A super high-performance recycled concrete and its preparation method

Abstract

The present invention belongs to the technical field of building materials, and discloses a super high performance recycled concrete and a preparation method thereof. In view of the characteristics of recycled fine aggregates of waste concrete, the present invention uses acrylic emulsion and micro-nano mineral fibers to repair the defects of recycled fine aggregates of waste concrete. The acrylic emulsion is beneficial to reducing the water absorption rate of recycled fine aggregates of waste concrete. The acrylic emulsion and micro-nano mineral fibers together improve the self-strength of recycled fine aggregates of waste concrete, thereby ensuring that the obtained super high performance recycled concrete has good workability and mechanical properties. In addition, by reasonably designing the binder system of the super high performance recycled concrete, adding a large amount of microbeads, heavy calcium carbonate and cooperating with the use of a slurry consistency regulator, the fluidity of the obtained super high performance recycled concrete can be effectively improved and its viscosity can be reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of building materials, and particularly to a ultra-high performance recycled concrete and a preparation method thereof. Background Art

[0002] As a large amount of waste, the comprehensive utilization rate of construction waste is less than 10%. At present, the utilization of construction waste, especially waste concrete, mainly focuses on recycled coarse and fine aggregates. However, compared with natural aggregates, the recycled aggregates processed from waste concrete have a large amount of old cement mortar attached to their surfaces. When used in the preparation of new concrete, it is easy to generate a multi-interface structure and a high interfacial water-cement ratio. Moreover, the recycled aggregates have many internal cracks, large porosity, high water absorption, high crushing index, low density and strength, resulting in obvious deterioration of the workability of the concrete mixture when using recycled aggregates to prepare concrete, and significant reduction of the mechanical properties and durability after hardening, which greatly limits its resource utilization. In some areas, there are many salt lakes and saline soils, with dry and less rainy climate and large temperature difference between day and night. Concrete mainly bears freeze-thaw cycles, salt erosion (such as sulfate ion, magnesium ion and sodium ion erosion) and wet-dry alternation in this environment, resulting in more limited use of recycled concrete in this area.

[0003] Ultra-high performance concrete (UHPC) is usually designed based on the most closely packed theory, and is a kind of ultra-high strength cement-based material with high strength, high toughness and low porosity, which is made by special mixing process from multi-component cementitious materials, fine aggregates, micro steel fibers, polycarboxylate superplasticizer, water, etc. According to different raw material compositions and curing methods, its compressive strength is usually 100MPa - 180MPa, flexural strength is 12 - 35MPa, electric flux ≤ 100C or chloride ion diffusion coefficient ≤ 1.5×10 -14 m 2 / s. Due to its excellent mechanical properties and impermeability, UHPC is particularly suitable for long-span bridges, blast-resistant structures and thin-walled structures, as well as for high-abrasion and high-corrosion environments. It is of great significance to use recycled fine aggregates from waste concrete to prepare ultra-high performance concrete. However, ultra-high performance concrete itself has a low water-binder ratio, usually 0.14 - 0.22, and a large amount of ultra-fine mineral materials are added during the preparation of ultra-high performance concrete, resulting in high viscosity. Slightly adding substances with large water absorption will greatly affect its workability. Therefore, at present, when using recycled fine aggregates to prepare ultra-high performance concrete, the substitution amount of quartz sand or natural sand is very low, generally not exceeding 30%. Once using recycled fine aggregates to completely replace the existing quartz sand or natural sand to prepare ultra-high performance concrete, the workability, strength and durability of ultra-high performance concrete will be significantly reduced due to the poor characteristics of recycled fine aggregates such as high water absorption and high crushing index. Therefore, it is urgent in this field to develop a recycled concrete with good workability, mechanical properties and durability. Summary of the Invention

[0004] In view of this, the present invention provides a super high-performance recycled concrete, which modifies the surface defects of recycled aggregates, reduces their water absorption rate, improves their own strength and the bond strength with cement paste. At the same time, the composition of the super high-performance recycled concrete is reasonably adjusted to suit the characteristics of recycled aggregates. The combined action of these factors ensures that the obtained super high-performance recycled concrete has good workability, mechanical properties and durability, so as to solve the problems of poor workability, mechanical properties and durability of existing recycled concrete.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] The present invention provides a super high-performance recycled concrete, which comprises the following raw materials in parts by mass: 500-650 parts of cement, 100-150 parts of fly ash microbeads, 50-80 parts of silica fume, 80-100 parts of heavy calcium carbonate, 6.5-9.5 parts of water reducing agent, 0.08-0.12 parts of paste consistency regulator, 800-1000 parts of modified waste concrete recycled fine aggregate and 180-200 parts of water; the super high-performance recycled concrete further comprises steel fibers; the dosage of the steel fibers is 1-2% of the volume of the super high-performance recycled concrete.

