Solid-waste-based expansive recycled aggregate interface enhancer as well as slurry coating method and application of solid-waste-based expansive recycled aggregate interface enhancer

Abstract

The invention discloses a solid-waste-based expansive type recycled aggregate interface enhancer as well as a slurry coating method and application thereof, belongs to the technical field of aggregate reinforcement and regeneration, and aims at solving the technical problem that the strength of recycled aggregate and the performance of prepared concrete need to be further improved in the prior art. The dry matrix powder is prepared from the following components in parts by weight: 42 to 47 parts of ardealite, 50 to 55 parts of blast furnace slag powder, 3 to 5 parts of silicon powder and 1.8 to 2.2 parts of carbide slag. The recycled aggregate is subjected to interface reinforcement regeneration by optimizing the composition of the interface reinforcer and a slurry coating method, so that the comprehensive performance of the recycled aggregate is effectively improved, the strength and the fluidity of a concrete sample are effectively improved when the recycled aggregate is applied to concrete processing, and the method is low in production cost and suitable for industrial production. And the method has the advantages of cost and environmental protection when being used for treating a large batch of recycled aggregates.

Description

Technical Field

[0001] The present invention relates to the technical field of aggregate reinforcement and regeneration, and in particular to a solid waste-based expansive regenerated aggregate interface strengthener, a slurry coating method and an application thereof. Background Art

[0002] With the acceleration of global urbanization, the construction industry's demand for building materials continues to increase, generating a large amount of construction waste. Much of this waste is landfilled or illegally dumped, occupying significant land and causing serious environmental pollution. In recent years, the resource utilization of construction waste has gradually gained attention. Converting construction waste into recycled aggregate and applying it to concrete production can achieve efficient resource recycling and significantly reduce carbon emissions.

[0003] However, the pores in recycled aggregates include macropores (>10μm), capillary pores (50nm~10μm), transition pores (10nm~50nm) and gel pores (<10nm). Among them, gel pores and transition pores have little effect on strength, while capillary pores have a significant impact on mechanical properties and durability. The interface defects between recycled aggregates and the concrete cementitious material matrix caused by factors such as surface characteristics, porosity and water absorption reduce the working performance and mechanical properties of concrete.

[0004] At present, the interface strengthening methods for recycled coarse aggregate from construction solid waste mainly include physical strengthening, chemical strengthening, biological strengthening and composite strengthening methods. Physical strengthening mainly improves the performance of recycled coarse aggregate through mechanical or thermal treatment, chemical strengthening uses chemical solutions or slurries to fill the aggregate pores and enhance the interface transition zone, and biological strengthening uses microbial metabolites to deposit calcium carbonate to fill the pores. The above three methods all require high-value energy or additives, and do not have cost and environmental protection advantages for the treatment of large quantities of recycled aggregate. In addition, the existing slurry with silicate cement as the hydration matrix mainly relies on the reaction of C3S and C2S with water to form CSH gel and Ca(OH)2. A large amount of water is required to participate in the rapid reaction in the early stage, and more water is needed to maintain fluidity. In addition, its setting time is extremely fast, and there is no sufficient operating time for the slurry coating. As a result, the strength of the recycled aggregate and the performance of the prepared concrete need to be further improved.

[0005] The present invention adheres to the principle of treating waste with waste and bulk treatment, uses a solid waste-based inorganic expansive slurry to modify and strengthen the surface of recycled aggregate, optimizes the performance of recycled aggregate in preparing concrete, helps solve the problem of construction waste treatment, and proposes a solution to the technical defects in this regard. Summary of the Invention

[0006] The purpose of the present invention is to provide a solid waste-based expansive recycled aggregate interface strengthener and its coating method and application, which are used to solve the technical problem in the prior art that the strength of recycled aggregate and the performance of the prepared concrete need to be further improved.

[0007] The purpose of the present invention can be achieved through the following technical solutions:

[0008] A solid waste-based expansive recycled aggregate interface strengthener, comprising dry matrix powder and water, with a viscosity of 8,000-12,000 cP. The dry matrix powder comprises the following components in parts by weight: 42-47 parts of phosphogypsum, 50-55 parts of blast furnace slag powder, 3-5 parts of silicon powder, and 1.8-2.2 parts of carbide slag. The silicon powder is composed of silicon fume and siloxane monomer in a weight ratio of 7:1-2.

