CN112408827A - Recycled concrete and preparation method thereof - Google Patents
Recycled concrete and preparation method thereof Download PDFInfo
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- CN112408827A CN112408827A CN202011417675.8A CN202011417675A CN112408827A CN 112408827 A CN112408827 A CN 112408827A CN 202011417675 A CN202011417675 A CN 202011417675A CN 112408827 A CN112408827 A CN 112408827A
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B40/00—Processes, in general, for influencing or modifying the properties of mortars, concrete or artificial stone compositions, e.g. their setting or hardening ability
- C04B40/0028—Aspects relating to the mixing step of the mortar preparation
- C04B40/0039—Premixtures of ingredients
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
- C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/00474—Uses not provided for elsewhere in C04B2111/00
- C04B2111/0075—Uses not provided for elsewhere in C04B2111/00 for road construction
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2201/00—Mortars, concrete or artificial stone characterised by specific physical values
- C04B2201/50—Mortars, concrete or artificial stone characterised by specific physical values for the mechanical strength
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Abstract
The application relates to the field of concrete, and particularly discloses recycled concrete and a preparation method thereof. The recycled concrete comprises 920-980 parts of recycled aggregate, 70-130 parts of cement, 0.84-1.6 parts of nano reinforcing liquid, 35-75 parts of water, 0.84-1.8 parts of steel fiber-PVA hybrid fiber, 4.5-9.3 parts of waste textile fiber, 0.7-1.3 parts of carborundum, 10-16 parts of soybean protein powder and 4-8 parts of trehalose; the preparation method comprises the following steps: s1, mixing and stirring nano reinforcing liquid, water and cement to obtain nano reinforcing slurry, soaking the recycled aggregate in the nano reinforcing slurry for a period of time, filtering, and drying to obtain nano reinforcing recycled aggregate; s2, mixing and stirring the nano reinforced recycled aggregate and other raw materials at the temperature of 20-30 ℃. The recycled concrete has the advantages of small porosity, high compactness and strong mechanical property.
Description
Technical Field
The application relates to the field of concrete, in particular to recycled concrete and a preparation method thereof.
Background
The regenerated concrete is prepared by crushing, cleaning and grading waste concrete blocks, mixing the crushed, cleaned and graded concrete blocks with a grading agent according to a certain proportion, partially or completely replacing coarse aggregates such as stones and the like, and adding cement, water and the like. The waste concrete is used as the coarse aggregate, so that the waste concrete can be effectively recycled, the damage of solid wastes to the environment can be reduced, resources such as sand and stone can be saved, and the method is one of important ways for realizing sustainable development of the concrete industry.
However, as a large amount of hardened cement mortar is adhered to the surface of the recycled aggregate, the performance of the interface transition area of the concrete is greatly reduced again, so that the compactness of the concrete is poor, the porosity is high, and the mechanical property is poor.
Disclosure of Invention
In order to improve the compaction degree of the recycled concrete and further improve the mechanical property of the recycled concrete, the application provides the recycled concrete and a preparation method thereof.
In a first aspect, the application provides a recycled concrete, which adopts the following technical scheme:
the recycled concrete comprises the following raw materials in parts by weight:
920-980 parts of recycled aggregate;
70-130 parts of cement;
0.84-1.6 parts of nano strengthening liquid;
35-75 parts of water;
0.84-1.8 parts of steel fiber-PVA hybrid fiber;
4.5-9.3 parts of waste textile fiber;
0.7-1.3 parts of carborundum;
10-16 parts of soybean protein powder;
4-8 parts of trehalose;
the nano strengthening liquid is nano SiO2Nano Al2O3Nano CaCO, nano-grade CaCO3And a mixed solution of nano GNP and a water reducing agent.
By adopting the technical scheme, the recycled concrete is prepared by mixing the components such as the nano reinforcing liquid with specific addition amount, the recycled aggregate and the like, and the nano reinforcing liquid contains nano materials, so that the nano materials have extremely small particle size and surface effect, size effect and interface effect, the microstructure of the recycled concrete can be improved, the pores in the recycled concrete can be filled, and the mechanical property of the recycled concrete can be improved. Meanwhile, the nano reinforcing liquid mixes the four nano-scale materials with the water reducing agent, so that the water reducing agent can fully exert the dispersing effect on the nano-scale materials, and the nano-scale materials are more easily dispersed in the recycled concrete, thereby improving the mechanical property of the recycled concrete.
