CN114477873B

CN114477873B - Recycled aggregate self-compacting concrete and preparation method thereof

Info

Publication number: CN114477873B
Application number: CN202210169373.6A
Authority: CN
Inventors: 钟晓欢
Original assignee: Shenzhen Baojinhua Concrete Co ltd
Current assignee: Shenzhen Baojinhua Concrete Co ltd
Priority date: 2022-02-23
Filing date: 2022-02-23
Publication date: 2022-08-23
Anticipated expiration: 2042-02-23
Also published as: CN114477873A

Abstract

The application relates to the field of building materials, and particularly discloses recycled aggregate self-compacting concrete and a preparation method thereof. The recycled aggregate self-compacting concrete comprises the following components in parts by weight: 260 parts of cement prepared by 220-; the modified coarse aggregate is a regenerated aggregate which is coated and modified by phenolic resin composite gel liquid; the preparation method comprises the following steps: and uniformly stirring the modified recycled aggregate, the sand, the mineral powder, the cement and the fly ash to prepare a mixed solid material, adding the additive into water, uniformly stirring, adding the mixture into the mixed solid material, and uniformly mixing to prepare the recycled aggregate self-compacting concrete. The recycled aggregate self-compacting concrete has the advantages of high compressive strength, good heat resistance and strong impermeability.

Description

Recycled aggregate self-compacting concrete and preparation method thereof

Technical Field

The application relates to the field of building materials, in particular to recycled aggregate self-compacting concrete and a preparation method thereof.

Background

Self-compacting concrete is concrete which can flow and be compact under the action of self gravity, can completely fill a mould even if compact steel bars exist, and simultaneously obtains good homogeneity without additional vibration. The recycled aggregate self-compacting concrete refers to concrete formed by replacing natural coarse aggregate in the self-compacting concrete with recycled coarse aggregate. Therefore, the recycled aggregate self-compacting concrete can inherit various advantages of the self-compacting concrete and can also recycle construction waste and recycled coarse aggregates, thereby achieving the purposes of protecting the environment and saving natural resources.

In the prior art, a Chinese patent application with the application number of 201610761652.6 discloses C20-grade steel slag-doped recycled aggregate self-compacting concrete and a preparation method thereof, wherein the raw material components of the concrete comprise the following raw materials in parts by weight: 1 part of water, 3.089 parts of natural coarse aggregate, 1.322 parts of regenerated coarse aggregate, 3.822 parts of fine aggregate, 0.970-0.1.213 parts of cement, 1.213-1.455 parts of steel slag, 0.609 part of fly ash, 0.064 part of additional water and 0.00495-0.0124 part of additive.

Aiming at the related technologies, the inventor finds that the obtained recycled coarse aggregate directly used in concrete has poor compactness and contains a large amount of gaps after the recycled aggregate is mechanically crushed, so that the water absorption of the recycled coarse aggregate is high, and the absorbed water participates in hydration reaction in the concrete mixing process, so that the water-cement ratio of a new cement mortar interface transition area of the recycled aggregate is increased, the structure of the interface area is loose, more pores are formed, and the mechanical property of a concrete material is obviously reduced.

Disclosure of Invention

In order to improve the mechanical strength of self-compacting concrete prepared from recycled aggregate, the application provides the self-compacting concrete of the recycled aggregate and a preparation method thereof.

In a first aspect, the application provides a recycled aggregate self-compacting concrete, which adopts the following technical scheme:

the recycled aggregate self-compacting concrete comprises the following components in parts by weight: 260 parts of cement prepared by 220-;

the modified coarse aggregate is a recycled aggregate which is coated and modified by phenolic resin composite gel liquid.

By adopting the technical scheme, the regenerated aggregate is coated by the phenolic resin composite gel liquid, the compactness of the regenerated aggregate is improved, and the capillary holes and the micro cracks of the regenerated aggregate are filled, so that the edges and corners of the regenerated aggregate are reduced, the roundness is increased, the workability and the compactness of concrete are improved, and the mechanical property and the working performance are improved.

Preferably, the phenolic resin composite gel liquid comprises the following components in parts by weight: 0.6-1 part of titanium carbonitride, 0.5-1 part of nano silicon compound and 0.5-1 part of phenolic resin.

