Preparation process of yellow river superfine sand 3D printing concrete material

Abstract

The application discloses a preparation process of a Yellow River superfine sand 3D printing concrete material, and comprises the following steps: (1) microcrystalline glass fine aggregate is immersed in a sodium silicate or potassium solution, dried, and pretreated fine aggregate is obtained; (2) heating seafoam powder and the pretreated fine aggregate dispersed in water, and modified fine aggregate a is obtained after completion; (3) mixing the modified fine aggregate a with liquid phase obtained through solid-liquid separation to form a mixture, then carbonizing the mixture in a carbon dioxide atmosphere, and heating the mixture to decompose silicic acid into silicon dioxide, and modified fine aggregate b is obtained; (4) taking silicate cement, the modified fine aggregate b, Yellow River superfine sand, silica fume, a water reducing agent and fibers as raw materials, mixing the raw materials, adding mixing water and stirring the mixture to obtain a 3D printing concrete material. The process not only relieves the bleeding phenomenon caused by the Yellow River superfine sand, but also makes the prepared concrete have good extrusion performance and the characteristics of keeping the shape stable after printing.

Description

Technical Field

[0001] This invention relates to the field of 3D printed concrete technology, specifically to a preparation process for 3D printed concrete material made from Yellow River ultrafine sand. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Traditional methods of constructing concrete structures require the assembly and dismantling of formwork and the pouring of concrete, necessitating significant manpower and resources, resulting in long construction cycles, heavy labor, and high costs. 3D printed concrete, on the other hand, is a rapid prototyping technology that uses digital models to create concrete structures layer by layer. It offers advantages such as convenience, efficiency, and the elimination of molds, significantly reducing labor costs, shortening construction cycles, and eliminating the production costs of formwork. Furthermore, because 3D printed concrete can operate 24 / 7, it significantly improves production efficiency.

[0004] 3D-printed concrete requires a large amount of fine aggregate to ensure the strength and performance of the printed concrete structure. This fine aggregate is typically natural river sand, but with the large-scale exploitation of this non-renewable resource, the production of high-quality natural river sand is struggling to meet the ever-increasing demand, leading to continuous price increases. Yellow River ultrafine sand is a type of sand with a fineness modulus of less than 0.6, as fine as flour, while the Yellow River carries an average of 1.6 billion tons of sediment annually. Therefore, utilizing Yellow River ultrafine sand not only helps reduce siltation but also helps alleviate the supply-demand imbalance of natural river sand. However, when Yellow River ultrafine sand is directly used to prepare concrete, bleeding occurs, making the printed concrete structure prone to deformation and even collapse. Summary of the Invention

[0005] This invention provides a process for preparing 3D printed concrete material using ultrafine sand from the Yellow River. This process not only alleviates the bleeding phenomenon caused by the ultrafine sand, but also enables the prepared concrete to exhibit good extrusion performance and shape stability after printing. Specifically, the technical solution of this invention is as follows.

[0006] A preparation process for 3D printed concrete material made from Yellow River ultrafine sand includes the following steps:

[0007] (1) The microcrystalline glass fine aggregate is immersed in sodium silicate or potassium silicate solution and heated and kept warm for surface treatment. After the solid-liquid separation is completed, the obtained solid product is dried to obtain the pretreated fine aggregate.

[0008] (2) After dispersing the sepiolite powder and the pretreated fine aggregate into water, stir and heat to react. After the reaction is completed, separate the fine aggregate to obtain modified fine aggregate a.

[0009] (3) The modified fine aggregate a is mixed with the liquid phase obtained from the solid-liquid separation in step (1) to form a mixture. Then the mixture is placed in a carbon dioxide atmosphere for carbonization treatment. After completion, it is heated to decompose the silicic acid in it into silicon dioxide, thus obtaining the modified fine aggregate b.

[0010] (4) Using silicate cement, the modified fine aggregate b, Yellow River ultrafine sand, silica fume, water-reducing agent and fiber as raw materials, mix them and add mixing water to stir evenly to obtain the 3D printed concrete material.

[0011] Further, in step (1), the ratio of the microcrystalline glass aggregate to the sodium silicate or potassium silicate solution is 1g:5~20ml. Optionally, the mass fraction of the sodium silicate or potassium silicate solution is 2~4%.