And, nano SiO2And nano CaCO3The cement can be effectively promoted to hydrate to generate C-S-H gel, and micropores of the recycled concrete are filled, so that the compactness of the recycled concrete is increased; nano Al2O3The cement has natural compatibility with cement, and the compactness of cement hardened slurry can be effectively improved; the oxygen-containing groups on the nano GNP (nano graphene) sheet layer have template effect and filling effect on the formation of cement hydration products, so that the shape of the hydration products can be optimized, the compaction degree of the recycled concrete is improved, and the mechanical property of the recycled concrete is improved.
This application adopts steel fibre and PVA fibre mixed use, and old and useless textile fiber of collocation, carborundum, soyabean protein powder and trehalose mixed use simultaneously, and the harmful hole in the recycled concrete is fully filled to full play synergism between each other to can improve the cohesive force of each component in the recycled concrete in coordination, further reduce the porosity of recycled concrete, improve the mechanical properties of recycled concrete.
Meanwhile, the waste textile fibers are adopted, so that the production cost of the recycled concrete can be effectively reduced, the resource recycling of the waste textile fibers is realized, the resources are saved, and the sustainable development is met.
In conclusion, the recycled concrete is prepared by mixing the nano reinforcing liquid, the steel fiber-PVA hybrid fiber, the waste textile fiber, the carborundum, the soybean protein powder, the trehalose, the recycled aggregate, the cement and the water, so that harmful pores in the recycled concrete can be effectively filled, the porosity of the recycled concrete is reduced, the compaction degree of the recycled concrete is improved, and the mechanical property of the recycled concrete is improved.
Preferably, the nano reinforcing liquid is prepared by the following method:
at the temperature of 30-35 ℃, the water reducing agent and the nano SiO2Nano Al2O3Nano CaCO, nano-grade CaCO3And performing ultrasonic emulsification and dispersion on the nano GNP for 20-30min to obtain a nano strengthening solution; wherein, the water reducing agent and the nano SiO2Nano Al2O3Nano CaCO, nano-grade CaCO3And the weight ratio of the nano GNP is 1 (0.02-0.08): (0.03-0.07): (0.02-0.08): 0.04-0.06).
Because the water reducing agent and the nano-grade material are difficult to dissolve in water and are easy to form cluster-shaped insoluble matters, by adopting the technical scheme, the ultrasonic dispersion instrument is used for dispersing the water reducing agent and the nano SiO2Nano Al2O3Nano CaCO, nano-grade CaCO3And the nano GNP is fully emulsified and dispersed, so that the nano-grade material can be fully dispersed in the recycled concrete, harmful pores in the recycled concrete are filled, hydration products in an interface transition area of the recycled concrete are enriched, the microstructure of the interface transition area is more compact, and the mechanical property of the recycled concrete is improved.
Preferably, the nano GNPs are modified by the following method:
mixing and stirring absolute ethyl alcohol, iminodiacetic acid, paraformaldehyde and nano GNP for 30-40min at the temperature of 20-25 ℃, heating to 60-80 ℃, removing the ethanol, performing reflux reaction at the temperature of 200-220 ℃, dispersing in an organic solvent after natural cooling, performing suction filtration, washing, drying, dispersing in an anhydrous chloroform solvent, adding 3-aminopropyltrimethoxysiloxane, performing reflux reaction for 20-24h, washing, filtering, and drying at the temperature of 40-50 ℃ for 1-2h to obtain modified nano GNP;
the weight ratio of the absolute ethyl alcohol, the iminodiacetic acid, the paraformaldehyde, the nano GNP and the 3-aminopropyl trimethoxy siloxane is (80-100): 2-3): 2.5-3.5: (2-2.5): 4-5.
By adopting the technical scheme, the nano GNP is modified by using the 3-aminopropyl trimethoxy siloxane as the modifier under specific reaction conditions, so that the dispersibility of the nano GNP, the compatibility of the nano GNP with components such as recycled aggregate and the like and the interface bonding strength are obviously improved, harmful pores in recycled concrete can be effectively filled, and the mechanical property of the recycled concrete is improved.
Preferably, the organic solvent comprises water, acetone and absolute ethyl alcohol in a weight ratio of (2.0-2.5): 1-2): 0.8-1.0.
Through adopting above-mentioned technical scheme, water, acetone and absolute ethyl alcohol of specific proportion are as the organic solvent when dispersing in this application, can be so that the material fully disperses in organic solvent, then use the material after water, acetone and the absolute ethyl alcohol suction filtration to wash in proper order, reduce the possibility that other impurity exist, have improved the modified effect of nanometer GNP.