By adopting the technical scheme, the titanium carbonitride has small particle size, can be dispersed in the phenolic resin and the nano silicon compound, reduces the size of the phenolic resin and the nano silicon compound, and enables the phenolic resin and the nano silicon compound to uniformly enter pores of the recycled aggregate, thereby achieving the purpose of filling and plugging, improving the compactness of concrete and improving the mechanical property; the nano silicon compound can obtain more stable and more fluid slurry, can improve the early and later strength of concrete and can play a more prominent role in the concrete, the nano silicon compound is added into a cement system to react with a cement hydration product quickly to generate a cement hydrate C-S-H colloidal structure with similar high silicon content, and the quickly generated C-S-H structure not only can bond cement and aggregate, but also can restrain excessive free water in the cement, so that the rheological property and the stability of the concrete are improved, and the fluidity and the stability of the concrete can be improved without increasing the plastic deformation of the concrete.

Preferably, the preparation method of the nano silicon composite comprises the following steps:

according to parts by weight, 1-2 parts of ethyl orthosilicate, 1-2 parts of absolute ethyl alcohol and 2-4 parts of deionized water are stirred for 30-40min in a water bath at 30-40 ℃, 0.02-0.03 part of dibutyltin dilaurate and 0.3-0.8 part of methyl triethoxysilane are added, and the mixture is stirred uniformly and then stands for aging.

According to the technical scheme, ethyl orthosilicate is used as an inorganic precursor, methyltriethoxysilane is used as an organic hybridization agent, the ethyl orthosilicate and the methyltriethoxysilane are subjected to polycondensation reaction under the catalysis of dibutyltin dilaurate to prepare the organic silicon and inorganic silicon hybrid gel, the hydrolysis rate of the ethyl orthosilicate is low under the catalysis of the dibutyltin dilaurate, and the nano silicon compound contains certain unhydrolyzed hydrophobic group alkoxy, so that a compact film structure can be formed, moisture is isolated, the hydrophobicity of the recycled aggregate is increased, and the impermeability is good.

Preferably, the titanium carbonitride is prepared by coupling graft modification.

By adopting the technical scheme, the titanium carbonitride modified by coupling grafting has better compatibility with the phenolic resin, can be dispersed more uniformly in the phenolic resin, and is not easy to generate aggregation.

Preferably, the titanium carbonitride coupling grafting modification method comprises the following steps: dissolving a silane coupling agent KH550 in absolute ethanol to prepare a KH550 ethanol solution with the mass concentration of 2-3%;

mixing titanium carbonitride and KH550 ethanol solution at a mass ratio of 2:1-1.5, stirring in water bath at 60-70 deg.C for 3-4 hr, cooling, and vacuum drying.

By adopting the technical scheme, because the titanium carbonitride has small particles and is easy to agglomerate, the titanium carbonitride cannot be uniformly dispersed in the phenolic resin composite gel liquid, the coupling agent is grafted on the surface of the titanium carbonitride, the interface effect of the titanium carbonitride is strengthened, the compatibility of the titanium carbonitride and the phenolic resin is enhanced, the dispersibility of the titanium carbonitride and the phenolic resin is increased, the titanium carbonitride effectively fills the pores of the recycled aggregate, the hardness of the recycled aggregate is improved, and the compactness and the mechanical strength of the self-compacting concrete are improved.

Preferably, the preparation method of the modified coarse aggregate comprises the following steps: mixing the nano silicon compound with ethanol to prepare a nano silicon compound ethanol solution with the mass concentration of 25-30%, mixing phenolic resin with ethanol to prepare a phenolic resin ethanol solution with the mass concentration of 25-30%, mixing the nano silicon compound ethanol solution with the phenolic resin ethanol solution according to the mass ratio of 1:1-2, then adding ammonia water ethanol solution, fully oscillating and ultrasonically treating for 1-3min, adding titanium carbonitride under heating of a water bath at 50-60 ℃, keeping the water bath temperature and aging for 20-24h to prepare phenolic resin composite gel liquid;

uniformly mixing the phenolic resin composite gel liquid and the recycled aggregate according to the mass ratio of 1:1-2, and drying to prepare the modified coarse aggregate.

