3D-printed foam concrete composition and slurry, method of construction of a building structure

Abstract

The present application relates to a kind of 3D printing foam concrete composition and slurry, construction method of building structure, wherein 3D printing foam concrete composition, including powder and liquid material for mixing with powder;Powder includes by weight parts: Portland cement 50-80 parts, phosphorus slag 10-30 parts, carbide slag 10-30 parts, foaming agent 1-3 parts, foam stabilizer 1-2 parts and foaming catalyst 1-2 parts;Liquid material includes by weight parts: water 20-40 parts, water reducing agent 0.06-0.12 parts and thickening agent 0.3-0.7 parts.Its beneficial effect is that, after 3D printing foam concrete printing, its bubble stability is good, pore size distribution is uniform, to improve the printable performance of foam concrete material.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, and in particular to 3D printed foam concrete compositions and slurries, and construction methods for building structures. Background Technology

[0002] Concrete 3D printing technology is a new type of concrete construction process that has emerged in recent years, boasting high resource utilization, fast manufacturing speed, the ability to create complex geometries, and low overall cost. Foamed concrete, as an important component of green building materials, is highly favored by the construction industry. Foamed concrete is a microporous material formed by mixing and solidifying prepared foam groups, cement, admixtures, water, and other additives in a certain proportion. Foamed concrete has advantages such as lightweight, heat insulation, sound insulation, and stability, which can reduce the self-weight of buildings. Combining the emerging 3D printing technology with foamed concrete not only fully utilizes the inherent advantages of the materials but also enables the realization of complex design shapes.

[0003] However, existing foamed concrete has drawbacks after 3D printing, such as poor foam stability, uneven pore distribution, low compressive strength, and large shrinkage. These drawbacks make the printed material prone to deformation and cracking after placement, affecting the volume stability and durability of 3D printed components. At the same time, the raw material cost of existing 3D printed foamed concrete is generally high, which restricts the promotion and application of concrete 3D printing technology. Summary of the Invention

[0004] (a) Technical problems to be solved In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a 3D printed foam concrete composition and slurry, and a construction method for building structures, which solves the technical problems of poor foam stability, uneven pore distribution, low compressive strength, and large shrinkage of foam concrete after 3D printing.

[0005] (II) Technical Solution To achieve the above objectives, the main technical solutions adopted by the present invention include: In a first aspect, embodiments of the present invention provide a 3D printed foamed concrete composition, comprising powder and liquid for mixing with the powder; the powder comprises, by weight: 50-80 parts of silicate cement, 10-30 parts of phosphorus slag, 10-30 parts of carbide slag, 1-3 parts of foaming agent, 1-2 parts of foam stabilizer and 1-2 parts of foaming catalyst; the liquid comprises, by weight: 20-40 parts of water, 0.06-0.12 parts of water-reducing agent and 0.3-0.7 parts of thickener.

[0006] Preferably, the powder and liquid materials are packaged separately, and the powder and liquid materials are mixed and foamed during use to obtain 3D printed foam concrete.

[0007] In a preferred embodiment of the present invention, the mass ratio of phosphorus slag to carbide slag in the 3D printed foam concrete composition is 1-3:1-3; the total mass of phosphorus slag and carbide slag accounts for 40% of the total mass of phosphorus slag, carbide slag and silicate cement.

[0008] In a preferred embodiment of the present invention, the 3D printed foamed concrete composition is prepared by mixing and foaming powder and liquid materials to obtain 3D printed foamed concrete slurry with a water-cement ratio of 0.28-0.35. The water-cement ratio is the mass ratio of water to the total mass of P·II42.5 ordinary Portland cement, phosphorus slag, and carbide slag.

