A 3D printing method for building materials with interlocking structures

Abstract

This invention discloses a 3D printing method for building materials with an interlocking structure. The method includes the following steps: preparing printing ink A, controlling the flow rate of ink A at 180-200 mm and the initial setting time at 110-140 minutes; using a concrete 3D printing device, printing several parallel strips of ink A on the top layer, with the center-to-center distance between adjacent strips being twice the width of the strip; filling the gaps between the top layer of ink A strips with ink B, and then printing over the top of the ink A strips; utilizing gravity above the ink A strips to compress and flow them; subsequently, filling the gaps between the top layer of ink B strips with ink A, and then printing over the top of the top layer of ink B strips; utilizing the structural deformation caused by the flow of ink A to achieve an interlocking concrete alternating 3D printed structure. This method can reduce defects at the interface between the two inks in the alternating concrete 3D printed structure and effectively optimize the microstructure and mechanical properties of the alternating printed product.

Description

Technical Field

[0001] This invention belongs to the field of functional building materials, and specifically relates to a 3D printing method for building materials with interlocking structures. Background Technology

[0002] To cope with complex and ever-changing construction environments, intelligent construction technologies, represented by 3D printing, have emerged. Compared with traditional construction processes, concrete 3D printing technology has advantages such as shorter construction time, better economy, more reasonable structure, and universal adaptability to various terrains, making it highly competitive.

[0003] However, most concrete 3D printing systems currently use a single type of printing ink. The shortcomings of this system are obvious: if cement is used as the printing ink, to meet the "early strength" and "fast hardening" requirements of 3D printing, more energy-intensive and polluting cement needs to be consumed, which contradicts the national development concept of "energy conservation and emission reduction"; if industrial solid wastes such as slag and fly ash are promoted as printing inks, although environmental pressure can be reduced, the ink performance may not meet actual construction needs.

[0004] To balance the conflicting demands of high-performance printing with energy conservation and environmental protection, researchers have developed an alternating 3D printing process using cement and industrial solid waste. This process allows for the optimal combination of performance in printed concrete structures. However, current alternating 3D printing techniques for concrete are still immature, leading to inconsistent shrinkage properties between the two materials and a tendency for cracking at the interface. Therefore, the mechanical properties and durability of currently produced alternating 3D printed concrete structures do not yet meet the demands of practical construction. Summary of the Invention

[0005] The purpose of this invention is to provide an interlocking alternating 3D printing method for building materials, which solves the problems of weak interfaces and low mechanical and durability properties in current alternating 3D concrete.

[0006] The technical solution to achieve the purpose of this invention is: a method for interlocking alternating 3D printing of building materials, comprising the following steps:

[0007] Step (1): Preparation of printing ink A and printing ink B: By adding a modifier, the flowability of printing ink A in the table test is 180-200 mm and the initial setting time is 110-140 minutes;

[0008] Step (2): Print several parallel ink lines A on the substrate, with the center-to-center distance between adjacent printed lines being twice the width of the printed line;

[0009] Step (3): Use ink B to print, fill the gaps in the ink A printing strip formed in step (2), and then use ink B to cover the printing strip of ink A. Under the gravity of the ink B printing strip, the ink A under the ink B printing strip flows, causing the position of the ink B printing strip to change accordingly.

[0010] Step (4): The gaps in the paper formed by the ink B printing strip in step (3) are filled by printing with ink A, and then the ink A printing strip is covered on top of the ink B printing strip. Because the deformation of ink A under the ink B printing strip causes the position of the ink B printing strip to change, thus forming an interlocking structure between adjacent printing layers.

[0011] Step (5): Repeat steps (2)-(4) until alternating printing is complete.

[0012] Furthermore, in step (1), printing ink A is alkali-activated slag or alkali-activated fly ash, and the modifier added when preparing printing ink A is a water-reducing agent, a retarder, or a combination of the above reagents; printing ink B is cement mortar.

