A recycled concrete composite material and a preparation method and application thereof

Abstract

The present application relates to the field of engineering and building material technology, and particularly relates to a recycled concrete composite material, a preparation method and application thereof.The recycled concrete composite material provided by the present application realizes high-strength recycled concrete composite material under the premise of ensuring the replacement rate of recycled aggregate through the synergistic effect of various components, and has low cost, realizes the dual goals of economic benefit and performance strengthening, and has wide application prospect.The recycled concrete composite material provided by the present application has high strength and high replacement rate of recycled aggregate, improves the strength performance while reducing the cost, and the performance such as the chloride ion diffusion coefficient does not obviously decrease, and even is improved, the comprehensive performance is obviously improved, and can be used in the field of road engineering, for example, roadbed, retaining wall and other application scenarios, and particularly meets the performance requirements of honeycomb roadbed.

Description

Technical Field

[0001] This invention relates to the field of engineering and building materials technology, and in particular to a recycled concrete composite material, its preparation method, and its application. Background Technology

[0002] With the development of the construction and engineering fields, concrete, as one of the most commonly used materials, has seen its performance level become a crucial factor in the development of these fields. Therefore, improving the performance of concrete has always been a key focus in the field of concrete materials.

[0003] Recycled concrete, as a green building material, is made from waste concrete blocks. After being crushed, washed, and graded, it is mixed with aggregates in a certain proportion to partially or completely replace natural aggregates such as sand and gravel (mainly coarse aggregates). Cement and water are then added to create new concrete. The emergence and development of recycled concrete is an important achievement in the resource utilization of construction waste, aiming to solve the resource waste and environmental pollution problems caused by traditional landfill methods.

[0004] Although recycled concrete offers significant social and economic benefits, its application is limited by its performance shortcomings. For example, its compressive strength is typically only 70-90% of that of ordinary concrete, and it decreases with increasing recycled aggregate replacement rates. When the recycled aggregate replacement rate exceeds 30%, the flexural strength of recycled concrete decreases by more than 15%. This is mainly attributed to the lower strength of recycled aggregates and the internal microcracks generated during the crushing process, which easily lead to stress concentration under axial stress.

[0005] Therefore, how to prepare a high-strength recycled concrete while ensuring the replacement rate of recycled aggregate is a problem faced by those skilled in the art. Summary of the Invention

[0006] In view of this, the present invention provides a recycled concrete composite material, its preparation method and application. The recycled concrete composite material provided by the present invention has both high strength and high recycled aggregate replacement rate.

[0007] This invention provides a recycled concrete composite material comprising the following components in parts by weight:

[0008] 10 parts cement, 2-4 parts fly ash, 10-18 parts recycled coarse aggregate, 5-6 parts polyethylene terephthalate, 2-3 parts polyoxymethylene, 8-13 parts fine aggregate, 0.1-0.5 parts water-reducing agent, and 5-10 parts water.

[0009] Preferably, the particle size of the fly ash is 1 to 20 micrometers.

[0010] Preferably, the recycled coarse aggregate is a type I recycled coarse aggregate.

[0011] Preferably, the polyethylene terephthalate has a melting point of 250-260 degrees Celsius.

[0012] Preferably, the polyoxymethylene is a polyoxymethylene homopolymer; the melting point of the polyoxymethylene is 175~185 degrees Celsius.

[0013] Preferably, the fine aggregate is river sand; the fineness modulus of the fine aggregate is 2.6~3.

[0014] Preferably, the water-reducing agent is a polycarboxylate high-performance water-reducing agent.

[0015] This invention also provides a method for preparing a recycled concrete composite material, wherein the recycled concrete composite material is the recycled concrete composite material described in the above-mentioned scheme, comprising the following steps:

[0016] (1) The recycled coarse aggregate, polyethylene terephthalate and polyoxymethylene are mixed and heated, heat-treated and cooled in sequence to obtain modified aggregate;

[0017] (2) The modified aggregate is mixed with cement, fly ash, fine aggregate, water-reducing agent and water to obtain recycled concrete composite material.

[0018] Preferably, the heating rate is 20~25℃ / min; the heat treatment temperature is 260~270℃, and the holding time is 30~50 minutes; the cooling rate is 5~10℃ / min.

[0019] The present invention also provides an application of recycled concrete composite material in the field of road engineering, wherein the recycled concrete composite material is the recycled concrete composite material described in the above scheme or the recycled concrete composite material obtained by the preparation method described in the above scheme.