[0009] As a preferred embodiment of the present invention, the 3D printed foam concrete composition... In the powder, the foaming agent is solid hydrogen peroxide crystal powder, in which the H2O2 content is 30-35 wt%; the foaming catalyst is manganese dioxide catalyst, in which the MnO2 content is 20-25 wt%. The foam stabilizer is selected from one or more of sodium dodecylbenzene sulfonate, xanthan gum and calcium stearate, that is, the foam stabilizer is selected from at least one of anionic surfactants, biopolymer thickeners and nonionic surfactants; the silicate cement is P·II42.5 ordinary silicate cement.

[0010] In a preferred embodiment of the present invention, the 3D printed foamed concrete composition contains ordinary silicate cement with a particle size range of 5-50 μm and an average particle size of 14-15 μm. The particle size range of phosphorus slag is 5-100 μm, with an average particle size of 16-17.5 μm; The particle size range of carbide slag is 3-50 μm, with an average particle size of 6-7 μm.

[0011] In a preferred embodiment of the present invention, the 3D printed foamed concrete composition contains a water-reducing agent, which is a polycarboxylate water-reducing agent or a polyphosphoric acid water-reducing agent, and a thickener selected from hydroxypropyl methylcellulose ether or sodium carboxymethyl cellulose.

[0012] Secondly, embodiments of the present invention provide a method for preparing 3D printing foamed concrete slurry, comprising the following steps: S1, material preparation: weighing powder, wherein the powder comprises, by weight, 50-80 parts of silicate cement, 10-30 parts of phosphorus slag, 10-30 parts of carbide slag, 1-2 parts of foam stabilizer, and 1-2 parts of foaming catalyst, and mixing the powder; taking water according to a water-cement ratio of 0.28-0.35, and weighing 0.06-0.12 parts by weight of water-reducing agent, 0.3-0.7 parts by weight of thickener, and 1-3 parts by weight of foaming agent; S2. Mix water and water-reducing agent to obtain a mixture, then mix the mixture with the mixed powder to obtain a slurry. S3. Add the foaming agent to the slurry, mix well, foam, add thickener to adjust the viscosity, and obtain 3D printing foamed concrete slurry.

[0013] As a preferred embodiment of the present invention, in the preparation method of the 3D printing foam concrete slurry, in S2, the process of mixing the mixture and the powder is as follows: first, stir at 60-70 r / min for 120-180 s, and then stir at 125-130 r / min for 60-120 s. In S3, the process of mixing the foaming agent with the slurry is as follows: first stir at 60-70 r / min for 120-180 s, then stir at 125-130 r / min for 60-120 s.

[0014] Thirdly, embodiments of the present invention provide a construction method for a building structure, comprising the following steps: Step 1: The 3D printing foamed concrete slurry prepared by the preparation method according to any one of claims 7-8 is used to 3D print a building structure; Alternatively, the 3D printing foamed concrete composition according to any one of claims 1-6 can be used to make a 3D printing foamed concrete slurry, and then the building structure can be obtained by 3D printing. Step 2: The building structure is obtained by performing ordinary curing and carbonization curing on the building structure.

[0015] As a preferred embodiment of the present invention, in the construction method of the building structure, step 2, the ordinary curing conditions are: curing at room temperature for 24 hours. The carbonization curing conditions are as follows: use CO2 gas with a concentration of 18%-100% and cure for 3-14 days at 0-1.2MPa, 20-60℃ and relative humidity of 50%-70%.