Preferably, the waste textile fibers comprise waste polyester fibers, waste cotton fibers and waste glass fibers in a weight ratio of (1.0-1.1) to (0.8-1.0) to (1.0-1.3).
By adopting the technical scheme, the waste polyester fibers, the waste cotton fibers and the waste glass fibers in a specific proportion are added into the recycled concrete, harmful pores in the recycled concrete can be filled, the porosity of the recycled concrete is reduced, the compactness of the recycled concrete is improved, and the mechanical property of the recycled concrete is improved.
Preferably, the waste glass fiber is modified by the following method:
a. after cleaning the waste glass fiber in an acetone solution, soaking the waste glass fiber in a hydrochloric acid solution with the concentration of 1-1.5mol/L for 7-8h at the temperature of 100-110 ℃, and then drying for 15-20min at the temperature of 40-45 ℃;
b. and (b) immersing the waste glass fiber treated in the step (a) into a silane coupling agent with the concentration of 2.0-2.2mol/L for 3-4h, then drying for 4-5h at the temperature of 80-85 ℃, repeating the process for 2-3 times, then ultrasonically cleaning for 20-30min in an ethanol solution, and drying for 2-3h at the temperature of 200-210 ℃.
Because the strength and the brittleness of the waste glass fiber are reduced, the technical scheme is adopted, the waste glass fiber is modified by adopting the silane coupling agent, and the silane coupling agent can adopt silane coupling agent-550 or silane coupling agent-560. Hydroxyl generated by hydrolyzing the silane coupling agent can be condensed with hydroxyl on the surface of the waste glass fiber to form a covalent bond, so that the silane coupling agent is grafted to the surface of the waste glass fiber, and the mechanical property of the waste glass fiber is enhanced.
Preferably, the raw material also comprises 25-30 parts of microemulsion;
the microemulsion is prepared by the following method:
mixing petroleum ether, 3-3.3mol/L polyacrylamide aqueous solution and surfactant at 20-25 deg.C, and dispersing for 30-40min to obtain microemulsion; wherein the weight ratio of the petroleum ether to the polyacrylamide aqueous solution to the surfactant is (20-23) to (2-3) to (0.3-0.4).
Preferably, the surfactant comprises sorbitan fatty acid ester and sorbitan monooleate polyoxyethylene ether in a weight ratio of (2.5-3.0) to (3-3.2).
By adopting the technical scheme, the microemulsion with the specific amount is added into the recycled concrete, and the microemulsion can form a cross-linked net structure in the recycled concrete, so that harmful pores of the recycled concrete are effectively filled, and the mechanical property of the recycled concrete is improved. However, the mutual aggregation of emulsion droplets can cause the phase interface tension to be lowered, so that the stability of the microemulsion is poor, and therefore, the method adopts the mixture of the sorbitan fatty acid ester and the sorbitan monooleate polyoxyethylene ether in a specific proportion as the surfactant, so that the reaction condition is mild, and the prepared microemulsion system is more stable, thereby well playing a role in enhancing the mechanical property of the recycled concrete.
Preferably, the water reducing agent is a polycarboxylic acid water reducing agent.
Through adopting above-mentioned technical scheme, polycarboxylate water reducing agent is adopted in this application, can utilize its excellent super dispersion ability fully to the nanometer material disperse to it can effectual reduction recycled concrete's water consumption, reduces the water cement ratio, reduces recycled concrete's porosity, thereby improves recycled concrete's mechanical properties.
In a second aspect, the present application provides a method for preparing recycled concrete, comprising the steps of:
s1, mixing and stirring the nano-reinforcing liquid, water and cement for 10-20min at the rotating speed of 300-350r/min to obtain nano-reinforcing slurry, then soaking the recycled aggregate in the nano-reinforcing slurry for 30-40min, filtering, and drying at the temperature of 30-35 ℃ for 1-2h to obtain nano-reinforcing recycled aggregate;
s2, mixing and stirring the nano reinforced recycled aggregate and all other raw materials at the rotating speed of 300-350r/min for 30-40min at the temperature of 20-30 ℃ to obtain the recycled concrete.
By adopting the technical scheme, the nano-reinforcing liquid, the water and the cement are mixed and stirred for a period of time, so that the nano-scale material is fully dispersed in the cement to form the nano-reinforcing slurry, and then the recycled aggregate is soaked in the nano-reinforcing slurry for a period of time, so that the nano-reinforcing slurry is attached to the surface of the recycled aggregate, a transition interface of the recycled aggregate is covered, microcracks of the recycled aggregate are filled, and the mechanical property of the recycled aggregate is improved. And then, the recycled aggregate reinforced by the nano reinforced slurry is fully and uniformly mixed with other components, so that the mechanical property of the prepared recycled concrete can be further improved.
