Multi-element solid waste-based recycled concrete and preparation method thereof

Abstract

This invention discloses a method for preparing multi-component solid waste-based recycled concrete. The raw material formula includes the following components in the indicated mass proportions: 63-105 parts silicate cement clinker, 189-273 parts composite modified cementitious material, 21-42 parts ultrafine slag powder, 21-42 parts granulated blast furnace slag powder, 198-461 parts modified recycled coarse aggregate, 141-283 parts modified recycled fine aggregate, 857-1120 parts crushed stone, 283-424 parts fine sand, 0.42-1.26 parts polycarboxylate superplasticizer, and 147 parts water. Its advantages are: 1) It can significantly improve the compressive strength of concrete materials. Experiments have shown that the multi-component solid waste-based recycled concrete prepared by the method of this invention has a 3-day compressive strength ≥15.0 MPa, a 7-day compressive strength ≥20.0 MPa, and a 28-day compressive strength ≥40.0 MPa. 2) It realizes the comprehensive utilization of various industrial and construction solid wastes.

Description

Technical Field

[0001] This invention relates to concrete production technology, and more particularly to a solid waste-based recycled concrete technology. Background Technology

[0002] Concrete is one of the most widely used building materials in society today. As a structural material, it is generally composed of water, aggregates, cement and mineral admixtures. After hydration and hardening, it forms a building material that meets the service requirements such as safety and durability. Concrete is widely used in civil buildings, public infrastructure construction, bridges and other concrete engineering construction. With the development of construction technology and the demand for low-carbon development in the construction industry, higher requirements have been put forward for the performance of concrete, including green and low-carbon, energy-saving and environmentally friendly, good mechanical properties, high durability and high workability.

[0003] Cement, the main material of ordinary concrete, is a high-carbon emission product, with carbon emissions reaching 0.732 tons of CO2 per ton of cement produced. However, cement alone accounts for approximately 10-12% of the total carbon emissions in China. Reducing the amount of high-carbon-emission cement per unit volume of concrete and replacing traditional high-carbon-emission cement with solid waste-based cementitious materials is a crucial path to achieving low-carbon development. Phosphorus slag, mineral powder, and ultrafine construction slag powder possess potential hydration activity and can achieve hydration and self-hardening under activating conditions. Using them as solid waste-based cementitious materials can achieve green and harmless disposal of these solid wastes while significantly reducing the carbon emissions of concrete. Besides cementitious materials and water, aggregates are also a major component of concrete, accounting for approximately 50%-80% of the concrete volume. Recycled aggregates are construction waste generated during infrastructure construction. The preparation of recycled aggregates from the massive volume of construction waste for use in concrete represents an important direction for its resource utilization.

[0004] Although the aforementioned solid wastes have certain utilization value, due to the special physicochemical properties of solid wastes themselves, they are difficult to apply directly. For example, phosphorus slag has problems such as slow setting and low early strength, while recycled aggregates have disadvantages such as high porosity, high water absorption, and low strength. They need to be pretreated and composited to achieve their effective application in concrete.

[0005] Therefore, based on the above problems, this invention modifies various solid waste materials and utilizes industrial solid waste and construction solid waste in a synergistic manner, giving full play to the self-modification of various solid wastes and their synergistic effects, and prepares multi-element solid waste-based recycled concrete, which is an effective way to achieve the synergistic disposal of solid waste resources. Summary of the Invention

[0006] To improve the compressive strength of concrete, this invention provides a multi-element solid waste-based recycled concrete and its preparation method.

[0007] The technical solution adopted in this invention is: a method for preparing multi-component solid waste-based recycled concrete. The raw material formula includes the following components in the following mass proportions: 63-105 parts of silicate cement clinker, 189-273 parts of composite modified cementitious material, 21-42 parts of ultrafine slag powder, 21-42 parts of granulated blast furnace slag powder, 198-461 parts of modified recycled coarse aggregate, 141-283 parts of modified recycled fine aggregate, 857-1120 parts of crushed stone, 283-424 parts of fine sand, 0.42-1.26 parts of polycarboxylate superplasticizer, and 147 parts of water.