[0009] Furthermore, the particle sizes of the phosphogypsum and carbide slag are both 0.1-0.6 mm; the calcium hydroxide content of the carbide slag is 70-85%; and the blast furnace slag powder is S95 grade slag powder.

[0010] Furthermore, the preparation method of the silicon powder is: mixing and stirring a siloxane monomer and anhydrous ethanol to obtain a siloxane solution, then adding silicon powder to the siloxane solution, stirring and mixing for 2-3 hours, raising the temperature of the reaction system to 50-60°C, and removing low-boiling substances under reduced pressure to obtain silicon powder. The siloxane monomer includes ethyl orthosilicate, methyl orthosilicate, triethoxysilane, and methyltriethoxysilane.

[0011] Furthermore, the preparation method of the interface enhancer is: adding drinking water to the dry matrix powder, stirring for 2-3 minutes, and standing for 3-5 minutes to fully wet the solid particles. Under stirring, drinking water is continued to be added thereto until the viscosity is 8000-12000 cP, the pH of the reaction system is measured, and the pH is adjusted to 12-13 to obtain the interface enhancer.

[0012] A coating method for solid waste-based expansive recycled aggregate comprises the steps of: applying a solid waste-based expansive recycled aggregate interface reinforcing agent in an atomized form to coat a coating layer on the outside of the recycled aggregate.

[0013] Furthermore, a method for coating solid waste-based expansive recycled aggregate comprises the following steps:

[0014] S1. Crushing and screening construction solid waste to obtain recycled aggregates of different particle sizes;

[0015] S2. The recycled aggregate is put into a mixer and stirred for 30-50 seconds. The interface strengthener is sprayed into the mixer in the form of atomized spraying. After spraying for 130-150 seconds, a water reducer is added to the mixer, stirred for 60-80 minutes, and discharged to obtain a primary coated aggregate;

[0016] S3, adding the primary coated aggregate to a vibrating screen, spraying the interface strengthening agent thereon in the form of atomized spraying, coating the aggregate until the desired thickness is reached, and discharging the aggregate to obtain the secondary coated aggregate;

[0017] S4. Curing the secondary coated aggregate for 14 days to obtain recycled aggregate.

[0018] Furthermore, in step S1, the preparation method of the recycled aggregate is: putting the construction waste into a crusher, crushing it, using countercurrent air sorting to remove light impurities, using a magnetic drum to separate and remove metal impurities, and then using a screen to screen it to obtain coarse recycled aggregate with a particle size of 10-20 mm and fine recycled aggregate with a particle size of 5-10 mm.

[0019] Furthermore, in step S2, the mixer is an inclined twin-shaft mixer with an inclination angle of 15° and a rotation speed of 18-20 rpm. The temperature of the interface strengthener is 25±2°C, the spraying pressure is 0.2 MPa, and the water reducer is a polycarboxylic acid water reducer, and the usage amount is 0.1% of the weight of the recycled aggregate.

[0020] Furthermore, in step S3, the vibrating screen is a three-dimensional elliptical vibrating screen with a vibration frequency of 2000-2500 times / min. In the secondary coated aggregate, the coating thickness of the coarse recycled aggregate is 1.2-1.8 mm, and the coating thickness of the fine recycled aggregate is 0.1-0.3 mm. In step S4, the curing temperature is 20±1°C and the humidity is 95-98%.

[0021] An application of solid waste-based expansive recycled aggregate, wherein the recycled aggregate prepared by a solid waste-based expansive recycled aggregate coating method is used to improve the surface pore structure of the recycled aggregate, reduce water absorption, and enhance the working performance and mechanical properties of concrete.

