Environmentally friendly cement concrete material and preparation method based on waste asphalt milling material

Abstract

This invention relates to the field of concrete technology, specifically to an environmentally friendly cement concrete material and preparation method based on waste asphalt milling aggregate. The material uses waste asphalt milling aggregate as a substitute aggregate, and is prepared in combination with cement, composite admixtures, synergists, energy-reducing agents, water-reducing agents, and water. The proportions of each component are as follows: Waste asphalt milling aggregate: replacing 30%~50% of traditional sand and gravel aggregate. The waste asphalt milling aggregate is used after pretreatment, with a cleanliness ≥95% and a surface asphalt film desorption rate ≥90%. Through the synergistic effect of the synergist and energy-reducing agent, the technical problem of insufficient performance in existing concrete containing waste asphalt milling aggregate is solved. Compared with solutions without synergists and energy-reducing agents, both mechanical properties and durability are significantly improved.

Description

Technical Field

[0001] This invention relates to the field of concrete technology, specifically to an environmentally friendly cement concrete material based on waste asphalt milling material and its preparation method. Background Technology

[0002] With the rapid development of highway construction and the maintenance and upgrading of existing roads in my country, a large amount of waste asphalt milling material is generated every year. If this solid waste is directly piled up or landfilled, it will not only occupy a large amount of land resources, but the asphalt components it contains will also seep into and pollute the soil and groundwater, causing serious environmental pressure. At the same time, the traditional cement concrete production process consumes a large amount of natural sand and gravel aggregates. Natural sand and gravel resources are non-renewable resources, and long-term over-exploitation will lead to ecological problems such as mountain destruction and soil erosion, which is inconsistent with the concept of green and low-carbon development.

[0003] Currently, some technologies have attempted to apply waste asphalt milling aggregate to cement concrete, but the following problems generally exist: First, the asphalt film adhering to the surface of the waste asphalt milling aggregate affects its compatibility with cement-based cementitious materials, resulting in poor bonding at the concrete interface and a decrease in mechanical properties and durability; second, the milling aggregate is not scientifically pretreated, resulting in unreasonable particle size distribution and high impurity content, further reducing the overall performance of concrete; third, there is a lack of targeted modifiers, making it difficult to effectively compensate for the performance shortcomings brought about by the replacement of natural sand and gravel with milling aggregate. Even with the addition of modifying components, some technologies still suffer from problems such as unreasonable formulation, complex preparation, and high cost, making it impossible to achieve large-scale application.

[0004] Furthermore, existing concrete performance testing standards are constantly being updated. Standards such as the "Test Procedures for Cement and Cement Concrete in Highway Engineering" (JTG 3420—2020) and the "Standard for Test Methods of Long-Term Performance and Durability of Concrete" (GB / T50082-2024) have placed higher requirements on the mechanical and durability testing of concrete. Concrete containing waste asphalt milling aggregate prepared using existing technologies is difficult to reliably meet the requirements for road base courses and secondary road surface courses in the aforementioned standards. Therefore, developing an environmentally friendly cement concrete material and preparation method that can achieve efficient resource utilization of waste asphalt milling aggregate, stable performance, simple preparation, and controllable cost has become an urgent technical challenge to be solved. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide an environmentally friendly cement concrete material based on waste asphalt milling material and its preparation method, so as to solve the problems mentioned in the background art.

[0006] The present invention solves the technical problem by adopting the following technical solution: This invention provides an environmentally friendly cement concrete material based on waste asphalt milling aggregate. It is prepared by using waste asphalt milling aggregate as a substitute aggregate, combined with cement, composite admixtures, additives, energy-reducing agents, water-reducing agents, and water. The composition of each component is as follows: Waste asphalt milling material: replaces 30%~50% of traditional sand and gravel aggregate. The waste asphalt milling material is used after pretreatment, and the cleanliness after pretreatment is ≥95%, and the asphalt film desorption rate on the surface is ≥90%. Cement: 320~380 kg / m³ 3 ; Composite admixtures: accounting for 13% to 20% of the total cementitious materials, consisting of 8% to 12% slag powder and 5% to 8% fly ash; Effective additive: The dosage is 2% to 4% of the total amount of cementitious materials; Energy enhancer: The dosage is 1% to 3% of the total amount of cementitious materials; Polycarboxylate superplasticizer: dosage is 0.8%~1.2% of the total amount of cementitious materials; Water: The water-cement ratio is 0.42~0.48, where the water-cement ratio is the mass ratio of water to cementitious materials, which include cement and composite admixtures.

