Coupling coarse aggregate as well as preparation method and application thereof

Abstract

The invention relates to the technical field of building materials, in particular to a coupling coarse aggregate and a preparation method and application thereof.The coupling coarse aggregate takes waste tempered glass particles with the particle size of 5-40 mm as an inner core, the inner core is coated with a red mud-based cementing material layer with the thickness of 1-5 mm, and the coating layer is composed of, by weight, 70-80 parts of red mud, 10-15 parts of fly ash and 5-20 parts of cement. The preparation method comprises the following steps: crushing and screening waste toughened glass, preparing red-mud-based gel slurry, coating the surfaces of glass particles with the red-mud-based gel slurry in a dip-coating or roll-coating manner, and carrying out standard curing for 28 days to obtain the coupling coarse aggregate. The aggregate can replace natural coarse aggregate to prepare large-dosage red mud-based concrete, wherein a cementing material comprises red mud, mineral powder, ardealite and cement. According to the invention, the alkali-silicon reaction is effectively blocked through the core-shell structure, and the aggregate-matrix interface performance is improved, so that the concrete has high compressive strength, excellent durability and low expansion rate, meanwhile, the synergistic resource utilization of bulk solid wastes of the red mud and the waste toughened glass is realized, and the concrete has remarkable environmental protection and economic benefits.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, and in particular to a coupled coarse aggregate, its preparation method and application, specifically to a coupled coarse aggregate with waste tempered glass as the core and red mud-based cementitious material as the coating layer, its preparation method, and the application of the coupled coarse aggregate in high-volume red mud-based concrete. Background Technology

[0002] Concrete, as the most important building material, consumes a large amount of natural sand and gravel aggregate in its production. In recent years, with the continuous development of infrastructure construction, natural aggregate resources have become increasingly scarce, and the mining process has also caused serious damage to the ecological environment. Therefore, finding and developing recycled materials to replace natural aggregates has become an urgent need for the sustainable development of the industry.

[0003] Waste tempered glass and red mud are two typical and difficult-to-treat industrial solid wastes. Waste tempered glass has high strength and stable chemical properties, but its smooth surface results in poor adhesion to cement paste, and the amorphous silica it contains easily undergoes an alkali-silicon reaction (ASR) in the alkaline environment of concrete, leading to concrete expansion and cracking, severely restricting its large-scale application. On the other hand, red mud is a large amount of strongly alkaline waste residue generated during alumina production, with large global stockpiles and low utilization rates. Its potential pollution risks to soil and water bodies have become a serious environmental problem. Although some studies have attempted to use red mud in building materials, its high alkalinity and low cementitious activity limit the amount that can be added, making large-scale disposal difficult.

[0004] Furthermore, phosphogypsum is a byproduct of wet-process phosphoric acid production, and its storage also occupies land and poses environmental risks. How to co-treat phosphogypsum with other solid wastes such as red mud and waste glass to achieve high-value-added resource utilization of multi-source solid waste is a current technological challenge.

[0005] Current technologies for utilizing these solid wastes mostly involve single or simple mixtures, failing to fundamentally address the application bottlenecks caused by the inherent defects of the materials themselves. For example, directly replacing some natural aggregates with crushed waste glass fails to effectively solve the alkali-silica reaction problem; partially replacing cement raw materials with red mud is limited in dosage due to its limited activity, typically not exceeding 30%, and its improvement on concrete performance is not significant. These traditional methods all have obvious drawbacks: the former faces durability issues caused by the alkali-silica reaction, limiting the dosage and application scope of waste glass; the latter has limited capacity for red mud utilization, failing to achieve large-scale resource utilization of red mud.

[0006] Therefore, developing new technologies and materials that can synergistically utilize multiple solid wastes and effectively overcome their respective application obstacles is of great practical significance. Summary of the Invention

[0007] The primary objective of this invention is to provide a core-shell structured coupled coarse aggregate, which uses waste tempered glass as the core and red mud-based cementitious material as the coating layer, aiming to simultaneously address the ASR risk of glass aggregate and realize the high-value utilization of red mud.

