3D printing cementing material preparation process based on building regenerated micro powder

Abstract

The invention discloses a 3D printing cementing material preparation process based on building regenerated micro powder, which comprises the following steps: (1) mixing and grinding waste concrete powder and absolute ethyl alcohol suspension of nano aluminum powder to obtain pretreated powder; (2) carrying out microwave heating treatment on the pretreated powder; and mixing and grinding the obtained modified powder and calcium stearate powder. And adding an absolute ethyl alcohol solution of sodium lactate into the obtained mixture, uniformly mixing, and drying to obtain the regenerated micro powder. And (3) adding the absolute ethyl alcohol solution of the polycarboxylate superplasticizer into the Portland cement powder, uniformly mixing, and drying to obtain the modified cement powder. And (4) uniformly mixing the regenerated micro powder, the modified cement powder, fine aggregate, fly ash and fibers, adding mixing water, and uniformly stirring to obtain the concrete. According to the process disclosed by the invention, the gelation activity is effectively improved and the water absorption rate is reduced by performing microwave activation modification on the waste concrete powder, so that resource utilization of solid wastes is facilitated, and carbon emission is also reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of 3D printing material preparation, and in particular to a process for preparing 3D printing gelling material based on building recycled micropowder. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance understanding of the overall background of the invention and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to those skilled in the art.

[0003] 3D-printed buildings are constructed by using a computer to create layered models and program instructions, followed by a printing machine that repeatedly lays down cement material layer by layer. This automated construction method significantly reduces the number of workers, reduces costs, and improves construction safety compared to traditional pouring methods. It also allows for customization based on specific needs, allowing for the creation of more complex structures. Currently, the cement used in 3D printing primarily uses Portland cement as the binder, but its production requires significant energy consumption and emits significant amounts of carbon dioxide.

[0004] The demolition process generates a large amount of waste concrete powder, which contains a large amount of cement hydration products. This construction waste not only has low gelling activity, making it difficult to reuse as a cementing component, but also has a high water absorption rate. When used as a component of cement for 3D printing, it can easily lead to insufficient rheological properties of the cement, thereby affecting the quality and mechanical properties of the printed building structure. Summary of the Invention

[0005] To address these issues, the present invention provides a process for preparing 3D-printable cementitious materials based on recycled building powder. This process effectively increases the activity and reduces water absorption by modifying waste concrete powder through microwave activation. Using this process to partially replace cement clinker in the preparation of 3D-printable cement materials not only contributes to the resource utilization of solid waste but also helps reduce carbon emissions. Specifically, the technical solution of the present invention is as follows.

[0006] A process for preparing 3D printing gelling materials based on building recycled micropowder comprises the following steps: (1) Waste concrete powder is mixed with an anhydrous ethanol suspension of nano-aluminum powder and then mechanically ground to obtain pretreated powder.

[0007] (2) The pretreated powder is subjected to microwave heating and then cooled to room temperature. The modified powder is then mixed with calcium stearate powder and ground again. After the mixture is ground, anhydrous ethanol solution of sodium lactate is added to the mixture, mixed evenly, and dried to obtain regenerated micropowder.

[0008] (3) Add anhydrous ethanol solution of polycarboxylic acid water reducer to silicate cement powder, mix well and dry to obtain modified cement powder.

[0009] (4) Take the following raw materials: the recycled micropowder, the modified cement powder, fine aggregate, fly ash, and fiber. Mix the above raw materials and add mixing water and stir evenly to obtain the 3D printing cementitious material.

[0010] Furthermore, in step (1), the nano aluminum powder accounts for 12-18% of the mass of the waste concrete powder.

[0011] Furthermore, in step (1), the mechanical grinding time is 30 to 40 minutes. Optionally, the fineness of the pretreated powder is 200 to 300 mesh.

[0012] Furthermore, in step (2), the microwave heating treatment is performed for 40 to 60 minutes at a power of 500 to 700W.