[0012] Further, in step (1), the heating and heat preservation temperature is 60~80℃, and the time is 2~3 hours. Optionally, the particle size of the microcrystalline glass fine aggregate is 1~3mm.

[0013] Furthermore, in step (1), the drying temperature is 50~80℃ and the time is 40~60min.

[0014] Further, in step (2), the sepiolite powder accounts for 22-30% of the mass of the pretreated fine aggregate. Optionally, the fineness of the sepiolite powder is 70-100 mesh.

[0015] Furthermore, in step (2), the ratio of the total amount of sepiolite powder and pretreated fine aggregate to water is 1g:25~40ml.

[0016] Furthermore, in step (2), the heating reaction is carried out at a temperature of 50-60°C for 6-8 hours.

[0017] Further, in step (3), the ratio of the modified fine aggregate a to the liquid phase is 1g:1.5~3ml.

[0018] Furthermore, in step (3), the carbonization process takes 1.5 to 2 hours.

[0019] Furthermore, in step (3), the temperature of the heat treatment is 180~250℃ and the time is 1~2 hours.

[0020] Further, in step (4), the proportions of each component in the raw material are as follows: silicate cement: modified fine aggregate b: silica fume: water-reducing agent: fiber = 70~105 parts by weight: 150~200 parts by weight: 10~17 parts by weight: 1.1~2 parts by weight: 5~8 parts by weight. The Yellow River ultrafine sand is 15~20% of the modified fine aggregate b content, and the water-cement ratio is 0.38~0.42.

[0021] Further, in step (4), the water-reducing agent includes any one of polycarboxylate water-reducing agents, lignin sulfonate water-reducing agents, naphthalene-based water-reducing agents, aliphatic water-reducing agents, etc.

[0022] Further, in step (4), the fiber includes at least one of polyethylene fiber, polypropylene fiber, polyvinyl alcohol fiber, basalt fiber, carbon fiber, etc. Optionally, the length of the fiber is 3~10mm.

[0023] Compared with the prior art, the present invention has at least the following beneficial technical effects:

[0024] This invention uses microcrystalline glass as fine aggregate. After surface treatment with sodium silicate or potassium silicate solution, the Si-O-Si and Si-O-Al structures in the silicon-oxygen tetrahedron and aluminum-oxygen tetrahedron structures on the microcrystalline glass surface undergo depolymerization and breakage, converting them into -Al(OH)2 and -Si(OH)3, thus forming a modified surface for the microcrystalline glass fine aggregate. Then, this invention reacts the microcrystalline glass fine aggregate with sepiolite powder in water under heating. During this process, the hydroxyl groups (-OH) on the sepiolite undergo a dehydration condensation reaction with the -Al(OH)2 and -Si(OH)3 on the surface of the microcrystalline glass fine aggregate to form Si-O and Al-O bonds, thereby loading the sepiolite powder onto the surface of the microcrystalline glass fine aggregate to form modified fine aggregate. Furthermore, this invention absorbs the liquid phase containing sodium silicate or potassium silicate into the sepiolite powder and performs carbonization treatment, converting the sodium silicate or silicic acid into solid silicic acid and sodium carbonate, while simultaneously utilizing the residual liquid phase. After being heated and decomposed, the solid silica is converted into silica particles, forming pretreated sepiolite micro powder with active silica and sodium carbonate loaded inside. At the same time, carbon dioxide is eliminated, reducing carbon emissions generated in the production of the cement components.

[0025] When using the aforementioned modified fine aggregate in combination with Yellow River ultrafine sand to prepare 3D printed concrete materials, on the one hand, the sepiolite on the surface of the fine aggregate has excellent water absorption capacity, which can effectively overcome the bleeding phenomenon in concrete materials caused by Yellow River ultrafine sand and microcrystalline glass fine aggregate. Simultaneously, during the extrusion printing process, the sepiolite releases moisture under pressure, maintaining good flowability and printability of the concrete material. After printing, the sepiolite reabsorbs moisture, preventing structural deformation of the printed concrete structure under its own weight. Furthermore, the silica particles in the sepiolite on the surface of the modified fine aggregate can react with calcium hydroxide produced during cement hydration to form hydrated calcium silicate cementitious components, increasing the cementitious component content in the concrete structure and improving the bonding force between the microcrystalline glass fine aggregate and the concrete structure, thereby enhancing the mechanical strength of the 3D printed concrete structure. In addition, the sodium / potassium carbonate in sepiolite reacts with calcium hydroxide, a cement hydration product, to form calcium carbonate and sodium / potassium hydroxide. The calcium carbonate can act as a cementing component of hydrated calcium silicate formed by dense silica particles. After the sodium / potassium hydroxide enters the concrete, it activates the silica fume with alkali, causing the silica fume to undergo a hydration reaction to form cementing components such as hydrated calcium silicate, which helps to improve the mechanical properties of the concrete structure. Attached Figure Description