In summary, the present application includes at least one of the following beneficial technical effects:
1. the interface transition zone of the recycled concrete has good performance, low porosity, high compactness and high mechanical property;
2. according to the preparation method of the recycled concrete, the transition interface of the recycled aggregate is covered, the microcracks of the recycled aggregate are filled, and the mechanical property of the recycled aggregate is improved;
3. the preparation method of the recycled concrete has the advantages of simple steps, easiness in operation, low cost of used raw materials, low production cost and suitability for large-scale production.
Detailed Description
The present application will be described in further detail with reference to examples.
The recycled aggregate is prepared from waste pavement plain concrete, the particle size is 5-10mm, and the physical properties are shown in table 1;
TABLE 1 basic physical Properties of recycled aggregates
| Aggregate type | Particle size/mm | Apparent density/(kg. m)-3) | Bulk density/(kg. m)-3) | Water absorption/%) | Crush index/%) |
| Recycled aggregate | 5-10 | 2550 | 1305 | 4.0 | 16.5 |
The carborundum of the application is purchased from Shandong Shimei terrace science and technology company;
iminodiacetic acid of the application is purchased from Shandong Weizhi chemical technology Co., Ltd;
paraformaldehyde of the present application is purchased from Ningbo Yu Chemie, Inc.;
the 3-aminopropyltrimethoxysiloxane of the present application is available from Shandonghao Shunhua chemical Co., Ltd;
silane coupling agent-550 and silane coupling agent-560 of the present application were purchased from jinan rong chemical ltd;
the sorbitan fatty acid ester and sorbitan monooleate polyoxyethylene ether are purchased from Nantong Orno chemical Co.
Preparation example 1
The preparation method of the nano strengthening liquid comprises the following steps:
at the temperature of 30 ℃, 10kg of polycarboxylic acid water reducing agent and 0.2kg of nano SiO20.3kg of nano Al2O30.2kg of nano CaCO3And 0.4kg of nano GNP is subjected to ultrasonic emulsification and dispersion for 20min by using an ultrasonic dispersion instrument to obtain a nano strengthening solution.
Preparation example 2
The preparation method of the nano strengthening liquid comprises the following steps:
10kg of polycarboxylic acid water reducing agent and 0.5kg of nano SiO at the temperature of 32.5 DEG C20.5kg of nano Al2O30.5kg of nano CaCO3And 0.5kg of nano GNP is subjected to ultrasonic emulsification and dispersion for 25min by using an ultrasonic dispersion instrument to obtain a nano strengthening solution.
Preparation example 3
The preparation method of the nano strengthening liquid comprises the following steps:
10kg of polycarboxylic acid water reducing agent and 0.8kg of nano SiO at the temperature of 35 DEG C20.7kg of nano Al2O30.8kg of nano CaCO3And 0.6kg of nano GNP is subjected to ultrasonic emulsification and dispersion for 30min by using an ultrasonic dispersion instrument to obtain a nano strengthening solution.
Preparation example 4
The preparation method of the nano strengthening liquid comprises the following steps:
10kg of polycarboxylic acid water reducing agent and 0.3kg of nano SiO at the temperature of 32 DEG C20.4kg of nano Al2O30.3kg of nano CaCO3And 0.45kg of nano GNP is subjected to ultrasonic emulsification and dispersion for 23min by using an ultrasonic dispersion instrument to obtain a nano strengthening solution.
Preparation example 5
The preparation method of the nano strengthening liquid comprises the following steps:
at 3410kg of polycarboxylic acid water reducing agent and 0.7kg of nano SiO at the temperature of20.6kg of nano Al2O30.7kg of nano CaCO3And 0.55kg of nano GNP is subjected to ultrasonic emulsification and dispersion for 23min by using an ultrasonic dispersion instrument to obtain a nano strengthening solution.
Example 1
A preparation method of recycled concrete comprises the following steps:
s1, mixing and stirring 0.84kg of nano-reinforcing liquid prepared in preparation example 1, 75kg of water and 130kg of cement at the rotating speed of 300r/min for 10min to obtain nano-reinforcing slurry, soaking 920kg of recycled aggregate in the nano-reinforcing slurry for 30min, filtering, and drying at the temperature of 30 ℃ for 1h to obtain nano-reinforcing recycled aggregate;
s2, mixing and stirring the nano reinforced recycled aggregate, 0.84kg of steel fiber-PVA hybrid fiber, 9.3kg of waste textile fiber (3.32 kg of waste polyester fiber, 2.66kg of waste cotton fiber and 3.32kg of waste glass fiber), 0.7kg of carborundum, 16kg of soybean protein powder and 4kg of trehalose at the rotating speed of 300r/min for 30min at the temperature of 20 ℃ to obtain recycled concrete.