By adopting the technical scheme, the nano silicon compound ethanol solution and the phenolic resin ethanol solution are mixed under the action of the ammonia water ethanol solution, the nano silicon compound and the phenolic resin are polymerized and are connected to the surface of the phenolic resin with strong interaction, and the titanium carbonitride enters pores of the recycled aggregate under the action of the composite gel to fill the recycled aggregate, so that the compactness of the recycled aggregate is improved, and the compressive strength, impermeability and heat resistance of concrete are improved; the phenolic resin which is not compounded with the nano silicon compound is hydrophilic, the hydrophobicity of the phenolic resin is improved along with the addition of the nano silicon compound, and the phenolic resin can be protected due to the fact that the nano silicon compound contains a certain hydrophobic group, a water-blocking barrier is formed on the recycled aggregate, and the anti-permeability performance of the concrete is improved; in addition, the proper dosage of the phenolic resin and the nano silicon compound can prevent the poor strength of the formed gel skeleton and incomplete gel structure due to the poor dosage of the phenolic resin, can not coat the recycled aggregate, and can prevent the more Si-OH bonds due to the large dosage of the nano silicon compound from further reacting during drying, thereby causing the serious shrinkage of the skeleton structure of the composite gel, increasing the mass concentration, increasing the roughness of the surface of the phenolic resin skeleton and reducing the impermeability.

Preferably, the admixture comprises 3-7 parts of water reducing agent, 2-10 parts of viscosity modifier and 10-14 parts of expanding agent.

By adopting the technical scheme, the water reducing agent can avoid the aggregation of cement, the dispersion of the cement is assisted, the expanding agent can be uniformly distributed in the concrete, the development of micro cracks is blocked, the anti-cracking effect is achieved, the viscosity of the concrete can be improved by the viscosity modifier, and the workability and the homogeneity of the concrete are improved.

Preferably, the viscosity modifier is porous hydroxyapatite, zeolite and boehmite sol with the mass ratio of 1:0.1-0.3:0.5-0.8, and the particle size of the porous hydroxyapatite and the zeolite is 5-10 mm.

By adopting the technical scheme, the porous hydroxyapatite and the zeolite have porous structures, can store and release water, can reduce the sensitivity of the workability of the concrete to the change of the free water content in the concrete, and ensure that the fluctuation of the free water content in the concrete within a certain range is the concrete workability maintaining temperature; the boehmite sol has large viscosity and good hydrophobicity, and can improve the anti-permeability performance of porous hydroxyapatite and zeolite.

Preferably, the fly ash is I-grade fly ash, the ignition loss is less than or equal to 3.0 percent, the 45-micron screen residue is less than or equal to 12 percent, the water demand ratio is less than or equal to 95 percent, and the water content is less than or equal to 1.0 percent;

the fineness modulus of the sand is 2.3-3.1, and the apparent density is 2600-2650kg/m ³ The bulk density is 1500- ³ 。

By adopting the technical scheme, the I-grade fly ash has small fineness and can be filled among aggregate particles, the compactness of the self-compacting concrete is improved, bleeding and segregation of the concrete are reduced, and the fluidity and the filling property are improved; the sand is proper in thickness, good in workability and construction workability, can be filled among modified recycled aggregates, improves compactness and improves workability of concrete.

In a second aspect, the application provides a preparation method of recycled aggregate self-compacting concrete, which adopts the following technical scheme: a preparation method of recycled aggregate self-compacting concrete comprises the following steps of uniformly stirring modified recycled aggregate, sand, mineral powder, cement and fly ash to prepare a mixed solid material, adding an additive into water, uniformly stirring, adding the mixture into the mixed solid material, and uniformly mixing to prepare the recycled aggregate self-compacting concrete.

By adopting the technical scheme, dry materials such as modified aggregates, sand, mineral powder, cement and fly ash are mixed firstly, so that the dry materials are mixed uniformly, and then the admixture is dissolved by water and added into a solid mixture, so that the viscosity of concrete can be improved, and the fluidity and the filling property are improved.

