CN114105561A

CN114105561A - Recycled concrete based on inorganic fibers and preparation method thereof

Info

Publication number: CN114105561A
Application number: CN202111410224.6A
Authority: CN
Inventors: 刘新春; 武文强
Original assignee: Shenzhen Tiandi Dongjian Concrete Co ltd
Current assignee: Shenzhen Tiandi Dongjian Concrete Co ltd
Priority date: 2021-11-24
Filing date: 2021-11-24
Publication date: 2022-03-01
Anticipated expiration: 2041-11-24
Also published as: CN114105561B

Abstract

The application relates to the field of recycled concrete, in particular to recycled concrete based on inorganic fibers and a preparation method thereof, and the recycled concrete based on the inorganic fibers comprises the following raw materials: the concrete comprises coarse aggregate, cement, modified recycled coarse aggregate, recycled fine aggregate, fly ash, silica fume, water, modified inorganic fiber, a water reducing agent, an expanding agent, a silane coupling agent, butylbenzene emulsion and an isocyanate curing agent; the modified inorganic fiber is modified by glass fiber and carbon fiber through a silane coupling agent; the modified recycled coarse aggregate is continuous graded particles with the particle size of 5-15mm, which are prepared by crushing, screening, physical treatment and chemical modification of waste concrete. The recycled concrete based on the inorganic fibers has excellent mechanical properties and crack resistance.

Description

Recycled concrete based on inorganic fibers and preparation method thereof

Technical Field

The application relates to the field of recycled concrete, in particular to recycled concrete based on inorganic fibers and a preparation method thereof.

Background

Along with the development and transformation of urban construction and other reasons, some buildings need to be dismantled, a large amount of waste concrete can be generated, and the waste concrete is piled as construction waste, so that the land area is occupied, and the environment is polluted. Therefore, how to effectively utilize the waste concrete becomes a topic to be urgently developed.

The recycled concrete is new concrete prepared by crushing, cleaning and grading waste concrete, partially or completely replacing natural aggregates such as sand stones and the like, and matching the natural aggregates with components such as cement, water and the like according to a certain proportion.

However, when the waste concrete is used as an aggregate of recycled concrete instead of part of gravel, the mechanical properties of the recycled concrete are poor.

Disclosure of Invention

In order to solve the problem of poor mechanical property of the recycled concrete, the application provides the recycled concrete based on the inorganic fiber and the preparation method thereof.

In a first aspect, the application provides a recycled concrete based on inorganic fibers, which adopts the following technical scheme: the inorganic fiber-based recycled concrete comprises the following raw materials in parts by weight: 280 parts of coarse aggregate, 240 parts of cement, 200 parts of modified and regenerated coarse aggregate, 370 parts of modified and regenerated fine aggregate, 50-90 parts of regenerated fine aggregate, 70-110 parts of fly ash, 50-90 parts of silica fume, 60-80 parts of water, 30-70 parts of modified inorganic fiber, 0.5-2 parts of water reducing agent, 11-15 parts of expanding agent, 20-28 parts of silane coupling agent, 5-10 parts of butylbenzene emulsion and 0.5-2.5 parts of isocyanate curing agent; the modified inorganic fiber comprises glass fiber and carbon fiber, and the weight ratio of the glass fiber to the carbon fiber is (0.5-2): 1; the glass fiber and the carbon fiber are obtained by modifying treatment of a silane coupling agent; the modified recycled coarse aggregate is continuous graded particles with the particle size of 5-15mm, which are prepared by crushing, screening, physical treatment and chemical modification of waste concrete.

By adopting the technical scheme, the carbon fiber has excellent performances such as high strength, high modulus, high temperature resistance, corrosion resistance and the like, can play a role in restraining the expansion of micro cracks in concrete, and improves the crack resistance and the mechanical property of the concrete; the glass fiber has good heat resistance, good corrosion resistance and good mechanical property, and can improve the mechanical property of concrete; but the carbon fiber and the glass fiber have poor adhesion with cement, so that the hydrophilic performance of the carbon fiber and the glass fiber is improved through modification of a silane coupling agent, the adhesion between the fiber and the cement is improved, and the mechanical property of the recycled concrete is further improved; the recycled coarse aggregate is continuous graded particles with the particle size of 5-15mm, which are prepared by screening, physical treatment and chemical modification of waste concrete, the used particles of the recycled coarse aggregate are continuous graded, so that large and small particles form a compact network structure, and aggregates with different sizes are mutually filled to reduce the porosity, reduce the water absorption rate of the recycled concrete and improve the mechanical property of the recycled concrete.