[0022] The present invention has the following beneficial effects:

[0023] 1. The solid waste-based expansive recycled aggregate interface strengthener of the present invention is a slurry material constructed by a phosphogypsum-slag-carbide slag-silica powder system, with blast furnace slag powder and silica powder as the main hydration raw materials in the dry matrix powder. The silica fume non-crystalline phase in the silica fume is amorphous and spherical with a relatively smooth surface. After hydrolysis, the silane monomer bonds with the silica fume to form a hydrophobic organic silicon network, which reduces the water absorption rate of the aggregate and reduces the accumulation of moisture on the interface. The blast furnace slag powder forms a glassy structure under the quenching process. Its particles are usually spherical or nearly spherical with a smooth surface. Compared with silicate cement particles with irregular or multi-angular surfaces, it has The obvious lubrication effect and packing density advantages make it easier for the recycled aggregate surface loose structure to seep in compared with traditional cement-based materials. The low calcium composition of blast furnace slag powder makes it require less water. In addition, the phosphogypsum and carbide slag in the present invention have no independent hydration ability. Therefore, under the condition of maintaining the later mechanical properties of the matrix at the same water-cement ratio, the slurry system provided by the present invention has more outstanding fluidity, making the cementitious system of the present invention more suitable for the uniform seepage of the loose interface structure of the recycled aggregate, improving the surface density of the recycled aggregate, reducing the water absorption rate, and improving the slump of the concrete mixed with the recycled aggregate.

[0024] 2. The solid waste-based expansive recycled aggregate interface strengthener of the present invention comprises the following: phosphogypsum provides sulfate ions, and blast furnace slag powder provides a source of aluminate; the spherical particles thereof promote slurry seepage through a lubricating effect, while providing calcium ions to participate in the hydration reaction; the strong alkalinity of carbide slag can be adjusted to make the reaction system present an alkaline environment, thereby promoting the orderly arrangement of ettringite crystals, avoiding premature wrapping of unreacted particles by calcium silicate gel, achieving a reasonable volume expansion relative to the hydrated raw materials, and being able to form effective hydration product filling in the structural parts where the slurry has not penetrated, thereby reducing the water absorption rate and crushing index of the recycled aggregate and improving the compressive strength of the concrete material.

[0025] 3. The solid waste-based expansive recycled aggregate coating method of the present invention regenerates different concrete aggregates through two vibration coatings, promotes the interface strengthener to fully penetrate into the micro cracks of construction waste, and utilizes the hydration expansion of the interface strengthener to fully fill the cracks, thereby improving the interface filling effect. In addition, the interface strengthener is mostly industrial solid waste (phosphogypsum, blast furnace slag, carbide slag), which reduces the land occupation and heavy metal leakage risks caused by traditional landfill disposal. In addition, the performance of the treated recycled aggregate is significantly improved, which increases the reuse rate of construction waste. Compared with the traditional crushing process (breaking the surface mortar layer), which consumes a lot of energy, it reduces carbon emissions. DETAILED DESCRIPTION

[0026] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0027] In the present invention, the particle size of the phosphogypsum is 0.1-0.6 mm, the content of calcium sulfate dihydrate is ≥80%, the content of water-soluble phosphorus pentoxide is ≤0.30%, the content of water-soluble fluoride ions is ≤0.20%, and the content of chloride ions is ≤0.04%;

[0028] In the present invention, the particle size of the carbide slag is 0.1-0.6 mm, and the calcium hydroxide content is 70-85%;

[0029] In the present invention, the blast furnace slag powder is S95 grade slag powder with a specific surface area of ≥400m 2 / kg, the 7-day intensity activity index and the 28-day intensity activity index were greater than 70% and 95%, respectively;

[0030] In the present invention, the silica fume is selected from Kaiyuan Hairui Refractory Material Co., Ltd. and implements the quality standard GB / T27690-2011. The silica content is 92-96%, the loss on ignition is ≤6%, and the Cl content is ≤0.02%.

[0031] Example 1

[0032] This embodiment provides a method for preparing a solid waste-based expansive recycled aggregate interface strengthener, comprising the following steps:

[0033] A1. Preparation of silicon powder

[0034] Weigh: 10 g of ethyl orthosilicate and 300 mL of anhydrous ethanol are added to a reaction flask and mixed. The mixture is stirred at room temperature for 20 min. 70 g of silica ash is added to the reaction flask and stirred for 2 h. The temperature of the reaction flask is raised to 50° C. Low-boiling substances are evaporated under reduced pressure to obtain silicon powder.