[0013] Furthermore, in step (2), the calcium stearate powder accounts for 7-11% of the mass of the modified powder.

[0014] Furthermore, in step (2), the mechanical grinding time is 20 to 35 minutes. Optionally, the fineness of the mixture is 350 to 450 mesh.

[0015] Furthermore, in step (2), the ratio of the mixture to the anhydrous ethanol solution of sodium lactate is 1 g: 0.3-0.55 ml. Optionally, the mass fraction of sodium lactate in the anhydrous ethanol solution is 1-2%.

[0016] Furthermore, in step (2), the drying temperature is 60-80° C., and the drying time is 10-15 minutes.

[0017] Furthermore, in step (3), the ratio of the silicate cement powder to the anhydrous ethanol solution of the polycarboxylate water-reducing agent is 1g: 0.2-0.35ml. Optionally, the mass fraction of the polycarboxylate water-reducing agent in the anhydrous ethanol solution is 2-5%.

[0018] Furthermore, in step (3), the drying temperature is 60-70° C., and the drying time is 10-20 min.

[0019] Furthermore, in step (4), the proportions of the raw materials are: 105-130 parts by weight of recycled micropowder, 40-55 parts by weight of modified cement powder, 310-360 parts by weight of fine aggregate, 20-35 parts by weight of fly ash, and 10-17 parts by weight of fiber.

[0020] Furthermore, in step (4), the mixing water is added according to a water-cement ratio of 0.38 to 0.43.

[0021] Furthermore, in step (4), the fiber comprises at least one of polyethylene fiber, polypropylene fiber, polyvinyl alcohol fiber, basalt fiber, etc. Optionally, the length of the fiber is 3 to 10 mm.

[0022] Compared with the prior art, the present invention has at least the following beneficial technical effects: As previously mentioned, waste concrete powder not only has low gelling activity but also easily leads to insufficient rheological properties of cement materials, affecting the quality and mechanical properties of 3D-printed building structures. To this end, the present invention first mixes waste concrete powder with an anhydrous ethanol suspension containing nano-aluminum powder and then mechanically grinds it. The nano-aluminum particles are then mechanically embedded into the waste concrete powder particles using mechanical force. Subsequently, microwave heating is used to heat the hydration products in the waste concrete powder particles, utilizing the microwave absorption of the nano-aluminum particles to dehydrate them and enhance their gelling activity. Furthermore, these nano-aluminum particles, due to their high temperature, are gradually converted into nano-alumina particles, which are then loaded into the waste concrete powder particles. When the modified regenerated micropowder obtained through this treatment is prepared into a 3D printing cementitious material, the dehydrated hydration products are rehydrated by mixing water to form a gelling product. Simultaneously, the formed nano-alumina particles undergo a secondary hydration reaction with the calcium hydroxide hydration product in the regenerated micropowder to form calcium aluminate hydrate. These cementitious products can bind the various components together to form a solid cement stone, ensuring that the 3D-printed building structure has good mechanical properties. Because the recycled micropowder of the present invention has excellent gelling activity, its use in place of the Portland cement component in traditional 3D printing cementitious materials can reduce the amount of Portland cement used, thereby not only promoting the resource utilization of waste concrete but also helping to reduce the carbon emissions associated with burning Portland cement.

[0023] Furthermore, the present invention utilizes calcium stearate to effectively reduce the water absorption rate of the regenerated micropowder, thereby reducing its impact on the rheological properties of the prepared cementitious material. The present invention also utilizes sodium lactate to surface-modify the regenerated micropowder, and utilizes a polycarboxylate water-reducing agent to surface-modify the silicate cement powder. This allows the regenerated micropowder particles to connect via hydrogen bonding between the sodium lactate molecules, and the silicate cement particles to connect via hydrogen bonding between the carboxyl groups on the polycarboxylate water-reducing agent and the olamine molecules on the regenerated micropowder particles. During extrusion printing, mechanical shear force is used to break the hydrogen bonds, allowing the cementitious material to maintain good rheological properties and facilitate good continuity during printing. After printing, the hydrogen bonds are restored, thereby improving the structural stability of the printed building structure, reducing structural deformation due to its own weight, and improving the dimensional accuracy of the building structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings, which constitute part of the present invention, are provided to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are provided to explain the present invention and do not constitute undue limitations thereon. The embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein: Figure 1 A diagram of a component printed using the 3D printing gelling material prepared in Example 1 below.