[0020] This invention provides a recycled concrete composite material. Through the synergistic effect of its components, the recycled concrete composite material provided by this invention achieves high strength while maintaining a high recycled aggregate replacement rate, and is also low in cost. This achieves the dual goals of economic benefits and performance enhancement, and has broad application prospects.

[0021] This invention also provides a method for preparing a recycled concrete composite material, wherein the recycled concrete composite material is the recycled concrete composite material described in the above-mentioned scheme. The preparation method provided by this invention is low in cost, simple in steps, convenient to operate, does not rely on large-scale equipment, and has the potential for industrial-scale production.

[0022] This invention also provides an application of recycled concrete composite material in the field of road engineering. The recycled concrete composite material is the recycled concrete composite material described in the above-described scheme or the recycled concrete composite material obtained by the preparation method described in the above-described scheme. The recycled concrete composite material provided by this invention combines high strength and a high recycled aggregate replacement rate, improving strength performance while reducing costs. Furthermore, properties such as chloride ion permeability coefficient do not show a significant decrease, and may even be improved, resulting in a significant improvement in overall performance. It can be used in road engineering applications such as roadbeds and retaining walls, especially meeting the performance requirements of cellular roadbeds. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of this invention, the accompanying drawings used in the embodiments of this invention or in the prior art are briefly described below. For those skilled in the art, other drawings can be derived from the following drawings without creative effort, and all such drawings are within the protection scope of this invention.

[0024] Figure 1 The graphs show the 28-day compressive strength of the recycled concrete composite materials in Examples 1-7 and Comparative Examples 1-6.

[0025] Figure 2 The diagram shows the chloride ion diffusion coefficient of the recycled concrete composite materials of Examples 1-7 and Comparative Examples 1-6 after 28 days.

[0026] Figure 3 The graphs show the 28-day flexural strength of the recycled concrete composite materials in Examples 1-7 and Comparative Examples 1-6. Detailed Implementation

[0027] This invention provides a recycled concrete composite material comprising the following components in parts by weight:

[0028] 10 parts cement, 2-4 parts fly ash, 10-18 parts recycled coarse aggregate, 5-6 parts polyethylene terephthalate, 2-3 parts polyoxymethylene, 8-13 parts fine aggregate, 0.1-0.5 parts water-reducing agent, and 5-10 parts water.

[0029] The recycled concrete composite material provided by the present invention comprises 10 parts of cement by weight; the cement is preferably ordinary Portland cement with a strength grade of 42.5.

[0030] Based on the mass fraction of the cement, the recycled concrete composite material provided by the present invention includes 2 to 4 parts of fly ash, preferably 2.4 to 3.6 parts, and more preferably 3.1 parts.

[0031] In this invention, the particle size of the fly ash is preferably 1-20 micrometers, more preferably 5-15 micrometers.

[0032] Based on the mass fraction of the cement, the recycled concrete composite material provided by the present invention includes 10 to 18 parts of recycled coarse aggregate, preferably 12 to 16 parts, and more preferably 14 to 14.5 parts.

[0033] In this invention, the recycled coarse aggregate is preferably a type I recycled coarse aggregate.

[0034] Based on the mass fraction of the cement, the recycled concrete composite material provided by the present invention includes 5-6 parts of polyethylene terephthalate, preferably 5.2-5.8 parts, and more preferably 5.4-5.6 parts.

[0035] In this invention, the melting point of the polyethylene terephthalate is preferably 250-260 degrees Celsius.

[0036] Based on the mass fraction of the cement, the recycled concrete composite material provided by the present invention includes 2 to 3 parts of polyoxymethylene, preferably 2.2 to 2.8 parts, and more preferably 2.4 to 2.6 parts.

[0037] In this invention, the polyoxymethylene is preferably a polyoxymethylene homopolymer; the melting point of the polyoxymethylene is preferably 175~185 degrees Celsius.

[0038] Based on the mass fraction of the cement, the recycled concrete composite material provided by the present invention includes 8 to 13 parts of fine aggregate, preferably 9 to 12 parts, and more preferably 10 to 11 parts.

[0039] In this invention, the fine aggregate is preferably river sand; the fineness modulus of the fine aggregate is preferably 2.6 to 3.

[0040] Based on the mass fraction of the cement, the recycled concrete composite material provided by the present invention includes 0.1 to 0.5 parts of water-reducing agent, preferably 0.2 to 0.4 parts, and more preferably 0.3 parts.