In summary, the present application has the following beneficial effects:

1. as the recycled aggregate is coated by adopting the phenolic resin composite gel liquid, capillary holes and micro cracks which are originally generated or cannot be damaged later are filled in the recycled aggregate, the roundness of the recycled aggregate is increased, the workability and the compactness of the concrete are improved, and the mechanical property of the concrete is improved.

2. Titanium carbonitride, nano silicon compound and phenolic resin are preferably adopted as coating gel liquid of the recycled aggregate, the titanium carbonitride has the advantages of high hardness, high melting point, good oxidation resistance and strong corrosion resistance, the nano silicon compound and the phenolic resin react to form gel, and the gel and the titanium carbonitride are coated on the recycled aggregate together, so that the heat resistance, impermeability and strength of the recycled aggregate can be improved.

3. In the application, ethyl orthosilicate, methyl triethoxysilane, dibutyltin dilaurate and the like are preferably used for preparing the nano silicon compound, and the introduction of the hydrophobic group enables the nano silicon compound to contain the hydrophobic group, so that the impermeability of the recycled aggregate is improved.

Detailed Description

Preparation examples 1 to 9 of modified recycled aggregate

The phenolic resin in preparation examples 1-9 was selected from Hengtong chemical Co., Ltd, Zhengzhou city, having a product number of 545 and a brand number of 2130; the titanium carbonitride is selected from Ningbo Jinlei nanometer material science and technology company, and has the model number of JL-TiCN-Y800; the cellulose ether is selected from Shanghai Kahn chemical company of 8821.

Preparation example 1: (1) mixing 0.5kg of nano silicon compound with ethanol to prepare a nano silicon compound ethanol solution with the mass concentration of 25%, mixing 0.5kg of phenolic resin with ethanol to prepare a phenolic resin ethanol solution with the mass concentration of 25%, mixing the nano silicon compound ethanol solution with the phenolic resin ethanol solution according to the mass ratio of 1:1, then adding 0.3kg of ammonia water ethanol solution, fully oscillating and carrying out ultrasonic treatment for 1min, adding 0.6kg of titanium carbonitride under the heating of a water bath at 60 ℃, keeping the temperature of the water bath and aging for 20h to prepare a phenolic resin compound gel solution; the nano silicon composite is prepared by the following method: stirring 1kg of ethyl orthosilicate, 1kg of anhydrous ethanol and 2kg of deionized water in a water bath at the temperature of 30 ℃ for 40min, adding 0.02kg of dibutyltin dilaurate and 0.3kg of methyltriethoxysilane, uniformly stirring, standing and aging; the titanium carbonitride is treated by a silane coupling agent, and the treatment method comprises the following steps: dissolving a silane coupling agent KH550 in absolute ethanol to prepare a KH550 ethanol solution with the mass concentration of 2%; mixing titanium carbonitride and KH550 ethanol solution according to the mass ratio of 2:1, stirring for 4h in water bath at 60 ℃, cooling and vacuum drying;

(2) uniformly mixing the phenolic resin composite gel liquid and the recycled aggregate according to the mass ratio of 1:1, and drying to prepare the modified recycled aggregate, wherein the recycled aggregate is prepared by crushing building waste concrete blocks to 10 mm.

Preparation example 2: (1) mixing 1kg of nano silicon compound with ethanol to prepare a nano silicon compound ethanol solution with the mass concentration of 20%, mixing 1kg of phenolic resin with ethanol to prepare a phenolic resin ethanol solution with the mass concentration of 30%, mixing the nano silicon compound ethanol solution with the phenolic resin ethanol solution according to the mass ratio of 1:2, then adding 0.5kg of ammonia water ethanol solution, fully oscillating and ultrasonically treating for 3min, adding 1kg of titanium carbonitride under the heating of a water bath at 50 ℃, keeping the water bath temperature and aging for 24h to prepare a phenolic resin compound gel solution; the nano silicon composite is prepared by the following method: stirring 3kg of ethyl orthosilicate, 3kg of absolute ethyl alcohol and 4kg of deionized water in a water bath at 40 ℃ for 30min, adding 0.03kg of dibutyltin dilaurate and 0.8kg of methyltriethoxysilane, uniformly stirring, standing and aging; the titanium carbonitride is treated by a silane coupling agent, and the treatment method comprises the following steps: dissolving a silane coupling agent KH550 in absolute ethanol to prepare a KH550 ethanol solution with the mass concentration of 3%; mixing titanium carbonitride and KH550 ethanol solution at a mass ratio of 2:1.5, stirring in water bath at 70 deg.C for 3 hr, cooling, and vacuum drying.