The silica fume has high volcanic activity and filling effect, and can reduce the difference between interface and cement mechanical performance, facilitate cement hydration reaction, promote C-S-H generation, inhibit calcium hydroxide production, reduce oriented calcium hydroxide crystal and pore in the transition area between aggregate and slurry interface, raise the interface adhesion performance and raise the mechanical performance of regenerated concrete.

Preferably, the recycled concrete comprises the following raw materials in parts by weight: 270 parts of coarse aggregate, 230 parts of cement, 340 parts of modified and regenerated coarse aggregate, 60-80 parts of regenerated fine aggregate, 80-100 parts of fly ash, 60-80 parts of silica fume, 65-75 parts of water, 40-60 parts of modified inorganic fiber, 1-1.5 parts of water reducing agent, 12-14 parts of expanding agent, 22-26 parts of silane coupling agent, 6-8 parts of styrene-butadiene emulsion and 1-2 parts of isocyanate curing agent.

By adopting the technical scheme, the mixing amount of the raw materials of the recycled concrete is further optimized, and the mechanical property of the recycled concrete is improved.

Preferably, the modified recycled coarse aggregate is prepared by the following steps:

s1, crushing and screening the waste concrete to obtain regenerated particles with the particle size of 5-15 mm;

s2, adding 1-1.5mol/L hydrochloric acid solution into the regenerated particles under the stirring state to obtain regenerated particles after hydrochloric acid treatment; wherein the weight ratio of the regenerated particles to the hydrochloric acid solution is 1: (0.1-0.5);

s3, carrying out vacuum drying treatment on the regenerated particles after hydrochloric acid treatment;

s4, placing the dried regenerated particles into a mixed solution of a siloxane aqueous solution, a sodium silicate aqueous solution and water-based epoxy resin for reaction for 4-6 hours to obtain modified regenerated coarse aggregate; wherein the weight ratio of the dried regenerated particles to the mixed solution is 100: (3-5), the mass fractions of the siloxane aqueous solution and the sodium silicate aqueous solution before mixing are both 25-35%.

By adopting the technical scheme, hydrochloric acid reacts with substances on the surfaces of the regenerated particles to form dents; vacuum drying is favorable for removing the liquid of the regenerated coarse aggregate after hydrochloric acid treatment; the mixed solution of the siloxane aqueous solution, the sodium silicate aqueous solution and the water-based epoxy resin has an affinity effect and can form a hydrophobic layer. Siloxane diffuses into the reticular voids of the recycled coarse aggregate, then a polymerization reaction occurs, and the produced hydrophobic film is converted into hydrophobic resin, so that the moisture absorption is reduced, the water absorption is reduced, and the mechanical property is improved; the sodium silicate aqueous solution contains hydroxyl groups, has hydrophilicity, but the hydroxyl groups can also improve the adhesion of siloxane attached to the capillary wall of the recycled coarse aggregate, and simultaneously, the sodium silicate can catalyze hydrolysis reaction to improve the water repellency of the film on the surface of the capillary wall; therefore, after the recycled coarse aggregate is treated by the mixed liquid of siloxane and sodium silicate, the siloxane is adsorbed on the surface of the capillary wall inside the recycled coarse aggregate through the sodium silicate to form a water repellent film; the water-based epoxy resin is a stable dispersion system prepared by using water as a dispersion medium, and the water-based epoxy resin and siloxane are physically blended, so that respective advantages can be exerted, and when the siloxane is attached to the capillary wall of the regenerated coarse aggregate to repel water, an interpenetrating network structure is formed when the water-based epoxy resin is cured, the cohesiveness among concrete materials is increased, and the mechanical property of the concrete is improved.

The waterborne epoxy resin can also form a bond force with the modified inorganic fiber, so that the bonding force between the modified inorganic fiber and the waterborne resin is increased, and the mechanical property of the recycled concrete is improved.

Preferably, in the step S3, the temperature of the drying treatment is 280-300 ℃. Preferably, the treatment temperature can be 290 ℃, 280-.

By adopting the technical scheme, the drying treatment temperature is set to be 280-300 ℃, which is beneficial to the thermal decomposition of the surface material of the recycled coarse aggregate or the disintegration of the attachment, improves the purity of the recycled coarse aggregate, is beneficial to increasing the caking property of the recycled coarse aggregate with cement and other raw materials, reduces pores and can improve the mechanical property of recycled concrete.

