High-performance 3D printing concrete material and preparation method thereof

Abstract

The invention provides a high-performance 3D printing concrete material. The high-performance 3D printing concrete material is prepared from the following raw materials in parts by weight: 100 parts of ordinary Portland cement, 1-5 parts of quick-hardening sulphoaluminate cement, 20-25 parts of silica fume, 60-70 parts of solid waste regenerated sand, 40-45 parts of solid waste regenerated stone, 45-50 parts of water, 0.1-0.5 part of a super plasticizer, 0.001-0.005 part of silica sol, 0.001-0.005 part of hydroxypropyl methyl cellulose and 1-5 parts of polypropylene fiber. The invention also provides a preparation method of the high-performance 3D printing concrete material. The high-performance 3D printing concrete material provided by the invention can meet the requirements of 3D printing on high strength and good pumpability, extrudability and constructability of the concrete material.

Description

Technical Field

[0001] The present invention relates to 3D printing materials, and particularly to a high-performance 3D printing concrete material based on solid waste recycled sand and gravel and a preparation method thereof. Background Art

[0002] 3D printing (3DP) is a kind of rapid prototyping technology, also known as additive manufacturing. It is a technology that constructs an object by layer-by-layer printing using powdery metals, plastics, concrete and other bondable materials based on a 3D model file. Its main features include rapid prototyping, reduced material waste, no need for formwork, high design freedom, and can significantly reduce carbon emissions. It is an innovative, environmentally friendly and efficient new component manufacturing method.

[0003] 3D printing ink refers to the bondable material used to print and form components in 3D printing technology. 3D printing concrete is one of them. Suitable 3D printing concrete needs to have appropriate fluidity, buildability, interlayer bond strength and setting time. Transforming the rheological properties and setting properties of traditional concrete into 3D printing concrete (3DPC) requires overcoming the following specific technical problems:

[0004] Pumpability, ensuring that the concrete can be transported by a pumpable feeding method, so there are certain requirements for the segregation resistance performance and pumping viscosity of 3DPC.

[0005] Extrudability, an ideal 3DPC needs to have viscoplastic Bingham fluid characteristics, that is, the shear thinning characteristics of the fluid, which is beneficial to the flow extrusion of 3DPC at the print head and the shaping of the stationary material.

[0006] Buildability (Buildability, Constructability), during the process of 3D printing layer-by-layer stacking, in order to ensure that the stacked materials remain stable and do not collapse during long-term printing, the lower-layer concrete should be promptly set and hardened. It should be noted that the setting and hardening time should be kept within an appropriate range, otherwise the window time for the mixing pot and the material transportation process is insufficient, resulting in printing failure.

[0007] In summary, the three concepts of pumpability, extrudability and buildability are combined into printability.

[0008] With the continuous development of 3D printing technology in the construction field, higher requirements are put forward for the performance of concrete materials. 3D printing concrete not only needs to have high strength to meet the load-bearing requirements of complex building structures, but also needs to have good workability, including pumpability, extrudability and constructability, to ensure the smooth progress of the printing process. In this context, the application of solid waste recycled materials has received extensive attention. Using recycled materials such as solid waste manufactured sand to prepare 3D printing concrete can not only effectively solve the problem of insufficient strength of traditional concrete materials, but also reduce production costs, reduce dependence on natural resources, and at the same time reduce environmental pollution and achieve sustainable development. This innovative material solution brings new opportunities to the construction industry and promotes the wider application of 3D printing technology in the construction field.

[0009] Existing technologies improve the performance of 3D printing concrete by adjusting the concrete mix ratio, adding admixtures, etc., but there are the following deficiencies:

[0010] 1) Compared with 3D printing mortar, the apparent quality of 3D printing concrete is usually worse. Sand, as fine aggregate, provides a more delicate and beautiful texture for the surface of the paste. Adding coarse aggregate will cause a sharp increase in the number of cavities (>1mm) and air bubbles on the surface of the fresh concrete paste. At the design level, the finished building components designed according to the traditional dry-hard concrete for printing ink have low density, and the structural durability has obvious disadvantages compared with the traditional cast-in-place structure. Concrete with good self-compacting performance usually has high fluidity and cannot be used for 3D printing. And the concrete with good stackability needs to be fully vibrated to ensure the denseness of the paste, while the 3D printing forming process has the characteristic of "non-vibratable", resulting in extremely low surface quality of 3D printing concrete on the market.

[0011] 2) 3D printing materials pay too much attention to printing workability and surface quality, and the final strength of the printed components is low.

[0012] 3) The utilization of solid waste recycled materials is not sufficient, which affects the economy and environmental protection of the materials.