[0025] Figure 2 This is a compressive strength test diagram of the following Example 1.

[0026] Figure 3 Component diagram prepared for calculating the structural deformation rate in the following Example 1.

[0027] Figure 4 This is a compressive strength test diagram of the following Example 2.

[0028] Figure 5 A diagram of a component prepared for calculating the structural deformation rate in the following Example 2. DETAILED DESCRIPTION

[0029] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are intended to illustrate the present invention only and are not intended to limit the scope of the invention. The experimental methods in the following examples, for which specific conditions are not specified, are generally carried out under conventional conditions or as recommended by the manufacturer. The present invention will be further described below in conjunction with specific embodiments.

[0030] Example 1 A process for preparing 3D printing gelling materials based on building recycled micropowder comprises the following steps: (1) Add a suspension of nano-aluminum powder in anhydrous ethanol to waste concrete powder, with the nano-aluminum powder accounting for 15% of the mass of the waste concrete powder. Then, grind the powder mechanically in a grinder for 30 minutes and pass through a 200-mesh sieve to obtain a pretreated powder.

[0031] (2) The pretreated powder was microwave-heated for 45 minutes at a power of 600 W. After cooling to room temperature, 8% by weight of calcium stearate powder was added to the modified powder and the mixture was mechanically ground again in a grinder for 30 minutes. After passing through a 400-mesh sieve, an anhydrous ethanol solution of sodium lactate (sodium lactate concentration of 1.5 wt.%) was added to the mixture at a ratio of 1 g:0.4 ml, and then dried at 70°C for 12 minutes to obtain regenerated micropowder.

[0032] (3) Add anhydrous ethanol solution of polycarboxylic acid water reducer (the concentration of polycarboxylic acid water reducer is 3.5 wt.%) to 42.5 ordinary Portland cement powder at a ratio of 1 g:0.3 ml, mix well and dry at 70 °C for 10 min to obtain modified cement powder.

[0033] (4) Take the following raw materials: 110 parts by weight of the recycled micropowder, 45 parts by weight of the modified cement powder, 330 parts by weight of river sand fine aggregate, 25 parts by weight of fly ash, and 13 parts by weight of polyethylene fiber with a length of 5 mm. Add the above raw materials to a mixer and dry mix for 3 minutes. Then, add mixing water at a final water-cement ratio of 0.41 and stir for 2 minutes to obtain a 3D printing cementitious material.

[0034] Performance test: 1. Use 3D printing equipment to print the 3D printing gelling material prepared in this embodiment into components (such as Figure 1 After natural curing for 28 days, the specimens were cut to obtain the test pieces. The compressive strength of the specimens was tested according to the "Test method for strength of cement mortar (ISO method)" (GBT 17671-2021) (as shown in the figure). Figure 2 2. Use 3D printing equipment to print the 3D printing gelling material of this embodiment into a component (as shown). Figure 3 After 7 days of natural curing, the structural deformation rate was calculated based on the average deformation of the component in the X, Y, and Z directions. 3. Thixotropic recovery was measured using a Thermo Fisher Hake Mars 40 rheometer. The results are shown in the table below.

[0035] Example 2 A process for preparing 3D printing gelling materials based on building recycled micropowder comprises the following steps: (1) Add a suspension of nano-aluminum powder in anhydrous ethanol to waste concrete powder, with the nano-aluminum powder accounting for 18% of the mass of the waste concrete powder. Then grind the powder mechanically in a grinder for 35 minutes and pass it through a 200-mesh sieve to obtain a pretreated powder.