Preferably, in step S4, the weight ratio of the siloxane aqueous solution, the sodium silicate aqueous solution and the aqueous epoxy resin is 1:1: (0.5-2).

By adopting the technical scheme, the proportion of the siloxane aqueous solution, the silicate aqueous solution and the water-based epoxy resin solution is optimized, and the mechanical property of the recycled concrete is improved.

Preferably, in step S4, the pressure of the reaction between the dried product and the mixed solution is controlled to be 0.2-0.3 MPa.

By adopting the technical scheme, the mixed liquid is pressed into the recycled coarse aggregate by applying external force to the reactant, so that relatively more mixed liquid can enter the recycled coarse aggregate, and after the aqueous epoxy resin is cured, the water absorption rate of the recycled coarse aggregate can be reduced, the cohesiveness among concrete components can be increased, and the mechanical property of recycled concrete can be further improved.

Preferably, the recycled concrete further comprises the following raw materials in parts by weight: 2-4 parts of nano titanium dioxide and 1-3 parts of nano silicon dioxide.

By adopting the technical scheme, the nano titanium dioxide has high specific surface area and reaction activity, can promote hydration reaction through a filling effect and a crystal nucleus effect, reduce the size of calcium hydroxide crystals and change the orientation of the calcium hydroxide crystals, so that an active powder concrete matrix is more compact, and the strength of the active powder concrete matrix is improved; the nano silicon dioxide can play a role of crystal nucleus in a cement composite structure, can be bonded with more nano crystals, plays a synergistic role with nano titanium dioxide, and can also play a positive role in improving an interface and improving the mechanical property of recycled concrete by consuming calcium hydroxide in cement hardening slurry.

In a second aspect, the present application provides a method for preparing the above recycled concrete based on inorganic fibers, comprising the following steps:

preparing modified recycled coarse aggregate;

preparing modified inorganic fibers;

and stirring and mixing the prepared modified recycled coarse aggregate, the modified inorganic fiber and other raw materials to obtain the recycled concrete based on the inorganic fiber.

In summary, the present application includes at least one of the following beneficial technical effects:

1. the inorganic fiber-based recycled concrete comprises the modified recycled coarse aggregate and the recycled fine aggregate, and can be used for treating waste concrete and then applying the treated waste concrete to the recycled concrete, so that resources are saved and the environment is protected;

2. in the application, the recycled concrete comprises the modified inorganic fiber, and the recycled coarse aggregate is modified, so that the highest compressive strength of a recycled concrete detection block 28d which is prepared by taking the recycled concrete as a raw material and is based on the inorganic fiber can reach 51.8MPa, the highest flexural strength can reach 7.7MPa, the lowest water seepage depth of water permeation resistance can reach 4.3mm, and the highest freezing-thawing cycle frequency of frost resistance can reach 370 times.

Detailed Description

The present application will be described in further detail with reference to specific examples.

The following raw materials in the application are all commercially available products, and specifically: the coarse aggregate is selected from basalt macadam of Jiangsu, Asian Bangbu mining Co., Ltd, and has continuous gradation of 5-20mm in particle size; the cement is 42.5 grade ordinary portland cement; the fly ash is selected from second-grade fly ash of new material of water stone (Zhejiang) GmbH; the silica fume is selected from Sichuan Hongzhi Qingyun environmental protection science and technology limited; the glass fiber is alkali-resistant fiber of Taishan mountain, Shandong, and has average length of 15 mm; the carbon fiber is selected from Dongli carbon fiber (Guangdong) Limited liability company, and the average length is 15 mm; the water reducing agent is selected from Shanxi Keteng environmental protection new materials GmbH; the expanding agent is selected from TD-U expanding agent of Shanxi Keteng environmental protection new material GmbH; the silane coupling agent and the siloxane are selected from 3- (2, 3-epoxypropoxy) propyl trimethoxy silane-KH 560 of caruncle morning light chemical industry Co., Ltd; the butylbenzene emulsion is selected from Hubei Xin Mingtai chemical company; the isocyanate curing agent is selected from SJ-2605 of Shanghai water New Material science and technology Limited; the sodium silicate is selected from Baoding Runfeng industries, Ltd; the waterborne epoxy resin is selected from S128-3 of Yangzhou Zhongjiang material technology Limited, and the epoxy value is 0.43-0.49eq/100 g; the nanometer titanium dioxide and the nanometer silicon dioxide are selected from Ningbo Ningmi-Nanna new materials science and technology limited company.

