Interface reinforcing agent based on 3D printing cement-based material and application of interface reinforcing agent in 3D printing cement-based material

Abstract

The invention discloses an interface reinforcing agent based on a 3D printing cement-based material and application of the interface reinforcing agent in the 3D printing cement-based material. The interface reinforcing agent comprises cement, nano silicon dioxide, EVA redispersible latex powder, POM polyformaldehyde fibers, mixing water, a water reducing agent and a retarder, the selection of the cement is consistent with the selection of cement in a 3D printing cement-based material, and ordinary Portland cement is preferably selected. The strength grade of the cement is consistent with the strength grade of the cement in the 3D printing cement-based material; the interface reinforcing agent is applied to a 3D printing cement-based material. By adopting the interface reinforcing agent disclosed by the invention, the problems of weak later strength, poor durability and the like caused by interface hole defects formed by a printing process in 3D printing can be effectively solved, and a certain reference value is provided for prolonging the service life of 3D printing concrete in different application scenes.

Description

Technical Field

[0001] This invention relates to the field of 3D printing materials technology, specifically to an interface enhancer for 3D printing cement-based materials and its application in 3D printing cement-based materials. Background Technology

[0002] 3D printing, a technology in additive manufacturing, is a three-dimensional printing technology based on digital models and utilizing the constructibility of the materials themselves. It achieves layer-by-layer construction through an extrusion process. As a novel construction technique, this technology can effectively reduce construction waste by 30-60%, shorten construction time by 50-70%, and save 50-80% of labor costs, and has received widespread attention and research in recent years.

[0003] In the layered deposition of 3D printed cement-based materials, the interlayer structures are affected by factors such as the printing window time, printing process parameters, and printing materials. This means that the stability between layers cannot be maintained under machine, software, or human control, leading to problems during the printing process and causing mechanical discontinuities in the printed structure. If this interruption time is much longer than the interval time, the resulting weak interfaces have a significant negative impact on the mechanical and durability properties of the structure. Furthermore, due to the lack of vibration compaction, the loose deposition between the interfaces further degrades the overall performance of the 3D printed part. The anisotropy inherent in the 3D printing material also enhances the instability of the printed specimen. Therefore, improving the interface strength is particularly important.

[0004] Researchers have made various attempts to improve the shortcomings of the printing interface.

[0005] For example, patent CN112759350B discloses an interlayer reinforcing binder for ettringite whiskers used in 3D printing and its application method. It utilizes N(C)-ASH gel generated from desulfurized gypsum, fly ash, and steel slag, along with ettringite whiskers. The gel-whisker combination provides interface strength, supplementing the strength of weak interlayer surfaces and reducing moisture evaporation caused by excessively long printing intervals. However, due to the influence of alkali-activated cementitious materials, the material's early setting and hardening rate is accelerated, and its performance is unstable, affecting later crack resistance and durability.

[0006] Patent CN115677382 discloses an interface reinforcing agent for 3D printed concrete, which uses nano-silica and hemihydrate gypsum whiskers to improve the bonding ability and interlayer density between interfaces. However, due to the poor stability of hemihydrate gypsum whiskers, it is necessary to stabilize the hemihydrate gypsum whiskers with sodium oleate, citric acid, sodium citrate, KH-550 and sodium phosphate, which increases the complexity of the experimental process.

[0007] The patent CN111331705B describes an apparatus and method for inducing fiber-reinforced 3D printing of concrete. This method involves incorporating composite fibers, namely one or more of steel fibers, organic fibers, and inorganic fibers, and using an electromagnet or universal adjuster to adjust the arrangement and direction of the steel fibers to achieve interface reinforcement. However, this method has a relatively complex processing flow, and incorporating multiple fibers into the printing slurry can have a certain impact on its extrudability.