[0026] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. Hereinafter, embodiments of the invention will be described in detail with reference to the accompanying drawings, wherein:

[0027] Figure 1 This is a rendering of concrete 3D printing according to Embodiment 1 of the present invention.

[0028] Figure 2 This is a test diagram of the compressive strength of Embodiment 1 of the present invention.

[0029] Figure 3 This is a rheological test diagram of Embodiment 1 of the present invention. Detailed Implementation

[0030] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. The present invention will now be further described with reference to specific embodiments.

[0031] Example 1: A preparation process for 3D printed concrete material made from Yellow River ultrafine sand, comprising the following steps:

[0032] (1) Microcrystalline glass fine aggregate with a particle size distribution between 1 and 2 mm is mixed with a sodium silicate solution with a mass fraction of 3% at a ratio of 1 g: 10 ml and stirred evenly. Then, it is heated to 70°C and kept at that temperature for 2.5 hours. After completion, the solid matter is filtered out and dried at 60°C for 50 minutes to obtain the pretreated fine aggregate.

[0033] (2) The sepiolite powder with a fineness of 80 mesh and the pretreated fine aggregate are dispersed in water and stirred evenly. The sepiolite powder accounts for 25% of the mass of the pretreated fine aggregate, and the ratio of the total amount of sepiolite powder and pretreated fine aggregate to water is 1g:30ml. Then, the mixture is heated to 60℃ and kept at that temperature for 7 hours. After completion, the fine aggregate is filtered to obtain modified fine aggregate a.

[0034] (3) The modified fine aggregate a is mixed with the liquid phase obtained by filtration in step (1) at a ratio of 1g:2ml and stirred evenly. The resulting mixture is placed in a carbon dioxide atmosphere for carbonization treatment for 1.5 hours. After completion, the resulting mixture is heated to 220℃ and kept warm for 1 hour to obtain the modified fine aggregate b.

[0035] (4) Take 100 parts by weight of 42.5 ordinary silicate cement, 180 parts by weight of the modified fine aggregate b prepared in this embodiment, 29 parts by weight of Yellow River ultrafine sand (fineness modulus distribution between 0.2 and 0.4), 12 parts by weight of silica fume, 1.45 parts by weight of polycarboxylate superplasticizer, and 6 parts by weight of polyvinyl alcohol fiber with a length of 5 mm. Mix the above raw materials and add mixing water at a water-cement ratio of 0.4 and stir evenly to obtain 3D printing concrete material.

[0036] After printing the 3D printed concrete material described in this embodiment (e.g.) Figure 1 (As shown) After natural curing, 3D printed concrete specimens were obtained by cutting. The 28-day compressive strength of the concrete specimens was tested according to the "Standard for Test Methods of Physical and Mechanical Properties of Concrete" (GB / T 50081-2019). Figure 2 (As shown). The bleeding rate of the 3D-printed concrete material prepared in this embodiment was tested according to the "Bleeding Test of Cement Concrete Mixtures" (T0528-2005). The thixotropy of the 3D-printed concrete material was tested using a Thermo Fisher Scientific Hack Mars 40 rheometer. Figure 3 As shown in Table 1 below, the test results are as follows.

[0037] Table 1

[0038]

[0039] Example 2: A preparation process for 3D printed concrete material made from Yellow River ultrafine sand, comprising the following steps:

[0040] (1) Microcrystalline glass fine aggregate with a particle size distribution between 1 and 3 mm is mixed with a 4% potassium silicate solution at a ratio of 1 g: 5 ml and stirred evenly. Then, the mixture is heated to 80°C and kept at that temperature for 2 hours. After completion, the solids are filtered out and dried at 50°C for 60 minutes to obtain the pretreated fine aggregate.

