CN111943587A

CN111943587A - Recycled concrete and preparation method thereof

Info

Publication number: CN111943587A
Application number: CN202010747469.7A
Authority: CN
Inventors: 曹均云
Original assignee: Individual
Current assignee: Individual
Priority date: 2020-07-29
Filing date: 2020-07-29
Publication date: 2020-11-17

Abstract

The invention discloses recycled concrete which is characterized by being prepared from the following raw materials in parts by weight: 180 parts of cement, 300 parts of modified recycled aggregate, 400 parts of fine river sand, 5-10 parts of attapulgite, 1-3 parts of porous beta-cyclodextrin cross-linked polymer nanofiber, 50-65 parts of blast furnace slag, 1-3 parts of mullite fiber, 2-5 parts of diazoalkyl urea, 4-8 parts of sulfonate-terminated hyperbranched waterborne polyurethane emulsion, 2-4 parts of an additive and 75-90 parts of water. The preparation raw materials of the recycled concrete also comprise: 2-4 parts of carboxyl-terminated liquid fluororubber and 1-3 parts of water-soluble hyperbranched epoxy resin. The invention also discloses a preparation method of the recycled concrete. The recycled concrete disclosed by the invention has the advantages of excellent comprehensive performance, high strength, low water absorption, good durability and workability and good workability.

Description

Recycled concrete and preparation method thereof

Technical Field

The invention relates to the technical field of building materials, in particular to recycled concrete and a preparation method thereof.

Background

With the development of modern construction and the promotion of urban and rural integrated process, the large-scale new city construction and old city reconstruction lead to the increasing of construction wastes which usually comprise brick and tile blocks, waste stone materials, concrete blocks and sand lime soil, if not treated, the construction wastes not only occupy a large amount of land resources and cause the waste of a large amount of resources, but also pollute the water environment and air around a construction waste stacking area. How to reasonably recycle the construction wastes and turn waste into wealth is a difficult problem to be solved by researchers in the industry.

The recycled concrete is prepared by crushing, cleaning, grading and mutually matching waste concrete according to a certain proportion to obtain aggregate and then using the recycled aggregate as part or all of the aggregate. The method is one of the main measures for developing green concrete and realizing sustainable development of building resource environment.

The coarse aggregate adopted in the preparation of the recycled concrete in the prior art is the aggregate which is formed by artificially crushing and processing waste concrete from different sources, and compared with natural aggregate, the development of the preparation technology of the recycled concrete is limited by the weak contact of the interface of new mortar and the recycled aggregate, the initial defect of the aggregate, the discrete and unstable pressure resistance and other factors. The mechanical properties and physical properties of the recycled concrete on the market are obviously different from those of common concrete, for example, the strength of the recycled concrete is lower than that of the common concrete, the water absorption rate is high, the durability and the workability are relatively poorer, the slump loss and the reduction of the workability are more obvious, and the actual application of the recycled concrete is directly influenced.

The invention relates to a water permeable cement concrete with application number 200810122127.5, which uses recycled concrete as aggregate and comprises the following raw materials in parts by weight: 250-400 parts of cement, 1500-2000 parts of recycled concrete aggregate, 25-40 parts of inorganic cementing agent and 2.5-5 parts of synthetic fiber; the recycled concrete aggregate is of a single size fraction of 5-12 mm, and the crushing value is less than or equal to 25%. The ecological pervious concrete not only increases the use approach of the high added value of the waste concrete, reduces the exploitation quantity of natural aggregates, reduces the cost for preparing pervious materials, but also improves the road driving safety factor, improves the environmental water circulation function, and the performance index can meet the set technical index requirements such as mechanical property and the like. However, the added synthetic fiber is one or more of polypropylene fiber, polyacrylonitrile fiber or polyester fiber; these fiber structures are hydrophobic structures, and interface action and compatibility between the fiber structures and other components of concrete are poor, so that the performance improvement effect of the conventional recycled concrete needs to be further improved.

Therefore, the recycled concrete with excellent comprehensive performance, high strength, low water absorption, good durability and workability and good workability is developed to meet the market demand, has higher market value and application prospect and has very important significance for promoting the development of the recycled concrete industry.