[0007] Preferably, the diameter of the steel fibers is 0.18-0.22 mm, the length is 13-15 mm, and the aspect ratio is 60-70:1.

[0008] Preferably, the cement is Portland cement with a strength grade ≥ 42.5 or ordinary Portland cement with a strength grade ≥ 42.5; the water demand ratio of the fly ash microbeads ≤ 90%, and the 28-day activity index ≥ 105%.

[0009] Preferably, the water demand ratio of the silica fume ≤ 125%, and the 28-day activity index ≥ 105%; the fineness of the heavy calcium carbonate ≥ 325 mesh.

[0010] Preferably, the water reducing agent is a powdered polycarboxylate superplasticizer, and the water reduction rate ≥ 30%; the paste consistency regulator is a mixture of lignosulfonate and sodium tripolyphosphate, and the mass ratio of lignosulfonate to sodium tripolyphosphate is 1:1.2-1.5.

[0011] Preferably, the preparation of the modified waste concrete recycled fine aggregate comprises the following steps: mixing acrylic emulsion, waste concrete recycled fine aggregate and micro-nano mineral fibers, and reacting to obtain the modified waste concrete recycled fine aggregate.

[0012] Preferably, the aspect ratio of the micro-nano mineral fiber is 15 to 20:1; the micro-nano mineral fiber is wollastonite fiber; the reaction temperature is 40 to 50 °C.

[0013] Preferably, the dosage of the acrylic emulsion is 5 to 8% of the mass of the recycled fine aggregate of waste concrete, and the dosage of the micro-nano mineral fiber is 0.5 to 1.5% of the mass of the recycled fine aggregate of waste concrete.

[0014] Preferably, the recycled fine aggregate of waste concrete is obtained by crushing and screening waste concrete with an original strength grade ≥ C30 to a fineness modulus of 2 to 2.5.

[0015] The present invention also provides a method for preparing the ultra-high performance recycled concrete, comprising the following steps: mixing cement, fly ash microspheres, silica fume, heavy calcium carbonate, water reducing agent, paste consistency regulator, modified recycled fine aggregate of waste concrete, steel fiber and water to obtain ultra-high performance recycled concrete.

[0016] It can be seen from the above technical solutions that, compared with the prior art, the beneficial effects of the present invention are as follows:

[0017] (1) In view of the characteristics of the recycled fine aggregate of waste concrete, the present invention uses acrylic emulsion and micro-nano mineral fiber to repair the defects of the recycled fine aggregate of waste concrete. The acrylic emulsion is beneficial to reducing the water absorption rate of the recycled fine aggregate of waste concrete. The combination of acrylic emulsion and micro-nano mineral fiber can jointly improve the self-strength of the recycled fine aggregate of waste concrete, thereby ensuring that the obtained ultra-high performance recycled concrete has good workability and mechanical properties. In addition, by reasonably designing the cementitious material system of the ultra-high performance recycled concrete, a large amount of microspheres and heavy calcium carbonate are added and combined with the use of a paste consistency regulator, which can effectively improve the fluidity of the obtained ultra-high performance recycled concrete and reduce its viscosity;

[0018] (2) The slump flow of the ultra-high performance recycled concrete obtained by the method of the present invention is between 670 and 730 mm, meeting the fluidity requirements of self-compacting ultra-high performance concrete. Its 3d compressive strength can reach about 110 MPa, its 7d compressive strength can reach about 130 MPa, and its 28d compressive strength can reach about 150 MPa. Moreover, the modification of the recycled fine aggregate of waste concrete by acrylic emulsion and micro-nano mineral fiber enables the concrete to have high toughness under a low steel fiber content. Its 3d flexural strength can reach about 22 MPa, its 7d flexural strength can reach about 30 MPa, and its 28d flexural strength can reach about 35 MPa. At the same time, its chloride ion diffusion coefficient can be as low as 1.0×10 -14 m 2 / s or so, and the anti-sulfate erosion grade is KS150.