[0041] In this invention, the water-reducing agent is preferably a polycarboxylate high-performance water-reducing agent.

[0042] Based on the mass fraction of the cement, the recycled concrete composite material provided by the present invention includes 5 to 10 parts of water, preferably 6 to 9 parts, and more preferably 7 to 8 parts.

[0043] In this invention, the water is preferably tap water or purified water.

[0044] This invention also provides a method for preparing a recycled concrete composite material, wherein the recycled concrete composite material is the recycled concrete composite material described in the above-mentioned scheme, comprising the following steps:

[0045] (1) The recycled coarse aggregate, polyethylene terephthalate and polyoxymethylene are mixed and heated, heat-treated and cooled in sequence to obtain modified aggregate;

[0046] (2) The modified aggregate is mixed with cement, fly ash, fine aggregate, water-reducing agent and water to obtain recycled concrete composite material.

[0047] This invention involves mixing recycled coarse aggregate, polyethylene terephthalate (PET), and polyoxymethylene (POM) (referred to as the first mixture), followed by sequential heating, heat treatment, and cooling to obtain modified aggregate. In this invention, the first mixture is preferably stirred; the stirring speed is preferably 200-300 rpm, more preferably 250 rpm; and the first mixing time is preferably 10-20 minutes, more preferably 15 minutes.

[0048] In this invention, the heating rate is preferably 20~25℃ / min, more preferably 24℃ / min.

[0049] In this invention, the heat treatment temperature is preferably 260-270 degrees Celsius, more preferably 265 degrees Celsius, and the heat treatment time is preferably 30-50 minutes, more preferably 40 minutes.

[0050] In this invention, the cooling rate is preferably 5~10℃ / min, more preferably 7℃ / min.

[0051] After obtaining the modified aggregate, the present invention mixes the modified aggregate with cement, fly ash, fine aggregate, water-reducing agent and water (denoted as the second mixture) to obtain a recycled concrete composite material. In the present invention, the second mixture is preferably stirred; the stirring speed is preferably 100~200 rpm, more preferably 120 rpm; the second mixing time is preferably 60~80 minutes, more preferably 70 minutes.

[0052] The present invention also provides an application of recycled concrete composite material in the field of road engineering, wherein the recycled concrete composite material is the recycled concrete composite material described in the above scheme or the recycled concrete composite material obtained by the preparation method described in the above scheme.

[0053] The recycled concrete composite material provided by this invention has both high strength and high recycled aggregate replacement rate. It improves strength performance while reducing costs, and there is no significant decrease in properties such as hardness. The overall performance is significantly improved, and it can be used in the field of road engineering, such as roadbeds and retaining walls, especially meeting the performance requirements of cellular roadbeds.

[0054] To further illustrate the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings and embodiments.

[0055] In a specific embodiment of the present invention, the polycarboxylate high-performance water-reducing agent is the SPF-300 water-reducing agent produced by Liaoning Kelong Fine Chemical Co., Ltd.

[0056] Example 1:

[0057] This embodiment prepares a recycled concrete composite material with the following components:

[0058] 10 kg of ordinary Portland cement with a strength grade of 42.5;

[0059] 3.1 kg of fly ash (particle size distribution of 5-15 micrometers);

[0060] 14.5 kg of Class I recycled coarse aggregate;

[0061] 5.6 kg of polyethylene terephthalate (melting point 255 degrees Celsius);

[0062] 2.6 kg of polyoxymethylene homopolymer (melting point 180 degrees Celsius);

[0063] 11 kg of river sand (fineness modulus 2.6~3);

[0064] 0.3 kg of polycarboxylate superplasticizer;

[0065] 8 kg of tap water.

[0066] The specific steps for preparing the recycled concrete composite material in this embodiment are as follows:

[0067] (1) Mix recycled coarse aggregate, polyethylene terephthalate and polyoxymethylene, stir at 250 rpm for 15 minutes, then heat at 24°C / min, heat at 265°C for 40 minutes, and cool to room temperature at 7°C / min to obtain modified aggregate.

[0068] (2) The prepared modified aggregate is mixed with cement, fly ash, fine aggregate, water-reducing agent and water, and the mixture is stirred at 120 rpm for 70 minutes to obtain recycled concrete composite material.