[0035] A2. Preparation of interface strengthening agent

[0036] Weigh 42 parts by weight of phosphogypsum, 50 parts of blast furnace slag powder, 3 parts of silicon powder and 1.8 parts of calcium carbide slag and mix them evenly to obtain a dry matrix powder;

[0037] The dry matrix powder was added to a reaction flask and stirred. Then, drinking water in an amount 0.4 times the weight of the dry matrix powder was added to the reaction flask, stirred for 2 minutes, allowed to stand for 3 minutes to fully moisten the solid particles, and stirred. While stirring, drinking water was continued to be added until the viscosity reached 8000 cP. The pH of the reaction system was measured, and the pH of the system was adjusted to 12 to obtain an interfacial strengthener.

[0038] Example 2

[0039] This embodiment provides a method for preparing a solid waste-based expansive recycled aggregate interface strengthener, comprising the following steps:

[0040] A1. Preparation of silicon powder

[0041] Weigh: 15 g of methyl orthosilicate and 300 mL of anhydrous ethanol are added to a reaction flask and mixed. The mixture is stirred at room temperature for 25 min. 70 g of silica ash is added to the reaction flask and stirred for 2.5 h. The temperature of the reaction flask is raised to 55° C. Low-boiling substances are evaporated under reduced pressure to obtain silicon powder.

[0042] A2. Preparation of interface strengthening agent

[0043] Weigh 44.5 parts of phosphogypsum, 52.5 parts of blast furnace slag powder, 4 parts of silicon powder and 2.0 parts of calcium carbide slag and mix them evenly to obtain a dry matrix powder;

[0044] The dry matrix powder was added to a reaction flask and stirred. Then, drinking water in an amount 0.4 times the weight of the dry matrix powder was added to the reaction flask, stirred for 2.5 minutes, and allowed to stand for 4 minutes to fully moisten the solid particles. The mixture was stirred and continued to be added with drinking water until the viscosity reached 10,000 cP. The pH of the reaction system was measured, and the pH of the system was adjusted to 12.5 to obtain an interfacial enhancer.

[0045] Example 3

[0046] This embodiment provides a method for preparing a solid waste-based expansive recycled aggregate interface strengthener, comprising the following steps:

[0047] A1. Preparation of silicon powder

[0048] Weigh: 20 g of methyltriethoxysilane and 300 mL of anhydrous ethanol are added to a reaction flask and mixed. The mixture is stirred at room temperature for 30 min. 70 g of silica ash is added to the reaction flask and stirred for 3 h. The temperature of the reaction flask is raised to 60°C, and low-boiling substances are evaporated under reduced pressure to obtain silicon powder.

[0049] A2. Preparation of interface strengthening agent

[0050] Weigh 47 parts of phosphogypsum, 55 parts of blast furnace slag powder, 5 parts of silicon powder and 2.2 parts of calcium carbide slag and mix them evenly to obtain a dry matrix powder;

[0051] The dry matrix powder was added to a reaction flask and stirred. Then, drinking water in an amount 0.4 times the weight of the dry matrix powder was added to the reaction flask, stirred for 3 minutes, allowed to stand for 5 minutes to fully moisten the solid particles, and stirred. While stirring, drinking water was continued to be added until the viscosity reached 12000 cP. The pH of the reaction system was measured, and the pH of the system was adjusted to 13 to obtain an interfacial strengthener.

[0052] Example 4

[0053] This embodiment provides a method for coating solid waste-based expansive recycled aggregate, comprising the following steps:

[0054] Step 1: Sorting of construction waste

[0055] The construction waste is put into the crusher. After crushing, countercurrent air separation is used to remove light impurities, magnetic drum separation is used to remove metal impurities, and then a screen is used to screen it to obtain coarse recycled aggregate with a particle size of 10-20mm and fine recycled aggregate with a particle size of 5-10mm.