[0041] (2) The sepiolite powder with a fineness of 70 mesh and the pretreated fine aggregate are dispersed in water and stirred evenly. The sepiolite powder accounts for 22% of the mass of the pretreated fine aggregate, and the ratio of the total amount of sepiolite powder and pretreated fine aggregate to water is 1g:25ml. Then, the mixture is heated to 55℃ and kept at that temperature for 6 hours. After completion, the fine aggregate is filtered to obtain modified fine aggregate a.

[0042] (3) The modified fine aggregate a is mixed with the liquid phase obtained by filtration in step (1) at a ratio of 1g:1.5ml and stirred evenly. The resulting mixture is placed in a carbon dioxide atmosphere for carbonization treatment for 2 hours. After completion, the resulting mixture is heated to 180℃ and kept warm for 2 hours to obtain the modified fine aggregate b.

[0043] (4) Take 70 parts by weight of 42.5 ordinary Portland cement, 150 parts by weight of the modified fine aggregate b prepared in this embodiment, 22.5 parts by weight of Yellow River ultrafine sand (fineness modulus distribution between 0.2 and 0.4), 12 parts by weight of silica fume, 1.1 parts by weight of polycarboxylate superplasticizer, and 5 parts by weight of polypropylene fiber with a length of 10 mm. Mix the above raw materials and add mixing water at a water-cement ratio of 0.38 and stir evenly to obtain 3D printing concrete material.

[0044] The 28-day compressive strength, bleeding rate, and thixotropy of the 3D printed concrete material prepared in this embodiment were tested using the same method as in Example 1 above. The test results are shown in Table 2 below.

[0045] Table 2

[0046]

[0047] Example 3: A preparation process for 3D printed concrete material made from Yellow River ultrafine sand, comprising the following steps:

[0048] (1) Microcrystalline glass fine aggregate with a particle size distribution between 1 and 3 mm is mixed with a sodium silicate solution with a mass fraction of 2% at a ratio of 1 g: 20 ml and stirred evenly. Then, it is heated to 60°C and kept at that temperature for 3 hours. After completion, the solid matter is filtered out and dried at 80°C for 40 min to obtain the pretreated fine aggregate.

[0049] (2) The 100-mesh sepiolite powder and the pretreated fine aggregate are dispersed in water and stirred evenly. The sepiolite powder accounts for 30% of the mass of the pretreated fine aggregate, and the ratio of the total amount of sepiolite powder and pretreated fine aggregate to water is 1g:40ml. Then, the mixture is heated to 50°C and kept at that temperature for 8 hours. After completion, the fine aggregate is filtered to obtain modified fine aggregate a.

[0050] (3) Mix the modified fine aggregate a with the liquid phase obtained by filtration in step (1) at a ratio of 1g:3ml and stir evenly. Place the resulting mixture in a carbon dioxide atmosphere for 2 hours. After completion, heat the resulting mixture to 250℃ and keep it warm for 1.5 hours to obtain the modified fine aggregate b.

[0051] (4) Take 105 parts by weight of 42.5 ordinary Portland cement, 200 parts by weight of the modified fine aggregate b prepared in this embodiment, 40 parts by weight of Yellow River ultrafine sand (fineness modulus distribution between 0.2 and 0.4), 17 parts by weight of silica fume, 2 parts by weight of sodium lignosulfonate water-reducing agent, and 8 parts by weight of basalt fiber with a length of 3 mm. Mix the above raw materials and add mixing water at a water-cement ratio of 0.42 and stir evenly to obtain 3D printing concrete material.

[0052] The 28-day compressive strength, bleeding rate, and thixotropy of the 3D printed concrete material prepared in this embodiment were tested using the same method as in Example 1 above. The test results are shown in Table 3 below.

[0053] Table 3

[0054]

[0055] Example 4: A preparation process for a 3D-printed concrete material made from Yellow River ultrafine sand includes the following steps: 100 parts by weight of 42.5 ordinary silicate cement, 180 parts by weight of microcrystalline glass fine aggregate with a particle size distribution between 1 and 2 mm, 29 parts by weight of Yellow River ultrafine sand (fineness modulus distribution between 0.2 and 0.4), 12 parts by weight of silica fume, 1.45 parts by weight of polycarboxylate superplasticizer, and 6 parts by weight of polyvinyl alcohol fiber with a length of 5 mm. The above raw materials are mixed, and mixing water is added at a water-cement ratio of 0.4 and stirred until homogeneous to obtain the 3D-printed concrete material.