[0008] The composite modified cementitious material is composed of electric furnace refining slag powder and modified electric furnace phosphorus slag powder in a mass ratio of 1:1.2 to 2.7;

[0009] The modified electric furnace phosphorus slag powder is composed of electric furnace phosphorus slag powder and a modifying component in a mass ratio of 27.3 to 79.6:1. The modifying component is composed of CSH nanocrystal nuclei and diethanol monoisopropanolamine in a mass ratio of 5 to 420:1.

[0010] Partial component descriptions:

[0011] The electric furnace refining slag powder described in this invention refers to the water-quenched slag produced by the electric furnace refining steel quenching process. This water-quenched slag, after being ground, becomes the electric furnace refining slag powder described in this invention. It should be noted that the electric furnace refining slag powder of this invention is different from the "steel slag" commonly referred to in the art. Steel slag refers to the general term for various oxides formed by the oxidation of impurities in pig iron during the smelting process, as well as the mixture composed of salts formed by the reaction of these oxides with solvents. Its source, composition, and properties are significantly different from the electric furnace refining slag powder of this invention.

[0012] The electric furnace phosphorus slag powder mentioned in this invention refers to the waste residue generated after the yellow phosphorus is produced by electric furnace method and discharged and water quenched. The electric furnace phosphorus slag powder is obtained by grinding the waste residue.

[0013] The ultrafine construction slag powder described in this invention refers to waste concrete or waste mortar that has been crushed, further ground, and sieved after removing impurities such as plastics, paper, and wood chips. 50 It is a powder with a particle size of 5–15 μm, namely the ultrafine slag powder mentioned above.

[0014] As will be readily understood by those skilled in the art, the granulated blast furnace slag powder of the present invention is obtained by drying and grinding granulated blast furnace slag that conforms to the GB / T203 standard.

[0015] As will be readily understood by those skilled in the art, the water described in this invention is water that conforms to the "Standard for Water Used in Concrete" (JGJ63).

[0016] As a further improvement of the present invention, the electric furnace refining slag powder satisfies the following condition: density ≥ 2.8 g / cm³.3 Specific surface area ≥ 400m² 2 / kg, chloride ion mass fraction ≤0.06%, sulfur trioxide mass fraction ≤3%, free calcium oxide mass fraction ≤4%, 6h autoclaving expansion rate ≤0.5%, internal irradiance index IRa ≤1.0, external irradiance index Iγ ≤1.0.

[0017] As a further improvement of the present invention, the electric furnace phosphorus slag powder satisfies the following condition: specific surface area ≥ 400 m². 2 / kg, Irradiance I Ra ≤1.3, Irradiance Index γ ≤1.3.

[0018] As a further improvement of the present invention, the silicate cement clinker meets the following requirements: C3S mass fraction ≥ 50%, total C3S and C2S mass fraction ≥ 66%, 3-day compressive strength ≥ 26.0 MPa, and 28-day compressive strength ≥ 52.5 MPa. The present invention uses silicate cement clinker as an early-strength component and strength-activating component in concrete. The C3S and C2S in the clinker possess hydraulic properties, which not only contribute to good strength but also, upon hydration, produce calcium hydroxide that has an alkali-activating effect on phosphorus slag and electric furnace refining slag. An appropriate amount of cement clinker is beneficial for better activating the activity of phosphorus slag powder and electric furnace refining slag powder, promoting their strength formation, and enhancing the early-stage activity of concrete.

[0019] As a further improvement of the present invention, the ultrafine slag powder satisfies: D 50 Its diameter is 5–15 μm, and its specific surface area is ≥900 m². 2 / kg, water requirement ≤105%, 28-day activity index ≥70%, methylene blue MB value <1.4, chloride ion mass fraction ≤0.06%, sulfur trioxide mass fraction ≤3%. Ultrafine construction waste powder exhibits a micro-aggregate effect, filling voids within the slurry and improving the workability of freshly mixed slurry. Simultaneously, construction waste contains unhydrated cement particles, calcium hydroxide, and other active components, possessing a certain degree of hydration activity. This allows for the reuse of unhydrated cement particles and other components from recycled construction waste, increasing the early strength of cement-based materials.