Example 2
A preparation method of recycled concrete comprises the following steps:
s1, mixing and stirring 1.22kg of the nano-reinforcing liquid prepared in preparation example 2, 55kg of water and 100kg of cement at the rotating speed of 325r/min for 15min to obtain nano-reinforcing slurry, soaking 950kg of recycled aggregate in the nano-reinforcing slurry for 35min, filtering, and drying at the temperature of 32.5 ℃ for 1.5h to obtain nano-reinforcing recycled aggregate;
s2, mixing and stirring the nano reinforced recycled aggregate, 1.32kg of steel fiber-PVA hybrid fiber, 6.9kg of waste textile fiber (2.46 kg of waste polyester fiber, 1.98kg of waste cotton fiber and 2.46kg of waste glass fiber), 1.0kg of carborundum, 13kg of soybean protein powder and 6kg of trehalose at the rotating speed of 325r/min for 35min at the temperature of 25 ℃ to obtain recycled concrete.
Example 3
A preparation method of recycled concrete comprises the following steps:
s1, mixing and stirring 1.6kg of the nano-reinforcing liquid prepared in preparation example 3, 35kg of water and 70kg of cement at the rotating speed of 350r/min for 20min to obtain nano-reinforcing slurry, soaking 980kg of recycled aggregate in the nano-reinforcing slurry for 40min, filtering, and drying at the temperature of 35 ℃ for 2h to obtain nano-reinforcing recycled aggregate;
s2, mixing and stirring the nano reinforced recycled aggregate, 1.8kg of steel fiber-PVA hybrid fiber, 4.5kg of waste textile fiber (1.61 kg of waste polyester fiber, 1.28kg of waste cotton fiber and 1.61kg of waste glass fiber), 1.3kg of carborundum, 10kg of soybean protein powder and 8kg of trehalose at the rotating speed of 350r/min for 40min at the temperature of 30 ℃ to obtain recycled concrete.
Example 4
A preparation method of recycled concrete comprises the following steps:
s1, mixing and stirring 0.9kg of the nano-reinforcing liquid prepared in preparation example 4, 40kg of water and 80kg of cement at a rotating speed of 310r/min for 12min to obtain nano-reinforcing slurry, soaking 935kg of recycled aggregate in the nano-reinforcing slurry for 33min, filtering, and drying at a temperature of 32 ℃ for 1.3h to obtain nano-reinforcing recycled aggregate;
s2, mixing and stirring the nano-reinforced recycled aggregate, 1.05kg of steel fiber-PVA hybrid fiber, 5.2kg of waste textile fiber (1.683 kg of waste polyester fiber, 1.53kg of waste cotton fiber and 1.989kg of waste glass fiber), 0.9kg of carborundum, 11.5kg of soybean protein powder and 5kg of trehalose at the rotating speed of 310r/min for 32min at the temperature of 23 ℃ to obtain recycled concrete.
Example 5
A preparation method of recycled concrete comprises the following steps:
s1, mixing and stirring 1.4kg of the nano-reinforcing liquid prepared in preparation example 5, 7kg of water and 120kg of cement at the rotating speed of 340r/min for 17min to obtain nano-reinforcing slurry, soaking 960kg of recycled aggregate in the nano-reinforcing slurry for 38min, filtering, and drying at the temperature of 34 ℃ for 1.8h to obtain nano-reinforcing recycled aggregate;
s2, mixing and stirring the nano reinforced recycled aggregate, 1.63kg of steel fiber-PVA hybrid fiber, 8.7kg of waste textile fiber (2.816 kg of waste polyester fiber, 2.56kg of waste cotton fiber and 3.328kg of waste glass fiber), 1.2kg of carborundum, 15kg of soybean protein powder and 7.5kg of trehalose at the rotating speed of 340r/min for 38min at the temperature of 27 ℃ to obtain recycled concrete.