[0056] The 28-day compressive strength, bleeding rate, and thixotropy of the 3D printed concrete material prepared in this embodiment were tested using the same method as in Example 1 above. The test results are shown in Table 4 below.

[0057] Table 4

[0058]

[0059] Example 5: A preparation process for 3D printed concrete material made from Yellow River ultrafine sand, comprising the following steps:

[0060] (1) Sepiolite powder with a fineness of 100 mesh and microcrystalline glass fine aggregate with a particle size distribution between 1 and 3 mm are dispersed in water and stirred evenly. The sepiolite powder accounts for 30% of the mass of the pretreated fine aggregate, and the ratio of the total amount of sepiolite powder and pretreated fine aggregate to water is 1 g: 40 ml. Then, the mixture is heated to 50°C and kept at that temperature for 8 hours. After completion, the fine aggregate is filtered to obtain modified fine aggregate a.

[0061] (2) The modified fine aggregate a is mixed with a sodium silicate solution with a mass fraction of 2% at a ratio of 1g:3ml and stirred evenly. The resulting mixture is placed in a carbon dioxide atmosphere for carbonization treatment for 2 hours. After completion, the resulting mixture is heated to 250℃ and kept at that temperature for 1.5 hours to obtain the modified fine aggregate b.

[0062] (3) Take 105 parts by weight of 42.5 ordinary Portland cement, 200 parts by weight of the modified fine aggregate b prepared in this embodiment, 40 parts by weight of Yellow River ultrafine sand (fineness modulus distribution between 0.2 and 0.4), 17 parts by weight of silica fume, 2 parts by weight of sodium lignosulfonate water-reducing agent, and 8 parts by weight of basalt fiber with a length of 3 mm. Mix the above raw materials and add mixing water at a water-cement ratio of 0.42 and stir evenly to obtain 3D printing concrete material.

[0063] The 28-day compressive strength, bleeding rate, and thixotropy of the 3D printed concrete material prepared in this embodiment were tested using the same method as in Example 1 above. The test results are shown in Table 5 below.

[0064] Table 5

[0065]

[0066] Example 6: A preparation process for 3D printed concrete material made from Yellow River ultrafine sand, comprising the following steps:

[0067] (1) Microcrystalline glass fine aggregate with a particle size distribution between 1 and 3 mm is mixed with a 4% potassium silicate solution at a ratio of 1 g: 5 ml and stirred evenly. Then, the mixture is heated to 80°C and kept at that temperature for 2 hours. After completion, the solids are filtered out and dried at 50°C for 60 minutes to obtain the pretreated fine aggregate.

[0068] (2) The sepiolite powder with a fineness of 70 mesh and the pretreated fine aggregate are dispersed in water and stirred evenly. The sepiolite powder accounts for 22% of the mass of the pretreated fine aggregate, and the ratio of the total amount of sepiolite powder and pretreated fine aggregate to water is 1g:25ml. Then, the mixture is heated to 55℃ and kept at that temperature for 6 hours. After completion, the fine aggregate is filtered to obtain modified fine aggregate a.

[0069] (3) Mix the modified fine aggregate a with the liquid phase obtained by filtration in step (1) at a ratio of 1g:1.5ml and stir evenly. Then heat the mixture to 180℃ and keep it warm for 2 hours to obtain the modified fine aggregate b.

[0070] (4) Take 70 parts by weight of 42.5 ordinary Portland cement, 150 parts by weight of the modified fine aggregate b prepared in this embodiment, 22.5 parts by weight of Yellow River ultrafine sand (fineness modulus distribution between 0.2 and 0.4), 12 parts by weight of silica fume, 1.1 parts by weight of polycarboxylate superplasticizer, and 5 parts by weight of polypropylene fiber with a length of 10 mm. Mix the above raw materials and add mixing water at a water-cement ratio of 0.38 and stir evenly to obtain 3D printing concrete material.

[0071] The 28-day compressive strength, bleeding rate, and thixotropy of the 3D printed concrete material prepared in this embodiment were tested using the same method as in Example 1 above. The test results are shown in Table 6 below.