[0056] Step 2: Coating of coarse recycled aggregate

[0057] The coarse recycled aggregate was placed in an inclined biaxial mixer at an inclination angle of 15° and a rotation speed of 18 rpm and stirred for 30 seconds. The interface strengthener prepared in Example 1 was atomized at an atomization pressure of 0.2 MPa and then sprayed into the mixer. After spraying for 130 seconds, 0.1% polycarboxylate water reducer based on the weight of the coarse recycled aggregate was added to the mixer, stirred for 60 minutes, and discharged to obtain a primary coated coarse aggregate.

[0058] The primary coated coarse aggregate is added to a three-dimensional elliptical vibrating screen, the vibration frequency is set to 2000 times / min, and the interface strengthener is sprayed into the primary coated coarse aggregate in the form of atomized spraying. The coating is carried out until the coating thickness reaches 1.2 mm, and the material is discharged to obtain the secondary coated coarse aggregate.

[0059] Step 3: Fine recycled aggregate coating

[0060] The fine recycled aggregate was placed in an inclined biaxial mixer at an inclination angle of 15° and a rotation speed of 18 rpm and stirred for 30 seconds. The interface strengthener prepared in Example 1 was atomized at an atomization pressure of 0.2 MPa and then sprayed into the mixer. After spraying for 130 seconds, 0.1% polycarboxylate water reducer based on the weight of the coarse recycled aggregate was added to the mixer, stirred for 60 minutes, and discharged to obtain a primary coated fine aggregate.

[0061] The primary coated fine aggregate is added to a three-dimensional elliptical vibrating screen, the vibration frequency is set to 2000 times / min, and the interface strengthener is sprayed into the primary coated coarse aggregate in the form of atomized spraying. The coating is carried out until the coating thickness reaches 0.1 mm, and the material is discharged to obtain the secondary coated fine aggregate.

[0062] Step 4: Preparation of recycled aggregate

[0063] The secondary coated coarse aggregate and the secondary coated fine aggregate are mixed in a weight ratio of 4:9 and spread into a curing box. The temperature of the curing box is set to 20°C and the humidity is 95%. The curing box is cured for 14 days and then discharged to obtain recycled aggregate.

[0064] Example 5

[0065] This embodiment provides a method for coating solid waste-based expansive recycled aggregate, comprising the following steps:

[0066] Step 1: Sorting of construction waste

[0067] The construction waste is put into the crusher. After crushing, countercurrent air separation is used to remove light impurities, magnetic drum separation is used to remove metal impurities, and then a screen is used to screen it to obtain coarse recycled aggregate with a particle size of 10-20mm and fine recycled aggregate with a particle size of 5-10mm.

[0068] Step 2: Coating of coarse recycled aggregate

[0069] The coarse recycled aggregate was placed in an inclined biaxial mixer at an inclination angle of 15° and a rotation speed of 19 rpm and stirred for 40 seconds. The interface strengthener prepared in Example 2 was atomized at an atomization pressure of 0.2 MPa and then sprayed into the mixer. After spraying for 140 seconds, 0.1% polycarboxylate water-reducing agent based on the weight of the coarse recycled aggregate was added to the mixer, stirred for 70 minutes, and discharged to obtain a primary coated coarse aggregate.

[0070] The primary coated coarse aggregate is added to a three-dimensional elliptical vibrating screen, the vibration frequency is set to 2250 times / min, and the interface strengthener is sprayed into the primary coated coarse aggregate in the form of atomized spraying. The coating is carried out until the coating thickness reaches 1.5 mm, and the material is discharged to obtain the secondary coated coarse aggregate.

[0071] Step 3: Fine recycled aggregate coating

[0072] The fine recycled aggregate was placed in an inclined biaxial mixer at an inclination angle of 15° and a rotation speed of 19 rpm and stirred for 40 seconds. The interface strengthener prepared in Example 2 was atomized at an atomization pressure of 0.2 MPa and then sprayed into the mixer. After spraying for 140 seconds, 0.1% polycarboxylate water-reducing agent based on the weight of the coarse recycled aggregate was added to the mixer, stirred for 70 minutes, and discharged to obtain a primary coated fine aggregate.