[0008] The second objective of this invention is to provide a method for preparing the above-mentioned coupled coarse aggregate, which is simple in process, low in cost, and easy to industrialize.

[0009] The third objective of this invention is to provide a high-volume red mud-based concrete, which uses the aforementioned coupled coarse aggregate as a skeleton and innovatively adopts a composite cementitious system containing red mud, mineral powder, phosphogypsum and cement to achieve high-volume synergistic utilization of multi-source solid waste.

[0010] The fourth objective of this invention is to provide a method for preparing the above-mentioned high-volume red mud-based concrete.

[0011] The fifth objective of this invention is to utilize coupled coarse aggregate as a substitute for natural coarse aggregate in the preparation of concrete products.

[0012] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a coupled coarse aggregate having a unique "core-shell" structure: a hard core of tempered glass particles, which is surrounded by a dense coating layer formed by the solidification of a red mud-based cementitious material. The red mud-based cementitious material coating layer is composed of three components: red mud, fly ash, and cement.

[0013] Preferably, the particle size of the tempered glass particles is controlled within the range of 5-40 mm to meet the gradation requirements of coarse aggregate in concrete. The thickness of the red mud-based cementitious material coating layer is controlled within the range of 1-5 mm. This thickness range ensures the formation of an effective physical isolation layer without excessively increasing the total weight and volume of the aggregate.

[0014] Preferably, the red mud-based cementitious material coating layer comprises, by mass, 70-80 parts red mud, 10-15 parts fly ash, and 5-20 parts cement. This proportion fully utilizes the red mud, while the synergistic effect of fly ash and cement ensures the workability of the coating layer slurry and its strength after curing.

[0015] Secondly, the present invention provides a method for preparing the above-mentioned coupled coarse aggregate, comprising the following steps: S1. Tempered glass processing: Collect waste tempered glass, crush it, and then screen it through screening equipment (such as a shaking screen) to separate tempered glass particles with a particle size in the range of 5-40mm, and remove impurities.

[0016] S2. Preparation of Red Mud-Based Cementitious Paste: Accurately weigh each dry powder component according to the mass ratio of 70-80 parts red mud, 10-15 parts fly ash, and 5-20 parts cement, and put them into a cement paste mixer. Then add an appropriate amount of water, controlling the water-cement ratio between 0.35 and 0.45, and start the mixer to stir for 2-3 minutes until a uniform red mud-based cementitious paste is formed.

[0017] S3. Coating and molding: Using a dip-coating or roller-coating device, the red mud-based gel slurry obtained in step S2 is uniformly coated onto the surface of the tempered glass particles prepared in step S1 to form a wet coating layer, and the thickness of the coating layer is controlled to be 1-5 mm.

[0018] S4. Curing and solidification: The particles coated with wet slurry are transferred to a standard curing room for curing. During this period, the red mud-based cementitious material is fully hydrated and hardened to form a dense and hard coating layer, and finally the coupled coarse aggregate is obtained.

[0019] Preferably, the standard maintenance conditions are a temperature of 20±2℃ and a relative humidity of ≥95%.

[0020] Preferably, the waste tempered glass comes from at least one of waste architectural curtain wall glass, door and window glass, automotive glass, or household appliance glass.

[0021] Thirdly, this invention provides a high-volume red mud-based concrete, which uses the aforementioned coupled coarse aggregate as the sole coarse aggregate, combined with specific cementitious materials, manufactured sand, water, and a water-reducing agent. The key difference lies in the fact that the cementitious material system is not a traditional cement-dominated system, but rather a composite of red mud, mineral powder, phosphogypsum powder, and cement. This cementitious system allows for the further high-volume utilization of red mud.

[0022] Preferably, the mineral powder is granulated blast furnace slag powder, grade S95; the phosphogypsum powder is obtained by crushing and ball milling undisturbed phosphogypsum and then screening it through a 200-mesh sieve; the manufactured sand is used as fine aggregate with a particle size of 1.60-4.75 mm.

[0023] Preferably, the mineral powder is granulated blast furnace slag powder; the phosphogypsum powder is obtained by crushing and ball milling undisturbed phosphogypsum and then screening it through a 200-mesh sieve.