Disclosure of Invention

In order to overcome the defects in the prior art, the invention provides recycled concrete and a preparation method thereof, the preparation method is simple, the operation and the control are convenient, the construction is easy, the production efficiency is high, the construction waste can be safely, quickly and efficiently recycled, the waste is changed into valuable, the economic benefit, the social benefit and the ecological benefit are high, and the method is suitable for continuous large-scale production; the recycled concrete prepared by the preparation method has the advantages of excellent comprehensive performance, high strength, low water absorption, good durability and workability and good workability.

In order to achieve the purpose of the invention, the technical scheme adopted by the invention is as follows: the recycled concrete is characterized by being prepared from the following raw materials in parts by weight: 180 parts of cement, 300 parts of modified recycled aggregate, 400 parts of fine river sand, 5-10 parts of attapulgite, 1-3 parts of porous beta-cyclodextrin cross-linked polymer nanofiber, 50-65 parts of blast furnace slag, 1-3 parts of mullite fiber, 2-5 parts of diazoalkyl urea, 4-8 parts of sulfonate-terminated hyperbranched waterborne polyurethane emulsion, 2-4 parts of an additive and 75-90 parts of water.

Preferably, the raw materials for preparing the recycled concrete further comprise: 2-4 parts of carboxyl-terminated liquid fluororubber and 1-3 parts of water-soluble hyperbranched epoxy resin.

Preferably, the recycled concrete is prepared from the following raw materials in parts by weight: 165 parts of cement, 270 parts of modified recycled aggregate, 430 parts of fine river sand, 7.5 parts of attapulgite, 2 parts of porous beta-cyclodextrin cross-linked polymer nanofiber, 57 parts of blast furnace slag, 2 parts of mullite fiber, 3.5 parts of diazo alkyl urea, 6 parts of sulfonate-terminated hyperbranched waterborne polyurethane emulsion, 83 parts of water, 3 parts of carboxyl-terminated liquid fluororubber and 2 parts of water-soluble hyperbranched epoxy resin.

Preferably, the preparation method of the water-soluble hyperbranched epoxy resin is described in chinese invention patent example 1 with application publication No. CN 102321232A; the preparation method of the carboxyl-terminated liquid fluororubber is disclosed in the patent example 1 of the Chinese invention with the application number of 201810738243.3; the preparation method of the end sulfonate type hyperbranched aqueous polyurethane emulsion is disclosed in the embodiment 1 of the Chinese invention patent with the application publication number of CN 103030765; the preparation method of the pore beta-cyclodextrin cross-linked polymer nanofiber is disclosed in the Chinese patent application publication No. CN111203199A, namely the example 1.

Preferably, the cement is portland cement numbered one or more of 52.5, 52.5R, 62.5 or 62.5R.

Preferably, the admixture is LEX-9P admixture.

Preferably, the preparation method of the modified recycled aggregate comprises the following steps: stirring and scattering the recycled aggregate obtained after sorting, cleaning, crushing and screening in sequence at 60-80 ℃ for 0.5-1 hour, then dropwise adding an ethanol solution of amino alkoxy silane into the recycled aggregate, continuously stirring for 3-5 hours within 1 hour, and finally drying in a vacuum drying oven at 85-95 ℃ to constant weight to obtain the modified recycled aggregate.

Preferably, the mass ratio of the recycled aggregate to the ethanol solution of the amino alkoxy silane is 1 (0.03-0.08).

Preferably, the mass percentage concentration of the ethanol solution of the amino alkoxy silane is 5-10%.

Preferably, the amino alkoxy silane is at least one of 3-aminopropyl tri (methoxy ethoxy) silane, 3-aminopropyl triethoxy silane, N-aminoethyl-3-aminopropyl triethoxy silane and 3- (diethoxy methyl silicon base) propylamine.

Preferably, the recycled aggregate is recycled coarse aggregate of broken tiles or broken bricks; the particle size of the recycled aggregate is 3-10 mm.

Preferably, the maximum particle size of the fine river sand is less than 2 mm.

Preferably, the length range of the mullite fiber is 5-15 mm.

Preferably, the particle size of the attapulgite is 50-200 meshes; the blast furnace slag is 50-100 meshes.

Another object of the present invention is to provide a method for preparing the recycled concrete, which comprises the following steps: uniformly mixing cement, fine river sand, attapulgite, porous beta-cyclodextrin cross-linked polymer nano-fibers, blast furnace slag and mullite fibers in parts by weight, stirring for 30-60 seconds, adding modified regenerated aggregate, continuously stirring for 25-45 seconds, finally adding diazoalkyl urea, sulfonate-terminated hyperbranched waterborne polyurethane emulsion, an additive and water, and stirring for 1-2 minutes.