[0008] Patent CN109020369B describes a concrete material and preparation method for 3D printing. The method improves the bonding strength between cementitious materials by spraying or brushing hot-melt epoxy resin adhesive at the interface. The hot-melt epoxy resin adhesive is selected from the condensation product of epichlorohydrin and bisphenol A, or the condensation product of epichlorohydrin and polyol. Although this method can significantly improve the bonding strength of the cementitious material interface, there is a risk of poor compatibility with the slurry. Summary of the Invention

[0009] To address the problems existing in the above-mentioned background technology, the present invention provides an interface enhancer based on 3D printing cement-based materials and its application in 3D printing cement-based materials. This interface enhancer can effectively improve weak interfaces in printing.

[0010] This invention utilizes silicate cement, the same material used in printing, ensuring good compatibility with the printing slurry. The addition of nano-silica effectively improves the pore structure of the slurry, enhancing its strength and crack resistance. The addition of EVA redispersible latex powder further ensures the slurry's density and adhesion, allowing the formed polymer film to continuously distribute around the pores created during cement curing. The addition of POM (polyoxymethylene) fibers further enhances the bond between the interface and the printing substrate through their pull-out effect, mitigating the differences in mechanical strength caused by anisotropy. Based on these materials, a water-reducing agent adjusts the slurry's workability, and a retarder extends the cement's setting time. This interface enhancer effectively addresses the problems of weak later-stage strength and poor durability caused by interfacial pore defects formed during the 3D printing process, providing valuable reference for extending the service life of 3D printed concrete in various application scenarios.

[0011] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: An interface reinforcing agent based on 3D printed cement-based materials, comprising the following components in parts by weight: 100 parts cement 5-10 parts of nano-silica 5-10 parts of EVA redispersible latex powder 6-10 parts of POM (polyoxymethylene) fiber Mix with 28-35 parts water. Water-reducing agent 1.0~1.5 parts, 1-2 parts of retarder; The selection of cement is consistent with that of cement in 3D printing cement-based materials, with ordinary Portland cement being preferred, and the cement strength grade being consistent with that of cement in 3D printing cement-based materials.

[0012] The nano-silica is a white powder with a particle size range of 70~140nm.

[0013] The water-reducing agent is a conventionally used polycarboxylate superplasticizer, which can be purchased from the market; specifically, the polycarboxylate superplasticizer is PCA®-III type admixture produced by Jiangsu Subote New Material Co., Ltd.

[0014] The retarder is selected from any one or a mixture of sodium tetraborate, sodium gluconate and tartaric acid; among them, sodium tetraborate can inhibit alkali-aggregate reaction and has a relatively stable retarding effect; sodium gluconate is currently the most widely used high-efficiency retarder; the advantage of tartaric acid is that the retarding time of the slurry is usually linearly related to the dosage after its addition, which makes the setting time controllable and facilitates the adjustment of the formula ratio.

[0015] The EVA redispersible latex powder is a copolymer formed from vinyl acetate and ethylene tert-carbonate.

[0016] The POM (polyoxymethylene) fiber has an elastic modulus of 10-15 GPa, a diameter of 0.10-0.14 mm, and a length range of 6-12 mm.

[0017] Furthermore, the present invention also provides a method for preparing the above-mentioned interface enhancer, comprising: directly mixing the above-mentioned components by stirring for 2-5 minutes to obtain the interface enhancer.

[0018] Furthermore, the present invention also provides an application of the above-mentioned interface enhancer in 3D printing cement-based materials, the specific application method of which is as follows: The cement-based material raw material is extruded from the hopper through a circular printing nozzle by the stirring and extrusion action of a spiral mixer. The printing speed and printing height are controlled at the same time. After each layer is printed, an interface reinforcing agent is applied to the interface between the layers. The above steps are repeated until 5 layers are printed to obtain a 3D printed cement-based material specimen block. An interface reinforcing agent is applied to the interface between every two 3D printed cement-based material specimen blocks to obtain a 3D printed cement-based material specimen. Finally, a designed oblique shear test is used as a test method to characterize the bonding performance of the interface. The application time of the interface enhancer at the interface of the entire 3D printed cement-based material specimen should be controlled within 10 minutes. The nozzle diameter is 40mm; The interface enhancer is applied along the printing direction, and the thickness of the interface enhancer is less than 5 mm. The printing height of each layer of the 3D printed cement-based material specimen block is controlled at 20~25mm, and the overall height of the printed specimen is controlled at 100mm.