Example 6
A method for producing recycled concrete, which is different from example 2 in that: the nano GNPs in preparation example 2 selected in step S1 were modified by the following method:
mixing and stirring 80kg of absolute ethyl alcohol, 2kg of iminodiacetic acid, 2.5kg of paraformaldehyde and 2kg of nano GNP for 30min at the temperature of 20 ℃, heating to 60 ℃, removing the ethanol, then carrying out reflux reaction for 4h at the temperature of 200 ℃, naturally cooling, dispersing in an organic solvent (water: acetone: absolute ethyl alcohol =2:1: 0.8), carrying out suction filtration, washing, drying, dispersing in an anhydrous chloroform solvent, adding 4kg of 3-aminopropyltrimethoxysiloxane, carrying out reflux reaction for 20h, washing, filtering, and drying for 1h at the temperature of 40 ℃ to obtain the modified nano GNP.
Example 7
A method for producing recycled concrete, which is different from example 2 in that: the nano GNPs in preparation example 2 selected in step S1 were modified by the following method:
mixing 100kg of absolute ethyl alcohol, 3kg of iminodiacetic acid, 3.5kg of paraformaldehyde and 2.5kg of nano GNP at the temperature of 25 ℃, stirring for 40min, heating to 80 ℃, removing the ethanol, performing reflux reaction for 5h at the temperature of 220 ℃, naturally cooling, dispersing in an organic solvent (water: acetone: absolute ethyl alcohol =2.5:2: 1), performing suction filtration, washing, drying, dispersing in an anhydrous chloroform solvent, adding 5kg of 3-aminopropyltrimethoxysiloxane, performing reflux reaction for 24h, washing, filtering, and drying at the temperature of 50 ℃ for 2h to obtain the modified nano GNP.
Example 8
A method for producing recycled concrete, which is different from example 2 in that: the waste glass fiber is modified by the following method:
a. cleaning waste glass fibers in an acetone solution, soaking the waste glass fibers in a hydrochloric acid solution with the concentration of 1mol/L for 7 hours at the temperature of 100 ℃, and then drying for 15 minutes at the temperature of 40 ℃;
b. and (b) immersing the waste glass fiber treated in the step (a) into a silane coupling agent-KH 550 with the concentration of 2.0mol/L for 3h, drying at the temperature of 80 ℃ for 4h, repeating the process for 2 times, ultrasonically cleaning in an ethanol solution for 20min, and drying at the temperature of 200 ℃ for 2 h.
Example 9
A method for producing recycled concrete, which is different from example 2 in that: the waste glass fiber is modified by the following method:
a. cleaning waste glass fibers in an acetone solution, soaking the waste glass fibers in a hydrochloric acid solution with the concentration of 1.5mol/L for 8 hours at the temperature of 110 ℃, and then drying for 20 minutes at the temperature of 45 ℃;
b. and (b) immersing the waste glass fiber treated in the step (a) in a silane coupling agent-KH 560 with the concentration of 2.2mol/L for 4h, drying at 85 ℃ for 54h, repeating the process for 3 times, ultrasonically cleaning in an ethanol solution for 30min, and drying at 210 ℃ for 3 h.
Example 10
A method for producing recycled concrete, which is different from example 2 in that: step S2 also comprises 25kg of microemulsion;
the microemulsion is prepared by the following method:
20kg of petroleum ether, 2kg of a 3mol/L polyacrylamide aqueous solution and 0.3kg of a surfactant (0.14 kg of sorbitan fatty acid ester and 0.16kg of sorbitan monooleate polyoxyethylene ether) were mixed at a temperature of 20 ℃ and dispersed for 30 minutes to obtain a microemulsion.
Example 11
A method for producing recycled concrete, which is different from example 2 in that: step S2 also comprises 30kg of microemulsion;
the microemulsion is prepared by the following method:
23kg of petroleum ether, 3kg of a 3.3mol/L polyacrylamide aqueous solution and 0.4kg of a surfactant (0.195 kg of sorbitan fatty acid ester and 0.205kg of sorbitan monooleate polyoxyethylene ether) were mixed at a temperature of 25 ℃ and dispersed for 40min to obtain a microemulsion.
Comparative example 1
The recycled concrete adopted in the existing market comprises the following components in percentage by weight: 8-12% of cement, 50-60% of natural macadam and 30-40% of recycled aggregate.
Comparative example 2
The difference from example 2 is that: 900kg of recycled aggregate, 150kg of cement, 0.7kg of nano-reinforcing liquid, 80kg of water, 0.6kg of steel fiber-PVA hybrid fiber, 10kg of waste textile fiber, 0.5kg of carborundum, 20kg of soybean protein powder and 2kg of trehalose.