[0020] As a further improvement of the present invention, the granulated blast furnace slag powder satisfies the following condition: density ≥ 2.8 g / cm³. 3 Specific surface area ≥ 400 m² 2 / kg, 28d activity index ≥95%, vitreous body mass fraction ≥85%, sulfur trioxide mass fraction ≤4%, chloride ion mass fraction ≤0.06%, internal irradiation index I Ra ≤1, Irradiance Index γ ≤1. This invention uses granulated blast furnace slag powder as an auxiliary cementitious material, which has high hydration activity and can effectively improve the strength of concrete.

[0021] The modified recycled coarse aggregate and modified recycled fine aggregate of the present invention can be prepared according to the following method:

[0022] S1. After crushing the waste concrete test blocks with original strength grades of C30 to C60, they are graded and shaped to obtain recycled coarse aggregate and recycled fine aggregate.

[0023] S2. The recycled coarse aggregate and recycled fine aggregate are soaked in a mixed solution of sodium silicate and polyvinyl alcohol for more than 2 hours, and then dried to obtain the final product. The mixed solution contains 8% to 10% sodium silicate and 6% to 10% polyvinyl alcohol by mass.

[0024] The modified recycled aggregate in this scheme undergoes particle shaping and pre-impregnation treatment, which removes the unstable old mortar surface layer on the one hand and strengthens the stable structure on the other, thus achieving the strengthening of the recycled aggregate.

[0025] As a further improvement of the present invention, the fine sand is a continuous particle size distribution sand with a particle size of less than 5 mm and an MB value of less than 1.4.

[0026] As a further improvement of the present invention, the crushed stone is rock particles with a particle size greater than 4.75 mm. The crushed stone is rock particles produced by mechanical processing such as crushing and screening of natural rocks, pebbles, or mine waste rock, and its properties meet the requirements of GB / T 14685 "Construction Pebbles and Crushed Stone".

[0027] The present invention also discloses a multi-component solid waste-based recycled concrete, which is prepared by the preparation method of the multi-component solid waste-based recycled concrete of the present invention.

[0028] The beneficial effects of this invention are: 1) It can significantly improve the compressive strength of concrete materials. Experiments have shown that the 3-day compressive strength of recycled concrete based on multi-element solid waste prepared by the method of this invention is ≥15.0 MPa, the 7-day compressive strength is ≥20.0 MPa, and the 28-day compressive strength is ≥40.0 MPa. 2) It realizes the comprehensive utilization of various industrial solid wastes and construction solid wastes. Detailed Implementation

[0029] The present invention will be further described below with reference to embodiments.

[0030] For ease of comparison, the following examples and comparative examples all use the same batch of raw materials, and the properties of each raw material are as follows:

[0031] Electric furnace refining slag powder: density 2.85 g / cm³ 3 Specific surface area 429m² 2 / kg, chloride ion mass fraction 0.02%, sulfur trioxide mass fraction 1.1%, free calcium oxide mass fraction 1.2%, 6h autoclaving expansion rate 0.22%, internal irradiance index IRa = 0.2, external irradiance index Iγ = 0.2.

[0032] Electric furnace phosphorus slag powder: Chemical composition (mass fraction): CaO = 51%, SiO2 = 42%, P2O5 = 1.2%, Al2O3 = 7%, Fe2O3 = 2.5%, F = 1%; Specific surface area 443 m² 2 / kg, Irradiance I Ra =1.1, Irradiance Index γ =0.8.

[0033] Silicate cement clinker: C3S mass fraction 61%, total mass fraction of C3S and C2S 72%, 3-day compressive strength 29.0 MPa, 28-day compressive strength 52.7 MPa.