[0019] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention incorporates nano-silica and EVA redispersible latex powder to fill the pore structure inside the coating slurry. Through the interaction between the coating layer and the printing layer, the hydration activity between the interface is stimulated, thereby improving the bonding strength of the interface.

[0020] (2) This invention improves the toughness and bonding strength of the interface by incorporating POM (polyoxymethylene) fiber through the pull-out effect of the fiber itself; by adding flexible POM fiber, its unique "bridging effect", that is, strong toughness, enhances the bonding performance between the interfaces, while being easy to disperse and having good compatibility with the slurry. (3) The present invention further adjusts the fluidity of the coating slurry and its compatibility with the printing slurry by adjusting the water-reducing agent and the retarder.

[0021] (4) The present invention applies the interface enhancer to each printing material interface by smearing. Through the gravity stacking and extrusion of the 3D printing process itself, the pore defects between the interface are improved and the interface strength is enhanced, providing a good guiding concept for later practical engineering applications. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the 3D printing cement-based material coated with the interface reinforcing agent of the present invention.

[0023] Figure 2 This is a schematic diagram of the oblique shear test at the interface of the 3D printed cement-based material according to the present invention.

[0024] Figure 1 The labels are as follows: 1-printing layer, 2-between printing layers, 3-between printing strips. Detailed Implementation

[0025] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] In the following examples and comparative examples, the component parts are by mass.

[0027] Example 1 This embodiment describes an interface reinforcing agent for improving the interlayer bonding performance of 3D printed cement-based materials. By weight, it comprises: 100 parts of ordinary silicate cement, 5 parts of nano silica, 5 parts of EVA redispersible latex powder, 6 parts of POM polyoxymethylene fiber, 28 parts of mixing water, 1.0 part of water-reducing agent, and 1 part of retarder. The polycarboxylate superplasticizer is PCA®-III type admixture produced by Jiangsu Subote New Material Co., Ltd. The particle size of the nano-silica is 70 nm; The POM (polyoxymethylene) fiber has a diameter of 0.12 mm, a length of 6 mm, and an aspect ratio of 50. The raw materials were weighed according to the above formula, mixed evenly, and stirred in a mixer for 2 minutes to obtain an interface reinforcing agent. The cement-based material raw materials were extruded through the hopper and through a 40mm diameter circular printing nozzle by the stirring and extrusion action of a spiral mixer. The printing speed and printing height were controlled at the same time. After each layer was printed, an interface reinforcing agent was applied to the interface between the layers. The above steps were repeated until 5 layers were printed to obtain a 3D printed cement-based material specimen block. An interface reinforcing agent was applied to the interface between every two 3D printed cement-based material specimen blocks to obtain a 3D printed cement-based material specimen. Finally, the designed oblique shear test was used as a test method to characterize the interface bonding performance. The application time of the interface reinforcing agent at the interface of the entire 3D printed cement-based material specimen was controlled within 10 minutes. The interface reinforcing agent was applied along the printing direction and the thickness of the interface reinforcing agent was within 5mm. The printing height of each layer of the 3D printed cement-based material specimen block was controlled at 20~25mm, and the overall height of the printed specimen was controlled at 100mm.

[0028] The interface strength enhancement effect was verified by oblique shear test. After the 3D printed cement-based specimens were printed and the interface enhancement treatment was applied, they were placed in a curing room for 28 days and then subjected to oblique shear test of the interface.