[0016] (III) Beneficial Effects The beneficial effects of this invention are as follows: The 3D-printed foamed concrete composition and slurry, and the construction method of the building structure of this invention, based on silicate cement as the main material, use phosphate slag as an auxiliary raw material and carbide slag as an alkaline activator, and the three are used in a specific ratio. Among them, carbide slag provides an alkaline environment as a source of calcium hydroxide, and a large amount of calcium hydroxide can effectively promote the pozzolanic reaction involving phosphate slag in the foamed concrete system: calcium hydroxide reacts with the active silica and active alumina in the phosphate slag to produce a more dense and stable hydrated calcium aluminosilicate (C(A)SH). Simultaneously, a pozzolanic reaction also occurs between the phosphate slag and silicate cement, further enhancing the stability of the foamed concrete system. In addition, the active alumina in the phosphate slag reacts with the carbide slag to form ettringite, providing more products for carbonization during the later solidification process of the foamed concrete. Combining these factors, the strength and durability of the 3D-printed foamed concrete material are improved. Tests have shown that the 14-day strength of the specimens reaches approximately 17 MPa or higher, meeting the mechanical requirements of building components. Phosphate slag can also accelerate the carbonization rate of 3D-printed foamed concrete. By combining foaming agents and foaming catalysts, the application-end performance of 3D printing materials is optimized, resulting in good bubble stability and uniform pore size distribution after 3D printing of foamed concrete, thereby improving the printability of foamed concrete materials.

[0017] Adding 0.06-0.12 parts of water-reducing agent disperses particles through electrostatic repulsion and steric hindrance, significantly improving fluidity. The fluidity is generally within the 160-180mm range, ensuring the foamed concrete meets pumpability requirements. It can also be extruded uniformly and continuously from the printing nozzle, making it suitable for 3D printing. Adding 0.3-0.7 parts of thickener increases the slurry viscosity and imparts thixotropy, maintaining high viscosity at rest and decreasing viscosity under shear (e.g., during printing extrusion). Phosphate slag powder fills the interlayer interfaces, reducing porosity, while CSH gel penetrates to the lower layers, forming chemical bonds and enhancing interlayer adhesion. Overall, the foamed concrete material meets the requirements of 3D printing processes for fluidity, extrudability, setting time, and interlayer bonding, adapting to the extrusion, stacking, and rapid prototyping needs of 3D printing, enabling continuous printing and the construction of complex building structures.

[0018] Compared to existing technologies, this 3D-printed foamed concrete exhibits high stability and effective carbon sequestration. The corresponding 3D printing material boasts advantages such as good bubble stability, uniform pore size distribution, high concrete strength, low shrinkage, and excellent printability. The raw materials, phosphorus slag and calcium carbide slag, are both solid wastes, widely available, and low in cost. Their preparation method is simple, convenient, and easily industrialized.

[0019] The foaming agent is solid hydrogen peroxide crystal powder. The foaming agent is combined with the catalyst manganese dioxide to optimize the application performance of 3D printing materials. The foamed concrete made using solid hydrogen peroxide crystal powder has the advantages of good bubble stability, uniform pore size distribution, high concrete strength, low shrinkage, and good printability.

[0020] Ordinary silicate cement has a particle size of 0.62-420 μm, phosphorus slag has a particle size of 0.58-157 μm, and carbide slag has an average particle size of 10-30 μm, which is conducive to activating the active substances to participate in the reaction in an aqueous environment. A fiber-reinforced thickener is selected, which disperses stress through molecular chain entanglement and inhibits the propagation of cracks in foamed concrete. Attached Figure Description

[0021] Figure 1 The building structure prepared according to Embodiment 4 of the present invention. Detailed Implementation

[0022] To better explain and facilitate understanding of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] The 3D-printed foamed concrete composition, slurry, and construction method for building structures proposed in this invention address technical problems such as poor foam stability, uneven pore distribution, low compressive strength, and large shrinkage in 3D-printed foamed concrete. The 3D-printed foamed concrete composition, slurry, and construction method of this invention uses silicate cement as the main material, with phosphorus slag as an auxiliary raw material and carbide slag as an alkaline activator, and the three are used in a specific ratio. Specifically, carbide slag provides an alkaline environment as a calcium hydroxide source, and a large amount of calcium hydroxide effectively promotes the pozzolanic reaction involving phosphorus slag within the foamed concrete system: calcium hydroxide reacts with active silica and active alumina in the phosphorus slag to produce a more dense and stable hydrated calcium aluminosilicate (C(A)SH). Simultaneously, a pozzolanic reaction also occurs between the phosphorus slag and silicate cement, further enhancing the stability of the foamed concrete system. Furthermore, the active alumina in the phosphorus slag reacts with the calcium carbide slag to form ettringite, providing more carbonization products during the later solidification process of the foamed concrete. These factors combined improve the strength and durability of the 3D-printed foamed concrete material. Tests show that the 14-day strength of the specimens all exceeded 20 MPa, meeting the mechanical requirements of building components. Phosphorus slag can also accelerate the carbonization rate of 3D-printed foamed concrete. By combining foaming agents and foaming catalysts, the application-end performance of the 3D printing material is optimized, resulting in good bubble stability and uniform pore size distribution after printing, thus improving the printability of the foamed concrete material.