Adopt the produced beneficial effect of above-mentioned technical scheme to lie in:

(1) the preparation method of the recycled concrete provided by the invention has the advantages that all raw materials are directly mixed and stirred, the process is simple and feasible, the operation and control are convenient, the construction is easy, the production efficiency is high, the construction wastes can be safely, quickly and efficiently recycled, the waste is changed into valuable, the economic benefit, the social benefit and the ecological benefit are high, and the preparation method is suitable for continuous large-scale production.

(2) The invention provides recycled concrete, which overcomes the defects that the coarse aggregate adopted in the preparation of the recycled concrete in the prior art is the aggregate which is formed by manually crushing and processing waste concrete with different sources, compared with natural aggregate, the development of the preparation technology of the recycled concrete is limited by the factors such as weak contact of the interface of new mortar and the recycled aggregate, initial defect of the aggregate, discrete and unstable compression resistance and the like, the recycled concrete on the market is obviously different from the common concrete in the aspects of mechanical property and physical property, for example, the strength of the recycled concrete is lower than that of the common concrete, the water absorption rate is high, the durability and the workability are relatively poor, the slump loss and the reduction of the workability are more obvious, the practical application of the recycled concrete is directly influenced, and the recycled concrete has the advantages of excellent comprehensive performance, high strength, low water absorption rate, good durability and workability, the workability is good.

(3) According to the recycled concrete provided by the invention, the waste recycled aggregate and the industrial waste blast furnace slag are used, and the wastes are recycled, so that the waste is changed into valuable, the energy is saved, the energy waste is reduced, the environmental protection is facilitated, and the recycled concrete has good social, environmental and economic values; the components of the water-soluble hyperbranched epoxy resin enter gaps between the recycled aggregate and other raw materials along with added water, and are subjected to curing reaction with amino groups modified on the surface of the recycled aggregate in an alkaline environment in concrete to form a three-dimensional network structure, so that the interface compatibility of each component is good, the comprehensive performance of the recycled concrete is effectively improved, and the concrete has good compactness and strong crack resistance and impact resistance.

(4) According to the recycled concrete provided by the invention, the carboxyl-terminated liquid fluororubber and the sulfonic acid group and the carboxyl group on the sulfonate type hyperbranched waterborne polyurethane emulsion can effectively play roles in inducing and reducing water, and in addition, play an important role in maintaining slump; the introduced carboxylate and sulfonate with negative charges are adsorbed on the surface of the cement particles, the early-stage dispersing capacity of the cement particles is improved under the action of electrostatic repulsion, the comprehensive performance is improved, the toughness of the recycled concrete is improved after the two substances enter the concrete, and the capacity of the recycled concrete for resisting external deformation is greatly improved.

(5) According to the recycled concrete provided by the invention, the addition of the attapulgite and the porous beta-cyclodextrin cross-linked polymer nano-fibers can further enhance the bonding performance among the components, and enhance the compactness of the concrete, so that the compression strength and the splitting tensile strength of the recycled concrete are improved; the introduction of the porous beta-cyclodextrin can improve the water absorption and retention functions, and can limit the generation and expansion of primary cracks formed by drying shrinkage and other factors in the early stage (plastic stage and hardening initial stage) of concrete; the introduction of the nanofiber structure and the mullite fiber can prevent the development of the initial defect crack of the interface between new mortar and aggregate in the concrete, and has obvious improvement effect on the interface crack between new mortar and old mortar which are specific to recycled concrete; the diazoalkyl urea is added into concrete as an additive, and can effectively play roles of retarding coagulation, early strength and plastic retention, so that the comprehensive performance of the concrete is better. All the raw materials have synergistic effect, can effectively improve the comprehensive performance, and further prolong the service life of the composite material.

Detailed Description

In order to make the technical solutions of the present invention better understood and make the above features, objects, and advantages of the present invention more comprehensible, the present invention is further described with reference to the following examples. The examples are intended to illustrate the invention only and are not intended to limit the scope of the invention.

The raw materials involved in the following examples of the present invention were all purchased commercially; the preparation method of the water-soluble hyperbranched epoxy resin is disclosed in the embodiment 1 of the Chinese invention patent with the application publication number of CN 102321232A; the preparation method of the carboxyl-terminated liquid fluororubber is disclosed in the patent example 1 of the Chinese invention with the application number of 201810738243.3; the preparation method of the end sulfonate type hyperbranched aqueous polyurethane emulsion is disclosed in the embodiment 1 of the Chinese invention patent with the application publication number of CN 103030765; the preparation method of the pore beta-cyclodextrin cross-linked polymer nanofiber is disclosed in the Chinese patent application publication No. CN111203199A, namely the example 1.