(2) Uniformly mixing the phenolic resin composite gel liquid and the recycled aggregate according to the mass ratio of 1:2, and drying, wherein the recycled aggregate is prepared by crushing waste building concrete blocks to 10 mm.

Preparation example 3: the difference from preparation example 1 is that titanium carbonitride was not treated with a coupling agent.

Preparation example 4: the difference from preparation example 1 is that titanium carbonitride was not added.

Preparation example 5: the difference from preparation example 1 is that the nano-silicon composite was not added.

Preparation example 6: the difference from the preparation example 1 is that the mass ratio of the phenolic resin ethanol solution to the nano silicon composite ethanol solution is 0.5: 1.

Preparation example 7: the difference from the preparation example 1 is that the mass ratio of the phenolic resin ethanol solution to the nano silicon composite ethanol solution is 2:1.

Preparation example 8: the difference from preparation example 1 is that, in preparing the nano-silicon composite, the same amount of hydroxyl-terminated silicone oil was used instead of methyltriethoxysilane.

Preparation example 9: the difference from preparation example 1 is that the same amount of cellulose ether was used instead of the nano-silicon composite.

Examples

In the present example, the raw materials used are as follows, but not limited thereto: the boehmite sol is selected from Shanghai Yingsheng New Material Co., Ltd, and has a model of YC-LRJ 15; the aliphatic (hydroxy) sulfonate high-efficiency water reducing agent is selected from Beijing Douda building materials Co, and has the model of RS-3; the composite fiber expanding agent is selected from Beijing Haishixing concrete admixture sales Limited company, and the model is HCPA.

Example 1: the recycled aggregate self-compacting concrete comprises the following raw materials in proportion as shown in table 1, wherein cement in the table 1 is P.O42.5 portland cement; the loss on ignition of the fly ash I-grade fly ash is less than or equal to 3 percent, the 4.5 mu m sieve residue is less than or equal to 12 percent, the water requirement ratio is less than or equal to 95 percent, and the water content is less than or equal to 1 percent; the mineral powder is S95 grade mineral powder, and the specific surface area is 400m ² The activity index of 28d is 95%, the fluidity ratio is 95%, the fineness modulus of the sand is 2.3, and the apparent density is 2600kg/m ³ Bulk density of 1500kg/m ³ (ii) a The additive is 3kg of water reducing agent, 10kg of viscosity modifier and 10kg of expanding agent, the water reducing agent is aliphatic (hydroxy) sulfonate high-efficiency water reducing agent, the expanding agent is composite fiber expanding agent,the viscosity modifier is selected from Guangdong Jiansheng high and new materials, and the model is CW; a modified recycled aggregate was prepared by preparative example 1.

The preparation method of the recycled aggregate self-compacting concrete comprises the following steps:

uniformly stirring the modified recycled aggregate, sand, mineral powder, cement and fly ash to prepare a mixed solid material, adding the additive into water, uniformly stirring, adding the mixture into the mixed solid material, and uniformly mixing to prepare the recycled aggregate self-compacting concrete.

TABLE 1 feed proportioning for examples 1-3

Examples 2 to 5: a recycled aggregate self-compacting concrete is different from the concrete of example 1 in that the raw materials are used in the amounts shown in Table 1.

Example 6: a recycled aggregate self-compacting concrete, which is different from example 1 in that a modified recycled aggregate was prepared from preparation example 2.

Example 7: a recycled aggregate self-compacting concrete, which is different from example 1 in that a modified recycled aggregate was prepared in preparation example 3.

Example 8: a recycled aggregate self-compacting concrete, which is different from example 1 in that the modified recycled aggregate was prepared in preparation example 4.

Example 9: a recycled aggregate self-compacting concrete, which is different from example 1 in that a modified recycled aggregate was prepared from preparation example 5.