[0024] To better understand the above technical solutions, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the present invention can be understood more clearly and thoroughly, and that the scope of the present invention can be fully conveyed to those skilled in the art.

[0025] Example 1 This embodiment provides a 3D printed foamed concrete and its preparation method, specifically including the following steps: (1) Weigh the following powder components by weight: 60 parts of P·II42.5 ordinary silicate cement, 20 parts of phosphorus slag, 20 parts of carbide slag, 1 part of sodium dodecylbenzene sulfonate (foam stabilizer), 1 part of manganese dioxide (catalyst), and 0.5 parts of hydroxypropyl methylcellulose ether (thickener). Mix the above powder components and stir for 60-120 seconds to mix thoroughly to obtain a well-mixed powder. (2) Based on the quality of the powder, take water with a total mass ratio (water-cement ratio) of 0.3 for water to P·II42.5 ordinary Portland cement, phosphorus slag and carbide slag, and take 0.09 parts of polycarboxylate standard water-reducing agent to mix evenly in water to prepare a mixed solution; (3) Mix the well-mixed powder with the mixed solution in step (2), and stir in a mixer at 60 r / min for 120-180 s, then at 125 r / min for 60-120 s to fully mix and obtain a slurry; (4) Take 2.05 parts of solid hydrogen peroxide crystal powder (foaming agent, H2O2 content is 30%) and put it into the slurry obtained in (3). In the mixer, first stir at 60r / min for 120-180s, then stir at 125r / min for 60-120s to fully integrate the foaming agent and the slurry, and obtain the slurry system for 3D printed foam concrete.

[0026] The chemical composition of silicate cement, phosphate slag, and carbide slag in this embodiment was analyzed by X-ray fluorescence (XRF) and is shown in Table 1. Table 1 Chemical composition of silicate cement, phosphorus slag and carbide slag

[0027] Example 2 This embodiment provides a 3D printed foam concrete and its preparation method. The difference between this embodiment and embodiment 1 is that in step (1), there are 30 parts of phosphorus slag and 10 parts of carbide slag.

[0028] Example 3 This embodiment provides a 3D printed foamed concrete and its preparation method. The difference between this embodiment and embodiment 1 is that in step (1), there are 10 parts of phosphorus slag and 30 parts of carbide slag.

[0029] Example 4 This embodiment provides a construction method for a building structure, specifically including the following steps: (1) The slurry system of 3D printed foam concrete prepared in Example 1 was used for 3D printing to print a building structure; wherein, the 3D printing process parameters were: printing at a printing speed of 30 mm / s, a layer thickness of 1 mm, a line width of 1.5 mm and an extrusion pressure of 0.5 MPa, 40 layers were stacked one by one, and the printed sample size was a cubic structure of 40 mm × 40 mm × 40 mm. (2) The building structure was subjected to ordinary curing and carbonization curing. The ordinary curing conditions were: curing at room temperature for 24 hours; the carbonization curing conditions were: curing in a CO2 gas atmosphere with a concentration of 18%-100%, a curing pressure of 0-1.2 MPa, a curing temperature of 20-60℃, a curing humidity of 50%-70%, and a curing time of 14 days; the final product was obtained Figure 1 The building structure shown.