Example 1

The recycled concrete is characterized by being prepared from the following raw materials in parts by weight: 150 parts of cement, 250 parts of modified recycled aggregate, 400 parts of fine river sand, 5 parts of attapulgite, 1 part of porous beta-cyclodextrin cross-linked polymer nanofiber, 50 parts of blast furnace slag, 1 part of mullite fiber, 2 parts of diazoalkyl urea, 4 parts of sulfonate-terminated hyperbranched waterborne polyurethane emulsion, 2 parts of an additive and 75 parts of water.

The preparation raw materials of the recycled concrete also comprise: 2 parts of carboxyl-terminated liquid fluororubber and 1 part of water-soluble hyperbranched epoxy resin.

The cement is Portland cement with the reference number of 52.5; the admixture is LEX-9P admixture.

The preparation method of the modified recycled aggregate comprises the following steps: stirring and scattering the recycled aggregate obtained by sorting, cleaning, crushing and screening sequentially at 60 ℃ for 0.5 hour, then dropwise adding an ethanol solution of amino alkoxy silane into the recycled aggregate, stirring for 3 hours within 1 hour, and finally drying in a vacuum drying oven at 85 ℃ to constant weight to obtain the modified recycled aggregate; the mass ratio of the recycled aggregate to the amino alkoxy silane ethanol solution is 1: 0.03; the mass percentage concentration of the amino alkoxy silane ethanol solution is 5%; the amino alkoxy silane is 3-aminopropyl tri (methoxy ethoxy) silane.

The recycled aggregate is broken tile recycled coarse aggregate; the particle size of the recycled aggregate is 3 mm; the maximum grain size of the fine river sand is less than 2 mm; the length range of the mullite fiber is 5 mm; the particle size of the attapulgite is 50 meshes; the blast furnace slag is 50 meshes.

The preparation method of the recycled concrete is characterized by comprising the following steps of: uniformly mixing cement, fine river sand, attapulgite, porous beta-cyclodextrin cross-linked polymer nano-fibers, blast furnace slag and mullite fibers in parts by weight, stirring for 30 seconds, adding modified regenerated aggregate, continuing to stir for 25 seconds, finally adding diazolidinyl urea, a sulfonate-terminated hyperbranched waterborne polyurethane emulsion, an additive and water, and stirring for 1 minute.

Example 2

The recycled concrete is characterized by being prepared from the following raw materials in parts by weight: 160 parts of cement, 260 parts of modified recycled aggregate, 410 parts of fine river sand, 6 parts of attapulgite, 1.5 parts of porous beta-cyclodextrin cross-linked polymer nanofiber, 55 parts of blast furnace slag, 1.5 parts of mullite fiber, 3 parts of diazo alkyl urea, 5 parts of sulfonate-terminated hyperbranched waterborne polyurethane emulsion, 2.5 parts of an additive and 80 parts of water.

The preparation raw materials of the recycled concrete also comprise: 2.5 parts of carboxyl-terminated liquid fluororubber and 1.5 parts of water-soluble hyperbranched epoxy resin.

The cement is Portland cement with the reference number of 52.5R; the admixture is LEX-9P admixture.

The preparation method of the modified recycled aggregate comprises the following steps: stirring and scattering the recycled aggregate obtained by sorting, cleaning, crushing and screening sequentially at 65 ℃ for 0.7 hour, then dropwise adding an ethanol solution of amino alkoxy silane into the recycled aggregate, stirring for 3.5 hours within 1 hour, and finally drying in a vacuum drying oven at 88 ℃ to constant weight to obtain the modified recycled aggregate; the mass ratio of the recycled aggregate to the amino alkoxy silane ethanol solution is 1: 0.05; the mass percentage concentration of the amino alkoxy silane ethanol solution is 6.5%; the amino alkoxy silane is 3-amino propyl triethoxy silane.

The recycled aggregate is broken brick recycled coarse aggregate; the particle size of the recycled aggregate is 5 mm; the maximum grain size of the fine river sand is less than 2 mm; the length range of the mullite fiber is 7 mm; the particle size of the attapulgite is 80 meshes; the blast furnace slag is 60 meshes.