[0013] Furthermore, the raw material composition for preparing alkali-activated slag is as follows: 2.5-3.0 kg of slag, 2.8-3.2 kg of standard sand, 0.25-0.35 kg of silica fume, 850-1000 g of water, 2-3 g of defoamer, 2-3 g of sodium gluconate retarder, the alkali activator containing 40-50 g of sodium hydroxide and 150-200 g of sodium silicate, and 50-70 g of UEA-type expanding agent.

[0014] Furthermore, the cement mortar slab test showed that the cement fluidity was 200±20mm and the initial setting time was 71±5min.

[0015] Furthermore, the raw material composition for preparing cement mortar is as follows: 2.5-3.0 kg of P·II 52.5 cement, 2.8-3.2 kg of standard sand, 0.25-0.35 kg of silica fume, 850-1000 g of water, 2-3 g of defoamer, 2.5-3.0 g of sodium gluconate retarder, and 2-3 g of high-efficiency water-reducing agent.

[0016] Furthermore, printing is performed using a printing device with two printing cylinders.

[0017] A building material with an interlocking structure is prepared using the method described above.

[0018] Compared with the prior art, the significant advantages of this invention are:

[0019] 1. The method described in this invention can achieve a tight bond between two building inks by simply adjusting the fluidity and setting time of the printing ink, thereby optimizing the interface between different materials in the alternating 3D printed concrete structure.

[0020] 2. This invention achieves the fusion of the same ink in adjacent layers through ink flow, and the resulting complete folded plate structure can also improve the mechanical and durability properties of alternating 3D printed concrete structures;

[0021] 3. This invention helps to improve alternating concrete 3D printing technology. It reduces the amount of cement used, which is highly polluting and energy-intensive, expands the application scope of industrial solid waste, and turns waste into treasure. Attached Figure Description

[0022] Figure 1 To form an interlocking alternating printed structural cross-section (UEA content is 2% of sand mass).

[0023] Figure 2 Cross-sectional view of an alternating printed structure without interlocking (UEA content is 0% of sand mass).

[0024] Figure 3 Cross-sectional view of an alternating printed structure without interlocking (UEA content is 5% of sand mass). Detailed Implementation

[0025] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments, but the scope of protection of the present invention is not limited thereto.

[0026] This invention discloses a method for interlocking alternating 3D printing of building materials. Specifically:

[0027] Step 1. Prepare the alkali-activated slag ink according to the designed mix proportions. Use 2.5-3.0 kg of slag produced by Jiangsu Jintu Construction Group Co., Ltd., 2.8-3.2 kg of standard sand conforming to ISO standards produced by Xiamen Aisiou, 0.25-0.35 kg of silica fume produced by Gansu Yuyang New Materials Co., Ltd., 850-1000 g of water, 2-3 g of defoamer, 2-3 g of sodium gluconate retarder, and an alkali activator containing 40-50 g of sodium hydroxide and 150-200 g of sodium silicate. To demonstrate the effect of the interlocking structure on the performance of alternating 3D printed concrete, add 60 g of UEA-type expansive agent produced by Jiangsu Tuoxiang New Building Materials Co., Ltd. to the alkali-activated slag to form an interlocking structure (denoted as U2); also prepare alkali-activated slag inks without UEA (denoted as U0) and with 150 g of UEA (denoted as U5). Through the table test, the flowability of U0, U2 and U5 was measured to be 200 mm, 180 mm and 160 mm, respectively, and the initial setting time was 88 min, 119 min and 135 min, respectively.

[0028] Step 2. Using a self-built concrete alternating 3D printing device (Invention Patent Publication No.: CN115256593A), add alkali-activated slag ink to the A barrel of the print head, and start the print head to print 7 parallel strips of alkali-activated slag ink on the bottom plate. The inner diameter of the print head is 20mm, and the center distance between adjacent print strips is 40mm.