[0030] Example 5 This embodiment provides a construction method for a building structure. The difference between this embodiment and embodiment 4 is that in step (1), the slurry system of 3D printed foam concrete prepared in embodiment 2 is used for 3D printing to print the building structure. The remaining steps are the same as in embodiment 4.

[0031] Example 6 This embodiment provides a construction method for a building structure. The difference between this embodiment and embodiment 4 is that in step (1), the 3D printing foam concrete slurry system prepared in embodiment 3 is used for 3D printing to print the building structure. The remaining steps are the same as in embodiment 4.

[0032] Comparative Example 1 This comparative example provides a 3D printed foamed concrete and its preparation method. The difference between this comparative example and Example 1 is that in step (1), 40 parts of phosphorus slag are used, and no carbide slag is added. The remaining steps are the same as in Example 1.

[0033] Comparative Example 2 This comparative example provides a 3D printed foamed concrete and its preparation method. The difference between this comparative example and Example 1 is that in step (1), 20 parts of phosphorus slag are replaced with 20 parts of quartz and 20 parts of carbide slag. The remaining steps are the same as in Example 1.

[0034] Comparative Example 3 This comparative example provides a 3D printed foamed concrete and its preparation method. The difference between this comparative example and Example 1 is that in step (1), no phosphorus slag is added, and 40 parts of carbide slag are added. The remaining steps are the same as in Example 1.

[0035] Comparative Example 4 This comparative example provides a 3D printed foamed concrete and its preparation method. The difference between this comparative example and Example 1 is that in step (1), 20 parts of phosphorus slag are replaced with 20 parts of carbide slag. The remaining steps are the same as in Example 1.

[0036] Comparative Example 5 This comparative example provides a construction method for a building structure. The difference between this comparative example and Example 4 is that in step (1), the 3D printed foam concrete slurry system prepared in Comparative Example 1 is 3D printed to produce the building structure. The remaining steps are the same as in Example 4.

[0037] Comparative Example 6 This comparative example provides a construction method for a building structure. The difference between this comparative example and Example 4 is that in step (1), the slurry system of 3D printed foam concrete prepared in Comparative Example 2 is 3D printed to produce the building structure. The remaining steps are the same as in Example 4.

[0038] Comparative Example 7 This comparative example provides a construction method for a building structure. The difference between this comparative example and Example 4 is that in step (1), the 3D printing foam concrete slurry system prepared in Comparative Example 3 is 3D printed to produce the building structure. The remaining steps are the same as in Example 4.

[0039] Comparative Example 8 This comparative example provides a construction method for a building structure. The difference between this comparative example and Example 4 is that in step (1), the 3D printing foam concrete slurry system prepared in Comparative Example 4 is 3D printed to produce the building structure. The remaining steps are the same as in Example 4.

[0040] The compressive strength of the building structure specimens prepared in Examples 4, 5, and 6, and Comparative Examples 5, 6, 7, and 8 was tested according to ASTM C349 standard. The compressive strength of the three specimens was tested using a hydraulic press, and the average value was taken as the result. The compressive strength of the concrete specimens after testing is shown in Table 2.

[0041] The flowability of the slurry prepared in Examples 1, 2, 3 and Comparative Examples 1, 2, 3, 4 was tested, and the results are detailed in Table 3.

[0042] Porosity tests were conducted on the building structure specimens prepared in Examples 4, 5, and 6, as well as Comparative Examples 5, 6, 7, and 8. The test results are detailed in Table 3. Shrinkage tests were conducted in accordance with JGJ70-2009 "Test Methods for Basic Performance of Building Mortar". The test results are detailed in Table 3. Carbon fixation rate tests were conducted in accordance with "Calculation Method for Carbon Fixation Capacity of Building Concrete throughout its Life Cycle". The test results are detailed in Table 3.