Preparation example

Preparation example 1

The modified recycled coarse aggregate is prepared by the following steps:

s3, carrying out vacuum drying treatment on the regenerated particles after hydrochloric acid treatment at 25 ℃;

s4, preparing a siloxane aqueous solution with the mass fraction of 30% and a sodium silicate aqueous solution with the mass fraction of 30%, and preparing a mixed solution from the siloxane aqueous solution, the sodium silicate aqueous solution and the water-based epoxy resin according to the weight ratio of 2:1: 1; placing the dried regenerated particles into the mixed solution, wherein the weight ratio of the dried regenerated particles to the mixed solution is 100: 4, and reacting for 6 hours under the pressure of 0.1MPa to obtain the modified recycled coarse aggregate.

Preparation examples 2 to 4

The modified recycled coarse aggregates of preparation examples 2 to 4 were prepared in the same manner as in preparation example 1 except that: the weight ratios of the siloxane aqueous solution, the sodium silicate aqueous solution, and the aqueous epoxy resin in step S4 were 1:1:0.5, 1:1:1, and 1:1:2, respectively.

Preparation example 5

The modified recycled coarse aggregate of the preparation example 5 is the same as the raw material mixing amount of the preparation example 3, except that: the processing temperature in step S3 is 290 ℃; the rest of the operations were the same as in preparation example 3.

Preparation examples 6 to 7

The modified recycled coarse aggregates of the preparation examples 6 to 7 have the same raw material mixing amount as that of the preparation example 3, except that: reacting the dried product in the step S4 with a mixed solution, wherein the pressure of the reaction is 0.2MPa and 0.3MPa respectively; the rest of the operations were the same as in preparation example 3.

Preparation example 8

The modified recycled coarse aggregate of the preparation example 8 is the same as the raw material mixing amount of the preparation example 6, except that: the processing temperature in step S3 is 290 ℃; the rest of the operations were the same as in preparation example 6. .

Preparation example 9

Preparation example 9 preparation of modified inorganic fiber: mixing 120kg of methanol and 15kg of deionized water, then adding 2kg of silane coupling agent KH560, and stirring and mixing to obtain a mixed solution; adding 40kg of carbon fiber and 40kg of glass fiber into the mixed solution, and performing ultrasonic dispersion for 2 hours under the power of 800W; filtering out the fiber, and drying in an oven at 90 ℃ for 20h to obtain the modified inorganic fiber.

Examples

Example 1

A recycled concrete based on inorganic fibers, which is prepared by the following method:

preparing a modified recycled coarse aggregate according to preparation example 1;

a modified inorganic fiber was prepared with reference to preparation example 9;

and (3) according to the mixing amount in the table 1, stirring and mixing the prepared modified recycled coarse aggregate, the modified inorganic fiber and other raw materials to obtain the recycled concrete based on the inorganic fiber.

Wherein the recycled fine aggregate is particles with the average particle size of 2mm obtained by crushing and screening waste concrete.

Examples 2 to 5

The recycled concrete based on inorganic fibers of examples 2 to 5 was prepared exactly in the same manner as in example 1, except that: the raw materials are different in mixing amount, and the mixing amount is shown in table 1; the rest is the same as in example 1.

TABLE 1 blending amounts (unit: kg) of respective raw materials of the inorganic fiber-based recycled concrete in examples 1 to 5

Examples 6 to 12

The recycled concrete based on inorganic fibers of examples 6 to 12 was prepared exactly in the same manner as in example 3, except that: the modified recycled coarse aggregate is prepared according to preparation examples 2-8 respectively; the rest is the same as in example 3.

Examples 13 to 15

The recycled concrete based on inorganic fibers of examples 13 to 15 was prepared exactly in the same manner as in example 12, except that: the raw materials also comprise nano titanium dioxide and nano silicon dioxide, wherein the raw materials in the embodiment 13 comprise 2kg of nano titanium dioxide and 1kg of nano silicon dioxide; example 14 includes 3kg of nano titanium dioxide and 2kg of nano silicon dioxide; example 15 includes 4kg of nano titanium dioxide and 3kg of nano silicon dioxide; the rest is the same as in example 12.

Comparative example

Comparative example 1

The recycled concrete based on inorganic fibers of comparative example 1 was prepared exactly in the same manner as in example 1, except that: the inorganic fiber is not modified; the rest is the same as in example 1.