[0029] Step 3. Prepare the printing cement mortar ink according to the designed mix proportions. Use 2.5-3.0 kg of P·II 52.5 cement produced by Nanjing Jiangnan Onoda Cement Co., Ltd., 2.8-3.2 kg of standard sand conforming to ISO standards produced by Xiamen Aisiou, 0.25-0.35 kg of silica fume produced by Gansu Yuyang New Materials Co., Ltd., 850-1000 g of water, 2-3 g of defoamer, 2.5-3.0 g of sodium gluconate retarder, and 2-3 g of high-efficiency water-reducing agent produced by Jiangsu Subote New Materials Co., Ltd. The flowability of the cement was measured to be 200 mm and the initial setting time to be 71 min through a jump table test.

[0030] Step 4. Using the self-built concrete alternation 3D equipment (invention patent publication number: CN115256593A), add cement mortar ink to the material cylinder of print head B, start the print head, print cement mortar ink along the gap of the uppermost alkali-activated slag print strip, and then cover the upper part of the alkali-activated slag print strip with printed cement mortar.

[0031] Step 5. Utilize the gravity of the cement above the slag to activate the alkali, causing the alkali-activated printing strip to flow, which in turn causes the position of the cement printing strip to change;

[0032] Step 6. Start print head A, fill the gaps of the top cement printing strip with alkali-activated slag, and then cover the top of the top cement mortar printing strip with alkali-activated slag; use the deformation of the alkali-activated slag below to cause the position of the cement printing strip to change.

[0033] Step 7. Repeat steps 4-6 until alternating printing is complete.

[0034] After 28 days of standard curing, the sample was cut to expose the cross-section of the alternating 3D-printed concrete. It was observed that group U2 exhibited a continuously bending cement layer and an alkali-activated slag layer, with the two ink layers interlocked (see...). Figure 1 In group U0 (where condensation is too rapid, see...) Figure 2 ) or U5 group (low fluidity, see Figure 3 None of them have formed a corresponding interlocking structure.

[0035] 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 preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for interlocking alternating 3D printing of building materials, characterized in that, Includes the following steps: Step (1): Prepare printing ink A and printing ink B: By adding a modifier, the flowability of printing ink A in the table test is 180-200 mm and the initial setting time is 110-140 min; printing ink B is cement mortar, and the flowability of cement mortar in the table test is 200±20 mm and the initial setting time is 71±5 min. Printing ink A is made from alkali-activated slag. The raw materials for preparing alkali-activated slag are as follows: 2.5-3.0 kg of slag, 2.8-3.2 kg of standard sand, 0.25-0.35 kg of silica fume, 850-1000 g of water, 2-3 g of defoamer, 2-3 g of sodium gluconate retarder, the alkali activator contains 40-50 g of sodium hydroxide and 150-200 g of sodium silicate, and 50-70 g of UEA-type expanding agent; Step (2): Print several parallel ink lines A on the substrate, with the center-to-center distance between adjacent printed lines being twice the width of the printed line; Step (3): Use ink B to print, fill the gaps in the ink A printing strip formed in step (2), and then use ink B to cover the printing strip of ink A. Under the gravity of the ink B printing strip, the ink A under the ink B printing strip flows, causing the position of the ink B printing strip to change accordingly. Step (4): The gap between the ink B printing strips formed in step (3) is filled with ink A, and then ink A printing strips are placed on top of the ink B printing strips. Because the deformation of ink A under the ink B printing strips causes the position of the ink B printing strips to change, thus forming an interlocking structure between adjacent printing layers. Step (5): Repeat steps (2)-(4) until alternating printing is complete.

2. The printing method according to claim 1, characterized in that, The raw materials for preparing cement mortar are as follows: 2.5-3.0 kg of P·II52.5 cement, 2.8-3.2 kg of standard sand, 0.25-0.35 kg of silica fume, 850-1000 g of water, 2-3 g of defoamer, 2.5-3.0 g of sodium gluconate retarder, and 2-3 g of high-efficiency water-reducing agent.

3. The printing method according to claim 2, characterized in that, Printing is performed using a printing device with two printing cylinders.

4. A building material with an interlocking structure, characterized in that, Prepared using the method described in any one of claims 1-3.

Images