring reaction for 3h, and then naturally air-dried and solidified. After grinding and sieving, the modified recycled aggregate with a particle size of 5-10mm is obtained.

[0060] Comparative Preparation Example 1

[0061] A modified recycled aggregate, which is different from the preparation example 1 in that no nanocellulose suspension is used to activate the recycled aggregate in this preparation example, specifically comprising the following steps:

[0062] (1) 20kg of recycled aggregate is added into a mixed strong acid mixed by sulfuric acid and nitric acid at a ratio of 3:1, ultrasonic immersion treatment is carried out for 2h, and then the recycled aggregate is washed with water, dried, and then immersed in water for 2h to obtain recycled aggregate;

[0063] (2) 10kg of polyurethane and 3kg of alkyl enone dimer are uniformly mixed and then dispersed in 20kg of water. The above-mentioned recycled aggregate is put into the stirring reaction for 3h, and then naturally air-dried and solidified. After grinding and sieving, the modified recycled aggregate with a particle size of 5-10mm is obtained.

[0064] Comparative Preparation Example 2

[0065] A modified recycled aggregate, which is different from the preparation example 1 in that no alkyl enone dimer is used to treat the recycled aggregate in this preparation example, specifically comprising the following steps:

[0066] (1) Take nanocellulose into water to control the temperature to 10℃ and ultrasonic treatment for 30min to obtain nanocellulose suspension with a mass concentration of 2g / L. 20kg of recycled aggregate is added into a mixed strong acid mixed by sulfuric acid and nitric acid at a ratio of 3:1, ultrasonic immersion treatment is carried out for 2h, and then the recycled aggregate is washed with water, dried, and then added into the nanocellulose suspension for immersion reaction for 2h to obtain activated recycled aggregate;

[0067] (2) 10kg of polyurethane is dispersed in 20kg of water. The activated recycled aggregate is put into the stirring reaction for 3h, and then naturally air-dried and solidified. After grinding and sieving, the modified recycled aggregate with a particle size of 5-10mm is obtained.

[0068] Example

[0069] Example 1

[0070] A construction waste recycled aggregate concrete, the preparation comprising the following steps:

[0071] (1) weighing each raw material component, adding 26 kg of cement, 9 kg of gravel, 3 kg of calcium silicate and 10 kg of water into mixing and stirring to obtain a first mixture;

[0072] (2) adding 17.5 kg of the modified recycled aggregate prepared in Preparation Example 1, 0.3 kg of polycarboxylate superplasticizer, 4 kg of polyacrylonitrile fiber and the remaining 10 kg of water into the above first mixture and stirring uniformly to obtain the construction waste recycled aggregate concrete.

[0073] Example 2

[0074] A construction waste recycled aggregate concrete, the preparation comprising the following steps:

[0075] (1) weighing each raw material component, adding 28 kg of cement, 10 kg of gravel, 2 kg of calcium silicate and 8 kg of water into mixing and stirring to obtain a first mixture;

[0076] (2) adding 15 kg of the modified recycled aggregate prepared in Preparation Example 3, 0.4 kg of polycarboxylate superplasticizer, 5 kg of polyacrylonitrile fiber and the remaining 8 kg of water into the above first mixture and stirring uniformly to obtain the construction waste recycled aggregate concrete.

[0077] Example 3

[0078] A construction waste recycled aggregate concrete, the preparation comprising the following steps:

[0079] (1) weighing each raw material component, adding 30 kg of cement, 8 kg of gravel, 4 kg of calcium silicate and 11 kg of water into mixing and stirring to obtain a first mixture;

[0080] (2) adding 20 kg of the modified recycled aggregate prepared in Preparation Example 2, 0.2 kg of polycarboxylate superplasticizer, 3 kg of polyacrylonitrile fiber and the remaining 11 kg of water into the above first mixture and stirring uniformly to obtain the construction waste recycled aggregate concrete.

[0081] Example 4

[0082] A construction waste recycled aggregate concrete, which is different from Example 1 in that the modified recycled aggregate added in the present example is prepared in Preparation Example 4.

[0083] Example 5

[0084] A construction waste recycled aggregate concrete, which is different from Example 1 in that the modified recycled aggregate added in the present example is prepared in Preparation Example 5.