[0019] (3) The present invention realizes the resource utilization of recycled fine aggregate of waste concrete in ultra-high performance concrete. Moreover, by using the method of the present invention to modify the recycled fine aggregate of waste concrete, the source applicability of the recycled fine aggregate of waste concrete is wide, and no environmentally harmful substances are generated during the whole modification process, which is conducive to industrialized popularization and application. Specific embodiments

[0020] The present invention provides an ultra-high performance recycled concrete, which comprises the following raw materials in parts by mass: 500 - 650 parts of cement, 100 - 150 parts of fly ash microspheres, 50 - 80 parts of silica fume, 80 - 100 parts of heavy calcium carbonate, 6.5 - 9.5 parts of water reducing agent, 0.08 - 0.12 parts of slurry consistency regulator, 800 - 1000 parts of modified recycled fine aggregate of waste concrete, and 180 - 200 parts of water.

[0021] In the present invention, the dosage of the cement is preferably 520 - 620 parts, more preferably 550 - 600 parts; the dosage of the fly ash microspheres is preferably 110 - 140 parts, more preferably 120 - 130 parts; the dosage of the silica fume is preferably 60 - 75 parts, more preferably 62 - 70 parts; the dosage of the heavy calcium carbonate is preferably 85 - 95 parts, more preferably 88 - 92 parts; the dosage of the water reducing agent is preferably 7 - 9 parts, more preferably 7.5 - 8.5 parts; the dosage of the slurry consistency regulator is preferably 0.09 - 0.11 parts, more preferably 0.1 part; the dosage of the modified recycled fine aggregate of waste concrete is preferably 850 - 950 parts, more preferably 900 - 920 parts; the dosage of the water is preferably 185 - 195 parts, more preferably 188 - 192 parts.

[0022] In the present invention, the ultra-high performance recycled concrete further comprises steel fibers; the dosage of the steel fibers is preferably 1 - 2% of the volume of the ultra-high performance recycled concrete, more preferably 1.2 - 1.8% of the volume of the ultra-high performance recycled concrete; the diameter of the steel fibers is preferably 0.18 - 0.22 mm, more preferably 0.19 - 0.21 mm, the length is preferably 13 - 15 mm, more preferably 13.5 - 14.5 mm, and the aspect ratio is preferably 60 - 70:1, more preferably 62 - 68:1.

[0023] In the present invention, the cement is preferably Portland cement with a strength grade ≥ 42.5 or ordinary Portland cement with a strength grade ≥ 42.5, more preferably ordinary Portland cement with a strength grade ≥ 42.5; the water demand ratio of the fly ash microspheres is preferably ≤ 90%, more preferably ≤ 88%, and the 28-day activity index is preferably ≥ 105%, more preferably ≥ 107%.

[0024] In the present invention, the water demand ratio of the silica fume is preferably ≤125%, more preferably ≤120%, the 28-day activity index is preferably ≥105%, more preferably ≥110%; the fineness of the heavy calcium carbonate is preferably ≥325 mesh, more preferably ≥400 mesh.

[0025] In the present invention, the water reducing agent is a powdered polycarboxylate superplasticizer, and the water reducing rate is preferably ≥30%, more preferably ≥35%; the slurry consistency regulator is a mixture of lignosulfonate and sodium tripolyphosphate, and the mass ratio of lignosulfonate to sodium tripolyphosphate is preferably 1:1.2 - 1.5, more preferably 1:1.3 - 1.4.

[0026] By adding lignosulfonate and sodium tripolyphosphate in the present invention, the whole system can be effectively dispersed, and the adverse effect of the modified waste concrete recycled fine aggregate on the consistency of the whole system can be reduced, so that the obtained ultra-high performance recycled concrete has good fluidity and low viscosity.

[0027] In the present invention, the preparation of the modified waste concrete recycled fine aggregate comprises the following steps: mixing an acrylic emulsion, waste concrete recycled fine aggregate and micro-nano mineral fibers, and reacting to obtain the modified waste concrete recycled fine aggregate.

[0028] In the present invention, the specific steps of mixing the acrylic emulsion, waste concrete recycled fine aggregate and micro-nano mineral fibers are as follows: first, dilute the acrylic emulsion and water according to a volume ratio of 1:1, then spray it onto the surface of the waste concrete recycled fine aggregate, and then add the micro-nano mineral fibers and mix.