The preparation method of the recycled concrete is characterized by comprising the following steps of: uniformly mixing cement, fine river sand, attapulgite, porous beta-cyclodextrin cross-linked polymer nano-fibers, blast furnace slag and mullite fibers in parts by weight, stirring for 40 seconds, adding modified regenerated aggregate, continuing stirring for 30 seconds, finally adding diazolidinyl urea, a sulfonate-terminated hyperbranched waterborne polyurethane emulsion, an additive and water, and stirring for 1.2 minutes.

Example 3

The recycled concrete is characterized by being prepared from the following raw materials in parts by weight: 165 parts of cement, 280 parts of modified recycled aggregate, 430 parts of fine river sand, 7.5 parts of attapulgite, 2 parts of porous beta-cyclodextrin cross-linked polymer nanofiber, 57 parts of blast furnace slag, 2 parts of mullite fiber, 3.5 parts of diazo alkyl urea, 6 parts of sulfonate-terminated hyperbranched waterborne polyurethane emulsion, 3 parts of additive and 83 parts of water.

The preparation raw materials of the recycled concrete also comprise: 3 parts of carboxyl-terminated liquid fluororubber and 2 parts of water-soluble hyperbranched epoxy resin.

The cement is Portland cement with the reference number of 62.5; the admixture is LEX-9P admixture.

The preparation method of the modified recycled aggregate comprises the following steps: stirring and scattering the recycled aggregate obtained by sorting, cleaning, crushing and screening sequentially at 70 ℃ for 0.7 hour, then dropwise adding an ethanol solution of amino alkoxy silane into the recycled aggregate, stirring for 4 hours within 1 hour, and finally drying in a vacuum drying oven at 90 ℃ to constant weight to obtain the modified recycled aggregate; the mass ratio of the recycled aggregate to the amino alkoxy silane ethanol solution is 1: 0.05; the mass percentage concentration of the amino alkoxy silane ethanol solution is 8%; the amino alkoxy silane is N-aminoethyl-3-aminopropyl triethoxysilane.

The recycled aggregate is broken tile recycled coarse aggregate; the particle size of the recycled aggregate is 7 mm; the maximum grain size of the fine river sand is less than 2 mm; the length range of the mullite fiber is 10 mm; the particle size of the attapulgite is 140 meshes; the blast furnace slag is 90 meshes.

The preparation method of the recycled concrete is characterized by comprising the following steps of: uniformly mixing cement, fine river sand, attapulgite, porous beta-cyclodextrin cross-linked polymer nano-fibers, blast furnace slag and mullite fibers in parts by weight, stirring for 45 seconds, adding modified regenerated aggregate, continuing to stir for 35 seconds, finally adding diazoalkyl urea, a sulfonate-terminated hyperbranched waterborne polyurethane emulsion, an additive and water, and stirring for 1.5 minutes.

Example 4

The recycled concrete is characterized by being prepared from the following raw materials in parts by weight: 175 parts of cement, 290 parts of modified recycled aggregate, 440 parts of fine river sand, 9 parts of attapulgite, 2.5 parts of porous beta-cyclodextrin cross-linked polymer nanofiber, 62 parts of blast furnace slag, 2.5 parts of mullite fiber, 4.5 parts of diazoalkyl urea, 7 parts of sulfonate-terminated hyperbranched waterborne polyurethane emulsion, 3.5 parts of additive and 86 parts of water.

The preparation raw materials of the recycled concrete also comprise: 3.5 parts of carboxyl-terminated liquid fluororubber and 2.5 parts of water-soluble hyperbranched epoxy resin.

The cement is Portland cement with the reference number of 62.5R; the admixture is LEX-9P admixture.

The preparation method of the modified recycled aggregate comprises the following steps: stirring and scattering the recycled aggregate obtained by sorting, cleaning, crushing and screening sequentially at 77 ℃ for 0.9 hour, then dropwise adding an ethanol solution of amino alkoxy silane into the recycled aggregate, stirring for 4.6 hours within 1 hour, and finally drying in a vacuum drying oven at 93 ℃ to constant weight to obtain the modified recycled aggregate; the mass ratio of the recycled aggregate to the amino alkoxy silane ethanol solution is 1: 0.07; the mass percentage concentration of the amino alkoxy silane ethanol solution is 9%; the amino alkoxy silane is formed by mixing 3-aminopropyl tri (methoxyethoxyethoxy) silane, 3-aminopropyl triethoxysilane, N-aminoethyl-3-aminopropyl triethoxysilane and 3- (diethoxymethyl silicon base) propylamine according to the mass ratio of 1:3:2: 1.