[0034] Ultrafine construction waste powder: D 50 =7.3μm, specific surface area 954m² 2 / kg, water requirement ratio 102%, 28-day activity index 73%, methylene blue MB value 1.2, chloride ion mass fraction 0.01%, sulfur trioxide mass fraction 1.2%.

[0035] Granulated blast furnace slag powder: density 2.86 g / cm³ 3 Specific surface area 449m² 2 / kg, 28d activity index 103%, vitreous body mass fraction 91%, sulfur trioxide mass fraction 1.3%, chloride ion mass fraction 0.02%, internal irradiation index I Ra =0.7, Irradiance Index γ =0.5.

[0036] Polycarboxylate superplasticizer: Polycarboxylate superplasticizer with a moisture content of 1.0% and a water reduction rate of 40%.

[0037] Fine sand: continuous particle size distribution with a particle size of less than 5 mm and an MB value of 0.9.

[0038] Crushed stone: Rock particles with a diameter greater than 4.75 mm.

[0039] Water: Tap water that meets the "Standard for Water Used in Concrete" (JGJ63-2006).

[0040] Modified recycled coarse aggregate and modified recycled fine aggregate: prepared according to the following method:

[0041] Waste concrete test blocks with original strength grades of C30 to C60 were selected, impurities were removed, and then crushed. The recycled aggregate was then screened according to the requirements of GB / T 25177-2010 "Recycled Coarse Aggregate for Concrete" and GB / T25176-2010 "Recycled Fine Aggregate for Concrete and Mortar". The crushed recycled aggregate was then screened according to particle size. The screened recycled aggregate was then shaped to remove unstable old mortar surface particles, resulting in recycled coarse aggregate and recycled fine aggregate.

[0042] Then, the recycled coarse aggregate and recycled fine aggregate were soaked in a mixed solution of sodium silicate and polyvinyl alcohol for 4 hours, and then dried in an oven at 40°C. The mixed solution contained 8% sodium silicate and 7% polyvinyl alcohol by mass.

[0043] Example 1:

[0044] Multi-component solid waste-based recycled concrete was prepared using the following method:

[0045] (1) Take the following components according to the production raw material formula:

[0046] The mixture comprises 105 parts silicate cement clinker, 233 parts composite modified cementitious material, 42 parts ultrafine slag powder, 42 parts granulated blast furnace slag powder, 198 parts modified recycled coarse aggregate, 141 parts modified recycled fine aggregate, 1120 parts crushed stone, 424 parts fine sand, 1.26 parts polycarboxylate superplasticizer, and 147 parts water. The composite modified cementitious material is composed of electric furnace refined slag powder and modified electric furnace phosphorus slag powder in a mass ratio of 1:1.78. The modified electric furnace phosphorus slag powder is composed of electric furnace phosphorus slag powder and a modifying component in a mass ratio of 69.7:1. The modifying component is composed of CSH nanocrystal nuclei (14.3% solid content) and diethanol monoisopropanolamine in a mass ratio of 210:1. After uniformly mixing all the above raw materials, a multi-component solid waste-based recycled concrete is obtained.

[0047] (2) The prepared concrete was poured into a 100mm×100mm×100mm mold, vibrated to compact it, and then placed in a standard curing room for curing at a relative humidity of ≥95% for 24 hours. After demolding, the test blocks were placed in the above standard curing environment for curing to the specified age (3d, 7d, 28d) and then their mechanical properties were tested. The testing method was carried out in accordance with the current standard "Standard for Test Methods of Mechanical Properties of Ordinary Concrete" GB / T 50081.

[0048] The test results are shown in Table 1.

[0049] Example 2:

[0050] Multi-component solid waste-based recycled concrete was prepared using the following method:

[0051] (1) Take the following components according to the production raw material formula:

[0052] The mixture comprises 105 parts silicate cement clinker, 235 parts composite modified cementitious material, 42 parts ultrafine slag powder, 42 parts granulated blast furnace slag powder, 198 parts modified recycled coarse aggregate, 141 parts modified recycled fine aggregate, 1120 parts crushed stone, 424 parts fine sand, 1.26 parts polycarboxylate superplasticizer, and 147 parts water. The composite modified cementitious material is composed of electric furnace refined slag powder and modified electric furnace phosphorus slag powder in a mass ratio of 1:1.24. The modified electric furnace phosphorus slag powder is composed of electric furnace phosphorus slag powder and a modifying component in a mass ratio of 33.8:1. The modifying component is composed of CSH nanocrystal nuclei (14.3% solid content) and diethanol monoisopropanolamine in a mass ratio of 123:1. After uniformly mixing all the above raw materials, a multi-component solid waste-based recycled concrete is obtained.