[0029] Example 2 This embodiment describes an interface reinforcing agent for improving the interlayer bonding performance of 3D printed cement-based materials. By weight, it comprises: 100 parts of ordinary silicate cement, 7 parts of nano silica, 7 parts of EVA redispersible latex powder, 8 parts of POM polyoxymethylene fiber, 30 parts of mixing water, 1.3 parts of water-reducing agent, and 1.3 parts of retarder. The particle size of the nano-silica is 100 nm; The POM (polyoxymethylene) fiber has a diameter of 0.12 mm, a length of 8 mm, and an aspect ratio of 67. The raw materials were weighed according to the above formula, mixed evenly, and stirred in a mixer for 3 minutes to obtain an interface reinforcing agent. The cement-based material raw materials were extruded through the hopper and through a 40mm diameter circular printing nozzle by the stirring and extrusion action of a spiral mixer. The printing speed and printing height were controlled at the same time. After each layer was printed, an interface reinforcing agent was applied to the interface between the layers. The above steps were repeated until 5 layers were printed to obtain a 3D printed cement-based material specimen block. An interface reinforcing agent was applied to the interface between every two 3D printed cement-based material specimen blocks to obtain a 3D printed cement-based material specimen. Finally, the designed oblique shear test was used as a test method to characterize the interface bonding performance. The application time of the interface reinforcing agent at the interface of the entire 3D printed cement-based material specimen was controlled within 10 minutes. The interface reinforcing agent was applied along the printing direction and the thickness of the interface reinforcing agent was within 5mm. The printing height of each layer of the 3D printed cement-based material specimen block was controlled at 20~25mm, and the overall height of the printed specimen was controlled at 100mm.

[0030] The interface strength enhancement effect was verified by oblique shear test. After the 3D printed cement-based specimens were printed and the interface enhancement treatment was applied, they were placed in a curing room for 28 days and then subjected to oblique shear test of the interface.

[0031] Example 3 This embodiment describes an interface reinforcing agent for improving the interlayer bonding performance of 3D printed cement-based materials. By weight, it comprises: 100 parts of ordinary silicate cement, 7 parts of nano silica, 10 parts of EVA redispersible latex powder, 8 parts of POM polyoxymethylene fiber, 33 parts of mixing water, 1.3 parts of water-reducing agent, and 1.6 parts of retarder. The particle size of the nano-silica is 100 nm; The POM (polyoxymethylene) fiber has a diameter of 0.12 mm, a length of 8 mm, and an aspect ratio of 67. According to the above formula, weigh the raw materials, mix them evenly, and stir them in a mixer for 5 minutes to obtain the interface reinforcing agent. The cement-based material raw materials are then extruded through a 40mm diameter circular printing nozzle using a spiral mixer. The printing speed and height are controlled simultaneously. After each layer is printed, an interface reinforcing agent is applied to the interlayer interface. This process is repeated until four layers are printed, resulting in a 3D printed cement-based material specimen. An interface reinforcing agent is applied to the interlayer interface between every two 3D printed cement-based material specimens to obtain a 3D printed cement-based material specimen. Finally, a designed oblique shear test is used to characterize the interface bonding performance. The application time of the interface reinforcing agent at the interface of the entire 3D printed cement-based material specimen is controlled within 10 minutes. The interface reinforcing agent is applied along the printing direction, and the thickness is within 5mm. The printing height of each layer of the 3D printed cement-based material specimen is controlled between 20 and 25mm, and the overall height of the printed specimen is controlled at 100mm.

[0032] The interface strength enhancement effect was verified by oblique shear test. After the 3D printed cement-based specimens were printed and the interface enhancement treatment was applied, they were placed in a curing room for 28 days and then subjected to oblique shear test of the interface.