[0085] Example 6

[0086] A construction waste recycled aggregate concrete, which is different from Example 1 in that the modified recycled aggregate added in the present example is prepared in Preparation Example 6.

[0087] Example 7

[0088] A construction waste recycled aggregate concrete, which is different from Example 1 in that the modified recycled aggregate added in the present example is prepared in Preparation Example 7.

[0089] Example 8

[0090] A construction waste recycled aggregate concrete, which is different from Example 1 in that 1 kg of volcanic ash is further added in the raw materials of the present example, and the preparation comprises the following steps:

[0091] (1) weigh each raw material component, add 26 kg of cement, 9 kg of gravel, 1 kg of volcanic ash, 3 kg of calcium silicate, and 10 kg of water into mixing and stirring to obtain a first mixture;

[0092] (2) add 17.5 kg of the modified recycled aggregate prepared in Preparation Example 1, 0.3 kg of polycarboxylate superplasticizer, 4 kg of polyacrylonitrile fiber, and the remaining 10 kg of water into the above first mixture and stir uniformly to obtain the construction waste recycled aggregate concrete.

[0093] Example 9

[0094] A construction waste recycled aggregate concrete, which is different from Example 1 in that 2 kg of fly ash is further added in the raw materials of the present example, and the preparation comprises the following steps:

[0095] (1) weigh each raw material component, add 26 kg of cement, 9 kg of gravel, 2 kg of fly ash, 3 kg of calcium silicate, and 10 kg of water into mixing and stirring to obtain a first mixture;

[0096] (2) add 17.5 kg of the modified recycled aggregate prepared in Preparation Example 1, 0.3 kg of polycarboxylate superplasticizer, 4 kg of polyacrylonitrile fiber, and the remaining 10 kg of water into the above first mixture and stir uniformly to obtain the construction waste recycled aggregate concrete.

[0097] Example 10

[0098] A construction waste recycled aggregate concrete, which is different from Example 1 in that 3 kg of slag is further added in the raw materials of the present example, and the preparation comprises the following steps:

[0099] (1) Weigh each raw material component, add 26 kg of cement, 9 kg of gravel, 3 kg of slag, 3 kg of calcium silicate, and 10 kg of water into the mixer and mix to obtain a first mixture;

[0100] (2) Add 17.5 kg of the modified recycled aggregate prepared in Preparation Example 1, 0.3 kg of polycarboxylate superplasticizer, 4 kg of polyacrylonitrile fiber, and the remaining 10 kg of water to the above first mixture and mix uniformly to obtain the construction waste recycled aggregate concrete.

[0101] Comparative Example

[0102] Comparative Example 1

[0103] A construction waste recycled aggregate concrete, which is different from Example 1 in that the recycled aggregate added in the present comparative example is not modified.

[0104] Comparative Example 2

[0105] A construction waste recycled aggregate concrete, which is different from Example 1 in that the modified recycled aggregate used in the present comparative example is prepared in Comparative Preparation Example 1.

[0106] Comparative Example 3

[0107] A construction waste recycled aggregate concrete, which is different from Example 1 in that the modified recycled aggregate used in the present comparative example is prepared in Comparative Preparation Example 2.

[0108] Performance Test

[0109] Test Method

[0110] The 7d and 28d compressive strength and splitting tensile strength of the hardened concrete were tested according to the test method of the national standard GB / T50081—2019 “Standard for Test Methods of Mechanical Properties of Ordinary Concrete”. The test sample was molded by a 100mm×100mm×100mm mold and mechanically vibrated for 10s, and the test was carried out by standard curing to the specified age.

[0111] Table 1 Test Data

[0112]

[0113]

[0114] It can be seen from Examples 1-3 and Comparative Example 1 and Table 1 that the experimental data of Examples 1-3 are better than those of Comparative Example 1, which shows that the modification of the recycled aggregate can improve the structure of the interface transition zone between the recycled aggregate and the cement mortar, increase the density and bonding strength of the interface transition zone, and thus improve the compressive strength and splitting tensile strength of the concrete.