[0053] (2) The detection method is the same as in Example 1, and the detection results are shown in Table 1.

[0054] Example 3:

[0055] Multi-component solid waste-based recycled concrete was prepared using the following method:

[0056] (1) Take the following components according to the production raw material formula:

[0057] The mixture comprises 105 parts silicate cement clinker, 233 parts composite modified cementitious material, 42 parts ultrafine slag powder, 42 parts granulated blast furnace slag powder, 330 parts modified recycled coarse aggregate, 198 parts modified recycled fine aggregate, 989 parts crushed stone, 367 parts fine sand, 1.26 parts polycarboxylate superplasticizer, and 147 parts water. The composite modified cementitious material is composed of electric furnace refined slag powder and modified electric furnace phosphorus slag powder in a mass ratio of 1:1.78. The modified electric furnace phosphorus slag powder is composed of electric furnace phosphorus slag powder and a modifying component in a mass ratio of 69.7:1. The modifying component is composed of CSH nanocrystal nuclei (14.3% solid content) and diethanol monoisopropanolamine in a mass ratio of 210:1. After uniformly mixing all the above raw materials, a multi-component solid waste-based recycled concrete is obtained.

[0058] (2) The detection method is the same as in Example 1, and the detection results are shown in Table 1.

[0059] Comparative Example 1:

[0060] This comparative example is a control experiment of Example 1, carried out according to the same steps and conditions as Example 1. All raw materials are from the same batch as in Example 1. The only difference is that the composite modified cementitious material is all modified electric furnace phosphorus slag powder (electric furnace refining slag powder is not used), and the total amount of composite modified cementitious material used is still 233 parts.

[0061] The detection method is the same as in Example 1, and the detection results are shown in Table 1.

[0062] Comparative Example 2:

[0063] This comparative example is a control experiment of Example 1, carried out according to the same steps and conditions as Example 1. All raw materials are from the same batch as in Example 1. The only difference is that all the composite modified cementitious materials are electric furnace refined slag powder (without using modified electric furnace phosphorus slag powder), and the total amount of composite modified cementitious materials used is still 233 parts.

[0064] The detection method is the same as in Example 1, and the detection results are shown in Table 1.

[0065] Comparative Example 3:

[0066] This comparative example is a control experiment of Example 1, carried out according to the same steps and conditions as Example 1. All raw materials are from the same batch as in Example 1. The only difference is that the electric furnace phosphorus slag powder has not been modified, and the amount used is the same as that of the modified electric furnace phosphorus slag powder in Example 1.

[0067] The detection method is the same as in Example 1, and the detection results are shown in Table 1.

[0068] Comparative Example 4:

[0069] This comparative example is a control experiment of Example 1, carried out according to the same steps and conditions as Example 1. All raw materials are from the same batch as in Example 1. The only difference is that all the composite modified cementitious materials are unmodified electric furnace phosphorus slag powder (without using electric furnace refined slag powder), and the total amount of composite modified cementitious materials used is still 233 parts.

[0070] The detection method is the same as in Example 1, and the detection results are shown in Table 1.

[0071] Comparative Example 5:

[0072] This comparative example is a control experiment of Example 1, carried out according to the same steps and conditions as Example 1. All raw materials are from the same batch as in Example 1. The only difference is that the modified recycled coarse aggregate and modified recycled fine aggregate are replaced with equal masses of recycled coarse aggregate and recycled fine aggregate that have not been soaked in the mixed solution.