[0069] Example 2:

[0070] This embodiment prepares a recycled concrete composite material with the following components:

[0071] 10 kg of ordinary Portland cement with a strength grade of 42.5;

[0072] 3.6 kg of fly ash (particle size distribution of 5-15 micrometers);

[0073] 14 kg of Class I recycled coarse aggregate;

[0074] 5.4 kg of polyethylene terephthalate (melting point 255 degrees Celsius);

[0075] 2.4 kg of polyoxymethylene homopolymer (melting point 180 degrees Celsius);

[0076] 11 kg of river sand (fineness modulus 2.6~3);

[0077] 0.3 kg of polycarboxylate superplasticizer;

[0078] 8 kg of tap water.

[0079] The specific steps for preparing the recycled concrete composite material in this embodiment are as follows:

[0080] (1) Mix recycled coarse aggregate, polyethylene terephthalate and polyoxymethylene, stir at 250 rpm for 15 minutes, then heat at 25℃ / min, heat at 265℃ for 40 minutes, and cool to room temperature at 7℃ / min to obtain modified aggregate.

[0081] (2) The prepared modified aggregate is mixed with cement, fly ash, fine aggregate, water-reducing agent and water, and the mixture is stirred at 120 rpm for 70 minutes to obtain recycled concrete composite material.

[0082] Example 3:

[0083] This embodiment prepares a recycled concrete composite material with the following components:

[0084] 10 kg of ordinary Portland cement with a strength grade of 42.5;

[0085] 2.4 kg of fly ash (particle size distribution of 5-15 micrometers);

[0086] 14 kg of Class I recycled coarse aggregate;

[0087] 5.8 kg of polyethylene terephthalate (melting point 255 degrees Celsius);

[0088] 2.6 kg of polyoxymethylene homopolymer (melting point 180 degrees Celsius);

[0089] 10 kg of river sand (fineness modulus 2.6~3);

[0090] 0.4 kg of polycarboxylate superplasticizer;

[0091] 9 kg of tap water.

[0092] The specific steps for preparing the recycled concrete composite material in this embodiment are as follows:

[0093] (1) Mix recycled coarse aggregate, polyethylene terephthalate and polyoxymethylene, stir at 250 rpm for 15 minutes, then heat at 20℃ / min, heat at 265℃ for 50 minutes, and cool to room temperature at 5℃ / min to obtain modified aggregate.

[0094] (2) The prepared modified aggregate is mixed with cement, fly ash, fine aggregate, water-reducing agent and water, and the mixture is stirred at 120 rpm for 70 minutes to obtain recycled concrete composite material.

[0095] Example 4:

[0096] This embodiment prepares a recycled concrete composite material with the following components:

[0097] 10 kg of ordinary Portland cement with a strength grade of 42.5;

[0098] 4 kg of fly ash (particle size distribution of 5-15 micrometers);

[0099] 16 kg of Class I recycled coarse aggregate;

[0100] 5.8 kg of polyethylene terephthalate (melting point 255 degrees Celsius);

[0101] 2.8 kg of polyoxymethylene homopolymer (melting point 180 degrees Celsius);

[0102] 10 kg of river sand (fineness modulus 2.6~3);

[0103] 0.2 kg of polycarboxylate superplasticizer;

[0104] 10 kg of tap water.

[0105] The specific steps for preparing the recycled concrete composite material in this embodiment are as follows:

[0106] (1) Mix recycled coarse aggregate, polyethylene terephthalate and polyoxymethylene, stir at 250 rpm for 15 minutes, then heat at 24°C / min, heat at 265°C for 40 minutes, and cool to room temperature at 10°C / min to obtain modified aggregate.

[0107] (2) The prepared modified aggregate is mixed with cement, fly ash, fine aggregate, water-reducing agent and water, and the mixture is stirred at 120 rpm for 70 minutes to obtain recycled concrete composite material.

[0108] Example 5:

[0109] This embodiment prepares a recycled concrete composite material with the following components:

[0110] 10 kg of ordinary Portland cement with a strength grade of 42.5;

[0111] 4 kg of fly ash (particle size distribution of 5-15 micrometers);

[0112] 12 kg of Class I recycled coarse aggregate;

[0113] 5.2 kg of polyethylene terephthalate (melting point 255 degrees Celsius);

[0114] 2.2 kg of polyoxymethylene homopolymer (melting point 180 degrees Celsius);

[0115] 13 kg of river sand (fineness modulus 2.6~3);

[0116] 0.5 kg of polycarboxylate superplasticizer;

[0117] 10 kg of tap water.