[0024] Fourthly, the present invention provides a method for preparing the above-mentioned high-volume red mud-based concrete, comprising the following steps: T1. Weigh the raw materials according to the following proportions: 50-70 parts red mud, 10-15 parts mineral powder, 5-20 parts phosphogypsum, 10-15 parts cement, 300-400 parts coarse aggregate, 200-300 parts manufactured sand, 35-55 parts water, and 0.5-2 parts water-reducing agent; all parts are by weight.

[0025] T2. Clean the mixing device: Before mixing, clean the mixing device to prevent impurities from getting in.

[0026] T3. Add all the powdered materials (red mud, mineral powder, phosphogypsum, cement) weighed in step T1 and all the aggregates (coupling coarse aggregate and manufactured sand) into the mixer and dry mix until they are evenly mixed.

[0027] T4. Add water pre-dissolved with water-reducing agent to the dry mix, then wet mix and continue stirring until the concrete mixture reaches a homogeneous state.

[0028] T5. Pour the well-mixed concrete mixture into the test mold or engineering mold, and then use a vibrating table or other vibration equipment to compact it to remove air bubbles and ensure that the concrete is dense.

[0029] T6. After casting, allow the specimen to stand at room temperature for 24 hours (1 day) before demolding. Immediately after demolding, transfer the specimen or component to a standard curing room (temperature 20±2℃, relative humidity ≥95%) and cure for 28 days.

[0030] Fifthly, the present invention provides a specific application of the above-mentioned coupled coarse aggregate in the field of building materials, namely, to replace traditional coarse aggregates such as natural crushed stone and pebbles in the preparation of various concrete products or structural components.

[0031] Compared with the prior art, the present invention has the following significant advantages: (1) High-efficiency synergistic utilization of multi-source solid waste: This invention innovatively integrates three major industrial solid wastes, namely waste tempered glass, red mud, and phosphogypsum, into a single material system. The coarse aggregate utilizes glass and red mud, while the concrete cementitious material system simultaneously utilizes red mud and phosphogypsum in large quantities, achieving "full utilization" of solid waste resources and extremely high resource utilization efficiency.

[0032] (2) Fundamentally suppress alkali-silicon reaction: The coarse aggregate is coated with red mud-based cementitious material to form a dense physical isolation between the glass core and the external alkaline solution, which effectively prevents the direct contact between the glass core and the external alkaline solution, so that the alkali-silicon reaction expansion rate of concrete is stably controlled at an extremely low level of ≤0.05%, which is far below the safety limit of 0.10%.

[0033] (3) Optimizing the microstructure of concrete and improving its overall performance: The tempered glass core provides high-strength support, and the hydration products of the red mud-phosphogypsum-mineral powder-cement composite cementitious system are dense, resulting in a 28-day compressive strength of 51-58 MPa for the concrete, fully meeting the requirements of high-strength concrete. The red mud-based coating provides a rough outer surface for the aggregate, significantly improving the mechanical interlocking between the aggregate and the cement paste. Microstructure analysis shows that the interface transition zone is denser, reducing the generation and development of microcracks, thereby improving the overall performance and durability of the concrete. This results in excellent freeze-thaw resistance of the concrete, with the relative dynamic modulus of elasticity remaining above 90% after 300 freeze-thaw cycles. The hydration process of the composite cementitious system promotes each other, resulting in low shrinkage, and the introduction of phosphogypsum also helps to regulate setting time and improve early strength.

[0034] (4) Win-win for both environment and economy: It has replaced a large amount of natural aggregates and cement, reducing production costs. At the same time, it has found a large-scale and high-value disposal method for a variety of difficult-to-treat solid wastes, which is in line with the economic development concept of green, low-carbon and circular economy. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0036] Figure 1 This is a schematic diagram of the structure of the coupled coarse aggregate provided by the present invention; Figure 2 This is a flowchart of the method for preparing coupled coarse aggregate provided by the present invention; Figure 3 This is a flowchart illustrating the preparation method of high-volume red mud-based concrete provided by the present invention. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0038] Example 1 Combination Figures 1 to 3As shown, this embodiment provides a coupled coarse aggregate and its preparation method, as well as a method for preparing high-volume red mud-based concrete. The coupled coarse aggregate is prepared from tempered glass particles and red mud-based cementitious materials. Specifically, the tempered glass particles serve as the core, and the red mud-based cementitious materials encapsulate the core of the tempered glass particles to form a coating layer. The coating layer is composed of red mud, fly ash, and cement.