[0043] Table 2 Compressive strength test results

[0044] Table 3 Test Results

[0045] Results analysis: Referring to Tables 2 and 3, Examples 1 and 4 are considered optimal embodiments. Comparison with Examples 5 and 6 corresponding to Examples 2 and 3 demonstrates that a 1:1 ratio of calcium carbide slag to phosphorus slag is optimal. The total mass of calcium carbide slag and phosphorus slag is approximately 2 / 3 of the mass of ordinary Portland cement, significantly reducing the use of energy-intensive raw materials like ordinary Portland cement. Furthermore, the calcium carbide slag and phosphorus slag are utilized as solid waste, making it economical and environmentally friendly.

[0046] Referring to Table 2, the compressive strength of the building structure prepared in Example 4 is higher than that in Comparative Example 5, indicating that the addition of carbide slag provides a good alkali activation effect. Furthermore, carbide slag can react with the active alumina in phosphorus slag to generate hydration products mainly composed of ettringite. The hydration products form and develop in the early stage, thereby improving the compressive strength of the building structure.

[0047] Referring to Table 2, Examples 4 and 6, it can be seen that when an equal amount of quartz is used to replace phosphorus slag, the compressive strength of the building structure prepared in Example 4 is higher than that in Comparative Example 6. This is because the addition of phosphorus slag not only accelerates the carbonization rate but also reacts with calcium hydroxide to form hydrated calcium aluminosilicate. Furthermore, the active alumina in the phosphorus slag reacts with carbide slag to form ettringite, providing more products for solidification and carbonization, ultimately improving the compressive strength of the building structure.

[0048] Referring to Table 2, the early compressive strength of Comparative Example 5 is less than that of Comparative Example 7, but the later compressive strength of Comparative Example 5 is significantly greater than that of Comparative Example 7. This is because the addition of phosphorus slag reduces the early heat of hydration and the amount of chemically bound water, slows down the rate of heat release during hydration, and has a retarding effect. The early hydration of cement is inhibited, which allows its crystal growth conditions to develop well, thereby significantly improving the quality of hydration products. The cement stone structure becomes denser, the porosity decreases, and the pore size becomes smaller, which is very beneficial to the development of the later strength of concrete, thus improving the later strength of concrete.

[0049] Referring to Table 2, it can be seen from Example 4 and Comparative Example 8 that the compressive strength of the building structure prepared in Example 4 is significantly higher than that in Comparative Example 8. That is, replacing carbide slag with quartz cannot achieve the same alkali activation effect as carbide slag. This further demonstrates that the addition of carbide slag activates the activity of phosphorus slag, producing a highly efficient pozzolanic effect. This generates a large amount of hydrated cementitious material that fills the pores, compensating for some of the drying shrinkage caused by pore water loss and improving the shrinkage of the concrete. Therefore, the compressive strength of the concrete is increased.

[0050] Referring to Table 3, the building structures prepared in Examples 4-6 exhibit better flowability, shrinkage rate, cumulative carbon fixation rate, and porosity than those in Comparative Examples 5-8. The reaction between carbide slag and phosphorus slag improves the compressive strength of the building structures. Furthermore, the combined action of water, water-reducing agent, and thickener in the foamed concrete ensures that the foamed concrete slurry meets the requirements of 3D printing processes for flowability, extrudability, setting time, and interlayer bonding. This adapts to the demands of extrusion, stacking, and rapid prototyping, enabling continuous printing and the construction of complex structures.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A 3D-printed foamed concrete composition, characterized in that, This includes powders and liquids used to mix with the powders; The powder comprises, by weight: 50-80 parts silicate cement, 10-30 parts phosphorus slag, 10-30 parts calcium carbide slag, 1-3 parts foaming agent, 1-2 parts foam stabilizer, 1-2 parts foaming catalyst, and 0.3-0.7 parts thickener; The liquid material includes, by weight: 20-40 parts water and 0.06-0.12 parts water-reducing agent; The mass ratio of phosphorus slag to calcium carbide slag is 1-3:1-3; The total mass of phosphorus slag and calcium carbide slag accounts for 40% of the total mass of phosphorus slag, calcium carbide slag and silicate cement. In the powder, the foaming agent is solid hydrogen peroxide crystal powder, and the foaming catalyst is manganese dioxide catalyst; The 3D printing foamed concrete slurry is prepared by mixing and foaming powder and liquid materials, with a water-cement ratio of 0.28-0.