[0073] The primary coated fine aggregate is added to a three-dimensional elliptical vibrating screen, the vibration frequency is set to 2250 times / min, and the interface strengthener is sprayed into the primary coated coarse aggregate in the form of atomized spraying. The coating is carried out until the coating thickness reaches 0.2 mm, and the material is discharged to obtain the secondary coated fine aggregate.

[0074] Step 4: Preparation of recycled aggregate

[0075] The secondary coated coarse aggregate and the secondary coated fine aggregate were mixed in a weight ratio of 5:9.5 and spread into a curing box. The temperature of the curing box was set at 20°C and the humidity was 97%. The curing was carried out for 14 days and the material was discharged to obtain recycled aggregate.

[0076] Example 6

[0077] This embodiment provides a method for coating solid waste-based expansive recycled aggregate, comprising the following steps:

[0078] Step 1: Sorting of construction waste

[0079] The construction waste is put into the crusher. After crushing, countercurrent air separation is used to remove light impurities, magnetic drum separation is used to remove metal impurities, and then a screen is used to screen it to obtain coarse recycled aggregate with a particle size of 10-20mm and fine recycled aggregate with a particle size of 5-10mm.

[0080] Step 2: Coating of coarse recycled aggregate

[0081] The coarse recycled aggregate was placed in an inclined biaxial mixer at an inclination angle of 15° and a rotation speed of 20 rpm and stirred for 50 seconds. The interface strengthener prepared in Example 3 was atomized at an atomization pressure of 0.2 MPa and then sprayed into the mixer. After spraying for 150 seconds, 0.1% polycarboxylate water reducer based on the weight of the coarse recycled aggregate was added to the mixer, stirred for 80 minutes, and discharged to obtain a primary coated coarse aggregate.

[0082] The primary coated coarse aggregate is added to a three-dimensional elliptical vibrating screen, the vibration frequency is set to 2500 times / min, and the interface strengthener is sprayed into the primary coated coarse aggregate in the form of atomized spraying. The coating is carried out until the coating thickness reaches 1.8 mm, and the material is discharged to obtain the secondary coated coarse aggregate.

[0083] Step 3: Fine recycled aggregate coating

[0084] The fine recycled aggregate was placed in an inclined biaxial mixer at an inclination angle of 15° and a rotation speed of 20 rpm and stirred for 50 seconds. The interface strengthener prepared in Example 3 was atomized at an atomization pressure of 0.2 MPa and then sprayed into the mixer. After spraying for 150 seconds, 0.1% polycarboxylate water-reducing agent based on the weight of the coarse recycled aggregate was added to the mixer, stirred for 80 minutes, and discharged to obtain a primary coated fine aggregate.

[0085] The primary coated fine aggregate is added to a three-dimensional elliptical vibrating screen, the vibration frequency is set to 2500 times / min, and the interface strengthener is sprayed into the primary coated coarse aggregate in the form of atomized spraying. The coating is carried out until the coating thickness reaches 0.3 mm, and the material is discharged to obtain the secondary coated fine aggregate.

[0086] Step 4: Preparation of recycled aggregate

[0087] The secondary coated coarse aggregate and the secondary coated fine aggregate were mixed in a weight ratio of 6:10 and spread into a curing box. The temperature of the curing box was set to 21°C and the humidity was 98%. The curing was carried out for 14 days and the material was discharged to obtain recycled aggregate.

[0088] Comparative Example 1

[0089] The difference between this comparative example and Example 6 is that, during the preparation of the interface strengthener used, the amount of phosphogypsum added is 65 parts.

[0090] Comparative Example 2

[0091] The difference between this comparative example and Example 6 is that, during the preparation of the interface strengthening agent used, silicate cement is used instead of blast furnace slag powder and silica fume.

[0092] Comparative Example 3

[0093] The difference between this comparative example and Example 6 is that, during the preparation of the interface strengthening agent, the silicon fume in step A1 replaces the silicon powder in step A2.

[0094] Comparative Example 4

[0095] The difference between this comparative example and Example 6 is that, in both step 2 and step 3, the secondary battering is eliminated, and the expected battering thickness is obtained directly with a single battering.