[0013] 4) In terms of workability, it is difficult to simultaneously meet pumpability, extrudability and constructability, which affects printing efficiency and quality. Summary of the Invention

[0014] The technical problem to be solved by the present invention is to provide a high-performance 3D printing concrete material that can meet the requirements of 3D printing for high strength of concrete materials and good pumpability, extrudability and constructability.

[0015] To solve the above technical problems, the technical solution of the present invention is:

[0016] A high-performance 3D printing concrete material is made from the following raw materials by weight: 100 parts of ordinary Portland cement, 1 - 5 parts of rapid hardening sulphoaluminate cement, 20 - 25 parts of silica fume, 60 - 70 parts of solid waste recycled sand, 40 - 45 parts of solid waste recycled stone, 45 - 50 parts of water, 0.1 - 0.5 parts of superplasticizer, 0.001 - 0.005 parts of silica sol, 0.001 - 0.005 parts of hydroxypropyl methylcellulose, and 1 - 5 parts of polypropylene fiber.

[0017] Among them, the solid waste recycled sand / solid waste recycled stone is sand / stone made by processing solid waste. The main raw materials include construction waste and industrial waste residue. The production process includes steps such as crushing, screening, cleaning, and drying. Its particle shape is regular, the gradation is reasonable, the strength is relatively high, and it has good environmental protection.

[0018] Further, the ordinary Portland cement in the present invention is P·O 42.5 cement.

[0019] Further, the rapid hardening sulphoaluminate cement in the present invention is R.SAC 42.5 cement.

[0020] Further, the particle size of the silica fume in the present invention is 100 - 300 μm.

[0021] Further, the particle size of the solid waste recycled sand in the present invention is 0.075 mm - 4.75 mm.

[0022] Further, the particle size of the solid waste recycled stone in the present invention is 4.75 mm - 9.5 mm.

[0023] Further, the superplasticizer in the present invention is polycarboxylate water-reducing powder.

[0024] Further, the particle size of the colloidal particles of the silica sol in the present invention is 10 - 100 nm.

[0025] Further, the length of the polypropylene fiber in the present invention is 5 - 10 mm, and the diameter is 50 - 100 μm.

[0026] Another technical problem to be solved by the present invention is to provide a preparation method of the above high-performance 3D printing concrete material.

[0027] To solve the above technical problems, the technical solution is:

[0028] A preparation method of a high-performance 3D printing concrete material includes the following steps:

[0029] S1. Weigh each raw material by weight. Add ordinary Portland cement, rapid hardening sulphoaluminate cement, silica fume, solid waste recycled sand, solid waste recycled stone, water, silica sol, and polypropylene fiber into a mixer, and stir at a stirring speed of 200 - 400 revolutions per minute for 4 - 6 minutes to obtain the first mixture;

[0030] S2. Add a superplasticizer into the first mixture obtained in step S1, and stir at a stirring speed of 200 - 400 revolutions per minute for 4 - 6 minutes to obtain the second mixture;

[0031] S3. Add hydroxypropyl methylcellulose into the second mixture obtained in step S2, and stir at a stirring speed of 500 - 700 revolutions per minute for 8 - 10 minutes to obtain a high - performance 3D printing concrete material.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] (1) The present invention proposes a 3D printing concrete material based on solid waste recycled sand / stone, and its advantages lie in good printability and excellent apparent quality. The present invention forms a dense microstructure through the combination of ordinary Portland cement, rapid hardening sulphoaluminate cement, silica fume, solid waste recycled sand, solid waste recycled stone, water, and silica sol, improving the mechanical properties and apparent quality of the material. At the same time, the addition of a superplasticizer and hydroxypropyl methylcellulose improves the workability of the concrete, making it have good pumpability, extrudability, and constructability, and can meet the requirements of continuous 3D printing.

[0034] (2) The present invention makes full use of solid waste recycled materials, reduces the consumption of natural resources, and reduces environmental pollution, which is in line with the concept of sustainable development.

[0035] (3) The present invention reduces the material cost while ensuring performance through reasonable mix design, and has good economic benefits.

[0036] (4) The silica sol used in the present invention can effectively improve the mechanical properties and durability of the material, and the polypropylene fiber can effectively improve the splitting tensile strength and toughness of the material. Specific Embodiments

[0037] The following will specifically describe the present invention with reference to specific embodiments. Here, the illustrative embodiments of the present invention and their descriptions are used to explain the present invention, but not to limit the present invention.