[0039] I. Preparation of Coupled Coarse Aggregate: S1. Tempered glass treatment: Tempered glass from abandoned building curtain walls is selected and initially crushed using a jaw crusher. The crushed glass fragments are then sieved using a ZS-100 standard vibrating screen to precisely select glass particles with a particle size distribution between 5mm and 20mm as the core raw material. Impurities such as metal and plastic are manually removed, and dust adhering to the surface of the glass particles is rinsed with clean water before being dried for later use.

[0040] S2, Preparation of Red Mud-Based Cementitious Paste Accurately weigh the following dry powder raw materials according to weight: 70 parts of red mud powder dried to constant weight at 105℃, 10 parts of fly ash, and 20 parts of ordinary Portland cement. Pour the weighed powders together into a cement paste mixer. Start the mixer, add water at low speed, and control the water-cement ratio at 0.35. Then switch to high speed and continue mixing for 2-3 minutes until a red mud-based cement paste with uniform color and suitable fluidity is obtained.

[0041] S3, Overmolding: The pretreated tempered glass granules are fed into a small laboratory roller coating machine. The roller is started and rotated slowly. The red mud-based gel slurry prepared in step S2 is slowly and evenly poured onto the surface of the rolling glass granules. By controlling the roller speed and feeding rate, it is ensured that the surface of each glass granule is completely coated with the slurry, and the average thickness of the formed wet coating layer is controlled at approximately 1 mm. The granule surface is observed to ensure uniform coating and no bare glass.

[0042] S4. Curing and hardening: Carefully transfer the coated wet granules into a plastic tray, spreading them out in a single layer to avoid sticking. Then place the entire tray in a standard curing chamber, setting the conditions to a temperature of 20±2℃ and a relative humidity of ≥95% for 28 consecutive days. After curing, remove the granules; the red mud-based coating layer will be fully cured and firmly bonded to the glass core, resulting in coupled coarse aggregate.

[0043] The performance of the coupled coarse aggregate prepared above was tested, and the results are recorded in Table 1.

[0044] Table 1 Performance indicators of the coupled coarse aggregate prepared in Example 1 II. High-volume red mud-based concrete T1. Raw material weighing: According to the design proportions, accurately weigh the following raw materials (by weight): A. Cementitious materials: 50 parts of red mud dried to constant weight at 105℃, 10 parts of mineral powder (S95 grade granulated blast furnace slag powder), 20 parts of phosphogypsum powder (raw phosphogypsum crushed, ball-milled and passed through a 200-mesh sieve), and 10 parts of ordinary silicate cement. B. Aggregate: 300 parts of coupled coarse aggregate and 200 parts of manufactured sand were prepared in this embodiment.

[0045] C. Other components: 55 parts water, 0.5 parts polycarboxylate superplasticizer.

[0046] T2. Preparation for mixing: Clean the inner wall and blades of the HJW-60 single-shaft forced concrete mixer to ensure there are no residues.

[0047] T3, Dry Mixing: Pour all the weighed powder materials (red mud, mineral powder, phosphogypsum, cement) and all the aggregates (coupling coarse aggregate, manufactured sand) into the mixer. Cover the mixer, start it, and dry mix for 2 minutes to ensure that all solid components are evenly mixed.

[0048] T4, Wet Mixing: Dissolve the water-reducing agent in water beforehand. While the mixer is running, slowly and evenly pour the water-reducing agent solution into the mixing pot. Continue mixing for 3 minutes until the concrete mixture reaches a good working state with uniform color, no standing water, and no lumps.