The recycled aggregate is recycled coarse aggregate of broken tiles or broken bricks; the particle size of the recycled aggregate is 9 mm; the maximum grain size of the fine river sand is less than 2 mm; the length range of the mullite fiber is 13 mm; the particle size of the attapulgite is 180 meshes; the blast furnace slag is 90 meshes.

The preparation method of the recycled concrete is characterized by comprising the following steps of: uniformly mixing cement, fine river sand, attapulgite, porous beta-cyclodextrin cross-linked polymer nano-fibers, blast furnace slag and mullite fibers in parts by weight, stirring for 55 seconds, adding modified recycled aggregate, continuing to stir for 42 seconds, finally adding diazolidinyl urea, a sulfonate-terminated hyperbranched waterborne polyurethane emulsion, an additive and water, and stirring for 1.9 minutes.

Example 5

The recycled concrete is characterized by being prepared from the following raw materials in parts by weight: 180 parts of cement, 300 parts of modified recycled aggregate, 450 parts of fine river sand, 10 parts of attapulgite, 3 parts of porous beta-cyclodextrin cross-linked polymer nanofiber, 65 parts of blast furnace slag, 3 parts of mullite fiber, 5 parts of diazoalkyl urea, 8 parts of sulfonate-terminated hyperbranched waterborne polyurethane emulsion, 4 parts of additive and 90 parts of water.

The preparation raw materials of the recycled concrete also comprise: 4 parts of carboxyl-terminated liquid fluororubber and 3 parts of water-soluble hyperbranched epoxy resin.

The cement is formed by mixing silicate cement with the labels of 52.5, 52.5R, 62.5 and 62.5R according to the mass ratio of 1:2:2: 1; the admixture is LEX-9P admixture.

The preparation method of the modified recycled aggregate comprises the following steps: stirring and scattering the recycled aggregate obtained by sorting, cleaning, crushing and screening sequentially at 80 ℃ for 1 hour, then dropwise adding an ethanol solution of amino alkoxy silane into the recycled aggregate, stirring for 5 hours continuously within 1 hour, and finally drying in a vacuum drying oven at 95 ℃ to constant weight to obtain the modified recycled aggregate; the mass ratio of the recycled aggregate to the amino alkoxy silane ethanol solution is 1: 0.08; the mass percentage concentration of the amino alkoxy silane ethanol solution is 10 percent; the amino alkoxy silane is 3- (diethoxymethyl silicon base) propylamine.

The recycled aggregate is recycled coarse aggregate of broken tiles or broken bricks; the particle size of the recycled aggregate is 10 mm; the maximum grain size of the fine river sand is less than 2 mm; the length range of the mullite fiber is 15 mm; the particle size of the attapulgite is 200 meshes; the blast furnace slag is 100 meshes.

The preparation method of the recycled concrete is characterized by comprising the following steps of: uniformly mixing cement, fine river sand, attapulgite, porous beta-cyclodextrin cross-linked polymer nano-fibers, blast furnace slag and mullite fibers in parts by weight, stirring for 60 seconds, adding modified regenerated aggregate, continuing stirring for 45 seconds, finally adding diazolidinyl urea, a sulfonate-terminated hyperbranched waterborne polyurethane emulsion, an additive and water, and stirring for 2 minutes.

Comparative example 1

A recycled concrete was prepared in substantially the same manner as in example 1 except that no attapulgite was added.

Comparative example 2

A recycled concrete, having substantially the same formulation and preparation as in example 1, except that the porous beta-cyclodextrin crosslinked polymer nanofibers were not added.

Comparative example 3

A recycled concrete was prepared in substantially the same manner as in example 1 except that no mullite fiber was added.

Comparative example 4

A recycled concrete was prepared in substantially the same manner as in example 1 except that no diazolidinyl urea was added.

Comparative example 5

The formula and the preparation method of the recycled concrete are basically the same as those of the example 1, except that the terminal sulfonate type hyperbranched waterborne polyurethane emulsion is not added.

Comparative example 6

A recycled concrete was prepared in substantially the same manner as in example 1 except that no carboxyl-terminated liquid fluororubber was added.