[0096] Performance testing:

[0097] The initial setting time and final setting time of the interface strengtheners used in Examples 4-6 and Comparative Examples 1-3 were measured with reference to the standard GB / T 1346-2011 "Test methods for water consumption, setting time and soundness of cement of standard consistency";

[0098] The crushing index of the recycled aggregates prepared in Examples 4-6 and Comparative Examples 1-4 was measured with reference to the standard GB / T 14685-2022 "Pebbles and crushed stones for construction";

[0099] Place the recycled aggregate in a blast drying oven at 45°C and dry it to constant weight. Record the weight as m1. Then place the dried recycled aggregate in a vacuum water retaining machine for 18 hours and record the weight as m2. According to the formula , testing the saturated water absorption of the recycled aggregates prepared in Examples 4-6 and Comparative Examples 1-4;

[0100] The specific test results are shown in Table 1 below.

[0101] Table 1 - Performance test data of recycled aggregate

[0102]

[0103] Data Analysis:

[0104] A comparative analysis of the data in Table 1 above shows that the initial setting time of the interface enhancer prepared by the present invention reaches 725 min, the final setting time reaches 890 min, the crushing index of the recycled aggregate reinforced by the interface enhancer coating reaches 11%, and the saturated water absorption rate is reduced to 3.5%. All performance test data are better than those of the comparative example, indicating that the present invention optimizes the composition of the interface enhancer to obtain an interface enhancer with a constant setting time and a coating method to perform interface reinforcement regeneration on the recycled aggregate, effectively improving the strength of the recycled aggregate and reducing the water absorption rate of the recycled aggregate.

[0105] The recycled aggregates prepared in Examples 4-6 and Comparative Examples 1-4 were used as fine aggregate to prepare C30 concrete samples, and the coarse recycled aggregate and fine recycled aggregate prepared in Step 1 of Example 6 were graded at a weight ratio of 6:10 to prepare C30 concrete, serving as a blank.

[0106] The slump of concrete samples prepared using recycled aggregate as fine aggregate prepared in Examples 4-6 and Comparative Examples 1-4 was measured with reference to the standard GB / T 50080-2016 "Standard for Test Methods of Performance of Ordinary Concrete Mixtures";

[0107] With reference to the specimen preparation and curing in the standard GB / T 50081-2019 "Standard for Test Methods for Physical and Mechanical Properties of Concrete", the concrete samples prepared using recycled aggregate as fine aggregate in Examples 4-6 and Comparative Examples 1-4 were prepared into 25 mm × 25 mm × 280 mm specimens, and the compressive strength of the test samples was measured after 3 days and 28 days of curing.

[0108] The specific test results are shown in Table 2 below.

[0109] Table 2 - Performance test data of C30 concrete samples prepared from recycled aggregate

[0110]

[0111] Data Analysis:

[0112] A comparative analysis of the data in Table 2 above shows that the slump of the C30 concrete sample prepared with recycled aggregate reaches 230 mm, the 3-day compressive strength reaches 35.1 MPa, and the 28-day compressive strength reaches 52.2 MPa. All performance test data are better than those of the comparative example and the blank example, indicating that the present invention optimizes the composition of the interface strengthener and the coating method to perform interface reinforcement on the recycled aggregate to prepare the recycled aggregate, and uses it to prepare C30 concrete, which not only effectively improves the fluidity, but also improves the compressive strength of the concrete sample.

[0113] The above contents are merely examples and explanations of the structure of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in a similar manner. As long as they do not deviate from the structure of the invention or exceed the scope defined by the claims, they shall fall within the scope of protection of the present invention.

[0114] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0115] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to specific embodiments. Obviously, many modifications and variations are possible based on the contents of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A solid waste-based expansive recycled aggregate interface strengthener, characterized in that: The solid waste-based expansive recycled aggregate interface enhancer is composed of dry matrix powder and water, and has a viscosity of 8000-12000 cP. The dry matrix powder includes the following components in parts by weight: 42-47 parts of phosphogypsum, 50-55 parts of blast furnace slag powder, 3-5 parts of silicon powder and 1.8-2.2 parts of calcium carbide slag, wherein the silicon powder is composed of silicon ash and siloxane monomer in a weight ratio of 7:1-2.