[0036] (2) The pretreated powder was microwave-heated for 60 min at a power of 500 W. After cooling to room temperature, 7% by weight of calcium stearate powder was added to the modified powder and the powder was mechanically ground again in a grinder for 20 min. After passing through a 350-mesh sieve, anhydrous sodium lactate solution (sodium lactate concentration of 1.0 wt.%) was added to the mixture at a ratio of 1 g:0.55 ml. The mixture was then dried at 80°C for 10 min to obtain regenerated micropowder.

[0037] (3) Add anhydrous ethanol solution of polycarboxylic acid water reducer (the concentration of polycarboxylic acid water reducer is 5 wt.%) to 42.5 ordinary Portland cement powder at a ratio of 1 g:0.2 ml, mix well and dry at 70 °C for 10 min to obtain modified cement powder.

[0038] (4) Take the following raw materials: 130 parts by weight of the recycled micropowder, 55 parts by weight of the modified cement powder, 360 parts by weight of river sand fine aggregate, 35 parts by weight of fly ash, and 17 parts by weight of 3 mm long polyvinyl alcohol fiber. Add the above raw materials to a blender and dry mix for 3 minutes. Then, add mixing water at a final water-cement ratio of 0.43 and stir for 2 minutes to obtain a 3D printing cementitious material.

[0039] The compressive strength of the 3D printing gelling material prepared in this embodiment (such as Figure 4 As shown in ), structural deformation rate (as shown in Figure 5 The thixotropic recovery rate was tested in the same manner as in Example 1, and the results are shown in the following table.

[0040] Example 3 A process for preparing 3D printing gelling materials based on building recycled micropowder comprises the following steps: (1) Add a suspension of nano-aluminum powder in anhydrous ethanol to waste concrete powder, with the nano-aluminum powder accounting for 12% of the mass of the waste concrete powder. Then grind the powder mechanically in a grinder for 40 minutes and pass through a 300-mesh sieve to obtain a pretreated powder.

[0041] (2) The pretreated powder was microwave-heated for 40 min at a power of 700 W. After cooling to room temperature, 11% of the weight of calcium stearate powder was added to the modified powder and the powder was mechanically ground again in a grinder for 35 min. After passing through a 450-mesh sieve, anhydrous sodium lactate solution (sodium lactate concentration of 2.0 wt.%) was added to the mixture at a ratio of 1 g:0.3 ml. The mixture was then dried at 60°C for 15 min to obtain regenerated micropowder.

[0042] (3) Add anhydrous ethanol solution of polycarboxylic acid water reducer (the concentration of polycarboxylic acid water reducer is 2 wt.%) to 42.5 ordinary Portland cement powder at a ratio of 1 g:0.35 ml, mix well and dry at 60 °C for 20 min to obtain modified cement powder.

[0043] (4) Take the following raw materials: 105 parts by weight of the recycled micropowder, 40 parts by weight of the modified cement powder, 310 parts by weight of river sand fine aggregate, 20 parts by weight of fly ash, and 10 parts by weight of polypropylene fiber with a length of 10 mm. Add the above raw materials to a blender and dry mix for 3 minutes. Then, add mixing water at a final water-cement ratio of 0.38 and stir for 2 minutes to obtain a 3D printing cementitious material.

[0044] The compressive strength, structural deformation rate, and thixotropic recovery rate of the 3D printing gelling material prepared in this embodiment were tested using the same method as in the above-mentioned embodiment 1. The results are shown in the following table.

[0045] Example 4 A process for preparing 3D printing gelling materials based on building recycled micropowder comprises the following steps: (1) The waste concrete powder is mechanically ground in a grinder and then passed through a 400-mesh sieve to obtain recycled fine powder.