[0007] Preferably, the active ingredient is prepared by ball milling and compounding an active ingredient solution and a pretreated nano-attapulgite clay solution. The specific preparation steps are as follows: S1: By weight, add 2-4 parts of nano-silica sol and 1-3 parts of lanthanum oxide to 5-8 parts of sodium citrate solution with a mass fraction of 5%, stir evenly, then add 3-5 parts of modified flake talc powder, continue stirring, and obtain the effective solution. S2: By weight, add 5-8 parts of nano-attapulgite to 10-15 parts of 10% sulfuric acid solution, stir thoroughly at 60-70℃, then wash with water until neutral, filter, and dry to obtain pretreated nano-attapulgite. S3: By weight, mix 5-8 parts of pretreated nano-attapulgite, 2-5 parts of nanocellulose and 5-8 parts of sodium dodecylbenzenesulfonate solution with a mass fraction of 5-8%, and stir thoroughly at 50-60℃ to obtain nano-attapulgite liquid. S4: The nano-attapulgite soil liquid and the effective preparation liquid are ball-milled at a weight ratio of (7-11):5. The ball milling speed is 1000-1500 r / min and the ball milling time is 2h. After the ball milling is completed, the mixture is filtered, dried, pulverized and sieved to obtain the effective preparation.

[0008] Preferably, the preparation steps of the modified flake talc powder are as follows: S11: By weight, 4-7 parts of flake talc powder, 2-5 parts of attapulgite and 3-5 parts of nano titanium dioxide are blended and sintered at 300-320℃ for 1 hour. After cooling, flake talc powder is obtained. S12: By weight, 5-8 parts of flake talc powder, 2-4 parts of urea solution with a mass fraction of 2-5% and 1-3 parts of lanthanum chloride solution with a mass fraction of 5-8% are mixed and ball-milled thoroughly. After ball milling, the mixture is filtered and dried to obtain modified flake talc powder.

[0009] Preferably, the preparation steps of the energizer are as follows: Step 1: Mix 2-5 parts by weight of silane coupling agent KH560, 4-7 parts by weight of 85% ethanol aqueous solution and 2-5 parts by weight of boron nitride, stir evenly to obtain the auxiliary energy liquid; Step 2: Immerse calcium sulfate whiskers in a sufficient amount of auxiliary energy solution, and sonicate them. The sonication power is 350-400W and the sonication time is 1 hour. After sonication, filter and dry to obtain the auxiliary energy agent.

[0010] Preferably, the cement is P·O 42.5 grade ordinary Portland cement; the slag powder has a specific surface area ≥ 400 m². 2 / kg; the fly ash is grade II or above; the water reduction rate of the polycarboxylate-based high-efficiency water-reducing agent is ≥25%.

[0011] This invention also provides a method for preparing an environmentally friendly cement concrete material based on waste asphalt milling material, comprising the following steps: (1) Pretreatment of waste asphalt milling material: The waste asphalt milling material is obtained by sequentially screening, heating and desorption, impurity removal and drying. (2) Preparation of each component: Weigh the pretreated waste asphalt milling material, cement, composite admixture, effective additive, auxiliary energy agent, polycarboxylate-based high-efficiency water-reducing agent and water according to the mixing ratio described in claim 1. (3) Segmented mixing: First, mix the pretreated waste asphalt milling material with the remaining traditional sand and gravel aggregate for 2-3 minutes, then add cement, composite admixture, effective additive and auxiliary energy agent and mix for 1-2 minutes, and finally add an aqueous solution containing water-reducing agent and mix for 4-5 minutes to obtain a uniform concrete mixture. (4) Molding and curing: Pour the concrete mixture into the mold, vibrate and compact it, smooth it, and then place it in a standard curing box for 7~28 days to obtain environmentally friendly cement concrete material.

[0012] Preferably, the specific process of pretreatment of waste asphalt milling material in step (1) is as follows: Screening: Screening out waste asphalt milling material particles with a particle size of 5~20mm; Heat desorption: Heat at 120~140℃ for 30~40 minutes and stir to remove the surface asphalt film; Impurity removal: High-pressure water rinsing removes residual impurities from the surface; Drying: Dry at 80~100℃ for 1~2 hours.