[0033] Example 4 This embodiment describes an interface reinforcing agent for improving the interlayer bonding performance of 3D printed cement-based materials. By weight, it comprises: 100 parts of ordinary silicate cement, 10 parts of nano silica, 10 parts of EVA redispersible latex powder, 10 parts of POM polyoxymethylene fiber, 35 parts of mixing water, 1.5 parts of water-reducing agent, and 2 parts of retarder. The particle size of the nano-silica is 140 nm; The POM (polyoxymethylene) fiber has a diameter of 0.12 mm, a length of 12 mm, and an aspect ratio of 100. The raw materials were weighed according to the above formula, mixed evenly, and stirred in a mixer for 2 minutes to obtain an interface reinforcing agent. The cement-based material raw materials were extruded through the hopper and through a 40mm diameter circular printing nozzle by the stirring and extrusion action of a spiral mixer. The printing speed and printing height were controlled at the same time. After each layer was printed, an interface reinforcing agent was applied to the interface between the layers. The above steps were repeated until 5 layers were printed to obtain a 3D printed cement-based material specimen block. An interface reinforcing agent was applied to the interface between every two 3D printed cement-based material specimen blocks to obtain a 3D printed cement-based material specimen. Finally, the designed oblique shear test was used as a test method to characterize the interface bonding performance. The application time of the interface reinforcing agent at the interface of the entire 3D printed cement-based material specimen was controlled within 10 minutes. The interface reinforcing agent was applied along the printing direction and the thickness of the interface reinforcing agent was within 5mm. The printing height of each layer of the 3D printed cement-based material specimen block was controlled at 20~25mm, and the overall height of the printed specimen was controlled at 100mm.

[0034] The interface strength enhancement effect was verified by oblique shear test. After the 3D printed cement-based specimens were printed and the interface enhancement treatment was applied, they were placed in a curing room for 28 days and then subjected to oblique shear test of the interface.

[0035] The interface reinforcing agents prepared in Examples 1-4 above were applied during the printing process to obtain 3D printed cement-based specimens with a certain reinforcing effect. These specimens were then placed in a curing room for standard curing for 28 days. An oblique shear test of the interface was conducted using a specially designed mold. The results are shown in Table 1. Table 1. Bond strength values ​​at inter-strip and inter-layer interfaces As shown in Table 1, when the interface reinforcing agent prepared in Example 3 is used, the interface bonding strength value is the largest after 28 days. The reason is that the synergistic effect between the components at this dosage makes the paste homogeneous and has high density and interface strength.

[0036] Based on the anisotropic parameters of Example 3, comparative examples 1-4 were also set up: Comparative Example 1 The difference between this comparative example and Example 3 is that direct inter-strip and inter-layer stacking printing is performed without using an interface enhancer.

[0037] Comparative Example 2 The difference between this comparative example and Example 3 is that no nano-silica and EVA redispersible latex powder are added.

[0038] The raw materials were weighed according to the above formula, mixed evenly, and stirred in a mixer for 2 minutes to obtain an interface reinforcing agent. The cement-based material raw materials were extruded through the hopper and through a 40mm diameter circular printing nozzle by the stirring and extrusion action of a spiral mixer. The printing speed and printing height were controlled at the same time. After each layer was printed, an interface reinforcing agent was applied to the interface between the layers. The above steps were repeated until 5 layers were printed to obtain a 3D printed cement-based material specimen block. An interface reinforcing agent was applied to the interface between every two 3D printed cement-based material specimen blocks to obtain a 3D printed cement-based material specimen. Finally, the designed oblique shear test was used as a test method to characterize the interface bonding performance. The application time of the interface reinforcing agent at the interface of the entire 3D printed cement-based material specimen was controlled within 10 minutes. The interface reinforcing agent was applied along the printing direction and the thickness of the interface reinforcing agent was within 5mm. The printing height of each layer of the 3D printed cement-based material specimen block was controlled at 20~25mm, and the overall height of the printed specimen was controlled at 100mm.