[0038] Example 1

[0039] High-performance 3D printing concrete material is made from the following raw materials by weight: 100 parts of ordinary Portland cement, 3 parts of rapid hardening sulphoaluminate cement, 23 parts of silica fume, 65 parts of solid waste recycled sand, 42 parts of solid waste recycled stone, 48 parts of water, 0.3 part of superplasticizer, 0.003 part of silica sol, 0.003 part of hydroxypropyl methylcellulose, and 3 parts of polypropylene fiber. Among them, the ordinary Portland cement is P·O 42.5 cement; the rapid hardening sulphoaluminate cement is R.SAC 42.5 cement; the particle size of the silica fume is 100 - 300 μm; the particle size of the solid waste recycled sand is 0.075 mm - 4.75 mm; the particle size of the solid waste recycled stone is 4.75 mm - 9.5 mm; the superplasticizer is polycarboxylate water reducing powder; the particle size of the colloidal particles of the silica sol is 10 - 100 nm; the length of the polypropylene fiber is 5 - 10 mm, and the diameter is 50 - 100 μm.

[0040] The preparation method of Example 1 includes the following steps:

[0041] S1. Weigh each raw material by weight, add the ordinary Portland cement, rapid hardening sulphoaluminate cement, silica fume, solid waste recycled sand, solid waste recycled stone, water, silica sol, and polypropylene fiber into a mixer, and stir at a speed of 300 revolutions per minute for 5 minutes to obtain mixture one;

[0042] S2. Add the superplasticizer into mixture one obtained in step S1, and stir at a speed of 300 revolutions per minute for 5 minutes to obtain mixture two;

[0043] S3. Add the hydroxypropyl methylcellulose into mixture two obtained in step S2, and stir at a speed of 600 revolutions per minute for 9 minutes to obtain the high-performance 3D printing concrete material.

[0044] Example 2

[0045] High-performance 3D printing concrete material is made from the following raw materials by weight: 100 parts of ordinary Portland cement, 5 parts of rapid hardening sulphoaluminate cement, 25 parts of silica fume, 70 parts of solid waste recycled sand, 45 parts of solid waste recycled stone, 50 parts of water, 0.5 part of superplasticizer, 0.005 part of silica sol, 0.005 part of hydroxypropyl methylcellulose, and 5 parts of polypropylene fiber. Among them, the ordinary Portland cement is P·O 42.5 cement; the rapid hardening sulphoaluminate cement is R.SAC 42.5 cement; the particle size of the silica fume is 100 - 300 μm; the particle size of the solid waste recycled sand is 0.075 mm - 4.75 mm; the particle size of the solid waste recycled stone is 4.75 mm - 9.5 mm; the superplasticizer is polycarboxylate water reducing powder; the particle size of the colloidal particles of the silica sol is 10 - 100 nm; the length of the polypropylene fiber is 5 - 10 mm, and the diameter is 50 - 100 μm.

[0046] The preparation method of Example 2 includes the following steps:

[0047] S1. Weigh each raw material by weight parts. Add ordinary Portland cement, rapid hardening sulphoaluminate cement, silica fume, solid waste recycled sand, solid waste recycled stone, water, silica sol, and polypropylene fiber into a mixer, and stir for 4 minutes at a stirring speed of 400 revolutions per minute to obtain mixture one;

[0048] S2. Add a superplasticizer into mixture one obtained in step S1, and stir for 4 minutes at a stirring speed of 400 revolutions per minute to obtain mixture two;

[0049] S3. Add hydroxypropyl methylcellulose into mixture two obtained in step S2, and stir for 8 minutes at a stirring speed of 700 revolutions per minute to obtain a high-performance 3D printing concrete material.

[0050] Example 3

[0051] The high-performance 3D printing concrete material is made from the following raw materials by weight parts: 100 parts of ordinary Portland cement, 4 parts of rapid hardening sulphoaluminate cement, 24 parts of silica fume, 68 parts of solid waste recycled sand, 44 parts of solid waste recycled stone, 47 parts of water, 0.4 part of superplasticizer, 0.004 part of silica sol, 0.004 part of hydroxypropyl methylcellulose, and 4 parts of polypropylene fiber. Among them, the ordinary Portland cement is P·O 42.5 cement; the rapid hardening sulphoaluminate cement is R.SAC 42.5 cement; the particle size of the silica fume is 100 - 300 μm; the particle size of the solid waste recycled sand is 0.075 mm - 4.75 mm; the particle size of the solid waste recycled stone is 4.75 mm - 9.5 mm; the superplasticizer is a polycarboxylate water-reducing powder; the particle size of the silica sol colloidal particles is 10 - 100 nm; the length of the polypropylene fiber is 5 - 10 mm, and the diameter is 50 - 100 μm.