[0115] It can be seen from the combination of embodiments 1-3 and comparative examples 2-3 and table 1 that the experimental data of embodiments 1-3 are all better than those of comparative examples 2-3, which shows that the use of nanocellulose to pre-activate the recycled aggregate and then further modified by alkyl alkene ketone dimers can greatly improve the performance of the recycled aggregate, improve the compatibility between the recycled aggregate and the remaining raw materials, and thus improve the compressive strength and splitting tensile strength of the concrete.

[0116] It can be seen from the combination of embodiments 1-4 and table 1 that the experimental data of embodiments 1-3 are all better than those of embodiment 4, which shows that the selection of resin material affects the modification effect on the recycled aggregate, and the use of polyurethane as the resin material can react with the hydroxyl groups on the surface of the modified recycled aggregate to form polyurethane chemical bonds, thereby bonding with the remaining raw materials in the concrete to improve the connection strength and thus improve the mechanical properties of the concrete.

[0117] It can be seen from the combination of embodiments 1 and embodiments 5-7 and table 1 that the experimental data of embodiments 5-7 are all better than those of embodiment 1, which shows that rare earth silicon iron powder can further fill the cracks of recycled aggregate, improve its structural defects, and improve its strength, thereby improving the performance of the concrete.

[0118] It can be seen from the combination of embodiments 1 and embodiments 8-10 and table 1 that the experimental data of embodiments 8-10 are all better than those of embodiment 1, which shows that the addition of active admixture can further fill the pores in the interfacial transition zone, improve the microstructure at the interface, and improve the compressive strength of the concrete.

[0119] The specific embodiments are only an explanation of the present application, and are not a limitation of the present application. Those skilled in the art can make modifications to the embodiments without creative contribution after reading the present specification, but as long as the modifications are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A construction waste recycled aggregate concrete, characterized by, The raw materials include the following weight parts: 15-20 parts of modified recycled aggregate, 3-5 parts of polyacrylonitrile fiber, 0.2-0.4 parts of polycarboxylate superplasticizer, 2-4 parts of calcium silicate, 26-30 parts of cement, 16-22 parts of water, and 8-10 parts of gravel; the modified recycled aggregate is a recycled aggregate modified by alkyl ketene dimer; The preparation of the modified recycled aggregate includes the following steps: (1) soaking the recycled aggregate by using strong acid to obtain acid-treated recycled aggregate, washing and drying the acid-treated recycled aggregate, and then adding nanocellulose suspension to impregnate the acid-treated recycled aggregate for 2-3 hours to obtain activated recycled aggregate; (2) mixing resin material and alkyl ketene dimer uniformly and dispersing them in water, putting the activated recycled aggregate into the mixture and stirring for 2-3 hours, naturally air-drying and solidifying, grinding and sieving to obtain the modified recycled aggregate.

2. A recycled aggregate concrete according to claim 1, characterised in that: 0.2-0.4 parts of rare earth ferrosilicon powder are further added in the step (2).

3. A recycled construction and demolition waste aggregate concrete according to claim 2, wherein: The weight ratio of the recycled aggregate to the resin material, the powder, and the alkyl ketene dimer in the modification process is 2:1-1.2:0.2:0.1-0.

5. The mass concentration of the nanocellulose suspension is 2-3 g / L.

4. The construction waste recycled aggregate concrete according to claim 1, characterized in that: The particle size of the modified recycled aggregate is 5-10 mm.

5. The construction waste recycled aggregate concrete according to claim 1, characterized in that: The resin material is polyurethane resin.

6. The construction waste recycled aggregate concrete as claimed in claim 1, wherein: 1-3 parts of admixture are further added in the raw materials, and the admixture is any one of slag, volcanic ash, or fly ash.

7. A method of producing a construction waste recycled aggregate concrete according to any one of claims 1 to 5, characterized in that, The method includes the following steps: (1) weighing each raw material component, adding cement, gravel, calcium silicate, and half of the water into a mixer and stirring to obtain a first mixture; (2) adding the modified recycled aggregate, the polycarboxylate superplasticizer, the polyacrylonitrile fiber, and the remaining water into the first mixture and stirring to obtain the building waste recycled aggregate concrete.

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