[0046] (2) Add anhydrous ethanol solution of polycarboxylic acid water reducer (the concentration of polycarboxylic acid water reducer is 3.5 wt.%) to 42.5 ordinary Portland cement powder at a ratio of 1 g:0.3 ml, mix well and dry at 70 °C for 10 min to obtain modified cement powder.

[0047] (3) Take the following raw materials: 110 parts by weight of the recycled micropowder, 45 parts by weight of the modified cement powder, 330 parts by weight of river sand fine aggregate, 25 parts by weight of fly ash, and 13 parts by weight of polyethylene fiber with a length of 5 mm. Add the above raw materials to a mixer and dry mix for 3 minutes. Then, add mixing water at a final water-cement ratio of 0.41 and stir for 2 minutes to obtain a 3D printing cementitious material.

[0048] The compressive strength, structural deformation rate, and thixotropic recovery rate of the 3D printing gelling material prepared in this embodiment were tested using the same method as in the above-mentioned embodiment 1. The results are shown in the following table.

[0049] Example 5 A process for preparing 3D printing gelling materials based on building recycled micropowder comprises the following steps: (1) The waste concrete powder was mechanically ground in a grinder for 30 min and then passed through a 200-mesh sieve to obtain pretreated powder.

[0050] (2) The pretreated powder was microwave-heated for 45 minutes at a power of 600 W. After cooling to room temperature, 8% by weight of calcium stearate powder was added to the modified powder and the mixture was mechanically ground again in a grinder for 30 minutes. After passing through a 400-mesh sieve, an anhydrous ethanol solution of sodium lactate (sodium lactate concentration of 1.5 wt.%) was added to the mixture at a ratio of 1 g:0.4 ml, and then dried at 70°C for 12 minutes to obtain regenerated micropowder.

[0051] (3) Add anhydrous ethanol solution of polycarboxylic acid water reducer (the concentration of polycarboxylic acid water reducer is 3.5 wt.%) to 42.5 ordinary Portland cement powder at a ratio of 1 g:0.3 ml, mix well and dry at 70 °C for 10 min to obtain modified cement powder.

[0052] (4) Take the following raw materials: 110 parts by weight of the recycled micropowder, 45 parts by weight of the modified cement powder, 330 parts by weight of river sand fine aggregate, 25 parts by weight of fly ash, and 13 parts by weight of polyethylene fiber with a length of 5 mm. Add the above raw materials to a mixer and dry mix for 3 minutes. Then, add mixing water at a final water-cement ratio of 0.41 and stir for 2 minutes to obtain a 3D printing cementitious material.

[0053] The compressive strength, structural deformation rate, and thixotropic recovery rate of the 3D printing gelling material prepared in this embodiment were tested using the same method as in the above-mentioned embodiment 1. The results are shown in the following table.

[0054] Example 6 A process for preparing 3D printing gelling materials based on building recycled micropowder comprises the following steps: (1) Add a suspension of nano-aluminum powder in anhydrous ethanol to waste concrete powder, with the nano-aluminum powder accounting for 18% of the mass of the waste concrete powder. Then grind the powder mechanically in a grinder for 35 minutes and pass it through a 200-mesh sieve to obtain a pretreated powder.

[0055] (2) The pretreated powder was subjected to microwave heating for 60 min at a power of 500 W. After cooling to room temperature, 7% by weight of calcium stearate powder was added to the modified powder and the powder was mechanically ground again in a grinder for 20 min. After the powder was sieved through a 350-mesh sieve, the regenerated micropowder was obtained.

[0056] (3) Add anhydrous ethanol solution of polycarboxylic acid water reducer (the concentration of polycarboxylic acid water reducer is 5 wt.%) to 42.5 ordinary Portland cement powder at a ratio of 1 g:0.2 ml, mix well and dry at 70 °C for 10 min to obtain modified cement powder.