[0052] The preparation method of Example 3 includes the following steps:

[0053] S1. Weigh each raw material by weight parts. Add ordinary Portland cement, rapid hardening sulphoaluminate cement, silica fume, solid waste recycled sand, solid waste recycled stone, water, silica sol, and polypropylene fiber into a mixer, and stir for 6 minutes at a stirring speed of 300 revolutions per minute to obtain mixture one;

[0054] S2. Add a superplasticizer into mixture one obtained in step S1, and stir for 6 minutes at a stirring speed of 300 revolutions per minute to obtain mixture two;

[0055] S3. Add hydroxypropyl methylcellulose into mixture two obtained in step S2, and stir for 10 minutes at a stirring speed of 600 revolutions per minute to obtain a high-performance 3D printing concrete material.

[0056] Example 4

[0057] High-performance 3D printing concrete materials are made from the following raw materials by weight: 100 parts of ordinary Portland cement, 1 part of rapid hardening sulphoaluminate cement, 20 parts of silica fume, 60 parts of solid waste recycled sand, 40 parts of solid waste recycled stone, 45 parts of water, 0.1 part of superplasticizer, 0.001 part of silica sol, 0.001 part of hydroxypropyl methylcellulose, and 1 part of polypropylene fiber. Among them, the ordinary Portland cement is P·O 42.5 cement; the rapid hardening sulphoaluminate cement is R.SAC 42.5 cement; the particle size of silica fume is 100-300μm; the particle size of solid waste recycled sand is 0.075mm-4.75mm; the particle size of solid waste recycled stone is 4.75mm-9.5mm; the superplasticizer is polycarboxylate water reducing powder; the particle size of the colloidal particles of silica sol is 10-100nm; the length of the polypropylene fiber is 5-10mm, and the diameter is 50-100μm.

[0058] The preparation method of Example 4 includes the following steps:

[0059] S1. Weigh each raw material by weight, add ordinary Portland cement, rapid hardening sulphoaluminate cement, silica fume, solid waste recycled sand, solid waste recycled stone, water, silica sol, and polypropylene fiber to a mixer, and stir at a speed of 200 revolutions per minute for 6 minutes to obtain Mixing material one;

[0060] S2. Add the superplasticizer to the mixing material one obtained in step S1, and stir at a speed of 200 revolutions per minute for 6 minutes to obtain Mixing material two;

[0061] S3. Add hydroxypropyl methylcellulose to the mixing material two obtained in step S2, and stir at a speed of 500 revolutions per minute for 10 minutes to obtain high-performance 3D printing concrete materials.

[0062] Comparative Example 1

[0063] The difference from Example 1 is that the raw materials do not contain superplasticizer.

[0064] Comparative Example 2

[0065] The difference from Example 1 is that the raw materials do not contain silica sol.

[0066] Comparative Example 3

[0067] The difference from Example 1 is that the raw materials do not contain hydroxypropyl methylcellulose.

[0068] Comparative Example 4

[0069] The difference from Example 1 is that the raw materials do not contain polypropylene fiber.

[0070] Experimental Example 1: Workability test

[0071] Referring to TJG F1001—2011 Technical Specification for Design and Construction of Cast-in-situ Foamed Lightweight Soil Subgrade, a cylindrical mold with a height of 800 mm and a diameter of 10 mm was used. The prepared 3D printed concrete materials (Examples 1-4, Comparative Example 1, Comparative Example 3) were poured into the cylindrical mold. After scraping flat with a spatula, it was quickly lifted vertically within 2 seconds. The remaining cylindrical height after 1 minute was measured using a vernier caliper, accurate to 0.1 mm.

[0072] The larger the remaining cylindrical height, the better the workability. The test results are shown in Table 1:

[0073] Remaining cylinder height (mm) Example 1 78 Example 2 82 Example 3 80 Example 4 73 Comparative Example 1 65 Comparative Example 3 68

[0074] Table 1

[0075] As can be seen from Table 1, the remaining cylindrical heights of Examples 1-4 of the present invention are all relatively large, indicating that the 3D printed concrete materials prepared by the present invention have good workability. Some of the raw materials used in Comparative Examples 1 and 3 are different from those in Example 1. Compared with Example 1, the remaining cylindrical heights of Comparative Examples 1 and 3 have both decreased, indicating that the superplasticizer and hydroxypropyl methylcellulose used in the present invention can effectively improve the workability of 3D printed concrete materials.