Comparative example 7

A recycled concrete was prepared in substantially the same manner as in example 1, except that no water-soluble hyperbranched epoxy resin was added.

The recycled concrete described in examples 1 to 5 and comparative examples 1 to 7 was subjected to a relevant performance test with reference to Standard test methods for mechanical Properties of general concrete (GB50081-2002), and the test results are shown in Table 1.

As can be seen from Table 1, the recycled concrete of the examples of the present invention has better and excellent mechanical properties, which are the result of the synergistic effect of the raw materials.

TABLE 1

The foregoing shows and describes the general principles, essential features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are merely illustrative of the principles of the invention, but that various changes and modifications may be made without departing from the spirit and scope of the invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims

1. The recycled concrete is characterized by being prepared from the following raw materials in parts by weight: 180 parts of cement, 300 parts of modified recycled aggregate, 400 parts of fine river sand, 5-10 parts of attapulgite, 1-3 parts of porous beta-cyclodextrin cross-linked polymer nanofiber, 50-65 parts of blast furnace slag, 1-3 parts of mullite fiber, 2-5 parts of diazoalkyl urea, 4-8 parts of sulfonate-terminated hyperbranched waterborne polyurethane emulsion, 2-4 parts of an additive and 75-90 parts of water.

2. The recycled concrete of claim 1, wherein the raw materials for preparing the recycled concrete further comprise: 2-4 parts of carboxyl-terminated liquid fluororubber and 1-3 parts of water-soluble hyperbranched epoxy resin.

3. The recycled concrete of claim 1, wherein the recycled concrete is prepared from the following raw materials in parts by weight: 165 parts of cement, 270 parts of modified recycled aggregate, 430 parts of fine river sand, 7.5 parts of attapulgite, 2 parts of porous beta-cyclodextrin cross-linked polymer nanofiber, 57 parts of blast furnace slag, 2 parts of mullite fiber, 3.5 parts of diazo alkyl urea, 6 parts of sulfonate-terminated hyperbranched waterborne polyurethane emulsion, 83 parts of water, 3 parts of carboxyl-terminated liquid fluororubber and 2 parts of water-soluble hyperbranched epoxy resin.

4. Recycled concrete according to claim 1, characterized in that said cement is portland cement with one or more of the designations 52.5, 52.5R, 62.5 or 62.5R.

5. The recycled concrete of claim 1, wherein the admixture is a LEX-9P admixture.

6. The recycled concrete of claim 1, wherein the preparation method of the modified recycled aggregate comprises the following steps: stirring and scattering the recycled aggregate obtained after sorting, cleaning, crushing and screening in sequence at 60-80 ℃ for 0.5-1 hour, then dropwise adding an ethanol solution of amino alkoxy silane into the recycled aggregate, continuously stirring for 3-5 hours within 1 hour, and finally drying in a vacuum drying oven at 85-95 ℃ to constant weight to obtain the modified recycled aggregate.

7. The recycled concrete of claim 6, wherein the mass ratio of the recycled aggregate to the ethanol solution of the amino alkoxy silane is 1 (0.03-0.08); the mass percentage concentration of the amino alkoxy silane ethanol solution is 5-10%; the amino alkoxy silane is at least one of 3-aminopropyl tri (methoxyethoxyethoxy) silane, 3-aminopropyl triethoxysilane, N-aminoethyl-3-aminopropyl triethoxysilane and 3- (diethoxymethyl silyl) propylamine.

8. The recycled concrete of claim 1, wherein the recycled aggregate is a recycled coarse aggregate of crushed tiles or crushed bricks; the particle size of the recycled aggregate is 3-10 mm.

9. The recycled concrete of claim 1, wherein the fine river sand has a maximum particle size of less than 2 mm; the length range of the mullite fiber is 5-15 mm; the particle size of the attapulgite is 50-200 meshes; the blast furnace slag is 50-100 meshes.

10. Recycled concrete according to any one of claims 2 to 9, characterized in that said method for the preparation of recycled concrete comprises the following steps: uniformly mixing cement, fine river sand, attapulgite, porous beta-cyclodextrin cross-linked polymer nano-fibers, blast furnace slag and mullite fibers in parts by weight, stirring for 30-60 seconds, adding modified regenerated aggregate, continuously stirring for 25-45 seconds, finally adding diazoalkyl urea, sulfonate-terminated hyperbranched waterborne polyurethane emulsion, an additive and water, and stirring for 1-2 minutes.