35.

2. The 3D-printed foamed concrete composition as described in claim 1, characterized in that, The H2O2 content in solid hydrogen peroxide crystal powder is 30-35 wt%. In the manganese dioxide catalyst, the MnO2 content is 20-25 wt%; The foam stabilizer is selected from one or more of sodium dodecylbenzene sulfonate, xanthan gum, and calcium stearate; The silicate cement is P·II42.5 silicate cement.

3. The 3D-printed foamed concrete composition as described in claim 2, characterized in that, The particle size range of silicate cement is 5-50 μm, with an average particle size of 14-15 μm; The particle size range of phosphorus slag is 5-100 μm, with an average particle size of 16-17.5 μm; The particle size range of carbide slag is 3-50 μm, with an average particle size of 6-7 μm.

4. The 3D-printed foamed concrete composition as described in claim 1, characterized in that, In the liquid material, the water-reducing agent is a polycarboxylate water-reducing agent or a polyphosphoric acid water-reducing agent; the thickener is selected from hydroxypropyl methylcellulose ether or sodium carboxymethyl cellulose.

5. A method for preparing 3D printed foamed concrete slurry, characterized in that, Includes the following steps: S1. Material preparation: Weigh out the powder, which contains 50-80 parts by weight of silicate cement, 10-30 parts of phosphorus slag, 10-30 parts of carbide slag, 1-2 parts of foam stabilizer, 1-2 parts of foaming catalyst and 0.3-0.7 parts of thickener, and mix the powder well. The mass ratio of phosphorus slag to calcium carbide slag is 1-3:1-3; The total mass of phosphorus slag and calcium carbide slag accounts for 40% of the total mass of phosphorus slag, calcium carbide slag and silicate cement. The foaming catalyst is a manganese dioxide catalyst; Take water at a water-cement ratio of 0.28-0.35, and weigh out 0.06-0.12 parts by weight of water-reducing agent and 1-3 parts by weight of foaming agent; The foaming agent is a solid hydrogen peroxide crystal powder; S2. Mix water and water-reducing agent to obtain a mixture, then mix the mixture with the mixed powder to obtain a slurry. S3. Add the foaming agent to the slurry, mix well, foam, and obtain 3D printing foamed concrete slurry.

6. The method for preparing 3D printed foamed concrete slurry as described in claim 5, characterized in that, In S2, the process of mixing the liquid and powder is as follows: first stir at 60-70 r / min for 120-180 s, then stir at 125-130 r / min for 60-120 s. In S3, the process of mixing the foaming agent with the slurry is as follows: first stir at 60-70 r / min for 120-180 s, then stir at 125-130 r / min for 60-120 s.

7. A construction method for a building structure, characterized in that, Includes the following steps: Step 1: The 3D printing foamed concrete slurry prepared by the preparation method according to any one of claims 5-6 is used to 3D print a building structure; Alternatively, the 3D printing foamed concrete composition according to any one of claims 1-4 can be used to make a 3D printing foamed concrete slurry, which is then 3D printed to obtain a building structure. Step 2: The building structure is obtained by performing ordinary curing and carbonization curing on the building structure.

8. The construction method for the building structure according to claim 7, characterized in that, In step 2, the normal curing conditions are: curing at room temperature for 24 hours; The carbonization curing conditions are as follows: use CO2 gas with a concentration of 18%-100% and cure for 3-14 days at 0-1.2MPa, 20-60℃ and relative humidity of 50%-70%.

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