Comparative example 2

The recycled concrete based on inorganic fibers of comparative example 2 was prepared exactly in the same manner as in example 1, except that: replacing the modified glass fibers with modified carbon fibers of equal weight; the rest is the same as in example 1.

Comparative example 3

The recycled concrete based on inorganic fibers of comparative example 3 was prepared exactly in the same manner as in example 1, except that: replacing modified carbon fibers with modified glass fibers of equal weight; the rest is the same as in example 1.

Comparative example 4

The recycled concrete based on inorganic fibers of comparative example 4 was prepared exactly in the same manner as in example 1, except that: no modified inorganic fiber is added; the rest is the same as in example 1.

Comparative example 5

The recycled concrete based on inorganic fibers of comparative example 5 was prepared exactly in the same manner as in example 1, except that: continuous graded particles with the particle size of 25-35mm are used for modifying the recycled coarse aggregate; the rest is the same as in example 1.

Comparative example 6

The recycled concrete based on inorganic fibers of comparative example 6 was the same as the raw material blending amount of example 1 except that: the preparation processes of the recycled coarse aggregate are different, the recycled coarse aggregate is not modified, and the preparation process is only carried out by crushing and screening to obtain continuous graded particles with the particle size of 5-15 mm; the rest is the same as in example 1.

Performance detection

The recycled concrete obtained in examples 1 to 15 and comparative examples 1 to 6 was subjected to a performance test as follows:

compressive strength: making a standard test block according to GB/T50081-2002 standard of common concrete mechanical property test method, and measuring the compressive strength of the standard test block 7d and 28 d;

breaking strength: making a standard test block according to GB/T50081-2002 standard of common concrete mechanical property test method, and measuring the flexural strength of the standard test block;

water penetration resistant water penetration depth: making a standard test block according to GB/T50082-2009 Standard test method for long-term performance and durability of common concrete, and testing the water seepage depth of the standard test block by a step-by-step pressurization method;

maximum number of freeze-thaw cycles of freezing resistance: making a standard test block by referring to GB/T50082-2009 Standard test method for testing the long-term performance and the durability of the common concrete, testing by adopting a slow freezing method, and evaluating the anti-freezing performance by the maximum freezing-thawing cycle number.

The results are shown in Table 2.

TABLE 2 Performance test results for different recycled concretes

The detection results shown in Table 2 indicate that the maximum number of freeze-thaw cycles of the compressive strength, the flexural strength, the water penetration depth resistant to water penetration and the freezing resistance of the recycled concrete based on inorganic fibers in examples 1 to 15 is superior to the corresponding performances of comparative examples 1 to 6, wherein the maximum 28d compressive strength in the examples of the present application can reach 51.8MPa, the maximum flexural strength can reach 7.7MPa, the water penetration depth resistant to water penetration can reach 4.3mm, the maximum number of freeze-thaw cycles of the freezing resistance can reach 370 times, and the performance of the recycled concrete based on inorganic fibers prepared is excellent.

Compared with the example 1, the inorganic fiber in the comparative example 1 is not modified, and has lower cohesiveness with cement, so that the mechanical property and the water permeability resistance of the prepared recycled concrete are reduced; only the modified glass fiber in comparative example 2 and only the modified carbon fiber in comparative example 3 show poor mechanical properties and water permeation resistance when only one inorganic fiber is used; compared with the embodiment 1, the inorganic fiber is not added in the comparative example 4, so that the mechanical property, the water permeability resistance and the freezing resistance are reduced; the modified recycled coarse aggregate of the comparative example 5 is continuous graded particles with the particle size of 25-35mm, and the porosity is large after the particles are larger, the water penetration resistance is reduced, and the mechanical property is reduced; comparative example 6 is a recycled concrete prepared based on unmodified recycled coarse aggregate as a raw material, the recycled coarse aggregate has poor cohesiveness with other components and high water absorption, and further the mechanical property and the water permeation resistance of the recycled concrete prepared from the recycled coarse aggregate are poor.

The results of examples 1 to 5 in Table 2 show that the mixing amounts of the raw materials are different, and influence the compressive strength, flexural strength, water penetration resistance and frost resistance of the recycled concrete.

As shown by the results of examples 6 to 8 in Table 2, when the weight ratio of the aqueous siloxane solution, the aqueous silicate solution and the aqueous epoxy resin is 1:1:1, the prepared modified recycled coarse aggregate has better performance, and the recycled concrete prepared based on the modified recycled coarse aggregate has better mechanical property, water penetration depth resistance and maximum freeze-thaw cycle times.