[0013] Preferably, in step (3), the stirring speed is 200~400 r / min; the slump of the concrete mixture is 120~140 mm.

[0014] Preferably, in step (4), the vibration frequency is 50~60Hz and the vibration time is 10~15s / site; the standard curing conditions are a temperature of 20±2℃ and a relative humidity of ≥95%.

[0015] Compared with the prior art, the present invention has the following beneficial effects: This invention achieves efficient resource utilization of waste asphalt milling material: through scientific pretreatment processes (screening, heating desorption, and impurity removal), the cleanliness and particle size distribution of waste asphalt milling material are effectively improved, enabling it to stably replace 30% to 50% of traditional sand and gravel aggregates, with a resource utilization rate of over 95%. This completely solves the problem of pollution from the accumulation of waste asphalt milling material, while also reducing the mining of natural sand and gravel resources and protecting the ecological environment.

[0016] The concrete exhibits excellent comprehensive performance: By adding a compatibilizer and an energy enhancer, the mechanical properties and durability of the concrete are synergistically improved. The modified flake talc powder and nano-attapulgite components in the compatibilizer effectively improve the compatibility between waste asphalt milling aggregate and cement-based cementitious materials, enhancing interfacial bonding. The energy enhancer improves the concrete's wear resistance, freeze-thaw resistance, and reduces drying shrinkage. Performance tests show that the concrete prepared by this invention has a compressive strength of 30-40 MPa and a flexural strength of 3.5-4.5 MPa, both meeting the requirements for road base courses and secondary road surface courses in the "Test Procedures for Cement and Cement Concrete in Highway Engineering" (JTG 3420-2020). The drying shrinkage is reduced by 8%-12%, and its wear resistance and freeze-thaw resistance are comparable to ordinary cement concrete, with superior durability.

[0017] Green and low-carbon, with significantly reduced energy consumption and carbon emissions: Life cycle assessment shows that compared with traditional cement concrete, the energy consumption of the material in this invention is reduced by 15% to 22% and carbon emissions are reduced by 18% to 25% during the production stage, which meets the policy requirements of national green building and low-carbon development and has significant environmental benefits.

[0018] The preparation method is simple and feasible, and the cost is controllable: the pretreatment process, additives, auxiliary agents and concrete preparation steps of this invention are simple, do not require complicated special equipment, are easy to operate and are suitable for large-scale production; at the same time, the replacement of waste asphalt milling material reduces aggregate costs, and the use of composite admixtures reduces cement usage. The overall production cost is 8% to 15% lower than that of traditional cement concrete, which has significant economic benefits.

[0019] By leveraging the synergistic effect of the additive and the energy enhancer, the technical challenge of insufficient performance of existing milled concrete containing waste asphalt has been solved. Compared with solutions without additives and energy enhancers, the mechanical properties and durability are significantly improved. At the same time, the preparation of modified flake talc powder optimizes the performance of the additive. Compared with the direct use of flake talc powder, it can further enhance the interfacial bonding force and strength of concrete, highlighting the inventiveness of this invention. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to specific examples. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Example 1.