[0029] In the present invention, the aspect ratio of the micro-nano mineral fibers is preferably 15 - 20:1, more preferably 16 - 19:1; the micro-nano mineral fibers are wollastonite fibers; the dosage of the acrylic emulsion is preferably 5 - 8% of the mass of the waste concrete recycled fine aggregate, more preferably 6 - 7%; the solid content of the acrylic emulsion is preferably 40 - 50%; the dosage of the micro-nano mineral fibers is preferably 0.5 - 1.5% of the mass of the waste concrete recycled fine aggregate, more preferably 0.8 - 1.2%; the reaction temperature is preferably 40 - 50°C, more preferably 42 - 48°C.

[0030] In the present invention, acrylic emulsion is sprayed on the surface of recycled fine aggregate of waste concrete. As the acrylic emulsion cures, it can repair the surface defects of the recycled fine aggregate of waste concrete, thereby reducing the water absorption rate of the recycled fine aggregate. Moreover, the addition of micro-nano mineral fibers can accelerate the curing of the acrylic emulsion and further enhance the curing strength between the acrylic emulsion and the recycled fine aggregate of waste concrete, thus effectively modifying and strengthening the surface defects of the recycled fine aggregate of waste concrete, improving its mechanical properties. At the same time, the micro-nano mineral fibers can be inserted into the cement concrete paste, effectively improving the bonding strength between the modified recycled fine aggregate of waste concrete and the cement paste, and further improving the toughness of the toughness ultra-high performance recycled concrete in cooperation with the cured acrylic emulsion.

[0031] In the present invention, the recycled fine aggregate of waste concrete is obtained by crushing and screening waste concrete with an original strength grade ≥C30 to a fineness modulus of 2 - 2.5; the fineness modulus of the recycled fine aggregate of waste concrete is preferably 2.1 - 2.3.

[0032] The present invention also provides a method for preparing the ultra-high performance recycled concrete, comprising the following steps: mixing cement, fly ash microbeads, silica fume, heavy calcium carbonate, water reducer, paste consistency regulator, modified recycled fine aggregate of waste concrete, steel fibers and water to obtain the ultra-high performance recycled concrete.

[0033] In the present invention, the specific steps for mixing cement, fly ash microbeads, silica fume, heavy calcium carbonate, water reducer, paste consistency regulator, modified recycled fine aggregate of waste concrete, steel fibers and water are as follows: first, perform the first mixing of cement, fly ash microbeads, silica fume, heavy calcium carbonate and paste consistency regulator, add the modified recycled fine aggregate of waste concrete for the second mixing, then add the water reducer and water for the third mixing, and finally add the steel fibers for the fourth mixing to obtain the ultra-high performance recycled concrete.

[0034] In the present invention, the time for the first mixing is preferably 1.5 - 2.5 min, more preferably 2 min; the time for the second mixing is preferably 0.5 - 1.5 min, more preferably 1 min; the time for the third mixing is preferably 2 - 4 min, more preferably 3 min; the time for the fourth mixing is preferably 1 - 3 min, more preferably 2 min. The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0035] The raw materials used in the examples and comparative examples are as follows: the cement is P.O52.5 cement; the water demand ratio of fly ash microspheres is 90%, and the 28-day activity index is 107%; the water demand ratio of silica fume is 120%, and the 28-day activity index is 115%; the fineness of heavy calcium carbonate is 325 mesh; the water reducing agent is a powdered polycarboxylate superplasticizer with a water reduction rate of 30%; the slurry consistency regulator is a mixture of lignosulfonate and sodium tripolyphosphate, and the mass ratio of lignosulfonate to sodium tripolyphosphate is 1:1.2; the diameter of the steel fiber is 0.2 mm, the length is 14 mm, and the aspect ratio is 70:1; the aspect ratio of micro-nano mineral fiber is 15:1; the recycled fine aggregate of waste concrete is obtained by crushing and screening the original waste concrete road slab with a strength grade of C40 to a fineness modulus of 2.3, and the micro-nano mineral fiber is wollastonite fiber;

[0036] The preparation of the modified recycled fine aggregate of waste concrete described in the following examples includes the following steps: Dilute the acrylic emulsion with a solid content of 44% and water in a volume ratio of 1:1 in advance, then spray it on the surface of the recycled fine aggregate of waste concrete, stir evenly, add micro-nano mineral fiber, and continue to stir to make it evenly mixed. Let it stand for a period of time in an environment of 40°C. After the acrylic emulsion is cured, the modified recycled fine aggregate of waste concrete is obtained. Among them, the dosage of the acrylic emulsion is 7% of the mass of the recycled fine aggregate of waste concrete, and the dosage of the micro-nano mineral fiber is 1.0% of the mass of the recycled fine aggregate of waste concrete.