[0073] The detection method is the same as in Example 1, and the detection results are shown in Table 1.

[0074] Comparative Example 6:

[0075] This comparative example serves as a control experiment for Example 1, conducted according to the same steps and conditions. All raw materials were from the same batch as in Example 1, the only difference being that the electric furnace refining slag powder was replaced with an equal mass of 433 m² specific surface area. 2 / kg of steel slag powder.

[0076] The detection method is the same as in Example 1, and the detection results are shown in Table 1.

[0077] Comparative Example 7:

[0078] This comparative example is a control experiment of Example 1, carried out according to the same steps and conditions as Example 1. All raw materials are from the same batch as in Example 1. The only difference is that the silicate cement clinker, composite modified cementitious material, ultrafine slag powder and granulated blast furnace slag powder in the raw materials are replaced with an equal mass of modified electric furnace phosphorus slag powder. After the replacement, the raw material formula contains a total of 420 parts of modified electric furnace phosphorus slag powder.

[0079] The detection method is the same as in Example 1, and the detection results are shown in Table 1.

[0080] Comparative Example 8:

[0081] This comparative example is a control experiment of Example 1, carried out according to the same steps and conditions as Example 1. All raw materials are from the same batch as in Example 1. The only difference is that the crushed stone in the raw materials is replaced with an equal mass of modified recycled coarse aggregate, and the fine sand is replaced with an equal mass of modified recycled fine aggregate. After the replacement, the modified recycled coarse aggregate in the raw material formula increases to 1318 parts and the modified recycled fine aggregate increases to 565 parts.

[0082] The detection method is the same as in Example 1, and the detection results are shown in Table 1.

[0083] Table 1. Results of compressive strength tests on concrete materials in the examples and comparative examples.

[0084]

[0085] As can be seen from the test results of Examples 1, 2 and 3 in Table 1, the multi-element solid waste-based recycled concrete prepared by the method of the present invention has a 3-day compressive strength > 15.0 MPa, a 7-day compressive strength > 22 MPa and a 28-day compressive strength > 43 MPa, and has excellent compressive performance.

[0086] The comparison of the test results of Example 1, Comparative Example 1, and Comparative Example 2 in Table 1 shows that, under the premise that the total amount of composite modified cementitious material used remains unchanged, the compressive strengths of Comparative Example 1, which uses modified electric furnace slag powder alone, at different ages are 9.3, 14.5, and 35.8 MPa, respectively. The compressive strengths of Comparative Example 2, which uses electric furnace refined slag powder alone, at different ages are 12.1, 16.4, and 32.1 MPa, respectively. Calculations show that when the two are used together in a mass ratio of electric furnace refined slag powder: modified electric furnace slag powder = 1:1.78, the theoretical compressive strengths at different ages should be 10.3, 15.2, and 34.5 MPa. However, the actual measured values ​​are 18.7, 29.7, and 58.3 MPa, which are much higher than the theoretical values. This indicates that the composite modified cementitious material composed of modified electric furnace slag powder and electric furnace refined slag powder has a significant synergistic effect in improving the compressive strength of concrete.

[0087] The test results of Comparative Examples 2, 3, and 4 show that the compressive strength of concrete using electric furnace refining slag alone and unmodified electric furnace phosphorus slag alone is not ideal. However, when the two are used in combination, the compressive strength of the concrete is close to the theoretical value, and no obvious synergistic effect is shown.

[0088] As can be seen from the comparison between Example 1 and Comparative Example 6, when the electric furnace refining slag is replaced with steel slag, the compressive strength of the concrete is significantly reduced, indicating that steel slag cannot be used in the system of the present invention.