[0022] 1.1 Raw material preparation Waste asphalt milling material: generated from road maintenance, pre-treated for later use (screening particle size 5~20mm, heating desorption temperature 130℃, heating time 35min, drying temperature after washing 90℃, drying time 1.5h, cleanliness 96%, asphalt film desorption rate 92%). Cement: P·O 42.5 grade ordinary Portland cement, dosage 350kg / m³ 3 ; Composite admixture: slag powder (specific surface area 420 m²) 2 / kg) 10%, fly ash (Grade II) 6%, both accounting for the total amount of cementitious materials; Effective additive: The dosage is 3% of the total amount of cementitious materials, and it is prepared according to the following method: S1: 2.5 parts of nano-silica sol and 2 parts of lanthanum oxide were added to 6 parts of sodium citrate solution with a mass fraction of 5%, stirred at 300 r / min for 18 min, 4 parts of modified flake talc powder were added, and stirring was continued for 25 min to obtain the effective solution; S2: 6 parts of nano-attapulgite were added to 12 parts of 10% sulfuric acid solution, stirred at 65℃ and 500r / min for 35min, washed with water until neutral, filtered, and dried at 108℃ for 2.5h to obtain pretreated nano-attapulgite. S3: 6 parts of pretreated nano-attapulgite clay, 3 parts of nanocellulose and 6 parts of sodium dodecylbenzenesulfonate solution with a mass fraction of 6% were stirred at 55℃ and 600r / min for 45min to obtain nano-attapulgite clay liquid. S4: The nano-attapulgite clay liquid and the effective preparation liquid were ball-milled at a weight ratio of 9:5 at a speed of 1200 r / min for 2 hours, filtered, dried at 115℃ for 3.5 hours, and pulverized through an 80-mesh sieve to obtain the effective preparation. Preparation of modified flaky talc powder: S11: 5 parts flaky talc powder, 3 parts palygorskite, and 4 parts nano-titanium dioxide were sintered at 310℃ for 1 h and then cooled; S12: 6 parts flaky talc powder, 3 parts urea solution (3% by mass), and 2 parts lanthanum chloride solution (6% by mass) were ball-milled at 900 r / min for 1.8 h, filtered, and dried at 102℃ for 2.5 h to obtain modified flaky talc powder.

[0023] Auxiliary energy agent: The dosage is 2% of the total amount of cementitious material, and it is prepared as follows: 2.5 parts of silane coupling agent KH560, 5 parts of 85% ethanol aqueous solution, and 3 parts of boron nitride are mixed and stirred at 300 r / min for 12 min to obtain auxiliary energy liquid; calcium sulfate whiskers are immersed in auxiliary energy liquid, sonicated at 380 W for 1 h, filtered, and dried at 108℃ for 2.5 h to obtain auxiliary energy agent; Polycarboxylate superplasticizer: dosage is 1.0% of the total cementitious material, water reduction rate is 28%; Water: Water-to-glue ratio 0.45, let stand for 24 hours in advance for later use; Traditional sand and gravel aggregate: particle size 5~20mm, usage is 50% of total aggregate (50% is replaced by waste asphalt milling material).

[0024] 1.2 Preparation method The pretreated waste asphalt milled material and traditional sand and gravel aggregate are put into a mixer and mixed at 250 r / min for 2.5 min until they are uniformly mixed. Add cement, slag powder, fly ash, additives, and energy-enhancing agents, and continue stirring for 1.5 minutes; Add the water-reducing agent to the water, stir evenly, and slowly add it to the mixer. Stir at 350 r / min for 4.5 min to obtain a uniform concrete mixture (slump 130 mm). Pour the mixture into a mold, vibrate at 55Hz for 12 seconds per section, smooth it out, and place it in a standard curing box (20±2℃, relative humidity ≥95%) for 28 days to obtain environmentally friendly cement concrete.

[0025] Example 2 differs from Example 1 in that: 30% of the traditional sand and gravel aggregate is replaced by waste asphalt milling material, and the cement dosage is 320 kg / m³. 3 The water-cement ratio was 0.42. The composite admixture contained 8% slag powder, 5% fly ash, 2% effective binder, 1% auxiliary energy agent, and 0.8% water-reducing agent. In the preparation of the effective binder, the weight ratio of nano-attapulgite clay liquid to the effective binder liquid was 7:5, and the ball milling speed was 1000 r / min. In the preparation of the auxiliary energy agent, the ultrasonic power was 350W. The stirring time was 2 min for the first step, 1 min for the second step, and 4 min for the third step. The curing time was 7 days. The remaining raw materials and preparation steps were the same as in Example 1.

[0026] Example 3 differs from Example 1 in that: 40% of the traditional sand and gravel aggregate is replaced by waste asphalt milling material, and the cement dosage is 380 kg / m³. 3 The water-cement ratio was 0.48. The composite admixture contained 12% slag powder, 8% fly ash, 4% effective binder, 3% auxiliary energy agent, and 1.2% water-reducing agent. In the preparation of the effective binder, the weight ratio of nano-attapulgite clay liquid to the effective binder liquid was 11:5, and the ball milling speed was 1500 r / min. In the preparation of the auxiliary energy agent, the ultrasonic power was 400 W. The stirring time was 3 min for the first step, 2 min for the second step, and 5 min for the third step. The curing time was 28 days. The remaining raw materials and preparation steps were the same as in Example 1.