[0072] Table 6

[0073]

[0074] Example 7: A preparation process for 3D printed concrete material made from Yellow River ultrafine sand, comprising the following steps:

[0075] (1) Microcrystalline glass fine aggregate with a particle size distribution between 1 and 2 mm is mixed with a sodium silicate solution with a mass fraction of 3% at a ratio of 1 g: 10 ml and stirred evenly. Then, it is heated to 70°C and kept at that temperature for 2.5 hours. After completion, the solid matter is filtered out and dried at 60°C for 50 minutes to obtain the pretreated fine aggregate.

[0076] (2) The sepiolite powder with a fineness of 80 mesh and the pretreated fine aggregate are dispersed in water and stirred evenly. The sepiolite powder accounts for 25% of the mass of the pretreated fine aggregate, and the ratio of the total amount of sepiolite powder and pretreated fine aggregate to water is 1g:30ml. Then, the mixture is heated to 60℃ and kept at that temperature for 7 hours. After completion, the fine aggregate is filtered to obtain modified fine aggregate a.

[0077] (3) Mix the modified fine aggregate a with water at a ratio of 1g:2ml and stir evenly. Place the resulting mixture in a carbon dioxide atmosphere for carbonization treatment for 1.5 hours. After completion, heat the resulting mixture to 220℃ and keep it warm for 1 hour to obtain the modified fine aggregate b.

[0078] (4) Take 100 parts by weight of 42.5 ordinary silicate cement, 180 parts by weight of the modified fine aggregate b prepared in this embodiment, 29 parts by weight of Yellow River ultrafine sand (fineness modulus distribution between 0.2 and 0.4), 12 parts by weight of silica fume, 1.45 parts by weight of polycarboxylate superplasticizer, and 6 parts by weight of polyvinyl alcohol fiber with a length of 5 mm. Mix the above raw materials and add mixing water at a water-cement ratio of 0.4 and stir evenly to obtain 3D printing concrete material.

[0079] The 28-day compressive strength, bleeding rate, and thixotropy of the 3D printed concrete material prepared in this embodiment were tested using the same method as in Example 1 above. The test results are shown in Table 7 below.

[0080] Table 7

[0081]

[0082] Example 8: A preparation process for 3D printed concrete material made from Yellow River ultrafine sand, comprising the following steps:

[0083] (1) The crushed stone fine aggregate with a particle size distribution between 1 and 3 mm is mixed with a sodium silicate solution with a mass fraction of 2% at a ratio of 1 g: 20 ml and stirred evenly. Then, the mixture is heated to 60°C and kept at that temperature for 3 hours. After completion, the solid matter is filtered out and dried at 80°C for 40 minutes to obtain the pretreated fine aggregate.

[0084] (2) The modified fine aggregate a of Example 3 is mixed with the liquid phase obtained by filtration in step (1) of this example at a ratio of 1g:3ml and stirred evenly. The resulting mixture is placed in a carbon dioxide atmosphere for carbonization treatment for 2 hours. After completion, the resulting mixture is heated to 250℃ and kept warm for 1.5 hours to obtain the modified fine aggregate b.

[0085] (3) Take 105 parts by weight of 42.5 ordinary Portland cement, 200 parts by weight of the modified fine aggregate b prepared in this embodiment, 40 parts by weight of Yellow River ultrafine sand (fineness modulus distribution between 0.2 and 0.4), 17 parts by weight of silica fume, 2 parts by weight of sodium lignosulfonate water-reducing agent, and 8 parts by weight of basalt fiber with a length of 3 mm. Mix the above raw materials and add mixing water at a water-cement ratio of 0.42 and stir evenly to obtain 3D printing concrete material.

[0086] The 28-day compressive strength, bleeding rate, and thixotropy of the 3D printed concrete material prepared in this embodiment were tested using the same method as in Example 1 above. The test results are shown in Table 8 below.