[0057] (4) Take the following raw materials: 130 parts by weight of the recycled micropowder, 55 parts by weight of the modified cement powder, 360 parts by weight of river sand fine aggregate, 35 parts by weight of fly ash, and 17 parts by weight of 3 mm long polyvinyl alcohol fiber. Add the above raw materials to a blender and dry mix for 3 minutes. Then, add mixing water at a final water-cement ratio of 0.43 and stir for 2 minutes to obtain a 3D printing cementitious material.

[0058] The compressive strength, structural deformation rate, and thixotropic recovery rate of the 3D printing gelling material prepared in this embodiment were tested using the same method as in the above-mentioned embodiment 1. The results are shown in the following table.

[0059] Example 7 A process for preparing 3D printing gelling materials based on building recycled micropowder comprises the following steps: (1) Add a suspension of nano-aluminum powder in anhydrous ethanol to waste concrete powder, with the nano-aluminum powder accounting for 12% of the mass of the waste concrete powder. Then grind the powder mechanically in a grinder for 40 minutes and pass through a 300-mesh sieve to obtain a pretreated powder.

[0060] (2) The pretreated powder was microwave-heated for 40 min at a power of 700 W. After cooling to room temperature, 11% of the weight of calcium stearate powder was added to the modified powder and the powder was mechanically ground again in a grinder for 35 min. After passing through a 450-mesh sieve, anhydrous sodium lactate solution (sodium lactate concentration of 2.0 wt.%) was added to the mixture at a ratio of 1 g:0.3 ml. The mixture was then dried at 60°C for 15 min to obtain regenerated micropowder.

[0061] (3) Take the following raw materials: 105 parts by weight of the recycled micropowder, 40 parts by weight of 42.5% ordinary Portland cement powder, 310 parts by weight of river sand fine aggregate, 20 parts by weight of fly ash, and 10 parts by weight of 10 mm long polypropylene fiber. Add the above raw materials to a blender and dry mix for 3 minutes. Then, add mixing water at a final water-cement ratio of 0.38 and stir for 2 minutes to obtain a 3D printing cementitious material.

[0062] The compressive strength, structural deformation rate, and thixotropic recovery rate of the 3D printing gelling material prepared in this embodiment were tested using the same method as in the above-mentioned embodiment 1. The results are shown in the following table.

[0063] Example 8 A process for preparing 3D printing gelling materials based on building recycled micropowder comprises the following steps: (1) Add a suspension of nano-aluminum powder in anhydrous ethanol to waste concrete powder, with the nano-aluminum powder accounting for 18% of the mass of the waste concrete powder. Then grind the powder mechanically in a grinder for 35 minutes and pass it through a 200-mesh sieve to obtain a pretreated powder.

[0064] (2) 7% by weight of calcium stearate powder was added to the pretreated powder and the mixture was mechanically ground again in a grinder for 20 minutes. After completion, the mixture was passed through a 350-mesh sieve. Then, an anhydrous ethanol solution of sodium lactate (sodium lactate concentration of 1.0 wt.%) was added to the obtained mixture at a ratio of 1 g:0.55 ml. The mixture was then dried at 80°C for 10 minutes to obtain regenerated micropowder.

[0065] (3) Add anhydrous ethanol solution of polycarboxylic acid water reducer (the concentration of polycarboxylic acid water reducer is 5 wt.%) to 42.5 ordinary Portland cement powder at a ratio of 1 g:0.2 ml, mix well and dry at 70 °C for 10 min to obtain modified cement powder.

[0066] (4) Take the following raw materials: 130 parts by weight of the recycled micropowder, 55 parts by weight of the modified cement powder, 360 parts by weight of river sand fine aggregate, 35 parts by weight of fly ash, and 17 parts by weight of 3 mm long polyvinyl alcohol fiber. Add the above raw materials to a blender and dry mix for 3 minutes. Then, add mixing water at a final water-cement ratio of 0.43 and stir for 2 minutes to obtain a 3D printing cementitious material.