[0027] Comparative Example 1 differs from Example 1 in that no active ingredient or excipient was added, while the remaining raw materials, formulation ratios, and preparation steps are the same as in Example 1.

[0028] Comparative Example 2 differs from Example 1 in that: no modified flake talc powder was added in the preparation of the active ingredient; instead, an equal amount of flake talc powder was used as a substitute. The remaining raw materials, proportions, and preparation steps are the same as in Example 1.

[0029] Comparative Example 3: This comparative example uses conventional ordinary cement concrete without the addition of waste asphalt milling aggregate, compatibilizers, or energy-enhancing agents, with a cement content of 400 kg / m³. 3 The water-cement ratio is 0.45, no composite admixtures are added, only traditional sand and gravel aggregates are used, and the remaining preparation steps are the same as in Example 1.

[0030] Performance testing.

[0031] The concrete specimens prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to mechanical property, durability, energy consumption, and carbon emission tests in accordance with the relevant provisions of the "Test Procedures for Cement and Cement Concrete in Highway Engineering" (JTG 3420-2020) and the "Standard for Test Methods of Long-Term Performance and Durability of Concrete" (GB / T50082-2024). The test results are shown in the table below.

[0032]

[0033] The test results above show that: The environmentally friendly cement concrete prepared in Examples 1-3 has a compressive strength of 30.8-39.7 MPa and a flexural strength of 3.5-4.4 MPa, both of which meet the requirements for use in road base courses and secondary arterial road surface courses. The drying shrinkage rate is 0.030-0.035%, which is 8.3%-25.0% lower than that of Comparative Example 1 (without additives and excipients). The wear loss and freeze-thaw resistance are better than those of Comparative Example 1 and Comparative Example 2, indicating that the addition of additives and excipients can significantly improve the mechanical properties and durability of concrete, and the use of modified flake talc powder can further optimize the effect of additives.

[0034] The energy consumption reduction rate of Examples 1-3 was 15.2%-21.7%, the carbon emission reduction rate was 18.1%-24.8%, and the milling material utilization rate was 95.5%-97.1%, all of which were better than those of Comparative Examples 1-3. This shows that the present invention can effectively reduce production energy consumption and carbon emissions, and realize the efficient resource utilization of waste asphalt milling material.

[0035] Compared with Comparative Example 1 and Comparative Example 3 (conventional concrete), Example 1 has comparable mechanical properties and durability to conventional concrete, with some indicators (drying shrinkage rate) being even better. Furthermore, it significantly reduces energy consumption and carbon emissions, resulting in lower costs and highlighting the advanced nature and practicality of the present invention.

[0036] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0037] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. An environmentally friendly cement concrete material based on waste asphalt milling material, characterized in that, It is prepared by using waste asphalt milled material as a substitute aggregate, combined with cement, composite admixtures, additives, energy-reducing agents, water-reducing agents, and water. The composition of each component is as follows: Waste asphalt milling material: replaces 30%~50% of traditional sand and gravel aggregate. The waste asphalt milling material is used after pretreatment, and the cleanliness after pretreatment is ≥95%, and the asphalt film desorption rate on the surface is ≥90%. Cement: 320~380 kg / m³ 3 ; Composite admixtures: accounting for 13% to 20% of the total cementitious materials, consisting of 8% to 12% slag powder and 5% to 8% fly ash; Effective additive: The dosage is 2% to 4% of the total amount of cementitious materials; Energy enhancer: The dosage is 1% to 3% of the total amount of cementitious materials; Polycarboxylate superplasticizer: dosage is 0.8%~1.2% of the total amount of cementitious materials; Water: The water-cement ratio is 0.42~0.48, where the water-cement ratio is the mass ratio of water to cementitious materials, which include cement and composite admixtures.