Comparative example 3
The difference from example 2 is that: 1000kg of recycled aggregate, 50kg of cement, 2kg of nano-reinforcing liquid, 30kg of water, 2kg of steel fiber-PVA hybrid fiber, 3kg of waste textile fiber, 2kg of carborundum, 5kg of soybean protein powder and 10kg of trehalose.
Performance test
1. The porosity (%) of the recycled concrete prepared in examples 1 to 11 and comparative examples 1 to 3 was measured with reference to JGJ55-2000 general concrete mix design rules, and the measurement results are shown in Table 2;
2. the 28d compressive strength (MPa) and 28d flexural strength (MPa) of the recycled concrete prepared in examples 1-11 and comparative examples 1-3 were measured with reference to GB/T50081-2002 Standard test method for mechanical Properties of general concrete, and the measurement results are shown in Table 2.
TABLE 2 table of Performance test results
| Item | Porosity (%) | 28d compressive Strength (MPa) | 28d breaking strength (MPa) |
| Standard requirements | ＜7 | ＞30 | - |
| Example 1 | 5.0 | 37.2 | 5.7 |
| Example 2 | 4.5 | 40.6 | 6.8 |
| Example 3 | 4.7 | 38.8 | 6.1 |
| Example 4 | 4.8 | 38.5 | 5.9 |
| Example 5 | 4.7 | 39.1 | 6.5 |
| Example 6 | 4.2 | 42.3 | 7.3 |
| Example 7 | 4.3 | 42.1 | 7.2 |
| Example 8 | 4.1 | 42.5 | 7.6 |
| Example 9 | 4.3 | 42.0 | 7.2 |
| Example 10 | 3.8 | 45.3 | 8.1 |
| Example 11 | 3.9 | 45.1 | 7.9 |
| Comparative example 1 | 6.8 | 32.5 | 4.5 |
| Comparative example 2 | 6.1 | 34.6 | 5.1 |
| Comparative example 3 | 5.7 | 34.1 | 4.9 |
As can be seen from Table 1, the recycled concrete prepared in examples 1 to 5 of the present application has a porosity of less than 5.0%, a 28d compressive strength in the range of 37.2 to 40.6MPa, and a 28d flexural strength in the range of 5.7 to 6.8 MPa; the porosity of comparative example 1 is 6.1%, the 28d compressive strength is 32.5MPa, and the 28d flexural strength is 4.5MPa, which shows that the recycled concrete prepared in examples 1 to 5 of the present application has a smaller porosity, a higher degree of compaction, and higher compressive strength and flexural strength.
The porosity of the examples 6-7 is less than that of the example 2, and the compressive strength and the flexural strength are greater than those of the example 2, which shows that the nano GNP in the nano reinforcing liquid is modified, so that the dispersing capacity of the nano GNP can be enhanced, harmful pores in recycled concrete can be fully filled, and the mechanical property of the recycled concrete can be improved.
The porosity of the concrete in the examples 8-9 is less than that in the example 2, and the compressive strength and the flexural strength are greater than those in the example 2, which shows that the toughness and the strength of the waste glass fiber can be enhanced by modifying the waste glass fiber, so that the waste glass fiber can fully play a role in improving the mechanical property of the recycled concrete.
The porosity of the examples 10-11 is less than that of the example 2, and the compressive strength and the flexural strength are greater than those of the example 2, which shows that the micro-emulsion prepared by the examples 10-11 can enable the components in the recycled concrete to be tightly bonded together, and the mechanical property of the recycled concrete is fully improved.
Comparative examples 2 to 3, in which the porosity was higher than that of example 2 and the compressive strength and the flexural strength were lower than those of example 2, show that the mechanical properties of recycled concrete were lowered when the amounts of recycled aggregate, cement, nano-reinforcing liquid, water, steel fiber-PVA hybrid fiber, waste textile fiber, emery, soy protein powder, and trehalose were used outside the range of the present application.
The embodiments of the present invention are preferred embodiments of the present application, and the scope of protection of the present application is not limited by the embodiments, so: all equivalent changes made according to the structure, shape and principle of the present application shall be covered by the protection scope of the present application.
Claims (10)
1. The recycled concrete is characterized by comprising the following raw materials in parts by weight:
920-980 parts of recycled aggregate;
70-130 parts of cement;
0.84-1.6 parts of nano strengthening liquid;
35-75 parts of water;
0.84-1.8 parts of steel fiber-PVA hybrid fiber;
4.5-9.3 parts of waste textile fiber;
0.7-1.3 parts of carborundum;
10-16 parts of soybean protein powder;
4-8 parts of trehalose;
the nano strengthening liquid is nano SiO2Nano Al2O3Nano CaCO, nano-grade CaCO3And a mixed solution of nano GNP and a water reducing agent.