The results of example 9 in table 2 show that when the treatment temperature of the modified recycled coarse aggregate preparation step S3 is 290 ℃, it is helpful to remove substances on the surface of the recycled coarse aggregate, so that the adhesion of the recycled coarse aggregate to other raw materials can be increased, the pores can be reduced, and the compressive strength, the flexural strength and the water penetration depth resistance of recycled concrete can be improved.

The results of examples 10 to 11 in table 2 show that when the pressure in the modified recycled coarse aggregate preparation step S4 is increased, the mixed liquid is pressed into the recycled coarse aggregate by an external force, and when the aqueous epoxy resin is cured, the water absorption of the recycled coarse aggregate can be reduced, the cohesiveness among concrete components can be increased, and the compressive strength, the flexural strength and the water penetration depth resistance of the recycled concrete can be improved.

The results of example 12 in table 2 show that when the treatment temperature of the modified recycled coarse aggregate preparation step S3 is 290 ℃ and the reaction pressure of the dried product and the mixed solution in the step S4 is 0.2MPa, the prepared modified recycled coarse aggregate can improve the compressive strength, the flexural strength, the water penetration depth resistance and the maximum number of freeze-thaw cycles of recycled concrete when applied to the recycled concrete.

The results of the examples 13 to 15 in table 2 show that the nano titanium dioxide and the nano silicon dioxide can make the recycled concrete matrix more compact, and meanwhile, the nano silicon dioxide can be bonded with more nano crystals to play a synergistic effect with the nano titanium dioxide, so that the mechanical property and the cohesiveness of the recycled concrete are improved.

The present embodiment is only for explaining the present application, and it is not limited to the present application, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present application.

Claims

1. The inorganic fiber-based recycled concrete is characterized by comprising the following raw materials in parts by weight: 280 parts of coarse aggregate, 240 parts of cement, 200 parts of modified and regenerated coarse aggregate, 370 parts of modified and regenerated fine aggregate, 50-90 parts of regenerated fine aggregate, 70-110 parts of fly ash, 50-90 parts of silica fume, 60-80 parts of water, 30-70 parts of modified inorganic fiber, 0.5-2 parts of water reducing agent, 11-15 parts of expanding agent, 20-28 parts of silane coupling agent, 5-10 parts of butylbenzene emulsion and 0.5-2.5 parts of isocyanate curing agent;

the modified inorganic fiber comprises glass fiber and carbon fiber, and the weight ratio of the glass fiber to the carbon fiber is (0.5-2): 1; the glass fiber and the carbon fiber are obtained by modifying treatment of a silane coupling agent;

the modified recycled coarse aggregate is continuous graded particles with the particle size of 5-15mm, which are prepared by crushing, screening, physical treatment and chemical modification of waste concrete.

2. The recycled inorganic fiber-based concrete as claimed in claim 1, which comprises the following raw materials in parts by weight: 270 parts of coarse aggregate, 230 parts of cement, 340 parts of modified and regenerated coarse aggregate, 60-80 parts of regenerated fine aggregate, 80-100 parts of fly ash, 60-80 parts of silica fume, 65-75 parts of water, 40-60 parts of modified inorganic fiber, 1-1.5 parts of water reducing agent, 12-14 parts of expanding agent, 22-26 parts of silane coupling agent, 6-8 parts of styrene-butadiene emulsion and 1-2 parts of isocyanate curing agent.

3. The inorganic fiber-based recycled concrete of claim 1, wherein the modified recycled coarse aggregate is prepared by the following steps:

4. The inorganic fiber-based recycled concrete of claim 3, wherein: in the step S3, the temperature of the drying process is 280-300 ℃.

5. The inorganic fiber-based recycled concrete of claim 3, wherein: in step S4, the weight ratio of the siloxane aqueous solution, the sodium silicate aqueous solution, and the aqueous epoxy resin is 1:1: (0.5-2).

6. The inorganic fiber-based recycled concrete of claim 3, wherein: in step S4, the pressure of the reaction between the dried product and the mixed solution is controlled to be 0.2-0.3 MPa.

7. The inorganic fiber-based recycled concrete of claim 1, further comprising the following raw materials in parts by weight: 2-4 parts of nano titanium dioxide and 1-3 parts of nano silicon dioxide.

8. A method for the preparation of recycled concrete based on inorganic fibres, as claimed in any one of claims 1 to 7, characterized in that it comprises the following operative steps:

preparing modified recycled coarse aggregate;

preparing modified inorganic fibers;