2. The environmentally friendly cement concrete material based on waste asphalt milling material according to claim 1, characterized in that, The active ingredient is prepared by ball milling and compounding an active ingredient solution and a pretreated nano-attapulgite clay solution. The specific preparation steps are as follows: S1: By weight, add 2-4 parts of nano-silica sol and 1-3 parts of lanthanum oxide to 5-8 parts of sodium citrate solution with a mass fraction of 5%, stir evenly, then add 3-5 parts of modified flake talc powder, continue stirring, and obtain the effective solution. S2: By weight, add 5-8 parts of nano-attapulgite to 10-15 parts of 10% sulfuric acid solution, stir thoroughly at 60-70℃, then wash with water until neutral, filter, and dry to obtain pretreated nano-attapulgite. S3: By weight, mix 5-8 parts of pretreated nano-attapulgite, 2-5 parts of nanocellulose and 5-8 parts of sodium dodecylbenzenesulfonate solution with a mass fraction of 5-8%, and stir thoroughly at 50-60℃ to obtain nano-attapulgite liquid. S4: The nano-attapulgite soil liquid and the effective preparation liquid are ball-milled at a weight ratio of (7-11):

5. The ball milling speed is 1000-1500 r / min and the ball milling time is 2h. After the ball milling is completed, the mixture is filtered, dried, pulverized and sieved to obtain the effective preparation.

3. The environmentally friendly cement concrete material based on waste asphalt milling material according to claim 2, characterized in that, The preparation steps of the modified flake talc powder are as follows: S11: By weight, 4-7 parts of flake talc powder, 2-5 parts of attapulgite and 3-5 parts of nano titanium dioxide are blended and sintered at 300-320℃ for 1 hour. After cooling, flake talc powder is obtained. S12: By weight, 5-8 parts of flake talc powder, 2-4 parts of urea solution with a mass fraction of 2-5% and 1-3 parts of lanthanum chloride solution with a mass fraction of 5-8% are mixed and ball-milled thoroughly. After ball milling, the mixture is filtered and dried to obtain modified flake talc powder.

4. The environmentally friendly cement concrete material based on waste asphalt milling material according to claim 1, characterized in that, The preparation steps of the energizer are as follows: Step 1: Mix 2-5 parts by weight of silane coupling agent KH560, 4-7 parts by weight of 85% ethanol aqueous solution and 2-5 parts by weight of boron nitride, stir evenly to obtain the auxiliary energy liquid; Step 2: Immerse calcium sulfate whiskers in a sufficient amount of auxiliary energy solution, and sonicate them. The sonication power is 350-400W and the sonication time is 1 hour. After sonication, filter and dry to obtain the auxiliary energy agent.

5. The environmentally friendly cement concrete material based on waste asphalt milling material according to claim 1, characterized in that, The cement is P·O 42.5 grade ordinary Portland cement; the slag powder has a specific surface area ≥ 400 m². 2 / kg; the fly ash is grade II or above; the water reduction rate of the polycarboxylate-based high-efficiency water-reducing agent is ≥25%.

6. A method for preparing an environmentally friendly cement concrete material based on waste asphalt milling material, characterized in that, Includes the following steps: (1) Pretreatment of waste asphalt milling material: The waste asphalt milling material is obtained by sequentially screening, heating and desorption, impurity removal and drying. (2) Preparation of each component: Weigh the pretreated waste asphalt milling material, cement, composite admixture, effective additive, auxiliary energy agent, polycarboxylate-based high-efficiency water-reducing agent and water according to the mixing ratio described in claim 1. (3) Segmented mixing: First, mix the pretreated waste asphalt milling material with the remaining traditional sand and gravel aggregate for 2-3 minutes, then add cement, composite admixture, effective additive and auxiliary energy agent and mix for 1-2 minutes, and finally add an aqueous solution containing water-reducing agent and mix for 4-5 minutes to obtain a uniform concrete mixture. (4) Molding and curing: Pour the concrete mixture into the mold, vibrate and compact it, smooth it, and then place it in a standard curing box for 7~28 days to obtain environmentally friendly cement concrete material.

7. The preparation method according to claim 6, characterized in that, The specific process of pretreatment of waste asphalt milling material in step (1) is as follows: Screening: Screening out waste asphalt milling material particles with a particle size of 5~20mm; Heat desorption: Heat at 120~140℃ for 30~40 minutes and stir to remove the surface asphalt film; Impurity removal: High-pressure water rinsing removes residual impurities from the surface; Drying: Dry at 80~100℃ for 1~2 hours.

8. The preparation method according to claim 6, characterized in that, In step (3), the stirring speed is 200~400 r / min; the slump of the concrete mixture is 120~140 mm.

9. The preparation method according to claim 6, characterized in that, In step (4), the vibration frequency is 50~60Hz and the vibration time is 10~15s / site; the standard curing conditions are temperature 20±2℃ and relative humidity ≥95%.

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