2. A recycled concrete as claimed in claim 1, wherein: the nano strengthening liquid is prepared by the following method:
at the temperature of 30-35 ℃, the water reducing agent and the nano SiO2Nano Al2O3Nano CaCO, nano-grade CaCO3And performing ultrasonic emulsification and dispersion on the nano GNP for 20-30min to obtain a nano strengthening solution; wherein, the water reducing agent and the nano SiO2Nano Al2O3Nano CaCO, nano-grade CaCO3And the weight ratio of the nano GNP is 1 (0.02-0.08): (0.03-0.07): (0.02-0.08): 0.04-0.06).
3. A recycled concrete as claimed in claim 2, wherein: the nano GNP is modified by the following method:
mixing and stirring absolute ethyl alcohol, iminodiacetic acid, paraformaldehyde and nano GNP for 30-40min at the temperature of 20-25 ℃, heating to 60-80 ℃, removing the ethanol, performing reflux reaction at the temperature of 200-220 ℃, dispersing in an organic solvent after natural cooling, performing suction filtration, washing, drying, dispersing in an anhydrous chloroform solvent, adding 3-aminopropyltrimethoxysiloxane, performing reflux reaction for 20-24h, washing, filtering, and drying at the temperature of 40-50 ℃ for 1-2h to obtain modified nano GNP;
the weight ratio of the absolute ethyl alcohol, the iminodiacetic acid, the paraformaldehyde, the nano GNP and the 3-aminopropyl trimethoxy siloxane is (80-100): 2-3): 2.5-3.5: (2-2.5): 4-5.
4. A recycled concrete as claimed in claim 3, wherein: the organic solvent comprises water, acetone and absolute ethyl alcohol in a weight ratio of (2.0-2.5) to (1-2) to (0.8-1.0).
5. A recycled concrete as claimed in claim 1, wherein: the waste textile fiber comprises waste polyester fiber, waste cotton fiber and waste glass fiber in a weight ratio of (1.0-1.1) to (0.8-1.0) to (1.0-1.3).
6. A recycled concrete as claimed in claim 5, wherein: the waste glass fiber is modified by adopting the following method:
a. after cleaning the waste glass fiber in an acetone solution, soaking the waste glass fiber in a hydrochloric acid solution with the concentration of 1-1.5mol/L for 7-8h at the temperature of 100-110 ℃, and then drying for 15-20min at the temperature of 40-45 ℃;
b. and (b) immersing the waste glass fiber treated in the step (a) into a silane coupling agent with the concentration of 2.0-2.2mol/L for 3-4h, then drying for 4-5h at the temperature of 80-85 ℃, repeating the process for 2-3 times, then ultrasonically cleaning for 20-30min in an ethanol solution, and drying for 2-3h at the temperature of 200-210 ℃.
7. A recycled concrete as claimed in claim 1, wherein: the raw materials also comprise 25 to 30 weight parts of microemulsion;
the microemulsion is prepared by the following method:
mixing petroleum ether, 3-3.3mol/L polyacrylamide aqueous solution and surfactant at 20-25 deg.C, and dispersing for 30-40min to obtain microemulsion; wherein the weight ratio of the petroleum ether to the polyacrylamide aqueous solution to the surfactant is (20-23) to (2-3) to (0.3-0.4).
8. Recycled concrete according to claim 7, characterized in that: the surfactant comprises sorbitan fatty acid ester and sorbitan monooleate polyoxyethylene ether in a weight ratio of (2.5-3.0) to (3-3.2).
9. A recycled concrete as claimed in claim 1, wherein: the water reducing agent is a polycarboxylic acid water reducing agent.
10. A method for the preparation of recycled concrete according to any one of claims 1 to 9, characterized in that it comprises the following steps:
s1, mixing and stirring the nano-reinforcing liquid, water and cement for 10-20min at the rotating speed of 300-350r/min to obtain nano-reinforcing slurry, then soaking the recycled aggregate in the nano-reinforcing slurry for 30-40min, filtering, and drying at the temperature of 30-35 ℃ for 1-2h to obtain nano-reinforcing recycled aggregate;
s2, mixing and stirring the nano reinforced recycled aggregate and all other raw materials at the rotating speed of 300-350r/min for 30-40min at the temperature of 20-30 ℃ to obtain the recycled concrete.
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