[0049] T5. Molding and Vibration Compaction: Pour the mixed concrete mixture into the test mold, fix the test mold on the GZ-85 type concrete vibrating table and vibrate for 2 seconds. Use a trowel to scrape off the excess mixture and smooth the surface.

[0050] T6. Demolding and Curing: After molding, the specimens were left to stand at room temperature (approximately 20°C) for 24 hours before being carefully demolded. The demolded specimens were then immediately placed in a standard curing room (temperature 20±2°C, relative humidity ≥95%) and cured continuously for 28 days.

[0051] Various performance tests were conducted on the concrete prepared in this embodiment, and the results are recorded in Table 2.

[0052] Table 2 Performance indicators of high-volume red mud-based concrete prepared in Example 1 Example 2: This embodiment provides a method for preparing coupled coarse aggregate and its preparation, as well as a method for preparing high-volume red mud-based concrete. Details are as follows: I. Preparation of Coupled Coarse Aggregate: S1. Tempered glass processing: Select waste automotive side window tempered glass and process it in the same way as in Example 1. Screen the glass to obtain glass particles with a particle size mainly concentrated between 20mm and 30mm, wash and dry them for later use.

[0053] S2. Preparation of red mud-based cementitious slurry: Accurately weigh out: 80 parts red mud, 12 parts fly ash, and 10 parts ordinary Portland cement. Add them to a cement paste mixer, control the water-cement ratio at 0.40, and mix at high speed for 2-3 minutes to obtain red mud-based cementitious paste.

[0054] S3. Coating and molding: Using a roller coating process similar to that in Example 1, the red mud-based gel slurry is coated onto the surface of the glass particles, and the average thickness of the wet coating layer is controlled to be about 3 mm.

[0055] S4. Curing and solidification: Under the same conditions as in Example 1, standard curing was performed for 28 days to obtain coupled coarse aggregate. The performance test results are shown in Table 3.

[0056] Table 3 Performance indicators of the coupled coarse aggregate prepared in Example 2 II. High-volume red mud-based concrete T1. Raw material weighing (parts by mass): A. Cementitious materials: 65 parts of red mud dried to constant weight at 105℃, 15 parts of mineral powder (S95 grade granulated blast furnace slag powder), 10 parts of phosphogypsum powder (raw phosphogypsum crushed, ball-milled and passed through a 200-mesh sieve), and 12 parts of ordinary silicate cement. B. Aggregates: 350 parts of coupled coarse aggregate and 300 parts of manufactured sand were prepared in this embodiment.

[0057] C. Other components: 40 parts water, 1 part polycarboxylate superplasticizer.

[0058] T2-T6, mixing, molding and curing: The process flow and parameters are the same as in Example 1, and will not be repeated here. The performance test results of the prepared concrete are shown in Table 4.

[0059] Table 4 Performance indicators of high-volume red mud-based concrete prepared in Example 2 Example 3: This embodiment provides a method for preparing coupled coarse aggregate and its preparation, as well as a method for preparing high-volume red mud-based concrete. Details are as follows: I. Preparation of Coupled Coarse Aggregate: S1. Tempered glass processing: Select tempered glass from discarded household appliances (such as microwave oven doors), and process it in the same way as in Example 1. Screen the glass to obtain glass particles with a particle size mainly concentrated between 30mm and 40mm, then wash and dry them for later use.

[0060] S2. Preparation of red mud-based cementitious slurry: Accurately weigh out: 75 parts red mud, 15 parts fly ash, and 5 parts ordinary Portland cement. Add them to a cement paste mixer, control the water-cement ratio at 0.45, and mix at high speed for 2-3 minutes to obtain red mud-based cementitious paste.

[0061] S3. Coating and molding: A roller coating process is used to coat the surface of the glass particles with red mud-based cementitious slurry, and the average thickness of the wet coating layer is controlled to be about 5mm.

[0062] S4. Curing and solidification: Under the same conditions as in Example 1, standard curing was performed for 28 days to obtain coupled coarse aggregate. The performance test results are shown in Table 5.