2. The solid waste-based expansive recycled aggregate interface strengthener according to claim 1, characterized in that: The particle sizes of the phosphogypsum and carbide slag are both 0.1-0.6 mm; the calcium hydroxide content of the carbide slag is 70-85%; and the blast furnace slag powder is S95 grade slag powder.

3. The solid waste-based expansive recycled aggregate interface strengthener according to claim 1, characterized in that: The preparation method of the silicon powder comprises: mixing and stirring a siloxane monomer and anhydrous ethanol to obtain a siloxane solution, then adding the silicon powder to the siloxane solution, stirring and mixing for 2-3 hours, raising the temperature of the reaction system to 50-60° C., and removing low-boiling substances by distillation under reduced pressure to obtain the silicon powder. The siloxane monomer comprises ethyl orthosilicate, methyl orthosilicate, triethoxysilane, and methyltriethoxysilane.

4. The solid waste-based expansive recycled aggregate interface strengthener according to claim 1, characterized in that: The preparation method of the interface enhancer comprises the following steps: adding drinking water to dry matrix powder, stirring for 2-3 minutes, and standing for 3-5 minutes to fully wet the solid particles; continuously adding drinking water while stirring until the viscosity reaches 8000-12000 cP; measuring the pH of the reaction system, and adjusting the pH to 12-13 to obtain the interface enhancer.

5. A method for coating solid waste-based expansive recycled aggregate, characterized in that: The solid waste-based expansive recycled aggregate interface strengthener according to any one of claims 1 to 4 is atomized to coat a slurry layer on the outside of the recycled aggregate.

6. The method for coating solid waste-based expansive recycled aggregate according to claim 5, characterized in that: The following steps are involved: S1. Crushing and screening construction solid waste to obtain recycled aggregates of different particle sizes; S2. The recycled aggregate is put into a mixer and stirred for 30-50 seconds. The interface strengthener is sprayed into the mixer in the form of atomized spraying. After spraying for 130-150 seconds, a water reducer is added to the mixer, stirred for 60-80 minutes, and discharged to obtain a primary coated aggregate; S3, adding the primary coated aggregate to a vibrating screen, spraying the interface strengthening agent thereon in the form of atomized spraying, coating the aggregate until the desired thickness is reached, and discharging the aggregate to obtain the secondary coated aggregate; S4. Curing the secondary coated aggregate for 14 days to obtain recycled aggregate.

7. The method for coating solid waste-based expansive recycled aggregate according to claim 6, characterized in that: In step S1, the preparation method of recycled aggregate is as follows: construction waste is placed in a crusher, and after crushing, countercurrent air separation is used to remove light impurities, magnetic drum separation is used to remove metal impurities, and then a screen is used to screen it to obtain coarse recycled aggregate with a particle size of 10-20 mm and fine recycled aggregate with a particle size of 5-10 mm.

8. The method for coating solid waste-based expansive recycled aggregate according to claim 6, characterized in that: In step S2, the mixer is an inclined twin-shaft mixer with an inclination angle of 15° and a rotation speed of 18-20 rpm. The temperature of the interface strengthener is 25±2°C, the spraying pressure is 0.2 MPa, and the water reducer is a polycarboxylate water reducer, and the usage amount is 0.1% of the weight of the recycled aggregate.

9. The method for coating solid waste-based expansive recycled aggregate according to claim 6, characterized in that: In step S3, the vibrating screen is a three-dimensional elliptical vibrating screen with a vibration frequency of 2000-2500 times / min. In the secondary coated aggregate, the coating thickness of the coarse recycled aggregate is 1.2-1.8 mm, and the coating thickness of the fine recycled aggregate is 0.1-0.3 mm. In step S4, the curing temperature is 20±1°C and the humidity is 95-98%.

10. An application of solid waste-based expansive recycled aggregate, characterized in that: The recycled aggregate prepared by the solid waste-based expansive recycled aggregate coating method as described in any one of claims 5 to 9 is used to improve the surface pore structure of the recycled aggregate, reduce water absorption, and improve the working performance and mechanical properties of concrete.

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