[0118] The specific steps for preparing the recycled concrete composite material in this embodiment are as follows:

[0119] (1) Mix recycled coarse aggregate, polyethylene terephthalate and polyoxymethylene, stir at 250 rpm for 15 minutes, then heat at 20 °C / min, heat at 265 °C for 40 minutes, and cool to room temperature at 7 °C / min to obtain modified aggregate.

[0120] (2) The prepared modified aggregate is mixed with cement, fly ash, fine aggregate, water-reducing agent and water, and the mixture is stirred at 120 rpm for 70 minutes to obtain recycled concrete composite material.

[0121] Example 6:

[0122] This embodiment prepares a recycled concrete composite material with the following components:

[0123] 10 kg of ordinary Portland cement with a strength grade of 42.5;

[0124] 2 kg of fly ash (particle size distribution of 5-15 micrometers);

[0125] 10 kg of Class I recycled coarse aggregate;

[0126] 5 kg of polyethylene terephthalate (melting point 255 degrees Celsius);

[0127] 2 kg of polyoxymethylene homopolymer (melting point 180 degrees Celsius);

[0128] 13 kg of river sand (fineness modulus 2.6~3);

[0129] 0.3 kg of polycarboxylate superplasticizer;

[0130] 6 kg of tap water.

[0131] The specific steps for preparing the recycled concrete composite material in this embodiment are as follows:

[0132] (1) Mix recycled coarse aggregate, polyethylene terephthalate and polyoxymethylene, stir at 250 rpm for 15 minutes, then heat at 25℃ / min, heat at 265℃ for 40 minutes, and cool to room temperature at 10℃ / min to obtain modified aggregate.

[0133] (2) The prepared modified aggregate is mixed with cement, fly ash, fine aggregate, water-reducing agent and water, and the mixture is stirred at 120 rpm for 70 minutes to obtain recycled concrete composite material.

[0134] Example 7:

[0135] This embodiment prepares a recycled concrete composite material with the following components:

[0136] 10 kg of ordinary Portland cement with a strength grade of 42.5;

[0137] 3.6 kg of fly ash (particle size distribution of 5-15 micrometers);

[0138] 18 kg of Class I recycled coarse aggregate;

[0139] 6 kg of polyethylene terephthalate (melting point 255 degrees Celsius);

[0140] 3 kg of polyoxymethylene homopolymer (melting point 180 degrees Celsius);

[0141] 8 kg of river sand (fineness modulus 2.6~3);

[0142] 0.1 kg of polycarboxylate superplasticizer;

[0143] 5 kg of tap water.

[0144] The specific steps for preparing the recycled concrete composite material in this embodiment are as follows:

[0145] (1) Mix recycled coarse aggregate, polyethylene terephthalate and polyoxymethylene, stir at 250 rpm for 15 minutes, then heat at 24°C / min, heat at 265°C for 40 minutes, and cool to room temperature at 7°C / min to obtain modified aggregate.

[0146] (2) The prepared modified aggregate is mixed with cement, fly ash, fine aggregate, water-reducing agent and water, and the mixture is stirred at 120 rpm for 70 minutes to obtain recycled concrete composite material.

[0147] Comparative Example 1:

[0148] The preparation method of this comparative example is the same as that of Example 1, except that the polyoxymethylene homopolymer is replaced with an equal mass of polyethylene terephthalate.

[0149] Comparative Example 2:

[0150] The preparation method of this comparative example is the same as that of Example 1, except that polyethylene terephthalate is replaced with an equal mass of polyoxymethylene homopolymer.

[0151] Comparative Example 3:

[0152] The preparation method of this comparative example is the same as that of Example 1, except that 3 kg of polyethylene terephthalate and 1 kg of polyoxymethylene are added.

[0153] Comparative Example 4:

[0154] The preparation method of this comparative example is the same as that of Example 1, except that 9 kg of polyethylene terephthalate and 6 kg of polyoxymethylene are added.

[0155] Comparative Example 5:

[0156] The preparation method of this comparative example is the same as that of Example 1, except that 25 parts of recycled coarse aggregate are added.

[0157] Comparative Example 6:

[0158] The preparation method of this comparative example is the same as that of Example 1, except that 8 parts of recycled coarse aggregate are added.

[0159] Test Example 1:

[0160] The mechanical properties of the recycled concrete composites from Examples 1-7 and Comparative Examples 1-6 were tested. The testing methods were as follows: 28-day compressive strength and 28-day flexural strength were tested according to GB / T 50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete"; 28-day chloride ion diffusion coefficient was tested according to GB / T 31289-2014 standard. The test results are shown in Table 1 and... Figures 1-3 As shown.