[0063] Table 5 Performance indicators of the coupled coarse aggregate prepared in Example 3 II. High-volume red mud-based concrete T1. Raw material weighing (parts by mass): A. Cementitious materials: 70 parts of red mud dried to constant weight at 105℃, 12 parts of mineral powder (S95 grade granulated blast furnace slag powder), 5 parts of phosphogypsum powder (raw phosphogypsum crushed, ball-milled and passed through a 200-mesh sieve), and 15 parts of ordinary silicate cement. B. Aggregate: 400 parts of coupled coarse aggregate and 250 parts of manufactured sand were prepared in this embodiment.

[0064] C. Other components: 35 parts water, 2 parts polycarboxylate superplasticizer.

[0065] T2-T6, mixing, molding and curing: The process flow and parameters are the same as in Example 1, and will not be repeated here. The performance test results of the prepared concrete are shown in Table 6.

[0066] Table 6 Performance indicators of high-volume red mud-based concrete prepared in Example 3 Comparative Example 1 (Concrete made entirely of waste glass aggregate): To compare the advantages of the present invention, Comparative Example 1 was set up. No coupling aggregate was prepared. Uncoated waste tempered glass particles of the same source and particle size as in Example 1 were used directly as coarse aggregate (300 parts). The cementitious material system was exactly the same as in Example 1 (50 parts red mud, 10 parts mineral powder, 20 parts phosphogypsum, 10 parts cement). The dosage of manufactured sand, water, water-reducing agent and preparation process were consistent with those in Example 1.

[0067] Test results showed that the 28-day compressive strength of the comparative concrete was only 35.0 MPa, and the 14-day expansion rate of the alkali-silica rapid reaction method was as high as 0.12%, exceeding the safety limit of 0.10%. After 300 freeze-thaw cycles, its relative dynamic modulus of elasticity decreased to 70%, and visible microcracks appeared on the surface of the specimen. This indicates that directly using waste glass aggregate poses serious ASR risks and durability problems.

[0068] Comparative Example 2 (Pure Red Mud-Based Artificial Aggregate Concrete): Comparative Example 2 was set up. A pure red mud-based artificial aggregate was prepared without a glass core. That is, only red mud, fly ash, and cement (with the same proportions as the aggregate coating layer in Example 1: 70 parts red mud, 10 parts fly ash, 20 parts cement, water-cement ratio 0.35) were used to prepare neat paste particles of similar size, which were then cured and used as coarse aggregate (300 parts). The cementitious material system, fine aggregate, water, water-reducing agent dosage, and preparation process of the concrete remained consistent with Example 1.

[0069] Test results showed that the 28-day compressive strength of the comparative concrete was 32.0 MPa. The pure red mud-based artificial aggregate itself had poor properties, with a cylinder compressive strength of only 18 MPa, a water absorption rate as high as 12%, and a particle breakage rate reaching 20% ​​in the crushing index test. This resulted in lower concrete strength and compromised durability.

[0070] Performance comparison analysis and conclusions: The key performance characteristics of the three embodiments of the present invention are compared with those of the two comparative examples, as shown in Table 7.

[0071] Table 7 Comparison of concrete performance between the embodiments of the present invention and the comparative examples Through a thorough comparison of the above embodiments and comparative examples, the following conclusions can be drawn: This invention successfully prepared coupled coarse aggregate with a "core-shell" structure, and used it as the core to prepare high-volume red mud-based concrete.

[0072] Compared with the direct use of waste glass aggregate (Comparative Example 1), the present invention effectively inhibits the alkali-silicon reaction through the red mud-based coating layer, and the expansion rate is far below the safety threshold. At the same time, the strength and durability (freeze-thaw resistance) of the concrete are greatly improved.

[0073] Compared with the use of pure red mud-based artificial aggregate (Comparative Example 2), the present invention introduces a composite structure formed by a high-strength glass core, which significantly enhances the mechanical properties of the aggregate itself (compressive strength, crush resistance), thereby improving the overall strength of concrete and reducing the water absorption rate of the aggregate.

[0074] The concrete in all three embodiments of this invention exhibits excellent comprehensive performance, with a 28-day compressive strength in the range of 51-58 MPa, meeting the requirements for strength grades of C50 and above. The key durability indicators (alkali-silica reaction expansion rate and freeze-thaw resistance) are all superior to the standard requirements, fully demonstrating the reliability, effectiveness, and wide applicability of the technology of this invention (covering the endpoint and intermediate values ​​within the mix proportion range).

[0075] In summary, this invention provides an innovative pathway for the resource utilization of solid waste. The resulting coupled coarse aggregate and its concrete not only exhibit excellent performance but also demonstrate significant environmental benefits and have promising application prospects.

[0076] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A coupling coarse aggregate, characterized by, The core is formed by tempered glass particles, and the cladding layer is formed by bauxite-based cementitious material which is wrapped outside the core and is composed of bauxite, fly ash and cement.

2. The coupled coarse aggregate of claim 1, wherein, The particle size of the tempered glass particles is 5-40 mm, and the thickness of the bauxite-based cementitious material cladding layer is 1-5 mm.

3. The coupled coarse aggregate of claim 1, wherein, In the bauxite-based cementitious material cladding layer, the components are as follows in terms of mass fraction: bauxite 70-80 parts, fly ash 10-15 parts, and cement 5-20 parts.

4. A method of producing a coupled coarse aggregate according to any one of claims 1 to 3, characterized in that, The method comprises the following steps: S1, tempered glass treatment: waste tempered glass is crushed and sieved to obtain tempered glass particles with a particle size of 5-40 mm; S2, bauxite-based cementitious slurry preparation: bauxite 70-80 parts, fly ash 10-15 parts, and cement 5-20 parts are weighed and added into a cement paste mixer, and after water is added, stirring is carried out for 2-3 minutes, and the water-binder ratio is 0.35-0.45, so as to prepare a bauxite-based cementitious slurry; S3, cladding forming: a dipping or rolling device is used to uniformly coat the bauxite-based cementitious slurry prepared in step S2 on the surface of the tempered glass particles prepared in step S1 to form a wet cladding layer, and the thickness of the cladding layer is controlled to be 1-5 mm; S4, curing and solidification: the coated particles are cured under standard curing conditions for 28 days to form dense and hard coupled coarse aggregate.

5. The preparation method according to claim 4, characterized in that, The standard curing conditions are a temperature of 20±2℃ and a relative humidity of ≥95%.

6. The preparation method according to claim 4, characterized in that, The waste tempered glass is at least one of waste building curtain wall glass, door and window glass, automobile glass or household appliance glass.

7. A high volume red mud based concrete characterised in that: The coupled coarse aggregate is prepared by using the coupled coarse aggregate according to any one of claims 1-3, cementitious material, machine-made sand, water and water reducing agent.

8. The high volume red mud based concrete as claimed in claim 6, wherein: The mineral powder is granulated blast furnace slag powder, and the phosphogypsum powder is obtained by crushing and ball milling raw phosphogypsum and then sieving through a 200-mesh sieve.

9. A method of producing a high volume red mud based concrete as claimed in any one of claims 7-8, characterised in that, The method comprises the following steps: T1, the components are weighed according to the proportion: bauxite 50-70 parts, mineral powder 10-15 parts, phosphogypsum 5-20 parts, cement 10-15 parts, coupled coarse aggregate 300-400 parts, machine-made sand 200-300 parts, water 35-55 parts, and water reducing agent 0.5-2 parts; T2, cleaning the stirring device; T3, the bauxite, mineral powder, phosphogypsum, cement, coupled coarse aggregate and machine-made sand weighed in step T1 are added into the stirring device and stirred uniformly; T4, water and water reducing agent are added, and stirring is carried out again until the mixture is uniform; T5, the uniformly stirred concrete is poured into a mold, and a vibrating table is used for vibration to ensure compactness; T6, demolding after 1 day, and curing under standard curing conditions for 28 days, wherein the standard curing conditions are a temperature of 20±2℃ and a relative humidity of ≥95%.

10. Use of the coupled coarse aggregate according to any one of claims 1 to 3 in construction materials, characterized in that, The coupled coarse aggregate is used to replace natural coarse aggregate to prepare a concrete product.

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