Example 10: a recycled aggregate self-compacting concrete, which is different from example 1 in that a modified recycled aggregate was prepared from preparation example 6.

Example 11: a recycled aggregate self-compacting concrete, which is different from example 1 in that a modified recycled aggregate was prepared from preparation example 7.

Example 12: a recycled aggregate self-compacting concrete, which is different from example 1 in that a modified recycled aggregate was prepared from preparation example 8.

Preparation example 13: a recycled aggregate self-compacting concrete, which is different from example 1 in that a modified recycled aggregate was prepared from preparation example 9.

Example 14: a recycled aggregate self-compacting concrete is different from the concrete in example 1 in that a viscosity modifier is porous hydroxyapatite, zeolite and boehmite sol in a mass ratio of 1:0.1:0.5, and the particle size of the porous hydroxyapatite and the zeolite is 5 mm.

Example 15: a recycled aggregate self-compacting concrete is different from the concrete in example 1 in that a viscosity modifier is porous hydroxyapatite, zeolite and boehmite sol in a mass ratio of 1:0.3:0.8, and the particle size of the porous hydroxyapatite and the zeolite is 10 mm.

Example 16: a recycled aggregate self-compacting concrete is different from the concrete in example 1 in that a viscosity modifier is porous hydroxyapatite and zeolite with the mass ratio of 1:0.3, and the particle size of the porous hydroxyapatite and the zeolite is 10 mm.

Example 17: a recycled aggregate self-compacting concrete is different from the concrete in example 1 in that a viscosity modifier is zeolite and boehmite sol in a mass ratio of 0.3:0.8, and the particle size of the zeolite is 10 mm.

Comparative example

Comparative example 1: a recycled aggregate self-compacting concrete is different from the concrete in example 1 in that the recycled aggregate which is not wrapped by phenolic resin gelling solution is used for replacing modified recycled aggregate.

Comparative example 2: a recycled aggregate self-compacting concrete is different from the concrete in example 1 in that the modified recycled aggregate is replaced by equal amount of broken stones.

Comparative example 3: the recycled aggregate self-compacting concrete comprises the following components, by weight, 32 parts of a cementing material, 35 parts of recycled fine aggregate, 20 parts of recycled coarse aggregate, 15 parts of natural aggregate, 1.2 parts of a water reducing agent and 16.5 parts of mixing water; wherein the particle size of the recycled fine aggregate D95 is 1.8mm, and the particle size of the recycled coarse aggregate D95 is 8.6 mm. The cementing material is PC42.5 and polyethylene oxide in a mass ratio of 1: 0.2. The natural aggregate is the existing common sandstone material, the specific particle size is 1-15mm, the D50 is 5.2 +/-0.5 mm, the waste sources of the recycled fine aggregate and the recycled coarse aggregate are three compositions of waste rock wool boards, building concrete and building bricks, the waste rock wool boards account for 16.5 wt%, the building concrete accounts for 68 wt% and the building bricks account for 15.5 wt%.

The preparation method of the recycled fine aggregate comprises the steps of taking waste rock wool boards, building concrete and/or building bricks, washing, crushing until the particle size is smaller than 10mm, then placing the waste rock wool boards, the building concrete and/or the building bricks into 1M acid liquor, carrying out ultrasonic treatment for 30min at 38KHz and 360W, standing, soaking for 14h, filtering, adding a proper amount of quicklime into the waste rock wool boards, stirring, mixing uniformly, injecting clear water into the waste rock wool boards, the quicklime and the clear water in a mass ratio of 10: 1: and 5, continuously stirring and mixing until the temperature is reduced to room temperature, then filtering out clear water, washing, drying in an inert atmosphere, and then crushing for the second time to obtain the product.

The preparation method of the recycled coarse aggregate comprises the steps of taking the waste rock wool boards, the building concrete and/or the building bricks, washing, crushing until the particle size is smaller than 10mm, then placing the crushed materials into 1M acid liquor, carrying out ultrasonic treatment on the crushed materials for 50min at 32KHz and 300W, standing and soaking for 15h, filtering out clear water, washing, then adding a proper amount of fiber composite material into the washed materials, stirring and uniformly mixing, and then injecting clear water into the mixed materials under the stirring condition, wherein the mass ratio of the waste particles to the fiber composite material to the clear water is 1: and 3, continuously stirring until the mixture is uniform, then drying in an inert atmosphere, and performing secondary crushing to obtain the product.