[0161] Table 1 Mechanical properties of recycled concrete composite materials from Examples 1-7 and Comparative Examples 1-6:

[0162]

[0163] According to Table 1 and Figures 1-3It can be seen that the recycled concrete composite materials prepared in Examples 1-7 of this invention have the advantages of high compressive strength and flexural strength, as well as low chloride ion diffusion coefficient. These effects are achieved under the condition that all coarse aggregate is recycled. Compared with Comparative Examples 1-2, it can be seen that polyoxymethylene homopolymer and polyethylene terephthalate (PET) play a role in improving strength and reducing chloride ion diffusion coefficient in the recycled concrete composite material system. This can be attributed to the synergistic effect of polyoxymethylene homopolymer and PET, which repairs the microstructure of the recycled aggregate and strengthens the surface coating. Compared with Comparative Examples 3-4, it can be seen that the polyoxymethylene homopolymer and PET need to be in a specific ratio to function effectively; otherwise, the strengthening effect is significantly reduced. Compared with Comparative Examples 5-6, it can be seen that the proportion of recycled aggregate in the recycled concrete composite material also has a significant impact on its strengthening effect. Within the limits of this invention, recycled aggregate can better function and ensure the desired effect.

[0164] As can be seen from the above embodiments, the recycled concrete composite material provided by the present invention has good strength and low chloride ion diffusion performance, and the replacement rate of recycled coarse aggregate reaches 100%. This is of key significance for the utilization of recycled coarse aggregate and the development of recycled concrete, and provides a new approach for the preparation of recycled concrete.

[0165] The embodiments of the present invention have been described above; however, these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. All other embodiments obtained by those skilled in the art based on the above embodiments of the present invention without inventive effort are within the protection scope of the present invention.

Claims

1. A recycled concrete composite material, characterized in that, The components include the following parts by mass: 10 parts cement, 2-4 parts fly ash, 10-18 parts recycled coarse aggregate, 5-6 parts polyethylene terephthalate, 2-3 parts polyoxymethylene, 8-13 parts fine aggregate, 0.1-0.5 parts water-reducing agent and 5-10 parts water; The preparation method of the recycled concrete composite material includes the following steps: (1) The recycled coarse aggregate, polyethylene terephthalate and polyoxymethylene are mixed and heated, heat-treated and cooled in sequence to obtain modified aggregate; (2) The modified aggregate is mixed with cement, fly ash, fine aggregate, water-reducing agent and water to obtain recycled concrete composite material.

2. The recycled concrete composite material according to claim 1, characterized in that, The particle size of the fly ash is 1-20 micrometers.

3. The recycled concrete composite material according to claim 1, characterized in that, The recycled coarse aggregate is a type I recycled coarse aggregate.

4. The recycled concrete composite material according to claim 1, characterized in that, The polyethylene terephthalate has a melting point of 250-260 degrees Celsius.

5. The recycled concrete composite material according to claim 1, characterized in that, The polyoxymethylene is a polyoxymethylene homopolymer; The melting point of the polyoxymethylene is 175~185 degrees Celsius.

6. The recycled concrete composite material according to claim 1, characterized in that, The fine aggregate is river sand; The fineness modulus of the fine aggregate is 2.6~3.

7. The recycled concrete composite material according to claim 1, characterized in that, The water-reducing agent is a polycarboxylate high-performance water-reducing agent.

8. A method for preparing a recycled concrete composite material, wherein the recycled concrete composite material is the recycled concrete composite material according to any one of claims 1 to 7, characterized in that, Includes the following steps: (1) The recycled coarse aggregate, polyethylene terephthalate and polyoxymethylene are mixed and heated, heat-treated and cooled in sequence to obtain modified aggregate; (2) The modified aggregate is mixed with cement, fly ash, fine aggregate, water-reducing agent and water to obtain recycled concrete composite material.

9. The method for preparing recycled concrete composite material according to claim 8, characterized in that, The heating rate is 20~25℃ / min; The heat treatment temperature is 260~270 degrees Celsius, and the holding time is 30~50 minutes; The cooling rate is 5~10℃ / min.

10. An application of a recycled concrete composite material in road engineering, characterized in that, The recycled concrete composite material is the recycled concrete composite material according to any one of claims 1 to 7 or the recycled concrete composite material obtained by the preparation method according to any one of claims 8 to 9.

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