[0037] Example 1

[0038] Ultra-high performance recycled concrete, including the following raw materials in parts by mass:

[0039] 500 parts of cement, 100 parts of fly ash microspheres, 80 parts of silica fume, 80 parts of heavy calcium carbonate, 6.5 parts of water reducing agent, 0.1 part of slurry consistency regulator, 800 parts of modified recycled fine aggregate of waste concrete, 180 parts of water, and 1.5% by volume of steel fiber in the ultra-high performance recycled concrete;

[0040] The preparation method is as follows:

[0041] Stir and mix the cement, fly ash microspheres, silica fume, heavy calcium carbonate, and slurry consistency regulator evenly for 2 minutes, then add the modified recycled fine aggregate of waste concrete and continue to stir for 1 minute. Then add the water reducing agent and water, stir for 3 minutes until the slurry appears, and then add the steel fiber and stir for 2 minutes to obtain ultra-high performance recycled concrete.

[0042] Example 2

[0043] The differences from Example 1 are as follows: The raw materials and their dosages are 600 parts of cement, 130 parts of fly ash microspheres, 50 parts of silica fume, 90 parts of heavy calcium carbonate, 8.5 parts of water reducer, 0.1 part of slurry consistency regulator, 900 parts of modified waste concrete recycled fine aggregate, 190 parts of water, and steel fibers with a volume fraction of 1.5% in ultra-high performance recycled concrete; other conditions are the same as those in Example 1.

[0044] Example 3

[0045] The differences from Example 1 are as follows: The raw materials and their dosages are 650 parts of cement, 150 parts of fly ash microspheres, 50 parts of silica fume, 80 parts of heavy calcium carbonate, 8.5 parts of water reducer, 0.12 part of slurry consistency regulator, 1000 parts of modified waste concrete recycled fine aggregate, 200 parts of water, and steel fibers with a volume fraction of 1.5% in ultra-high performance recycled concrete; other conditions are the same as those in Example 1.

[0046] Example 4

[0047] The differences from Example 1 are as follows: The raw materials and their dosages are 600 parts of cement, 100 parts of microspheres, 80 parts of silica fume, 100 parts of heavy calcium carbonate, 7.5 parts of water reducer, 0.12 part of slurry consistency regulator, 1000 parts of modified waste concrete recycled fine aggregate, 190 parts of water, and steel fibers with a volume fraction of 1.5% in ultra-high performance recycled concrete; other conditions are the same as those in Example 1.

[0048] Example 5

[0049] The differences from Example 1 are as follows: The raw materials and their dosages are 550 parts of cement, 150 parts of microspheres, 80 parts of silica fume, 90 parts of heavy calcium carbonate, 8.5 parts of water reducer, 0.08 part of slurry consistency regulator, 800 parts of modified waste concrete recycled fine aggregate, 180 parts of water, and steel fibers with a volume fraction of 1.5% in ultra-high performance recycled concrete; other conditions are the same as those in Example 1.

[0050] Example 6

[0051] The differences from Example 1 are as follows: The raw materials and their dosages are 630 parts of cement, 150 parts of microspheres, 70 parts of silica fume, 100 parts of heavy calcium carbonate, 9.5 parts of water reducer, 0.08 part of slurry consistency regulator, 900 parts of modified waste concrete recycled fine aggregate, 200 parts of water, and steel fibers with a volume fraction of 1.5% in ultra-high performance recycled concrete; other conditions are the same as those in Example 1.

[0052] Comparative Example 1

[0053] The raw material ratio of the ultra-high performance recycled concrete in this comparative example is the same as that in Example 6. The difference from Example 6 is that the recycled fine aggregate of waste concrete in this comparative example is obtained by crushing and screening the waste concrete pavement construction waste with an original strength grade of C40 to a fineness modulus of 2.3, and it is not modified by the method of the example; others are the same as Example 6.

[0054] Comparative Example 2

[0055] The raw material ratio of the ultra-high performance recycled concrete in this comparative example is the same as that in Example 6. The difference from Example 6 is that the ultra-high performance recycled concrete in this comparative example does not add the paste consistency regulator of Example 6.