The fiber composite material comprises magnesium oxide fibers, polylactic acid fibers, polyacrylamide and fly ash, and the mass ratio of the raw materials is 1:0.3:0.3: 4.

Based on the selection and preparation of the raw materials, the preparation method of the recycled aggregate self-compacting concrete comprises the following steps:

1) taking materials according to the weight part, blending the cementing material and the recycled coarse aggregate, stirring for 30-60s, then adding the natural aggregate and the recycled fine aggregate, continuously stirring and mixing for 60-90s, then injecting the water reducing agent and the mixing water into the mixture, and continuously stirring for 60-180s to obtain concrete slurry;

2) and grouting the concrete slurry according to production needs, pouring in a reverse mold, demolding, and curing to obtain the concrete product.

Performance test

Recycled aggregate self-compacting concretes were prepared according to the methods in the examples and comparative examples, and the properties of the concretes were examined with reference to the following methods, and the examination results are recorded in table 2.

1. 28d compressive strength: the detection is carried out according to GB/T50081-2002 Standard of test methods for mechanical properties of common concrete.

2. The expansion degree is as follows: GB/T50080-2016 standard of common concrete mixture performance test method.

3. Heat resistance: the standard test block is prepared according to the method in GB/T50081-2016 Standard test method for mechanical Properties of ordinary concrete, 3 molded test pieces are taken from each group, after standard curing for 28d, dried for 24h at 110 ℃, placed in a high temperature furnace, burned for 3h at constant temperature at 300 ℃, then naturally cooled to room temperature, and the compressive strength after high temperature burning is tested.

4. Impermeability: according to GB/T50082-2009 Standard test method for the long-term performance and the durability of common concrete, the water penetration depth is tested by adopting a step-by-step pressurization method to test a standard test block.

TABLE 2 concrete Properties test of examples and comparative examples

As can be seen from the data in Table 2, the modified recycled aggregates prepared in preparation examples 1 and 6, which were prepared in examples 1 to 5 and prepared in preparation example 1, and the modified recycled aggregates prepared in preparation example 2 and prepared in example 6, were used to prepare concrete having high compressive strength, high expansion, good fluidity, less loss of compressive strength at high temperature, good heat resistance, small water penetration height, and good impermeability.

In example 7, the modified recycled aggregate prepared in preparation example 3 was used, and the phenolic resin composite gel liquid was treated without a coupling agent by adding titanium carbonitride, and the data in table 2 shows that the compressive strength of the concrete prepared in example 7 was reduced.

In example 8, the modified recycled aggregate prepared in preparation example 4 was used, and titanium carbonitride was not added to the phenolic resin composite gel liquid, so that the concrete prepared in example 8 was degraded in mechanical properties and heat resistance.

In example 9, the modified recycled aggregate prepared in preparation example 5 was used, and the nano-silicon composite was not added to the phenol resin composite gel liquid, and the concrete prepared in example 9 had a reduced extension degree, a large water penetration height, and a reduced heat resistance, as compared to example 1.

In example 10, the modified recycled aggregate prepared in preparation example 6 was used, and the amount of the phenolic resin used was reduced, and table 2 shows that the compressive strength of the concrete was reduced.

Example 11 the modified recycled aggregate prepared in preparation example 7 was used, in which the amount of the nano-silicon composite used was increased, the water penetration height of the concrete was increased, and the water resistance was lowered.

Example 12 the modified recycled aggregate prepared in preparation example 8, in which hydroxyl-terminated silicone oil was used instead of methyltriethoxysilane, was subjected to polycondensation with tetraethoxysilane to form a nano-silicon composite, which was incorporated into a phenolic resin composite gel liquid, the impermeability of the coated recycled aggregate was decreased, the water penetration height of the concrete was increased, and the heat resistance was decreased.