[0087] Table 8

[0088]

[0089] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A preparation process for 3D printed concrete material made from Yellow River ultrafine sand, characterized in that, Includes the following steps: (1) The microcrystalline glass fine aggregate is immersed in sodium silicate or potassium silicate solution and heated and kept at a constant temperature for surface treatment. After the solid-liquid separation is completed, the obtained solid product is dried to obtain the pretreated fine aggregate. (2) After dispersing the sepiolite powder and the pretreated fine aggregate in water, stir and heat to react. After the reaction is completed, separate the fine aggregate to obtain modified fine aggregate a; (3) The modified fine aggregate a is mixed with the liquid phase obtained from the solid-liquid separation in step (1) to form a mixture. Then the mixture is placed in a carbon dioxide atmosphere for carbonization treatment. After completion, it is heated to decompose the silicic acid in it into silicon dioxide, thus obtaining the modified fine aggregate b. (4) Using silicate cement, the modified fine aggregate b, Yellow River ultrafine sand, silica fume, water-reducing agent and fiber as raw materials, mix them and add mixing water to stir evenly to obtain the 3D printed concrete material.

2. The preparation process of the Yellow River ultrafine sand 3D printed concrete material according to claim 1, characterized in that, In step (1), the ratio of the microcrystalline glass aggregate to sodium silicate or potassium silicate solution is 1g:5~20ml.

3. The preparation process of the Yellow River ultrafine sand 3D printed concrete material according to claim 1, characterized in that, In step (1), the mass fraction of the sodium silicate or potassium silicate solution is 2-4%.

4. The preparation process of the Yellow River ultrafine sand 3D printed concrete material according to claim 1, characterized in that, In step (1), the heating and heat preservation temperature is 60~80℃ and the time is 2~3 hours.

5. The preparation process of the Yellow River ultrafine sand 3D printed concrete material according to claim 1, characterized in that, In step (1), the particle size of the microcrystalline glass fine aggregate is 1~3mm.

6. The preparation process of the Yellow River ultrafine sand 3D printed concrete material according to claim 1, characterized in that, In step (1), the drying temperature is 50~80℃ and the time is 40~60min.

7. The preparation process of the Yellow River ultrafine sand 3D printed concrete material according to claim 1, characterized in that, In step (2), the sepiolite powder is 22-30% of the mass of the pretreated fine aggregate.

8. The preparation process of the Yellow River ultrafine sand 3D printed concrete material according to claim 1, characterized in that, In step (2), the fineness of the sepiolite powder is 70~100 mesh.

9. The preparation process of the Yellow River ultrafine sand 3D printed concrete material according to claim 1, characterized in that, In step (2), the ratio of the total amount of sepiolite powder and pretreated fine aggregate to water is 1g: 25~40ml.

10. The preparation process of 3D printed concrete material made from Yellow River ultrafine sand according to claim 1, characterized in that, In step (2), the heating reaction is carried out at a temperature of 50-60°C for 6-8 hours.

11. The preparation process of 3D printed concrete material made from Yellow River ultrafine sand according to claim 1, characterized in that, In step (3), the ratio of the modified fine aggregate a to the liquid phase is 1g:1.5~3ml.

12. The preparation process of 3D printed concrete material made from Yellow River ultrafine sand according to claim 1, characterized in that, In step (3), the carbonization process takes 1.5 to 2 hours.

13. The preparation process of the Yellow River ultrafine sand 3D printed concrete material according to claim 1, characterized in that, In step (3), the temperature of the heat treatment is 180~250℃ and the time is 1~2 hours.

14. The preparation process of the Yellow River ultrafine sand 3D printed concrete material according to claim 1, characterized in that, In step (4), the proportions of each component in the raw material are as follows: silicate cement: modified fine aggregate b: silica fume: water-reducing agent: fiber = 70~105 parts by weight: 150~200 parts by weight: 10~17 parts by weight: 1.1~2 parts by weight: 5~8 parts by weight; the Yellow River ultrafine sand is 15~20% of the modified fine aggregate b content, and the water-cement ratio is 0.38~0.

42.

15. The preparation process of Yellow River ultrafine sand 3D printed concrete material according to any one of claims 1-14, characterized in that, In step (4), the water-reducing agent includes any one of polycarboxylate water-reducing agent, lignin sulfonate water-reducing agent, naphthalene-based water-reducing agent, and aliphatic water-reducing agent.

16. The preparation process of Yellow River ultrafine sand 3D printed concrete material according to any one of claims 1-14, characterized in that, In step (4), the fiber includes at least one of polyethylene fiber, polypropylene fiber, polyvinyl alcohol fiber, basalt fiber, and carbon fiber.

17. The preparation process of Yellow River ultrafine sand 3D printed concrete material according to any one of claims 1-14, characterized in that, In step (4), the length of the fiber is 3~10mm.

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