[0039] The strength enhancement effect at maturity was verified by oblique shear test. After the 3D printed cement-based specimens were printed and the interface was reinforced, they were placed in a curing room for 28 days and then subjected to oblique shear test at the interface.

[0040] Comparative Example 3 The difference between this comparative example and Example 3 is that no POM (polyoxymethylene) fiber is added.

[0041] The raw materials were weighed according to the above formula, mixed evenly, and stirred in a mixer for 2 minutes to obtain an interface reinforcing agent. The cement-based material raw materials were extruded through the hopper and through a 40mm diameter circular printing nozzle by the stirring and extrusion action of a spiral mixer. The printing speed and printing height were controlled at the same time. After each layer was printed, an interface reinforcing agent was applied to the interface between the layers. The above steps were repeated until 5 layers were printed to obtain a 3D printed cement-based material specimen block. An interface reinforcing agent was applied to the interface between every two 3D printed cement-based material specimen blocks to obtain a 3D printed cement-based material specimen. Finally, the designed oblique shear test was used as a test method to characterize the interface bonding performance. The application time of the interface reinforcing agent at the interface of the entire 3D printed cement-based material specimen was controlled within 10 minutes. The interface reinforcing agent was applied along the printing direction and the thickness of the interface reinforcing agent was within 5mm. The printing height of each layer of the 3D printed cement-based material specimen block was controlled at 20~25mm, and the overall height of the printed specimen was controlled at 100mm.

[0042] The interface strength enhancement effect was verified by oblique shear test. After the 3D printed cement-based specimens were printed and the interface enhancement treatment was applied, they were placed in a curing room for 28 days and then subjected to oblique shear test of the interface.

[0043] Comparative Example 4 The difference between this comparative example and Example 3 is that no water-reducing agent or retarder is added.

[0044] The raw materials were weighed according to the above formula, mixed evenly, and stirred in a mixer for 2 minutes to obtain an interface reinforcing agent. The cement-based material raw materials were extruded through the hopper and through a 40mm diameter circular printing nozzle by the stirring and extrusion action of a spiral mixer. The printing speed and printing height were controlled at the same time. After each layer was printed, an interface reinforcing agent was applied to the interface between the layers. The above steps were repeated until 5 layers were printed to obtain a 3D printed cement-based material specimen block. An interface reinforcing agent was applied to the interface between every two 3D printed cement-based material specimen blocks to obtain a 3D printed cement-based material specimen. Finally, the designed oblique shear test was used as a test method to characterize the interface bonding performance. The application time of the interface reinforcing agent at the interface of the entire 3D printed cement-based material specimen was controlled within 10 minutes. The interface reinforcing agent was applied along the printing direction and the thickness of the interface reinforcing agent was within 5mm. The printing height of each layer of the 3D printed cement-based material specimen block was controlled at 20~25mm, and the overall height of the printed specimen was controlled at 100mm.

[0045] The interface strength enhancement effect was verified by oblique shear test. After the 3D printed cement-based specimens were printed and the interface enhancement treatment was applied, they were placed in a curing room for 28 days and then subjected to oblique shear test of the interface.

[0046] The interface reinforcing agents prepared using the above comparative examples 1-4 were applied during the printing process to obtain 3D printed cement-based specimens with a certain reinforcing effect. These specimens were then cured in a curing room for 28 days. Oblique shear tests were conducted on the interface using a specially designed mold. The results are shown in Table 1. Table 2. Bond strength values ​​at inter-strip and inter-layer interfaces The results are shown in Table 2: Without the use of an interface enhancer (Comparative Example 1), the interfacial oblique shear strength of the 3D printed parts was much lower than that of the parts coated with an interface enhancer (Example 3). Without the addition of nano-silica and EVA redispersible latex powder (Comparative Example 2), the interfacial oblique shear strength of the 3D printed parts is lower than that of the parts coated with an interfacial reinforcing agent (Example 3) because the density and film-forming properties of the slurry cannot be guaranteed. The oblique shear strength of the 3D printed interface obtained without the addition of POM polyoxymethylene fiber (Comparative Example 3) is lower than that of the interface with the coating of interface reinforcing agent (Example 3) due to the pull-out effect without fiber action. Without the addition of water-reducing agents and retarders (Comparative Example 4), the interfacial shear strength of the 3D printed interface was poor due to the poor homogeneity of the slurry and the rapid hardening of the specimen, resulting in insignificant or even worse interfacial reinforcement.