[0067] The compressive strength, structural deformation rate, and thixotropic recovery rate of the 3D printing gelling material prepared in this embodiment were tested using the same method as in the above-mentioned embodiment 1. The results are shown in the following table.

[0068] 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 aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein with equivalents. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A process for preparing 3D printing gelling materials based on building recycled micropowder, characterized in that: The steps include: (1) Mixing waste concrete powder with an anhydrous ethanol suspension of nano-aluminum powder and then mechanically grinding them to obtain pretreated powder; (2) subjecting the pretreated powder to microwave heating and cooling to room temperature; The modified powder obtained is then mixed with calcium stearate powder and ground again; After completion, add anhydrous ethanol solution of sodium lactate to the obtained mixture, mix well and then dry to obtain regenerated micropowder; (3) Add anhydrous ethanol solution of polycarboxylate water reducer to silicate cement powder, mix well and dry to obtain modified cement powder; (4) Take the following raw materials: the recycled micropowder, the modified cement powder, fine aggregate, fly ash, fiber, and water reducer; mix the above raw materials evenly, add mixing water, and stir evenly to obtain a 3D printing cementitious material.

2. The process for preparing 3D printing gelling materials based on building recycled micropowder according to claim 1, characterized in that: In step (1), the nano aluminum powder accounts for 12-18% of the mass of the waste concrete powder.

3. The process for preparing 3D printing gelling materials based on building recycled micropowder according to claim 1, characterized in that: In step (1), the mechanical grinding time is 30-40 minutes; optionally, in step (1), the fineness of the pretreated powder is 200-300 mesh.

4. The process for preparing 3D printing gelling materials based on building recycled micropowder according to claim 1, characterized in that: In step (2), the microwave heating treatment time is 40-60 minutes, and the power is 500-700W.

5. The process for preparing 3D printing gelling materials based on building recycled micropowder according to claim 1, characterized in that: In step (2), the calcium stearate powder is 7-11% of the mass of the modified powder; Optionally, in step (2), the mechanical grinding time is 20 to 35 minutes; Optionally, in step (2), the fineness of the mixture is 350-450 mesh.

6. The process for preparing 3D printing gelling materials based on building recycled micropowder according to claim 1, characterized in that: In step (2), the ratio of the mixture to the anhydrous ethanol solution of sodium lactate is 1 g: 0.3-0.55 ml; Optionally, in step (2), the mass fraction of sodium lactate in the anhydrous ethanol solution is 1-2%; Optionally, in step (2), the drying temperature is 60-80° C., and the drying time is 10-15 minutes.

7. The process for preparing 3D printing gelling materials based on building recycled micropowder according to claim 1, characterized in that: In step (3), the ratio of the silicate cement powder to the anhydrous ethanol solution of the polycarboxylate water reducer is 1g:0.2~0.35ml.

8. The process for preparing 3D printing gelling materials based on building recycled micropowder according to claim 1, characterized in that: In step (3), the mass fraction of the polycarboxylate water-reducing agent in the anhydrous ethanol solution is 2-5%; optionally, in step (3), the drying temperature is 60-70° C., and the drying time is 10-20 min.

9. The process for preparing 3D printing gelling materials based on building recycled micropowder according to any one of claims 1 to 8, characterized in that: In step (4), the proportions of the raw materials are: 105-130 parts by weight of recycled micropowder, 40-55 parts by weight of modified cement powder, 310-360 parts by weight of fine aggregate, 20-35 parts by weight of fly ash, and 10-17 parts by weight of fiber; optionally, in step (4), the mixing water is added according to a water-cement ratio of 0.38-0.

43.

10. The process for preparing 3D printing gelling materials based on building recycled micropowder according to any one of claims 1 to 8, characterized in that: In step (4), the fiber includes: at least one of polyethylene fiber, polypropylene fiber, polyvinyl alcohol fiber, and basalt fiber; optionally, in step (4), the length of the fiber is 3 to 10 mm.

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