[0056] The properties of the ultra-high performance recycled concrete of Examples 1 to 6 and Comparative Examples 1 to 2 were tested, and the results are shown in Table 1.

[0057] Table 1 Performance test results of the ultra-high performance recycled concrete of Examples 1 to 6 and Comparative Examples 1 to 2

[0058]

[0059] As can be seen from Table 1, the slump flow of the ultra-high performance recycled concrete of Examples 1 to 6 of the present invention is between 670 and 730 mm, meeting the fluidity requirements of ultra-high performance concrete. Its 3d compressive strength can reach about 110 MPa, its 7d compressive strength can reach about 130 MPa, and its 28d compressive strength can reach about 150 MPa. Moreover, due to the modification of the recycled fine aggregate of waste concrete by acrylic emulsion and micro-nano mineral fibers, it has high toughness under a low steel fiber content. Its 3d flexural strength can reach about 22 MPa, its 7d flexural strength can reach about 30 MPa, and its 28d flexural strength can reach about 35 MPa. At the same time, its chloride ion diffusion coefficient can be as low as 1.0×10 -14 m 2 / s or so, and the sulfate resistance grade is KS150. Moreover, the mechanical properties, sulfate resistance and chloride ion erosion resistance of the ultra-high performance recycled concrete of Examples 1 to 6 of the present invention are significantly better than those of the comparative examples.

[0060] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A super high-performance recycled concrete, characterized in that it comprises raw materials in the following parts by mass: 500 - 650 parts of cement, 100 - 150 parts of fly ash microspheres, 50 - 80 parts of silica fume, 80 - 100 parts of heavy calcium carbonate, 6.5 - 9.5 parts of water reducing agent, 0.08 - 0.12 parts of paste consistency regulator, 800 - 1000 parts of modified waste concrete recycled fine aggregate, and 180 - 200 parts of water; the super high-performance recycled concrete further comprises steel fibers; the dosage of the steel fibers is 1 - 2% of the volume of the super high-performance recycled concrete; the water reducing agent is a powdered polycarboxylate superplasticizer with a water reduction rate ≥ 30%; the paste consistency regulator is a mixture of lignosulfonate and sodium tripolyphosphate, and the mass ratio of lignosulfonate to the sodium tripolyphosphate is 1:1.2 - 1.5; the preparation of the modified waste concrete recycled fine aggregate comprises the following steps: mixing acrylic emulsion, waste concrete recycled fine aggregate, and micro-nano mineral fibers, and reacting to obtain the modified waste concrete recycled fine aggregate; the aspect ratio of the micro-nano mineral fibers is 15 - 20:1; the micro-nano mineral fibers are wollastonite fibers; the reaction temperature is 40 - 50 °C; the dosage of the acrylic emulsion is 5 - 8% of the mass of the waste concrete recycled fine aggregate, and the dosage of the micro-nano mineral fibers is 0.5 - 1.5% of the mass of the waste concrete recycled fine aggregate.

2. The super high-performance recycled concrete according to claim 1, characterized in that the diameter of the steel fibers is 0.18 - 0.22 mm, the length is 13 - 15 mm, and the aspect ratio is 60 - 70:

1.

3. The super high-performance recycled concrete according to claim 1, characterized in that the cement is Portland cement with a strength grade ≥ 42.5 or ordinary Portland cement with a strength grade ≥ 42.5; the water demand ratio of the fly ash microspheres ≤ 90%, and the 28-day activity index ≥ 105%.

4. The super high-performance recycled concrete according to claim 3, characterized in that the water demand ratio of the silica fume ≤ 125%, and the 28-day activity index ≥ 105%; the fineness of the heavy calcium carbonate ≥ 325 mesh.

5. The super high-performance recycled concrete according to claim 1, characterized in that the waste concrete recycled fine aggregate is obtained by crushing and screening waste concrete with an original strength grade ≥ C30 to a fineness modulus of 2 - 2.

5.

6. The preparation method of the super high-performance recycled concrete according to any one of claims 1 - 5, characterized in that it comprises the following steps: mixing cement, fly ash microspheres, silica fume, heavy calcium carbonate, water reducing agent, paste consistency regulator, modified waste concrete recycled fine aggregate, steel fibers, and water to obtain the super high-performance recycled concrete.

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