[0047] Therefore, it can be concluded that the interfacial shear strength of the interface reinforcing agent prepared by the combined action of nano silica, EVA redispersible latex powder, POM polyoxymethylene fiber, retarder and water-reducing agent, when applied to the surface of the printed part, is better than that of the individual components without nano silica and EVA redispersible latex powder (Comparative Example 2), without POM polyoxymethylene fiber (Comparative Example 3), and without retarder and water-reducing agent (Comparative Example 4).

[0048] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of the equivalents of the claims be included within the present invention.

Claims

1. An interface reinforcing agent based on 3D printed cement-based materials, characterized in that, The components include the following parts by mass: 100 parts cement 5-10 parts of nano-silica 5-10 parts of EVA redispersible latex powder 6-10 parts of POM (polyoxymethylene) fiber Mix with 28-35 parts water. Water-reducing agent 1.0~1.5 parts, 1-2 parts of retarder; The selection of cement is consistent with that of cement in 3D printing cement-based materials, with ordinary Portland cement being preferred, and the cement strength grade being consistent with that of cement in 3D printing cement-based materials.

2. The interface reinforcing agent based on 3D printed cement-based materials according to claim 1, characterized in that, The nano-silica is a white powder with a particle size range of 70~140nm.

3. The interface reinforcing agent based on 3D printed cement-based materials according to claim 1, characterized in that, The water-reducing agent is a polycarboxylate superplasticizer, preferably a PCA®-III type admixture produced by Jiangsu Subote New Material Co., Ltd.

4. The interface reinforcing agent based on 3D printed cement-based materials according to claim 1, characterized in that, The retarder is selected from any one or a mixture of sodium tetraborate, sodium gluconate and tartaric acid.

5. The interface reinforcing agent based on 3D printed cement-based materials according to claim 1, characterized in that, The EVA redispersible latex powder is a copolymer formed from ethylene carbonate and ethylene tert-carbonate.

6. The interface reinforcing agent based on 3D printed cement-based materials according to claim 1, characterized in that, The POM (polyoxymethylene) fiber has an elastic modulus of 10-15 GPa, a diameter of 0.10-0.14 mm, and a length range of 6-12 mm.

7. A method for preparing the interface enhancer according to any one of claims 1 to 6, characterized in that, include: The interface enhancer is obtained by directly mixing the above components for 2-5 minutes.

8. The application of the interface enhancer according to any one of claims 1 to 6 in 3D printing cement-based materials.

9. The application according to claim 8, characterized in that, The specific application method includes: the cement-based material raw material is extruded through the hopper and through the circular printing nozzle by the stirring and extrusion action of the spiral mixer, while controlling the printing speed and printing height. After each layer is printed, an interface reinforcing agent is applied to the interface between the layers. The above steps are repeated until 5 layers are printed to obtain a 3D printed cement-based material specimen block. An interface reinforcing agent is applied to the interface between every two 3D printed cement-based material specimen blocks to obtain a 3D printed cement-based material specimen. The application time of the interface enhancer at the interface of the entire 3D printed cement-based material specimen should be controlled within 10 minutes. The interface enhancer is applied along the printing direction, and the thickness of the interface enhancer coating is less than 5 mm.

10. The application according to claim 9, characterized in that, The nozzle diameter is 40mm; The printing height of each layer of the 3D printed cement-based material specimen block is controlled at 20~25mm, and the overall height of the printed specimen is controlled at 100mm.

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