Claims

1. A method for preparing multi-element solid waste-based recycled concrete, characterized in that, The raw materials for production include the following components in the following mass proportions: 63-105 parts silicate cement clinker, 189-273 parts composite modified cementitious material, 21-42 parts ultrafine slag powder, 21-42 parts granulated blast furnace slag powder, 198-461 parts modified recycled coarse aggregate, 141-283 parts modified recycled fine aggregate, 857-1120 parts crushed stone, 283-424 parts fine sand, 0.42-1.26 parts polycarboxylate superplasticizer, and 147 parts water. The composite modified cementitious material is composed of electric furnace refining slag powder and modified electric furnace phosphorus slag powder in a mass ratio of 1:1.2 to 2.7; The modified electric furnace phosphorus slag powder is composed of electric furnace phosphorus slag powder and a modifying component in a mass ratio of 27.3 to 79.6:

1. The modifying component is composed of CSH nanocrystal nuclei and diethanol monoisopropanolamine in a mass ratio of 5 to 420:

1. The components are measured according to the above-mentioned raw materials, and the raw materials are mixed evenly to obtain multi-component solid waste-based recycled concrete.

2. The method for preparing multi-element solid waste-based recycled concrete according to claim 1, characterized in that, The electric furnace refining slag powder meets the following requirements: density ≥ 2.8 g / cm³. 3 Specific surface area ≥ 400m² 2 / kg, chloride ion mass fraction ≤0.06%, sulfur trioxide mass fraction ≤3%, free calcium oxide mass fraction ≤4%, 6h autoclaving expansion rate ≤0.5%, internal irradiance index I Ra ≤1.0, Irradiance Index γ ≤1.

0.

3. The method for preparing multi-element solid waste-based recycled concrete according to claim 1, characterized in that, The electric furnace phosphorus slag powder meets the following requirement: specific surface area ≥ 400 m² 2 / kg, Irradiance I Ra ≤1.3, Irradiance Index γ ≤1.

3.

4. The method for preparing multi-element solid waste-based recycled concrete according to claim 1, characterized in that, The silicate cement clinker meets the following requirements: C3S mass fraction ≥ 50%, total mass fraction of C3S and C2S ≥ 66%, 3-day compressive strength ≥ 26.0 MPa, and 28-day compressive strength ≥ 52.5 MPa.

5. The method for preparing multi-element solid waste-based recycled concrete according to claim 1, characterized in that, The ultrafine slag powder satisfies: D 50 Its diameter is 5–15 μm, and its specific surface area is ≥900 m². 2 / kg, water requirement ratio ≤105%, 28d activity index ≥70%, methylene blue MB value <1.4, chloride ion mass fraction ≤0.06%, sulfur trioxide mass fraction ≤3%.

6. The method for preparing multi-element solid waste-based recycled concrete according to claim 1, characterized in that, The granulated blast furnace slag powder meets the following requirement: density ≥ 2.8 g / cm³. 3 Specific surface area ≥ 400 m² 2 / kg, 28d activity index ≥95%, vitreous body mass fraction ≥85%, sulfur trioxide mass fraction ≤4%, chloride ion mass fraction ≤0.06%, internal irradiation index I Ra ≤1, Irradiance Index γ ≤1.

7. The method for preparing multi-element solid waste-based recycled concrete according to any one of claims 1 to 6, characterized in that, The preparation methods of the modified recycled coarse aggregate and the modified recycled fine aggregate are as follows: S1. After crushing the waste concrete test blocks with original strength grades of C30 to C60, they are graded and shaped to obtain recycled coarse aggregate and recycled fine aggregate. S2. The recycled coarse aggregate and recycled fine aggregate are soaked in a mixed solution of sodium silicate and polyvinyl alcohol for more than 2 hours, and then dried to obtain the final product. The mixed solution contains 8% to 10% sodium silicate and 6% to 10% polyvinyl alcohol by mass.

8. The method for preparing multi-element solid waste-based recycled concrete according to any one of claims 1 to 6, characterized in that: The fine sand is a continuous particle size distribution sand with a particle size of less than 5 mm and an MB value of less than 1.

4.

9. The method for preparing multi-element solid waste-based recycled concrete according to any one of claims 1 to 6, characterized in that: The crushed stone consists of rock particles with a diameter greater than 4.75 mm.

10. The multi-component solid waste-based recycled concrete prepared by the method of preparing multi-component solid waste-based recycled concrete according to any one of claims 1 to 9.

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