The modified recycled aggregate prepared in preparation example 9 was used in example 13, in which cellulose ether was used instead of the nano-silicon composite, and the data in table 2 showed that the heat resistance of the concrete was inferior to that of example 1 and the impermeability of the concrete was reduced.

In examples 14 and 15, the porous hydroxyapatite, zeolite and boehmite sol were used as viscosity modifiers, and the development of concrete was increased and workability and fluidity were further improved as compared with example 1.

In examples 16 and 17, the viscosity modifier was added without boehmite sol and without porous hydroxyapatite, and the concrete was less extended and less workable than in example 14.

In comparative example 1, the recycled aggregate not coated with the phenolic resin composite gel liquid was used, and the compressive strength of the concrete was significantly reduced and the heat resistance was insufficient as compared with example 1.

In comparative example 2, the crushed stone is used to replace the modified recycled aggregate, and the concrete prepared in comparative example 2 has reduced mechanical strength, reduced heat resistance and reduced impermeability.

Comparative example 3 is a recycled aggregate self-compacting concrete prepared by the prior art, which has a small degree of expansion, poor fluidity, and inferior heat resistance to example 1.

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 recycled aggregate self-compacting concrete is characterized by comprising the following components in parts by weight: 260 parts of cement prepared by 220-;

the modified coarse aggregate is a recycled aggregate which is coated and modified by phenolic resin composite gel liquid;

the phenolic resin composite gel liquid comprises the following components in parts by weight: 0.6-1 part of titanium carbonitride, 0.5-1 part of nano silicon compound and 0.5-1 part of phenolic resin;

the preparation method of the nano silicon composite comprises the following steps:

according to parts by weight, stirring 1-2 parts of ethyl orthosilicate, 1-2 parts of absolute ethyl alcohol and 2-4 parts of deionized water in a water bath at 30-40 ℃ for 30-40min, adding 0.02-0.03 part of dibutyltin dilaurate and 0.3-0.8 part of methyltriethoxysilane, uniformly stirring, standing and aging;

the preparation method of the modified coarse aggregate comprises the following steps: mixing a nano silicon compound with ethanol to prepare a nano silicon compound ethanol solution with the mass concentration of 25-30%, mixing phenolic resin with ethanol to prepare a phenolic resin ethanol solution with the mass concentration of 25-30%, mixing the nano silicon compound ethanol solution with the phenolic resin ethanol solution according to the mass ratio of 1:1-2, then adding an ammonia water ethanol solution, fully oscillating and ultrasonically treating for 1-3min, adding titanium carbonitride under the heating of a water bath at 50-60 ℃, keeping the temperature of the water bath and aging for 20-24h to prepare a phenolic resin composite gel solution;

2. The recycled aggregate self-compacting concrete according to claim 1, wherein the titanium carbonitride is titanium carbonitride prepared by coupling graft modification.

3. The recycled aggregate self-compacting concrete according to claim 2, wherein the titanium carbonitride coupling grafting modification method comprises the following steps: dissolving a silane coupling agent KH550 in absolute ethanol to prepare a KH550 ethanol solution with the mass concentration of 2-3%;

4. The recycled aggregate self-compacting concrete according to claim 1, wherein the admixture comprises 3-7 parts of a water reducing agent, 2-10 parts of a viscosity modifier and 10-14 parts of an expanding agent.

5. The recycled aggregate self-compacting concrete according to claim 4, wherein the viscosity modifier is porous hydroxyapatite, zeolite and boehmite sol in a mass ratio of 1:0.1-0.3:0.5-0.8, and the particle size of the porous hydroxyapatite and zeolite is 5-10 mm.

6. The recycled aggregate self-compacting concrete according to claim 1, wherein the fly ash is class I fly ash, the loss on ignition is less than or equal to 3.0%, the 45 μm screen residue is less than or equal to 12%, the water demand ratio is less than or equal to 95%, and the water content is less than or equal to 1.0%;

the fineness modulus of the sand is 2.3-3.1, and the apparent density is 2600-2650kg/m ³ The bulk density is 1500-g/m ³ 。

7. The method for preparing the recycled aggregate self-compacting concrete according to any one of claims 1 to 6, which is characterized by comprising the following steps: