A tailings concrete and its preparation and use in the preparation of 3D printed components

Abstract

The present application relates to the technical field of new building materials, and particularly relates to tailing concrete and preparation and application thereof in preparation of 3D printing components.The tailing concrete comprises cement: 100-120 parts;diatom ooze: 5-20 parts;recycled coarse aggregate: 120-180 parts;recycled fine aggregate: 80-120 parts;fiber: 6-10 parts;silica fume: 15-20 parts;expansive agent: 4-8 parts;water reducing agent: 0.4-1.2 parts;and water: 40-60 parts.The present application not only improves the resource utilization of tailing solid waste, but also reduces the usage amount of cement and natural sandstone, reduces the production cost of concrete, and has obvious economic and environmental benefits;the tailing concrete of the present application further comprises diatom ooze, the porosity of which can be as high as 95%, and the present application finds that when the diatom ooze content is appropriate, the adsorption performance and carbon loading capacity of the concrete can be improved.

Description

Technical Field

[0001] This invention relates to the field of new building materials technology, and in particular to a tailings concrete, its preparation and its application in the preparation of 3D printed components. Background Technology

[0002] With the rapid development of the global economy and the advancement of industrialization, mining and infrastructure construction have generated a large amount of industrial solid waste, such as tailings (an industrial solid waste generated after ore extraction and processing, containing abundant metallic and non-metallic minerals). Currently, tailings have become the solid waste with the largest output and the lowest comprehensive utilization rate. Therefore, the development and utilization of tailings is not only an important task of the circular economy of mining, but also of great significance to the sustainable development of resources.

[0003] Some researchers have applied tailings to the preparation of concrete, which has achieved the rational utilization of tailings resources. However, how to further improve the mechanical properties and durability of concrete on this basis remains a major problem to be solved. Summary of the Invention

[0004] To address the aforementioned problems, the present invention aims to provide tailings concrete, its preparation, and its application in the fabrication of 3D printed components. The tailings concrete of the present invention comprises: cement: 100-120 parts; diatomaceous earth: 5-20 parts; recycled coarse aggregate: 120-180 parts; recycled fine aggregate: 80-120 parts; fiber: 6-10 parts; silica fume: 15-20 parts; expansion agent: 4-8 parts; water-reducing agent: 0.4-1.2 parts; and water: 40-60 parts. This invention not only improves the resource utilization of tailings solid waste but also reduces the amount of cement and natural sand and gravel used, lowering concrete production costs and demonstrating significant economic and environmental benefits. The tailings concrete of the present invention also contains diatomaceous earth, whose porosity can reach up to 95%. The present invention has found that when the amount of diatomaceous earth is appropriate, it can improve the adsorption performance and carbon loading capacity of the concrete.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] The first object of the present invention is to provide tailings concrete, comprising the following components in parts by weight:

[0007] Cement: 100-120 parts; Diatomaceous earth: 5-20 parts; Recycled coarse aggregate: 120-180 parts; Recycled fine aggregate: 80-120 parts; Fiber: 6-10 parts; Silica fume: 15-20 parts; Expansion agent: 4-8 parts; Water-reducing agent: 0.4-1.2 parts; Water: 40-60 parts.

[0008] When the amount of diatomaceous earth is too small, the significant reduction in pore structure will significantly decrease the carbonization rate of 3D printed components, resulting in poor carbon fixation effect. When the amount of diatomaceous earth is too large, although excessive diatomaceous earth can increase the carbonization speed of 3D printed components, since diatomaceous earth is not an auxiliary cementing material, its presence will reduce the mechanical properties and durability of 3D printed components.

[0009] Furthermore, the tailings concrete comprises the following components in parts by weight:

[0010] Cement: 100-115 parts; Diatomaceous earth: 12-18 parts; Recycled coarse aggregate: 140-160 parts; Recycled fine aggregate: 100-110 parts; Fiber: 7-9 parts; Silica fume: 16-19 parts; Expansion agent: 6-7 parts; Water-reducing agent: 0.7-1.1 parts; Water: 45-55 parts.

[0011] Furthermore, tailings concrete comprises the following components in parts by weight:

[0012] Cement: 105 parts; Diatomaceous earth: 15 parts; Recycled coarse aggregate: 150 parts; Recycled fine aggregate: 105 parts; Fiber: 8 parts; Silica fume: 19 parts; Expansion agent: 7 parts; Water-reducing agent: 1.0 part; Water: 45 parts.

[0013] In one embodiment of the present invention, the cement is tailings silicate cement;

[0014] The active oxide content (SiO2+Al2O3+Fe2O3) in the tailings silicate cement is ≥95%, and the average particle size is ≤5μm.

[0015] In one embodiment of the present invention, the recycled coarse aggregate and recycled fine aggregate are pretreated mine tailings waste.

[0016] In one embodiment of the present invention, the particle size of the recycled coarse aggregate adopts a continuous gradation of 5mm-10mm:10mm-16mm = 4:6.

[0017] In one embodiment of the present invention, the recycled fine aggregate has a particle size range of 1-5 mm and a fineness modulus of 2.68.

[0018] In one embodiment of the present invention, the fiber is composed of steel fiber, polypropylene fiber and basalt fiber, and the mass ratio of steel fiber, polypropylene fiber and basalt fiber is 2:2:1.

[0019] In one embodiment of the present invention, the steel fiber is a copper-plated straight steel fiber with a length of 12 mm and a diameter of 1 mm; the polypropylene fiber has a length of 12-16 mm, and the basalt fiber has a length of 16-18 mm.

[0020] In one embodiment of the present invention, the average particle size of the silica fume is 0.08-0.4 μm, and the specific surface area is 20-100 m². 2 / g.

[0021] In one embodiment of the present invention, the expanding agent is a UEA expanding agent;

[0022] The water-reducing agent is a polycarboxylate high-efficiency water-reducing agent with a solid content of 20-40%.

[0023] In this invention, the incorporation of UEA expansive agent promotes the formation of needle-like ettringite in the system, generating a slight expansion effect, which in turn compensates for the shrinkage of the material. As the content of UEA expansive agent increases, the shrinkage compensation effect becomes more significant, thereby effectively improving the crack resistance of concrete.

[0024] In one embodiment of the present invention, the water is tap water with a pH of 7.5.

[0025] A second objective of this invention is to provide a method for preparing tailings concrete, comprising the following steps:

[0026] (S1) Mix cement, diatomaceous earth, natural coarse aggregate, recycled coarse aggregate, recycled fine aggregate and silica fume to obtain a first mixture;

[0027] (S2) Add water to the first mixture obtained in step (S1) and mix well to obtain the second mixture;

[0028] (S3) Add the expansion agent and water-reducing agent to the second mixture prepared in step (S2) and mix well to obtain tailings concrete.

[0029] In one embodiment of the present invention, the cement is prepared by the following method:

[0030] (A1) Mix tailings, limestone and gypsum, then add water and stir to obtain a mixture;

[0031] (A2) The mixture obtained in step (A1) is granulated and then processed to obtain cement particles;

[0032] (A3) The cement particles prepared in step (A2) are calcined and cooled to obtain pretreated cement;

[0033] (A4) The pretreated cement obtained from the grinding step (A3) is used to obtain tailings silicate cement;

[0034] The mass ratio of tailings, limestone and gypsum is 2:2:1.

[0035] In one embodiment of the present invention, the recycled coarse aggregate and recycled fine aggregate are prepared by the following method:

[0036] The solid waste from mine tailings is crushed, screened, and washed in sequence, then placed in a Ca(OH)2 solution, stirred thoroughly, and dried to obtain recycled coarse aggregate (particle size 5mm-16mm) and recycled fine aggregate (particle size 1mm-5mm).

[0037] The stirring time is 12-24h, which allows the Ca(OH)2 solution to fully coat the surface of the tailings aggregate particles and completely fill the pores inside the tailings aggregate particles.

[0038] A third objective of this invention is to provide an application of tailings concrete in the preparation of 3D printed components.

[0039] In this invention, diatomaceous earth has a porous structure with a porosity of up to 95% and contains a large number of mesoporous structures. When the amount of diatomaceous earth added is appropriate, the presence of mesoporous structures can provide a larger pore size than micropores, improving the adsorption performance of concrete. This allows the diatomaceous earth to better adsorb carbon dioxide, thereby improving its carbon loading capacity. Furthermore, when preparing 3D printed components, these mesoporous structures can expand the surface area of ​​the material and increase the carbon fixation effect of the 3D printed components.

[0040] When the amount of diatomaceous earth is too low, the significant reduction in pore structure will significantly decrease the carbonization rate of 3D printed components, resulting in poor carbon fixation effect. When the amount of diatomaceous earth is too high, although excessive diatomaceous earth can increase the carbonization speed of 3D printed components, since diatomaceous earth is not an auxiliary cementing material, its presence will reduce the mechanical properties and durability of 3D printed components.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] (1) This invention prepares tailings silicate cement by mixing tailings slag with active oxides as the main component with cement clinker, and partially replaces natural aggregates with tailings coarse aggregates. This not only improves the resource utilization of tailings solid waste, but also reduces the amount of cement and natural sand and gravel used, thereby reducing the production cost of concrete and having significant economic and environmental benefits.

[0043] (2) This invention employs techniques such as chemical activation, heat treatment, and mechanical grinding to increase the lattice distortion of active oxides and other components in tailings or to generate active substances through reactions, thereby activating the pozzolanic effect of tailings. After activation treatment, tailings can be used as an auxiliary cementitious material in the preparation of concrete. By promoting the hydration of tailings silicate cement to generate CSH cementitious substances and promoting the secondary hydration reaction of the aluminate phase of tailings silicate cement, the pore structure of concrete is improved and its crack resistance is enhanced.

[0044] (3) By converting tailings aggregate into recycled aggregate, the pores and cracks in the tailings can provide channels for CO2 infiltration and transport. Simultaneously, utilizing the high specific surface area of ​​the tailings coarse aggregate, the unhydrated tailings silicate cement, calcium hydroxide, and hydrated calcium silicate gel in the aggregate undergo a carbonation reaction. When carbon dioxide in the air reacts with alkaline substances on the aggregate surface, carbonates are generated. This reaction is even faster and more efficient due to the high specific surface area of ​​the unhydrated tailings silicate cement. The formation of carbonates fills the gaps, fissures, and surface pores in the aggregate, resulting in a smooth outer surface of the 3D printed component and increasing interlayer bonding. This carbonized 3D printed concrete exhibits superior mechanical properties and crack resistance. Furthermore, the formation of the carbonate protective layer fills the micropores and gaps on the surface of the unhydrated tailings particles, improving the aggregate density. This density enhances the impermeability and durability of the 3D printed component.

[0045] (4) In this invention, diatomaceous earth has a porous structure with a porosity of up to 95% and contains a large number of mesoporous structures. When the amount of diatomaceous earth is appropriate, the presence of mesoporous structures can provide a larger pore size than micropores, improving the adsorption performance of concrete. This allows diatomaceous earth to better adsorb carbon dioxide, thereby improving its carbon loading capacity. Furthermore, when preparing 3D printed components, these mesoporous structures can expand the surface area of ​​the material and increase the carbon fixation effect of the 3D printed components. Detailed Implementation

[0046] This invention provides tailings concrete, comprising the following components in parts by weight:

[0047] Cement: 100-120 parts; Diatomaceous earth: 5-20 parts; Recycled coarse aggregate: 120-180 parts; Recycled fine aggregate: 80-120 parts; Fiber: 6-10 parts; Silica fume: 15-20 parts; Expansion agent: 4-8 parts; Water-reducing agent: 0.4-1.2 parts; Water: 40-60 parts.

[0048] Furthermore, the tailings concrete comprises the following components in parts by weight:

[0049] Cement: 100-115 parts; Diatomaceous earth: 12-18 parts; Recycled coarse aggregate: 140-160 parts; Recycled fine aggregate: 100-110 parts; Fiber: 7-9 parts; Silica fume: 16-19 parts; Expansion agent: 6-7 parts; Water-reducing agent: 0.7-1.1 parts; Water: 45-55 parts.

[0050] Furthermore, tailings concrete comprises the following components in parts by weight:

[0051] Cement: 105 parts; Diatomaceous earth: 15 parts; Recycled coarse aggregate: 150 parts; Recycled fine aggregate: 105 parts; Fiber: 8 parts; Silica fume: 19 parts; Expansion agent: 7 parts; Water-reducing agent: 1.0 part; Water: 45 parts.

[0052] In one embodiment of the present invention, the cement is tailings silicate cement;

[0053] The active oxide content (SiO2+Al2O3+Fe2O3) in the tailings silicate cement is ≥95%, and the average particle size is ≤5μm.

[0054] In one embodiment of the present invention, the recycled coarse aggregate and recycled fine aggregate are pretreated mine tailings waste.

[0055] In one embodiment of the present invention, the particle size of the recycled coarse aggregate adopts a continuous gradation of 5mm-10mm:10mm-16mm = 4:6.

[0056] In one embodiment of the present invention, the recycled fine aggregate has a particle size range of 1-5 mm and a fineness modulus of 2.68.

[0057] In one embodiment of the present invention, the fiber is composed of steel fiber, polypropylene fiber and basalt fiber, and the mass ratio of steel fiber, polypropylene fiber and basalt fiber is 2:2:1.

[0058] In one embodiment of the present invention, the steel fiber is a copper-plated straight steel fiber with a length of 12 mm and a diameter of 1 mm; the polypropylene fiber has a length of 12-16 mm, and the basalt fiber has a length of 16-18 mm.

[0059] In one embodiment of the present invention, the average particle size of the silica fume is 0.08-0.4 μm, and the specific surface area is 20-100 m². 2 / g.

[0060] In one embodiment of the present invention, the expanding agent is a UEA expanding agent;

[0061] The water-reducing agent is a polycarboxylate high-efficiency water-reducing agent with a solid content of 20-40%.

[0062] In this invention, the incorporation of UEA expansive agent promotes the formation of needle-like ettringite in the system, generating a slight expansion effect, which in turn compensates for the shrinkage of the material. As the content of UEA expansive agent increases, the shrinkage compensation effect becomes more significant, thereby effectively improving the crack resistance of concrete.

[0063] In one embodiment of the present invention, the water is tap water with a pH of 7.5.

[0064] This invention provides a method for preparing tailings concrete, comprising the following steps:

[0065] (S1) Mix cement, diatomaceous earth, natural coarse aggregate, recycled coarse aggregate, recycled fine aggregate and silica fume to obtain a first mixture;

[0066] (S2) Add water to the first mixture obtained in step (S1) and mix well to obtain the second mixture;

[0067] (S3) Add the expansion agent and water-reducing agent to the second mixture prepared in step (S2) and mix well to obtain tailings concrete.

[0068] In one embodiment of the present invention, the cement is prepared by the following method:

[0069] (A1) Mix tailings, limestone and gypsum, then add water and stir to obtain a mixture;

[0070] (A2) The mixture obtained in step (A1) is granulated and then processed to obtain cement particles;

[0071] (A3) The cement particles prepared in step (A2) are calcined and cooled to obtain pretreated cement;

[0072] (A4) The pretreated cement obtained from the grinding step (A3) is used to obtain tailings silicate cement;

[0073] The mass ratio of tailings, limestone and gypsum is 2:2:1.

[0074] In one embodiment of the present invention, the recycled coarse aggregate and recycled fine aggregate are prepared by the following method:

[0075] The solid waste from mine tailings is crushed, screened, and washed in sequence, then placed in a Ca(OH)2 solution, stirred thoroughly, and dried to obtain recycled coarse aggregate (particle size 5mm-16mm) and recycled fine aggregate (particle size 1mm-5mm).

[0076] The stirring time is 12-24h, which allows the Ca(OH)2 solution to fully coat the surface of the tailings aggregate particles and completely fill the pores inside the tailings aggregate particles.

[0077] This invention provides an application of tailings concrete in the preparation of 3D printed components.

[0078] The present invention will now be described in detail with reference to specific embodiments.

[0079] Unless otherwise specified, all reagents used in the following embodiments are commercially available reagents, and all detection methods and techniques used are conventional detection methods and techniques in the art.

[0080] Example 1

[0081] This embodiment provides a tailings silicate cement and its preparation method, specifically including the following steps:

[0082] (A1) Mix tailings, limestone and gypsum in a mass ratio of 2:2:1 (total weight 6kg), add water and stir to obtain a mixture;

[0083] (A2) The mixture obtained in step (A1) is fed into a disc granulator to prepare particles with a particle size of 1-2 mm, and then dried at 100°C to constant weight to obtain cement particles.

[0084] (A3) Add the cement particles prepared in step (A2) into a high-temperature incineration resistance furnace and heat them from room temperature to 1500°C at a heating rate of 8°C / min. Calcinate them at 1500°C for 60 min and then cool them to room temperature within 5 min to obtain pretreated cement.

[0085] (A4) Grind the pretreated cement obtained in step (A3) using a planetary ball mill (100 rpm, 1 h) to obtain tailings silicate cement.

[0086] In this embodiment, the active oxide content (SiO2+Al2O3+Fe2O3) in the tailings silicate cement is 96.48%, and the average particle size is 2.36μm.

[0087] Example 2

[0088] This embodiment provides a recycled coarse aggregate and its preparation method, specifically including the following steps:

[0089] The mine tailings solid waste was crushed in a drum crusher, and then the crushed particles with a particle size of 5mm-16mm were screened. After washing with water, the particles were placed in a Ca(OH)2 solution with a solid-liquid ratio of 0.2g / ml and stirred for 24h. After drying at 100℃, recycled coarse aggregate with a particle size of 5mm-16mm and a fineness modulus of 2.68 was obtained.

[0090] Comparative Example 1

[0091] Compared with Example 2, this comparative example was not subjected to stirring in a Ca(OH)2 solution with a solid-liquid ratio of 0.2 g / ml.

[0092] Example 3

[0093] This embodiment provides a recycled fine aggregate and its preparation method, specifically including the following steps:

[0094] The solid waste of mine tailings is crushed in a drum crusher, and then the crushed particles with a particle size of 1mm-5mm are screened out. After washing with water, the particles are placed in a Ca(OH)2 solution with a solid-liquid ratio of 0.2g / ml and stirred for 24h. After drying at 100℃, recycled fine aggregate with a particle size of 1mm-5mm is obtained.

[0095] Comparative Example 1

[0096] Compared with Example 3, this comparative example was not subjected to stirring in a Ca(OH)2 solution with a solid-liquid ratio of 0.2 g / ml.

[0097] Example 4

[0098] This embodiment provides tailings concrete, comprising the following components in parts by weight:

[0099] Cement: 105 parts; Diatomaceous earth: 15 parts; Recycled coarse aggregate: 150 parts; Recycled fine aggregate: 105 parts; Fiber: 8 parts; Silica fume: 19 parts; Expansion agent: 7 parts; Water-reducing agent: 1.0 part; Water: 45 parts;

[0100] The cement used was the tailings silicate cement prepared in Example 1; the recycled coarse aggregate was the recycled coarse aggregate prepared in Example 2, with a continuous gradation of (5mm-10mm):(10mm-16mm) = 4:6 (based on the theory of close packing of aggregates, concrete with a continuous gradation of 5mm-10mm and 10mm-16mm can form a uniform particle distribution, resulting in no obvious gaps between particles, thereby improving the compactness and strength of the concrete and reducing the risk of shrinkage and cracking); the recycled fine aggregate was the recycled fine aggregate prepared in Example 3; the fibers were steel fibers (12mm long, 1mm diameter copper-plated straight steel fibers), polypropylene fibers (14mm long), and basalt fibers (16mm long) with a mass ratio of 2:2:1; the average particle size of silica fume was 0.2μm, and the specific surface area was 56.37m². 2 / g; the expanding agent is UEA expanding agent; the water reducing agent is polycarboxylate high-efficiency water reducing agent with a solid content of 30%; and the water is tap water.

[0101] The preparation process specifically includes the following steps:

[0102] (S1) Place cement, diatomaceous earth, natural coarse aggregate, recycled coarse aggregate, recycled fine aggregate and silica fume in a mixer and mix them evenly (mixing speed is 100 rpm, mixing time is 4 min) to obtain the first mixture;

[0103] (S2) Add water to the first mixture obtained in step (S1) and continue to stir and mix (stirring speed is 100 rpm, stirring time is 4 min) to obtain the second mixture;

[0104] (S3) Add the expansion agent and water-reducing agent to the second mixture prepared in step (S2), and continue to stir and mix (stirring speed is 100 rpm, stirring time is 4 min) to obtain tailings concrete.

[0105] Example 5

[0106] The difference between this embodiment and Embodiment 4 is that the tailings concrete in this embodiment includes the following components in parts by weight:

[0107] Cement: 110 parts; Diatomaceous earth: 18 parts; Recycled coarse aggregate: 140 parts; Recycled fine aggregate: 110 parts; Fiber: 7 parts; Silica fume: 19 parts; Expansion agent: 6 parts; Water-reducing agent: 1.1 parts; Water: 45 parts.

[0108] Example 6

[0109] The difference between this embodiment and Embodiment 4 is that the tailings concrete in this embodiment includes the following components in parts by weight:

[0110] Cement: 115 parts; Diatomaceous earth: 12 parts; Recycled coarse aggregate: 160 parts; Recycled fine aggregate: 100 parts; Fiber: 9 parts; Silica fume: 16 parts; Expansion agent: 7 parts; Water-reducing agent: 0.7 parts; Water: 55 parts.

[0111] Example 7

[0112] The difference between this embodiment and Embodiment 4 is that the tailings concrete in this embodiment includes the following components in parts by weight:

[0113] Cement: 112 parts; Diatomaceous earth: 16 parts; Recycled coarse aggregate: 145 parts; Recycled fine aggregate: 108 parts; Fiber: 8 parts; Silica fume: 18 parts; Expansion agent: 6 parts; Water-reducing agent: 0.9 parts; Water: 50 parts.

[0114] Example 8

[0115] The difference between this embodiment and Embodiment 4 is that the tailings concrete in this embodiment includes the following components in parts by weight:

[0116] Cement: 100 parts; Diatomaceous earth: 20 parts; Recycled coarse aggregate: 120 parts; Recycled fine aggregate: 120 parts; Fiber: 6 parts; Silica fume: 20 parts; Expansion agent: 4 parts; Water-reducing agent: 1.2 parts; Water: 40 parts.

[0117] Example 9

[0118] The difference between this embodiment and Embodiment 4 is that the tailings concrete in this embodiment includes the following components in parts by weight:

[0119] Cement: 120 parts; Diatomaceous earth: 5 parts; Recycled coarse aggregate: 180 parts; Recycled fine aggregate: 80 parts; Fiber: 10 parts; Silica fume: 15 parts; Expansion agent: 8 parts; Water-reducing agent: 0.4 parts; Water: 60 parts.

[0120] Example 10

[0121] The difference between this embodiment and Embodiment 4 is that the tailings concrete in this embodiment includes the following components in parts by weight:

[0122] Cement: 110 parts; Diatomaceous earth: 10 parts; Recycled coarse aggregate: 130 parts; Recycled fine aggregate: 115 parts; Fiber: 8 parts; Silica fume: 18 parts; Expansion agent: 5 parts; Water-reducing agent: 0.6 parts; Water: 50 parts.

[0123] Comparative Example 3

[0124] The difference between this comparative example and Example 4 is that this comparative example does not use diatomaceous earth.

[0125] Comparative Example 4

[0126] The difference between this comparative example and Example 4 is that the tailings concrete in this comparative example comprises the following components in parts by weight:

[0127] Cement: 130 parts; Diatomaceous earth: 3 parts; Recycled coarse aggregate: 190 parts; Recycled fine aggregate: 70 parts; Fiber: 12 parts; Silica fume: 10 parts; Expansion agent: 10 parts; Water-reducing agent: 0.1 parts; Water: 70 parts.

[0128] Comparative Example 5

[0129] The difference between this comparative example and Example 4 is that the tailings concrete in this comparative example comprises the following components in parts by weight:

[0130] Cement: 90 parts; Diatomaceous earth: 25 parts; Recycled coarse aggregate: 110 parts; Recycled fine aggregate: 130 parts; Fiber: 5 parts; Silica fume: 25 parts; Expansion agent: 3 parts; Water-reducing agent: 1.5 parts; Water: 30 parts.

[0131] Comparative Example 6

[0132] The difference between this comparative example and Example 4 is that the recycled coarse aggregate in this comparative example is the recycled coarse aggregate prepared in Comparative Example 1.

[0133] Comparative Example 7

[0134] The difference between this comparative example and Example 4 is that the recycled fine aggregate in this comparative example is the recycled fine aggregate prepared in Comparative Example 1.

[0135] Example 11

[0136] This embodiment provides a 3D printed component and its preparation method, specifically including the following steps:

[0137] In this embodiment, 3D printed components were prepared using tailings concrete obtained in Example 4. The components were cut using a fully automatic infrared stone cutting machine, and then further polished using a double-end grinding machine. X / Y / Z directions were marked on the surface of the specimens. The loading direction for mechanical properties and crack resistance was the Z-direction. The strength value in each loading direction was determined by calculating the average strength of three specimens. Detailed preparation methods are described in the following literature: Liu Huawai, Liu Chao, Bai Guoliang, et al. Experimental study on mechanical properties of 3D printed coarse aggregate concrete based on pore structure defects [J]. Journal of Civil Engineering, 2022, 55(12):11.

[0138] Example 12

[0139] The difference between this embodiment and embodiment 11 is that this embodiment uses the tailings concrete prepared in embodiment 5 to prepare 3D printed components.

[0140] Example 13

[0141] The difference between this embodiment and embodiment 11 is that this embodiment uses the tailings concrete prepared in embodiment 6 to prepare 3D printed components.

[0142] Example 14

[0143] The difference between this embodiment and embodiment 11 is that this embodiment uses the tailings concrete prepared in embodiment 7 to prepare 3D printed components.

[0144] Example 15

[0145] The difference between this embodiment and embodiment 11 is that this embodiment uses the tailings concrete prepared in embodiment 8 to prepare 3D printed components.

[0146] Example 16

[0147] The difference between this embodiment and embodiment 11 is that this embodiment uses the tailings concrete prepared in embodiment 9 to prepare 3D printed components.

[0148] Example 17

[0149] The difference between this embodiment and embodiment 11 is that this embodiment uses the tailings concrete prepared in embodiment 10 to prepare 3D printed components.

[0150] Comparative Example 8

[0151] The difference between this embodiment and embodiment 11 is that this embodiment uses the tailings concrete prepared in Comparative Example 3 to prepare 3D printed components.

[0152] Comparative Example 9

[0153] The difference between this embodiment and embodiment 11 is that this embodiment uses the tailings concrete prepared in Comparative Example 4 to prepare 3D printed components.

[0154] Comparative Example 10

[0155] The difference between this embodiment and embodiment 11 is that this embodiment uses the tailings concrete prepared in Comparative Example 5 to prepare 3D printed components.

[0156] Comparative Example 11

[0157] The difference between this embodiment and embodiment 9 is that this embodiment uses the tailings concrete prepared in comparative example 6 to prepare 3D printed components.

[0158] Comparative Example 12

[0159] The difference between this embodiment and embodiment 11 is that this embodiment uses the tailings concrete prepared in Comparative Example 7 to prepare 3D printed components.

[0160] Performance testing:

[0161] 1) The mechanical properties were tested according to the method specified in GB / T 50081-2019, and the results are shown in Table 1;

[0162] 2) The crack resistance test was conducted according to the method specified in GB / T 50082-2009, and the results are shown in Table 1;

[0163] 3) Carbon adsorption test (results are shown in Table 1): The concrete specimen and the 3D-printed specimen were placed in a sealed space filled with carbon dioxide for 48 hours. The carbon adsorption parameter η was obtained by measuring the initial and final concentrations of carbon dioxide. The calculation formula is as follows:

[0164]

[0165] Among them, C 初始浓度 C represents the carbon dioxide content in a confined space at 0h, i.e., the initial concentration of CO2; 最终浓度This represents the carbon dioxide content in a confined space over 48 hours, i.e., the final concentration of CO2.

[0166] Table 1. Performance summary of Examples 4-17 and Comparative Examples 3-12

[0167]

[0168]

[0169]

[0170] As shown in Table 1, the tailings concrete of the present invention not only improves the resource utilization of tailings solid waste, but also reduces the amount of cement and natural sand and gravel used, thereby reducing the production cost of concrete and having significant economic and environmental benefits. It can also effectively improve the strength and durability of concrete, improve its crack resistance, and enhance its carbon fixation capacity. When the proportion of tailings concrete is 105 parts cement, 15 parts diatomaceous earth, 150 parts recycled coarse aggregate, 105 parts recycled fine aggregate, 8 parts fiber, 19 parts silica fume, 7 parts expansion agent, 1.0 part water-reducing agent, and 45 parts water, the synergy among the components is the best, and its mechanical properties, crack resistance, and carbon fixation capacity are the strongest.

[0171] Furthermore, compared to concrete specimens, 3D-printed components have a significantly larger specific surface area, which greatly enhances their carbon adsorption performance. Specifically, concrete specimens are made through casting in molds, resulting in a smooth surface and a relatively small specific surface area; while 3D-printed components are created through layer-by-layer deposition, resulting in numerous micropores and gaps on their surface. This increases the specific surface area of ​​the 3D-printed component, and the micropores and gaps provide more carbon adsorption sites, thus enhancing its carbon adsorption capacity.

[0172] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the interpretation of the present invention, without departing from the scope of the invention, should be within the protection scope of the present invention.

Claims

1. A tailings concrete, characterized in that, The components include the following parts by weight: Cement: 100-120 parts; Diatomaceous earth: 5-20 parts; Recycled coarse aggregate: 120-180 parts; Recycled fine aggregate: 80-120 parts; Fiber: 6-10 parts; Silica fume: 15-20 parts; Expanding agent: 4-8 parts; Water-reducing agent: 0.4-1.2 parts; Water: 40-60 parts; Wherein, the cement is tailings silicate cement; the recycled coarse aggregate and recycled fine aggregate are pretreated mine tailings waste; the expansive agent is UEA expansive agent; the particle size of the recycled coarse aggregate adopts a continuous gradation of 5mm-10mm:10mm-16mm=4:6; the particle size range of the recycled fine aggregate is 1-5mm, and the fineness modulus is 2.68; The cement is prepared by the following method: (A1) After mixing tailings slag, limestone and gypsum, water is added and stirred to obtain a mixture; the mass ratio of tailings, limestone and gypsum is 2:2:1; (A2) The mixture prepared in step (A1) is granulated and then processed to obtain cement particles; (A3) The cement particles prepared in step (A2) are calcined and cooled to obtain pretreated cement; (A4) The pretreated cement obtained in the grinding step (A3) is used to obtain tailings silicate cement; The recycled coarse aggregate and recycled fine aggregate are prepared by the following method: The solid waste from mine tailings is crushed, screened, and washed in sequence, then placed in a Ca(OH)2 solution, stirred for 12-24 hours, and dried to obtain recycled coarse aggregate and recycled fine aggregate.

2. The tailings concrete according to claim 1, characterized in that, The active oxide content in the tailings silicate cement is ≥95%, and the average particle size is ≤5μm.

3. The tailings concrete according to claim 1, characterized in that, The fiber is composed of steel fiber, polypropylene fiber and basalt fiber, with a mass ratio of 2:2:

1.

4. The tailings concrete according to claim 1, characterized in that, The average particle size of silica fume is 0.08-0.4 μm, and the specific surface area is 20-100 m². 2 / g.

5. The tailings concrete according to claim 1, characterized in that, The water-reducing agent is a polycarboxylate high-efficiency water-reducing agent with a solid content of 20-40%.

6. The application of tailings concrete as described in any one of claims 1-5 in the preparation of 3D printed components.

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