[0076] Experimental Example 2: Compressive Strength Test

[0077] Referring to GB / T 50081-2019 Standard for Test Methods of Physical and Mechanical Properties of Concrete, the compressive strengths of the prepared 3D printed concrete materials (Examples 1-4, Comparative Example 2) were measured respectively. The test conditions were as follows: the temperature was 20 °C, the relative air humidity was 55-62%, the curing condition was standard curing, the curing time was 28 d, and the specimen size was 150 mm × 150 mm × 150 mm.

[0078] The test results are shown in Table 2:

[0079] Compressive strength (MPa) Example 1 33.3 Example 2 36.4 Example 3 34.8 Example 4 30.9 Comparative Example 2 28.2

[0080] Table 2

[0081] As can be seen from Table 2, the compressive strengths of Examples 1-4 of the present invention are all relatively high, indicating that the 3D printed concrete materials prepared by the present invention have good mechanical properties. Some of the raw materials used in Comparative Example 2 are different from those in Example 1. Compared with Example 1, the compressive strength of Comparative Example 2 has decreased significantly, indicating that the silica sol used in the present invention can effectively improve the mechanical properties of 3D printed concrete materials.

[0082] Experimental Example 3: Splitting Tensile Strength Test

[0083] Refer to GB / T 50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete" to measure the splitting tensile strength of the prepared 3D printed concrete materials (Examples 1-4, Comparative Example 4) respectively. Test conditions: temperature is 20°C, relative air humidity is 55-62%, curing condition is standard curing, curing time is 28 days, and the specimen size is 150mm×150mm×150mm.

[0084] The test results are shown in Table 3:

[0085] Splitting tensile strength (MPa) Example 1 3.4 Example 2 3.9 Example 3 3.7 Example 4 3.1 Comparative Example 4 2.5

[0086] Table 3

[0087] It can be seen from Table 3 that the splitting tensile strengths of Examples 1-4 of the present invention are all relatively high. Some of the raw materials used in Comparative Example 4 are different from those in Example 1. Compared with Example 1, the splitting tensile strength of Comparative Example 4 is significantly reduced, indicating that the polypropylene fiber used in the present invention can effectively improve the splitting tensile strength of 3D printed concrete materials.

[0088] The above embodiments only illustratively explain the principles and effects of the present invention, rather than limiting the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A high-performance 3D printing concrete material, characterized by: The invention is made of the following raw materials in parts by weight: 100 parts of ordinary Portland cement, 1-5 parts of fast-hardening sulphoaluminate cement, 20-25 parts of silica fume, 60-70 parts of solid waste regenerated sand, 40-45 parts of solid waste regenerated stone, 45-50 parts of water, 0.1-0.5 parts of superplasticizer, 0.001-0.005 parts of silica sol, 0.001-0.005 parts of hydroxypropyl methylcellulose and 1-5 parts of polypropylene fiber.

2. A high performance 3D printing concrete material according to claim 1, characterized in that: The ordinary Portland cement is P·O42.5 cement.

3. A high performance 3D printing concrete material according to claim 1, characterized in that: The rapid hardening sulphoaluminate cement is R.SAC42.5 cement.

4. The high performance 3D printing concrete material according to claim 1, characterized in that: The particle size of the silica fume is 100-300 μm.

5. The high performance 3D printing concrete material according to claim 1, characterized in that: The particle size of the solid waste regenerated sand is 0.075mm-4.75mm.

6. A high performance 3D printing concrete material according to claim 1, characterized in that: The particle size of the solid waste regenerated stone is 4.75mm-9.5mm.

7. The high performance 3D printing concrete material according to claim 1, characterized in that: The superplasticizer is polycarboxylic acid water reducing powder.

8. The high performance 3D printing concrete material according to claim 1, characterized in that: The colloidal particles of the silica sol have a particle size of 10-100 nm.

9. The high performance 3D printing concrete material according to claim 1, characterized in that: The polypropylene fiber has a length of 5-10 mm and a diameter of 50-100 μm.

10. A method for preparing a high-performance 3D printing concrete material according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1. Weigh the raw materials in parts by weight, add ordinary Portland cement, fast-hardening sulphoaluminate cement, silica fume, solid waste regenerated sand, solid waste regenerated stone, water, silica sol, polypropylene fiber to a mixer, and stir at a stirring speed of 200-400 rpm for 4-6 minutes to obtain a mixture; S2. The superplasticizer is added to the mixture obtained in step S1, and stirred at a stirring speed of 200-400 rpm for 4-6 minutes to obtain a mixture II; S3. Add hydroxypropyl methylcellulose to the mixture 2 obtained in step S2, and stir at a stirring speed of 500-700 rpm for 8-10 minutes to obtain a high-performance 3D printing concrete material.